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1

Homogeneous Catalysis of the Water Gas Shift Reaction by Bridged Dinuclear Pyrazolate Rhodium Complexes. FT-IR, 1H and 13C NMR In Situ Studies  

Microsoft Academic Search

Homogeneous catalysts for the water gas shift reaction prepared from Rh2(µ-Pz)2(COD)2 (Pz = pyrazolate ion and COD = 1,5-cyclooctadiene) in aqueous organic solvent media (pyridine, 4-picoline or 2-ethoxyethanol) and Rh2(µ-Pz)2(CO)2(TPPMS)2 (TPPMS = meta-sulfonatophenyl-diphenyldiphosphine) in acidic aqueous media under mild conditions are described. In situ FT-IR, 1H and 13C NMR spectroscopic studies of the Rh2(µ-Pz)2(COD)2 catalytic system reveal the presence of

A. J. Pardey; M. Fernández; M. A. Moreno; J. Alvarez; A. B. Rivas; M. C. Ortega; B. Mendez; P. J. Baricelli; C. Longo

2000-01-01

2

Determination of the degree of substitution of acetylated starch by hydrolysis, 1H NMR and TGA\\/IR  

Microsoft Academic Search

The suitability of TGA\\/IR method for the analysis of the degree of substitution (DS) of acetylated starch (SA) was assessed. Ten standard samples were analysed for their DS by hydrolysis method and, those of the standards which could be properly dissolved, also by 1H NMR. NMR analysis shows as well that the standards had other structural differences than DS. By

Matti Elomaa; Tomas Asplund; Pasi Soininen; Reino Laatikainen; Soili Peltonen; Sari Hyvärinen; Arto Urtti

2004-01-01

3

A classical approach in simple nuclear fusion reaction {sub 1}H{sup 2}+{sub 1}H{sup 3} using two-dimension granular molecular dynamics model  

SciTech Connect

Molecular dynamics in 2-D accompanied by granular model provides an opportunity to investigate binding between nuclei particles and its properties that arises during collision in a fusion reaction. A fully classical approach is used to observe the influence of initial angle of nucleus orientation to the product yielded by the reaction. As an example, a simplest fusion reaction between {sub 1}H{sup 2} and {sub 1}H{sup 3} is observed. Several products of the fusion reaction have been obtained, even the unreported ones, including temporary {sub 2}He{sup 4} nucleus.

Viridi, S.; Kurniadi, R.; Waris, A.; Perkasa, Y. S. [Nuclear Physics and Biophysics Research Division, Institut Teknologi Bandung, Bandung 40132 (Indonesia); Doctoral Program in Physics, Institut Teknologi Bandung, Bandung 40132 Physics Department, Universitas Islam Negeri Sunan Gunung Djati, Bandung 40614 (Indonesia)

2012-06-06

4

1-(Organosulfonyloxy)-3(1H)-1,2-benziodoxoles: Preparation and Reactions with Alkynyltrimethylsilanes.  

PubMed

Organosulfonyloxy derivatives of 1,2-benziodoxol-3(1H)-one (3a-c) and 3,3-bis(trifluoromethyl)-3(1H)-1,2-benziodoxole (5a-c) can be prepared in high yield by the reaction of 1-hydroxybenziodoxoles 1 or 4 and the corresponding sulfonic acids or Me(3)SiOTf in the form of stable, but moderately hygroscopic, microcrystalline solids. Reaction of the triflate derivatives 3a and 5a with alkynyltrimethylsilanes affords either alkynyliodonium triflates 6, or (E)-beta-(trifluoromethanesulfonyloxy)alkenyliodonium triflates 7, while the same reaction in the presence of pyridine selectively gives the respective 1-alkynylbenziodoxoles 8 and 9 in 82-90% yield. PMID:11667518

Zhdankin, Viktor V.; Kuehl, Chris J.; Krasutsky, Alexei P.; Bolz, Jason T.; Simonsen, Angela J.

1996-09-20

5

IR, 1H NMR, mass, XRD and TGA/DTA investigations on the ciprofloxacin/iodine charge-transfer complex  

NASA Astrophysics Data System (ADS)

The charge-transfer complex (CTC) of ciprofloxacin drug (CIP) as a donor with iodine (I 2) as a sigma acceptor has been studied spectrophotometrically in CHCl 3. At maximum absorption bands, the stoichiometry of CIP:iodine system was found to be 1:1 ratio according to molar ratio method. The essential spectroscopic data like formation constant ( KCT), molar extinction coefficient ( ?CT), standard free energy (? G°), oscillator strength ( f), transition dipole moment ( ?), resonance energy ( RN) and ionization potential ( ID) were estimated. The spectroscopic techniques such as IR, 1H NMR, mass and UV-vis spectra and elemental analyses (CHN) as well as TG-DTG and DTA investigations were used to characterize the chelating behavior of CIP/iodine charge-transfer complex. The iodine CT interaction was associated with a presence of intermolecular hydrogen bond. The X-ray investigation was carried out to investigate the iodine doping in the synthetic CT complex.

Refat, Moamen S.; El-Hawary, W. F.; Moussa, Mohamed A. A.

2011-05-01

6

Measurement of the 1H(?,?p)?0 reaction using a novel nucleon spin polarimeter.  

PubMed

We report the first large-acceptance measurement of polarization transfer from a polarized photon beam to a recoiling nucleon. The measurement pioneers a novel polarimetry technique, which can be applied to many other nuclear and hadron physics experiments. The commissioning reaction of 1H(?,?p)?0 in the range 0.4

Sikora, M H; Watts, D P; Glazier, D I; Aguar-Bartolomé, P; Akasoy, L K; Annand, J R M; Arends, H J; Bantawa, K; Beck, R; Bekrenev, V S; Berghäuser, H; Braghieri, A; Branford, D; Briscoe, W J; Brudvik, J; Cherepnya, S; Codling, R F B; Demissie, B T; Downie, E J; Drexler, P; Fil'kov, L V; Freehart, B; Gregor, R; Hamilton, D; Heid, E; Hornidge, D; Howdle, D A; Jaegle, I; Jahn, O; Jude, T C; Kashevarov, V L; Keshelashvili, I; Kondratiev, R; Korolija, M; Kotulla, M; Koulbardis, A A; Kruglov, S P; Krusche, B; Lisin, V; Livingston, K; MacGregor, I J D; Maghrbi, Y; Manley, D M; Marinides, Z; Martinez, M; McGeorge, J C; McKinnon, B; McNicoll, E F; Mekterovic, D; Metag, V; Micanovic, S; Middleton, D G; Mushkarenkov, A; Nefkens, B M K; Nikolaev, A; Novotny, R; Ostrick, M; Otte, P B; Oussena, B; Pedroni, P; Pheron, F; Polonski, A; Prakhov, S; Robinson, J; Rosner, G; Rostomyan, T; Schumann, S; Sober, D I; Starostin, A; Strakovsky, I I; Suarez, I M; Supek, I; Thiel, M; Thomas, A; Unverzagt, M; Werthmüller, D; Workman, R L; Zamboni, I; Zehr, F

2014-01-17

7

Search for the Halo Effect in the 1H(6He, 6Li)n Reaction  

NASA Astrophysics Data System (ADS)

The angular distributions of the charge exchange reaction 1H(6He, 6Li)n were measured in reverse kinematics with a secondary 6He beam at the energy of 4.17 A MeV. The data were analysed in the context of a microscopic calculation. It is shown that both the ground state of 6He and the second excited state of 6Li (3.563 MeV, 0+) have a halo structure.

Li, Zhi-Hong; Liu, Wei-Ping; Bai, Xi-Xiang; Wang, You-Bao; Lian, Gang; Li, Zhi-Chang; Shen, Qing-Biao; Lin, Cheng-Jian; Zeng, Sheng; Fu, Chang-Bo

2002-03-01

8

Competing reaction channels in IR-laser-induced unimolecular reactions  

SciTech Connect

The competing reaction channels in the unimolecular decomposition of two molecules, formaldehyde and tetralin were studied. A TEA CO/sub 2/ laser was used as the excitation source in all experiments. The dissociation of D/sub 2/CO was studied by infrared multiphoton dissociation (MPD) and the small-molecule nature of formaldehyde with regard to MPD was explored. The effect of collisions in MPD were probed by the pressure dependence of the MPD yield and ir fluorescence from multiphoton excited D/sub 2/CO. MPD yield shows a near cubic dependence in pure D/sub 2/CO which is reduced to a 1.7 power dependence when 15 torr of NO is added. The peak amplitude of 5 ..mu..m ir fluorescence from D/sub 2/CO is proportional to the square of the D/sub 2/CO pressure in pure D/sub 2/CO or in the presence of 50 torr of Ar. Results are explained in terms of bottlenecks to excitation at the v = 1 level which are overcome by a combination of vibrational energy transfer and rotational relaxation. The radical/molecule branching ratio in D/sub 2/CO MPD was 0.10 +- 0.02 at a fluence of 125 J/cm/sup 2/ at 946.0 cm/sup -1/. The barrier height to molecular dissociation was calculated to be 3.6 +- 2.0 kcal/mole below the radical threshold or 85.0 +- 3.0 kcal/mole above the ground state of D/sub 2/CO. In H/sub 2/CO, this corresponds to 2.5 +- 2.0 kcal/mole below the radical threshold or 83.8 +- 3.0 kcal/mole above the ground state. Comparison with uv data indicate that RRKM theory is an acceptable description of formaldehyde dissociation in the 5 to 10 torr pressure range. The unimolecular decomposition of tetralin was studied by MPD and SiF/sub 4/ - sensitized pyrolysis. Both techniques induce decomposition without the interference of catalytic surfaces. Ethylene loss is identified as the lowest energy reaction channel. Dehydrogenation is found to result from step-wise H atom loss. Isomerization via disproportionation is also identified as a primary reaction channel.

Berman, M.R.

1981-01-01

9

Fractionation and characterization of sludge bacterial extracellular polymers by FT-IR, 13C-NMR, 1H-NMR.  

PubMed

Sludge bacterial extracellular (BEP) polymers exhibit a strong affinity with metals in addition to their role in the bioflocculation of activated sludge. It is of utmost importance in elucidating the chemical characterization of sludge BEP prior to a better understanding of its environmental behavior. Sludge BEP extracted from activated sludge was characterized by FT-IR, 1H-NMR, and 13C-NMR and fractionated into 6 fractions (hydrophilic acid, base, and neutral; and hydrophobic acid, base, and neutral). The results indicated that sludge BEP contained more polysaccharides but fewer amino acids or proteinaceous materials compared to dissolved organic matter (DOM) derived from sludge. No aromatic substance was found in sludge BEP as indicated by NMR. Sludge BEP was dominated by hydrophilic fractions, accounting for 65% of total DOC of sludge BEP and hydrophilic neutral constituted about 58% of the hydrophilic fraction. The chemical fraction and characterization indicated that sludge BEP might exhibit a higher capability in enhancing the transport of the associated contaminants through porous media than that of sludge DOM. PMID:11794684

Zhou, L X; Liang, J R; Zha, X H; Wong, J W

2001-01-01

10

IR, 1H NMR, mass, XRD and TGA/DTA investigations on the ciprofloxacin/iodine charge-transfer complex.  

PubMed

The charge-transfer complex (CTC) of ciprofloxacin drug (CIP) as a donor with iodine (I(2)) as a sigma acceptor has been studied spectrophotometrically in CHCl(3). At maximum absorption bands, the stoichiometry of CIP:iodine system was found to be 1:1 ratio according to molar ratio method. The essential spectroscopic data like formation constant (K(CT)), molar extinction coefficient (?(CT)), standard free energy (?G°), oscillator strength (f), transition dipole moment (?), resonance energy (R(N)) and ionization potential (I(D)) were estimated. The spectroscopic techniques such as IR, (1)H NMR, mass and UV-vis spectra and elemental analyses (CHN) as well as TG-DTG and DTA investigations were used to characterize the chelating behavior of CIP/iodine charge-transfer complex. The iodine CT interaction was associated with a presence of intermolecular hydrogen bond. The X-ray investigation was carried out to investigate the iodine doping in the synthetic CT complex. PMID:21317025

Refat, Moamen S; El-Hawary, W F; Moussa, Mohamed A A

2011-05-01

11

Syntheses and reactions of metal organics. XXL Syntheses of (1 H,1 H,2 H,2 H-polyfluoroalkyl)triisocyanate silanes and surface modification of glass  

Microsoft Academic Search

Four silane coupling agents having a fluorocarbon chain and three isocyanate groups as reactive centers, i.e. CF3(CF2)3CH2CH2Si(NCO)3 (1), CF3(CF2)5CH2CH2Si(NCO)3 (2), CF3(CF2)7CH2CH2Si(NCO)3 (3) and CF3(CF2)9CH2CH2Si(NCO)3 (4), were prepared by the hydrosilylation reaction of trichlorosilane with the corresponding 1H,1H,2H-polyfluoro-1-alkene [CF3(CF2)nCH=CH2, n = 3, 5, 7 and 9 in the presence of hydrogen hexachloroplatinate(IV), followed by reaction with silver cyanate. Their application to

Norio Yoshino; Yukishige Kondo; Takashi Yamauchi

1996-01-01

12

Electron screening in the 1 H( 7 Li,) 4 He reaction  

Microsoft Academic Search

We have measured the cross-section for the 1H(7Li,)4He reaction at lithium beam energies from 0.34 to 1.05MeV. Hydrogen was forced by diffusion into Pd and PdAg alloy foils.\\u000a A large electron screening effect was observed only when foils were under tensile stress. A dependence of the screening potential\\u000a on hydrogen concentration or Hall coefficient of the metallic host could not

M. Lipoglavšek; I. ?adež; S. Markelj; P. Pelicon; P. Vavpeti?

2010-01-01

13

Severe Infusion Reactions to Cetuximab Occur within 1 h in Patients with Metastatic Colorectal Cancer: Results of a Nationwide, Multicenter, Prospective Registry Study of 2126 Patients in Japan  

PubMed Central

Objective Infusion reactions are common adverse reactions associated with antibody preparations. However, no studies have examined the time to onset of serious infusion reactions after administering cetuximab. We aimed to investigate the timing and severity of IRs affecting Japanese patients after administration of cetuximab. Methods Study subjects were identified from a nationwide prospective registry of 2126 metastatic colorectal cancer patients scheduled to receive cetuximab. Infusion reactions were examined in 2006 patients with adequate safety data. Results Infusion reactions of any grade occurred in 114 patients (5.7%), including Grade 3–4 infusion reactions in 22 patients (1.1%). Premedications were antihistamine plus corticosteroid (88.9% of patients with infusion reactions), antihistamine alone (9.2%) or corticosteroid alone (1.1%). In 95 patients (83.3%), infusion reactions occurred after the first dose. Twenty of the 22 Grade 3–4 infusion reactions occurred within 1 h of the first dose (the timing of the infusion reaction was unknown in one patient while another infusion reaction occurred after the fourth dose). Infusion reactions resolved in 111/114 patients (97.4%) while one patient recovered with sequelae, one patient died and one patient failed to recover within the follow-up period. Thirteen patients (15.7% of patients with infusion reactions) with Grade 1–2 infusion reactions showed recurrence after readministration of cetuximab; the recurrent infusion reactions were less severe than the initial reactions. Conclusions Grade 3–4 infusion reactions occurred in 1.1% of colorectal cancer patients, and most occurred within 1 h of receiving the first dose of cetuximab. Therefore, patients should be carefully observed following cetuximab infusion, especially during the first hour after the first infusion.

Yamaguchi, Kensei; Watanabe, Toshiaki; Satoh, Taroh; Ishiguro, Megumi; Izawa, Makiko; Inoshiri, Shogo; Sugihara, Kenichi; Sakata, Yuh

2014-01-01

14

Discovering [superscript 13]C NMR, [superscript 1]H NMR, and IR Spectroscopy in the General Chemistry Laboratory through a Sequence of Guided-Inquiry Exercises  

ERIC Educational Resources Information Center

This sequence of three guided-inquiry labs is designed for a second-semester general chemistry course and challenges students to discover basic theoretical principles associated with [superscript 13]C NMR, [superscript 1]H NMR, and IR spectroscopy. Students learn to identify and explain basic concepts of magnetic resonance and vibrational…

Iler, H. Darrell; Justice, David; Brauer, Shari; Landis, Amanda

2012-01-01

15

Reactions of 2-Pyrones with 7-Aminoindazole: The First Synthesis of N-(1H-7Indazolyl)-pyridinones  

Microsoft Academic Search

New N-(1H-7-indazolyl)-pyridinones have been prepared by the condensation of 2-pyrone derivatives with 7-aminoindazole in the presence of acid medium. They have been characterized by means of H and C NMR, IR, and mass spectroscopy. The structure of the compounds and the mechanism of their formation are reported.

E. M. Rakib; L. Bouissane; A. Hannioui; M. Benchidmi; E. M. Essassi

2008-01-01

16

Study of inclusion complex between 2,6-dinitrobenzoic acid and ?-cyclodextrin by (1)H NMR, 2D (1)H NMR (ROESY), FT-IR, XRD, SEM and photophysical methods.  

PubMed

The formation of host-guest inclusion complex of 2,6-dinitrobenzoic acid (2,6-DNB) with nano-hydrophobic cavity of ?-cyclodextrin (?-CD) in solution phase has been studied by UV-visible spectroscopy and electrochemical analysis (cyclic voltammetry, CV). The effect of acid-base concentrations of 2,6-DNB has been studied in presence and absence of ?-CD to determination for the ground state acidity constant (pKa). The binding constant of inclusion complex at 303K was calculated using Benesi-Hildebrand plot and thermodynamic parameter (?G) was also calculated. The solid inclusion complex formation between ?-CD and 2,6-DNB was confirmed by (1)H NMR, 2D (1)H NMR (ROESY), FT-IR, XRD and SEM analysis. A schematic representation of this inclusion process was proposed by molecular docking studies using patch dock server. PMID:24769381

Srinivasan, Krishnan; Stalin, Thambusamy

2014-09-15

17

Study of inclusion complex between 2,6-dinitrobenzoic acid and ?-cyclodextrin by 1H NMR, 2D 1H NMR (ROESY), FT-IR, XRD, SEM and photophysical methods  

NASA Astrophysics Data System (ADS)

The formation of host-guest inclusion complex of 2,6-dinitrobenzoic acid (2,6-DNB) with nano-hydrophobic cavity of ?-cyclodextrin (?-CD) in solution phase has been studied by UV-visible spectroscopy and electrochemical analysis (cyclic voltammetry, CV). The effect of acid-base concentrations of 2,6-DNB has been studied in presence and absence of ?-CD to determination for the ground state acidity constant (pKa). The binding constant of inclusion complex at 303 K was calculated using Benesi-Hildebrand plot and thermodynamic parameter (?G) was also calculated. The solid inclusion complex formation between ?-CD and 2,6-DNB was confirmed by 1H NMR, 2D 1H NMR (ROESY), FT-IR, XRD and SEM analysis. A schematic representation of this inclusion process was proposed by molecular docking studies using patch dock server.

Srinivasan, Krishnan; Stalin, Thambusamy

2014-09-01

18

HPLC analysis of ecdysteroids in plant extracts using superheated deuterium oxide with multiple on-line spectroscopic analysis (UV, IR, 1H NMR, and MS).  

PubMed

HPLC, using superheated D20 as the mobile phase, combined with on-line characterization via a combination of diode array UV, 1H NMR, FT-IR spectroscopy, and mass spectrometry has been used for the analysis of a standard of 20-hydroxyecdysone- and ecdysteroid-containing plant extracts. This combination of spectrometers enabled the on-flow collection of UV, 1H NMR, IR, and mass spectra not only for pure 20-hydroxyecdysone (100-400 microg on column) but also the major ecdysteroids present in crude extracts of Silene otites, Silene nutans, and Silene frivaldiskyana. The ecdysteroids unequivocally identified in these extracts included 20-hydroxyecdysone, polypodine B, and integristerone A. PMID:11795808

Louden, Dave; Handley, Alan; Lafont, Rene; Taylor, Steve; Sinclair, Ian; Lenz, Eva; Orton, Timothy; Wilson, Ian D

2002-01-01

19

Problem of Description of the sup 1 H(d,p)X Reaction at Deuteron Relativistic Energies.  

National Technical Information Service (NTIS)

Calculations of the momentum spectra of protons, emitted both with large and zero transverse momenta, in the /sup 1/H(d,p)X reaction (the detection angles of protons are 0.139 and 0 rad, respectively), have been performed for different reaction mechanisms...

L. S. Azhgirej M. A. Ignatenko S. V. Razin N. P. Yudin

1987-01-01

20

Investigation of silyl-substituted alkylthioacetates by IR and UV spectroscopy, 1 H and 29 Si NMR, and mass spectrometry  

Microsoft Academic Search

The IR, UV, NMR, and mass spectra of silyl-substituted alkylthioacetates have been investigated. Intramolecular coordination of the carbonyl group with the silicon atom has been shown to exist in molecules of trifluoroaeetylthiomethylsilane in the condensed state and in a polar solvent (acetonitrile).

M. G. Voronkov; S. V. Basenko; R. G. Mirskov; É. I. Brodskaya; D. D. Toryashinova; V. A. Pestunovich; M. F. Larin; V. Yu. Vitkovskii

1985-01-01

21

Extremely strong temperature-dependent Davydow-splitting effects in the polarized IR spectra of the hydrogen bond: Pyrazole and quinolin-2(1H)-one crystals  

NASA Astrophysics Data System (ADS)

Polarized IR spectra were recorded in the spectral range of the ?N-H and ?N-D proton stretching vibration bands for the isotopically neat and isotopically diluted crystals of pyrazole (Pzl) and quinolin-2(1H)-one (2HQ). The spectra measured in the temperature range of 77-293 K have shown that temperature extremely strongly influenced the magnitude of the Davydow-splitting effects in the crystalline spectra. Two different competing vibrational Davydow-coupling mechanisms involving hydrogen bonds, i.e., the ‘tail-to-head' and the ‘side-to-side', were responsible for the generation of the temperature effects in the polarized spectra.

Hachu?a, Barbara; Flakus, Henryk T.; Tyl, Aleksandra; Polasz, Anna

2014-04-01

22

Elucidation of solution state complexation in wet-granulated oven-dried ibuprofen and beta-cyclodextrin: FT-IR and 1H-NMR studies.  

PubMed

The effect of oven-dried wet granulation on the complexation of beta-cyclodextrin with ibuprofen (IBU) in solution was investigated using Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H NMR), and molecular modeling. Granulation was carried out using 5 mL of three different granulating solvents; water, ethanol (95% v/v), and isopropanol and the granules were oven-dried at 60 degrees C for 2 h. The granules were compared to oven-dried physical mixture and conventionally prepared complex. Phase solubility study was performed to investigate the stability of the granulation-formed complexes in solution. FT-IR was used to examine the complexation in the granules while 1H NMR, and molecular modeling studies were carried out to determine the mechanism of complexation in the water-prepared granules. The solubility studies suggested a 1:1 complex between IBU and betaCD. It also showed that the stability of the complex in solution was in the following order with respect to the granulating solvents: ethanol > water > isopropanol. The FT-IR study revealed a shift in the carboxylic acid stretching band and decrease in the intensities of the C-H bending bands of the isopropyl group and the out-of-plane aromatic ring, of IBU, in granules compared to the oven-dried physical mixture. This indicated that granules might have some extent of solid state complexation that could further enhance dissolution and the IBU-betaCD solution state complexation. 1H NMR showed that water prepared oven-dried granules had a different 1H NMR spectrum compared to similarly made oven-dried physical mixture, indicative of complexation in the former. The 1H NMR and the molecular modeling studies together revealed that solution state complexation from the granules occurred by inclusion of the isopropyl group together with part of the aromatic ring of IBU into the betaCD cavity probably through its wider side. These results indicate that granulation process induced faster complexation in solution which enhances the solubility and the dissolution rate of poorly soluble drugs. The extent of complexation in the granules was dependent on the type of solvent used. PMID:11485173

Ghorab, M K; Adeyeye, M C

2001-08-01

23

FT-IR, dispersive Raman, NMR, DFT and antimicrobial activity studies on 2-(Thiophen-2-yl)-1H-benzo[d]imidazole  

NASA Astrophysics Data System (ADS)

2-(Thiophen-2-yl)-1H-benzo[d]imidazole (TBI) was synthesized under microwave conditions and was characterized by FT-IR, dispersive Raman, 1H-, 13C-, DEPT-, HETCOR-NMR spectroscopies and density functional theory (DFT) computations. The FT-IR and dispersive Raman spectra of TBI were recorded in the regions 4000-400 cm-1 and 4000-100 cm-1. The experimental vibrational spectra were interpreted with the help of normal coordinate analysis based on DFT/B3LYP/6-311++G(d,p) theory level for the more stable tautomeric form (Tautomer 1). The complete vibrational assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. A satisfactory consistency between the experimental and theoretical findings was obtained. The frontier molecular orbitals (FMOs), atomic charges and NMR shifts of the two stable tautomeric forms were also obtained at the same theory level without any symmetry restrictions. In addition, the title compound was screened for its antimicrobial activity and was found to be exhibit antifungal and antibacterial effects.

Ünal, Arslan; Eren, Bilge

2013-10-01

24

FT-IR, dispersive Raman, NMR, DFT and antimicrobial activity studies on 2-(Thiophen-2-yl)-1H-benzo[d]imidazole.  

PubMed

2-(Thiophen-2-yl)-1H-benzo[d]imidazole (TBI) was synthesized under microwave conditions and was characterized by FT-IR, dispersive Raman, (1)H-, (13)C-, DEPT-, HETCOR-NMR spectroscopies and density functional theory (DFT) computations. The FT-IR and dispersive Raman spectra of TBI were recorded in the regions 4000-400 cm(-1) and 4000-100 cm(-1). The experimental vibrational spectra were interpreted with the help of normal coordinate analysis based on DFT/B3LYP/6-311++G(d,p) theory level for the more stable tautomeric form (Tautomer 1). The complete vibrational assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. A satisfactory consistency between the experimental and theoretical findings was obtained. The frontier molecular orbitals (FMOs), atomic charges and NMR shifts of the two stable tautomeric forms were also obtained at the same theory level without any symmetry restrictions. In addition, the title compound was screened for its antimicrobial activity and was found to be exhibit antifungal and antibacterial effects. PMID:23756262

Unal, Arslan; Eren, Bilge

2013-10-01

25

FT-IR, FT-Raman, NMR spectra and DFT simulations of 4-(4-fluoro-phenyl)-1H-imidazole  

NASA Astrophysics Data System (ADS)

The FT-IR, FT-Raman and FT-NMR spectra of the compound 4-(4-Fluoro-phenyl)-1H-imidazole (4-FPI) were recorded and analyzed. Density functional method (B3LYP level with the 6-311G(d, p) and 6-311++G(d, p) and cc-pVQZ as basis sets) has been used to compute optimized geometry, vibrational wavenumbers of the 4-FPI. Only one tautomeric form was found most stable by using DFT/B3LYP. The detailed interpretation of the vibrational spectra was carried out with the aid of total energy distribution following the scaled quantum mechanical force field methodology. Potential Energy Surface scan studies has also been carried out by ab initio calculations with the same basis sets.

Erdogdu, Y.; Manimaran, D.; Güllüo?lu, M. T.; Amalanathan, M.; Hubert Joe, I.; Yurdakul, S?.

2013-04-01

26

FT-IR, Laser-Raman spectra and quantum chemical calculations of methyl 4-(trifluoromethyl)-1H-pyrrole-3-carboxylate-A DFT approach.  

PubMed

In this study the experimental and theoretical vibrational frequencies of a newly synthesized anti-tumor and anti-inflammatory agent namely, methyl 4-(trifluoromethyl)-1H-pyrrole-3-carboxylate have been investigated. The experimental FT-IR (4000-400cm(-1)) and Laser-Raman spectra (4000-100cm(-1)) of the molecule in solid phase have been recorded. The theoretical vibrational frequencies and optimized geometric parameters (bond lengths, bond angles and torsion angles) have been calculated using density functional theory (DFT/B3LYP: Becke, 3-parameter, Lee-Yang-Parr and DFT/M06-2X: highly parameterized, empirical exchange correlation function) with 6-311++G(d,p) basis set by Gaussian 03 software, for the first time. The assignments of the vibrational frequencies have been done by potential energy distribution (PED) analysis using VEDA 4 software. The theoretical optimized geometric parameters and vibrational frequencies have been found to be in good agreement with the corresponding experimental data and results in the literature. In addition, the highest occupied molecular orbital (HOMO) energy, the lowest unoccupied molecular orbital (LUMO) energy and the other related molecular energy values of the compound have been investigated using the same theoretical calculations. PMID:24632165

Sert, Yusuf; Sreenivasa, S; Do?an, H; Manojkumar, K E; Suchetan, P A; Ucun, Fatih

2014-06-01

27

FT-IR, Laser-Raman spectra and quantum chemical calculations of methyl 4-(trifluoromethyl)-1H-pyrrole-3-carboxylate-A DFT approach  

NASA Astrophysics Data System (ADS)

In this study the experimental and theoretical vibrational frequencies of a newly synthesized anti-tumor and anti-inflammatory agent namely, methyl 4-(trifluoromethyl)-1H-pyrrole-3-carboxylate have been investigated. The experimental FT-IR (4000-400 cm-1) and Laser-Raman spectra (4000-100 cm-1) of the molecule in solid phase have been recorded. The theoretical vibrational frequencies and optimized geometric parameters (bond lengths, bond angles and torsion angles) have been calculated using density functional theory (DFT/B3LYP: Becke, 3-parameter, Lee-Yang-Parr and DFT/M06-2X: highly parameterized, empirical exchange correlation function) with 6-311++G(d,p) basis set by Gaussian 03 software, for the first time. The assignments of the vibrational frequencies have been done by potential energy distribution (PED) analysis using VEDA 4 software. The theoretical optimized geometric parameters and vibrational frequencies have been found to be in good agreement with the corresponding experimental data and results in the literature. In addition, the highest occupied molecular orbital (HOMO) energy, the lowest unoccupied molecular orbital (LUMO) energy and the other related molecular energy values of the compound have been investigated using the same theoretical calculations.

Sert, Yusuf; Sreenivasa, S.; Do?an, H.; Manojkumar, K. E.; Suchetan, P. A.; Ucun, Fatih

2014-06-01

28

Proposed model for in vitro interaction between fenitrothion and DNA, by using competitive fluorescence, (31)P NMR, (1)H NMR, FT-IR, CD and molecular modeling.  

PubMed

In this work we proposed a model for in vitro interaction of fenitrothion (FEN) with calf thymus-DNA by combination of multispectroscopic and two dimensional molecular modeling (ONIOM) methods. The circular dichroism results showed that FEN changes the conformation of B-DNA and caused some changes to C-DNA form. The FT-IR results confirmed a partial intercalation between FEN and edges of all base pairs. The competitive fluorescence, using methylene blue as fluorescence probe, in the presence of increasing amounts of FEN, revealed that FEN is able to release the non-intercalated methylene blue from the DNA. The weak chemical shift and peak broadening of (1)H NMR spectrum of FEN in the presence of DNA confirmed a non-intercalation mode. The (31)P NMR showed that FEN interacts more with DNA via its -NO2 moiety. The ONIOM, based on the hybridization of QM/MM (DFT, 6.31++G (d,p)/UFF) methodology, was also performed by Gaussian 2003 package. The results revealed that the interaction is base sequence dependent, and FEN interacts more with AT base sequences. PMID:23153512

Ahmadi, Farhad; Jafari, Batool; Rahimi-Nasrabadi, Mehdi; Ghasemi, Sahar; Ghanbari, Kumars

2013-03-01

29

Communication: Enhanced oxygen reduction reaction and its underlying mechanism in Pd-Ir-Co trimetallic alloys  

SciTech Connect

Based on a combined density functional theory and experimental study, we present that the electrochemical activity of Pd{sub 3}Co alloy catalysts toward oxygen reduction reaction (ORR) can be enhanced by adding a small amount of Ir. While Ir tends to favorably exist in the subsurface layers, the underlying Ir atoms are found to cause a substantial modification in the surface electronic structure. As a consequence, we find that the activation barriers of O/OH hydrogenation reactions are noticeably lowered, which would be mainly responsible for the enhanced ORR activity. Furthermore, our study suggests that the presence of Ir in the near-surface region can suppress Co out-diffusion from the Pd{sub 3}Co substrate, thereby improving the durability of Pd-Ir-Co catalysts. We also discuss the relative roles played by Ir and Co in enhancing the ORR activity relative to monometallic Pd catalysts.

Ham, Hyung Chul; Hwang, Gyeong S., E-mail: gshwang@che.utexas.edu [Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States); Manogaran, Dhivya [Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas 78712 (United States)] [Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas 78712 (United States); Lee, Kang Hee; Jin, Seon-ah; You, Dae Jong; Pak, Chanho [Energy Lab, Samsung Advanced Institute of Technology, Samsung Electronics Co., Ltd., Suwon (Korea, Republic of)] [Energy Lab, Samsung Advanced Institute of Technology, Samsung Electronics Co., Ltd., Suwon (Korea, Republic of); Kwon, Kyungjung [Department of Energy and Mineral Resources Engineering, Sejong University, Seoul 143-747 (Korea, Republic of)] [Department of Energy and Mineral Resources Engineering, Sejong University, Seoul 143-747 (Korea, Republic of)

2013-11-28

30

The CIELO Collaboration: Neutron Reactions on 1H, 16O, 56Fe, 235,238U, and 239Pu  

NASA Astrophysics Data System (ADS)

CIELO (Collaborative International Evaluated Library Organization) provides a new working paradigm to facilitate evaluated nuclear reaction data advances. It brings together experts from across the international nuclear reaction data community to identify and document discrepancies among existing evaluated data libraries, measured data, and model calculation interpretations, and aims to make progress in reconciling these discrepancies to create more accurate ENDF-formatted files. The focus will initially be on a small number of the highest-priority isotopes, namely 1H, 16O, 56Fe, 235,238U, and 239Pu. This paper identifies discrepancies between various evaluations of the highest priority isotopes, and was commissioned by the OECD's Nuclear Energy Agency WPEC (Working Party on International Nuclear Data Evaluation Co-operation) during a meeting held in May 2012. The evaluated data for these materials in the existing nuclear data libraries - ENDF/B-VII.1, JEFF-3.1, JENDL-4.0, CENDL-3.1, ROSFOND, IRDFF 1.0 - are reviewed, discrepancies are identified, and some integral properties are given. The paper summarizes a program of nuclear science and computational work needed to create the new CIELO nuclear data evaluations.

Chadwick, M. B.; Dupont, E.; Bauge, E.; Blokhin, A.; Bouland, O.; Brown, D. A.; Capote, R.; Carlson, A.; Danon, Y.; De Saint Jean, C.; Dunn, M.; Fischer, U.; Forrest, R. A.; Frankle, S. C.; Fukahori, T.; Ge, Z.; Grimes, S. M.; Hale, G. M.; Herman, M.; Ignatyuk, A.; Ishikawa, M.; Iwamoto, N.; Iwamoto, O.; Jandel, M.; Jacqmin, R.; Kawano, T.; Kunieda, S.; Kahler, A.; Kiedrowski, B.; Kodeli, I.; Koning, A. J.; Leal, L.; Lee, Y. O.; Lestone, J. P.; Lubitz, C.; MacInnes, M.; McNabb, D.; McKnight, R.; Moxon, M.; Mughabghab, S.; Noguere, G.; Palmiotti, G.; Plompen, A.; Pritychenko, B.; Pronyaev, V.; Rochman, D.; Romain, P.; Roubtsov, D.; Schillebeeckx, P.; Salvatores, M.; Simakov, S.; Soukhovitski?˜, E. Sh.; Sublet, J. C.; Talou, P.; Thompson, I.; Trkov, A.; Vogt, R.; van der Marck, S.

2014-04-01

31

Synthesis of 3,4-dihydro-1,8-naphthyridin-2(1H)-ones via microwave-activated inverse electron-demand Diels-Alder reactions.  

PubMed

Substituted 3,4-dihydro-1,8-naphthyridin-2(1H)-ones have been synthesized with the inverse electron-demand Diels-Alder reaction from 1,2,4-triazines bearing an acylamino group with a terminal alkyne side chain. Alkynes were first subjected to the Sonogashira cross-coupling reaction with aryl halides, the product of which then underwent an intramolecular inverse electron-demand Diels-Alder reaction to yield 5-aryl-3,4-dihydro-1,8-naphthyridin-2(1H)-ones by an efficient synthetic route. PMID:24605148

Fadel, Salah; Hajbi, Youssef; Khouili, Mostafa; Lazar, Said; Suzenet, Franck; Guillaumet, Gérald

2014-01-01

32

In Situ FT-IR Study on the Blocking Reaction of Isocyanate with Naphthol  

Microsoft Academic Search

The blocking reactions of phenyl isocyanate with 1-naphthol and 2-naphthol were investigated with in situ FT-IR. The reaction kinetics was studied and the reaction rates were described by a second-order equation. It was found that there was a remarkable induction period in the reaction. The induction period shortened with increase of temperature, and the induction period of 1-naphthol was obviously

Peng Fei Yang; Yong De Han; Jun Ying Li; Tian Duo Li

2011-01-01

33

Separation of the longitudinal and transverse cross sections in the {sup 1}H(e,e{prime} K{sup +}){Lambda} and {sup 1}H(e,e{prime} K{sup +}){Sigma}{sup 0} reactions  

SciTech Connect

We report measurements of cross sections for the reaction {sup 1}H(e,e{prime} K{sup +})Y, for both the {Lambda} and {Sigma}{sup 0} hyperon states, at an invariant mass of W = 1.84 GeV and four-momentum transfers 0.5 < Q{sup 2} < 2 (GeV/c){sup 2}. Data were taken for three values of virtual photon polarization {epsilon}, allowing the decomposition of the cross sections into longitudinal and transverse components. The {Lambda} data are a revised analysis of prior work, whereas the {Sigma}{sup 0} results have not been previously reported.

R.M. Mohring; David Abbott; Abdellah Ahmidouch; Thomas Amatuni; Pawel Ambrozewicz; Tatiana Angelescu; Christopher Armstrong; John Arrington; Ketevi Assamagan; Steven Avery; Kevin Bailey; Kevin Beard; S Beedoe; Elizabeth Beise; Herbert Breuer; Roger Carlini; Jinseok Cha; C. Chang; Nicholas Chant; Evaristo Cisbani; Glenn Collins; William Cummings; Samuel Danagoulian; Raffaele De Leo; Fraser Duncan; James Dunne; Dipangkar Dutta; T Eden; Rolf Ent; Laurent Eyraud; Lars Ewell; John Finn; H. Terry Fortune; Valera Frolov; Salvatore Frullani; Christophe Furget; Franco Garibaldi; David Gaskell; Donald Geesaman; Paul Gueye; Kenneth Gustafsson; Jens-Ole Hansen; Mark Harvey; Wendy Hinton; Ed Hungerford; Mauro Iodice; Ceasar Jackson; Cynthia Keppel; Wooyoung Kim; Kouichi Kino; Douglas Koltenuk; Serge Kox; Laird Kramer; Antonio Leone; Allison Lung; David Mack; Richard Madey; M Maeda; Stanislaw Majewski; Pete Markowitz; T Mart; C Martoff; David Meekins; A. Mihul; Joseph Mitchell; Hamlet Mkrtchyan; Sekazi Mtingwa; Maria-Ioana Niculescu; R. Perrino; David Potterveld; John Price; Brian Raue; Jean Sebastien Real; Joerg Reinhold; Philip Roos; Teijiro Saito; Geoff Savage; Reyad Sawafta; Ralph Segel; Stepan Stepanyan; Paul Stoler; Vardan Tadevosyan; Liguang Tang; Liliana Teodorescu; Tatsuo Terasawa; Hiroaki Tsubota; Guido Urciuoli; Jochen Volmer; William Vulcan; T. Welch; Robert Williams; Stephen Wood; Chen Yan; Benjamin Zeidman

2003-05-19

34

Ion-pair charge transfer complex with near-IR absorption: Synthesis, crystal structure and properties of [Hb] 2[Cu(mnt) 2] (Hb = 1-(4-((1H-imidazol-1-yl)methyl)benzyl)-1H-imidazol-3-ium)  

NASA Astrophysics Data System (ADS)

The compound [Hb] 2[Cu(mnt) 2] ( 1) [Hb = 1-(4-((1H-imidazol-1-yl)methyl)benzyl)-1H-imidazol-3-ium] has been synthesized, starting from 1,4-bis((1H-imidazol-1-yl)methyl)benzene, cupric chloride, and Na 2mnt in methanol. Compound 1 crystallizes in monoclinic system with C2/ c space group. In the crystal structure, the interactions between cations and anions via bifurcated C sbnd H···(NC-mnt) 2 hydrogen bonds give rise to a two dimensional supramolecular network. It has also been observed that two cation moieties (Hb) are attached together by a very short C sbnd H···N hydrogen bonding interaction with H···N distance of 1.74 Å, ?CHN bond angle of 174.9°. Compound 1 is additionally characterized by cyclic voltammetry, UV-Vis, IR, 1H NMR and EPR spectroscopy. The ion-pair compound 1 shows an intense absorption in the near-IR region at ˜1214 nm which has been described as a charge transfer band from HOMO of the copper dithiolate anion [Cu(mnt) 2] 2-, to LUMO of the [Hb] + cation. The title compound exhibits an oxidative response at +0.46 V vs. Ag/AgCl and a reductive event at -0.67 V vs. Ag/AgCl.

Kishore, Ravada; Tripuramallu, Bharat Kumar; Durgaprasad, Gummadi; Das, Samar K.

2011-03-01

35

Synthesis of o-(Dimethylamino)aryl Ketones, Acridones, Acridinium Salts, and 1H-Indazoles by the Reaction of Hydrazones and Arynes  

PubMed Central

A novel, efficient route to biologically and pharmaceutically important o-(dimethylamino)aryl ketones, acridones, acridinium salts, and 1H-indazoles has been developed starting from readily available hydrazones of aldehydes and o-(trimethylsilyl)aryl triflates. The reaction proceeds through arynes under mild conditions, tolerates a wide range of functional groups, and provides the final products in good to excellent yields.

Dubrovskiy, Anton V.; Larock, Richard C.

2012-01-01

36

Spectroscopy of Ir-Pt-Au nuclei near stability by complete and incomplete fusion reactions  

NASA Astrophysics Data System (ADS)

High-spin states of 194,195Au, 195Pt and 193Ir have been studied using an in-beam ?-ray spectroscopic technique following the reaction of 7Li on an 192Os target at 44 MeV. Several bands in these nuclei have been identified and extended up to high-spin states. The ? and t emission channels leading to 193Ir and 195Pt, respectively, are strongly enhanced which may be explained by incomplete fusion reaction; the t and ? fragments from the break-up of weakly bound 7Li nucleus fusion with 192Os target.

Fang, Y. D.; Zhang, Y. H.; Zhou, X. H.; Liu, M. L.; Zheng, Y.; Hua, W.; Guo, S.; Wang, J. G.; Guo, Y. X.; Lei, X. G.; Zhang, N. T.; Wu, X. G.; He, C. Y.; Zheng, Y.; Wang, Z. M.; Shi, Y.; Xu, F. R.

2013-05-01

37

Molecular motions contributions to optical nonlinearity of N-benzyl-2-methyl-4-nitroaniline studied by temperature-dependent FT-IR, 1H NMR spectroscopy and DFT calculations  

NASA Astrophysics Data System (ADS)

The fourier transform infrared (FT-IR) spectra of polycrystalline orthorhombic N-benzyl-2-methyl-4-nitroaniline (BNA) were recorded in the 380-4000 cm-1 region within the 11-297 K temperature range while the 1H NMR spin-lattice relaxation time and the second moment of 1H NMR resonance line were measured in the 145-373 K and 80-400 K temperature range, respectively. Above 80 K the methyl group rotation is found to be dominant among other motions and leading to a significant reduction of the proton second moment which agrees with proposed models for the rigid structure and for the internal rotations in the BNA crystal such as methyl group C3 rotation, phenyl ring rotation and trans-gauche motion of methylene group. Activation energies for the nitro and methyl group rotations were experimentally estimated by FT-IR and 1H NMR, appropriately. For comparison the potential barriers for these two group motions in BNA molecule were calculated by DFT quantum chemical methods. The role of molecular motions in the BNA crystal in the large temperature range is discussed from the point of view of its nonlinear optical properties.

Piela, Katarzyna; Ho?derna-Natkaniec, Krystyna; Baranowski, Miko?aj; Misiaszek, Tomasz; Baran, Jan; Magdalena Szostak, M.

2013-02-01

38

FT-IR and 1H NMR studies of the state of solubilized water in water-in-oil microemulsions stabilized by mixtures of single- and double-tailed cationic surfactants.  

PubMed

The structure of solubilized water in water-in-n-heptane aggregates stabilized by mixtures of single- and double-tail quaternary ammonium surfactants, namely didodecyldimethylammonium chloride/dodecyltrimethylammonium chloride (DDAC/DTAC) or didodecyldimethylammonium bromide/dodecyltrimethylammonium bromide (DDAB/DTAB) was studied by two noninvasive techniques, (1)H NMR and FT-IR. In the former, the chemical shift data, ?(obs), were used to calculate the so-called deuterium/protium fractionation factor, ?(M), of the aggregate-solubilized water and were found to be unity. In the FT-IR study, upon increasing water/surfactant molar ratio, W, the frequency, ?(OD), of the HOD species decreases, while its full width at half height and its area increase. The results obtained from both techniques indicate that the water appears to be present as a single nano-phase and the structure varies continuously as a result of increasing W. In addition, the effect of changing the counter-ion (Br(-) or Cl(-)) on (1)H NMR and FT-IR results was investigated. In spite of the known difference in the dissociation of these counter-ions from micellar aggregates, this was found not to affect the state of solubilized water. This report gives further insight into the contradictory scientific debates on the structure of water in the polar nano-cores of microemulsions. PMID:23200348

Bumajdad, Ali; Madkour, Metwally; Shaaban, Ehab; El Seoud, Omar A

2013-03-01

39

Three Component Reaction: An Efficient Synthesis and Reactions of 3,4-Dihydropyrimidin-2(1H)-Ones and Thiones Using New Natural Catalyst  

PubMed Central

Synthesis of 3,4-dihydropyrimidin-2(1H)-one and 3,4-dihydropyrimidin-2(1H)-thione derivatives from aldehydes, 1,3-dicarbonyl derivatives and urea or thiourea using granite and quartz as new, natural and reusable catalysts. Some of the 3,4-dihydropyrimidin-2(1H)-thione derivatives were used to prepare new heterocyclic compounds. The antimicrobial activity of selected examples of the synthesized compounds was tested and showed moderate activity.

Elmaghraby, A. M.; Mousa, I. A.; Harb, A. A.; Mahgoub, M. Y.

2013-01-01

40

Determination of the time course of an enzymatic reaction by 1H NMR spectroscopy: hydroxynitrile lyase catalysed transhydrocyanation  

NASA Astrophysics Data System (ADS)

The time course of the enzyme catalysed transhydrocyanation of benzaldehyde to give ( S)-mandelonitrile was investigated using a hydroxynitrile lyase from Hevea brasiliensis as catalyst and acetone cyanohydrin as cyanide donor. Employing special techniques it was possible to apply 1H NMR spectroscopy in aqueous medium to monitor the concentration changes of all substrates and products. By this technique strong evidence for inhibition of the enzyme at higher substrate concentrations was obtained.

Hickel, A.; Gradnig, G.; Griengl, H.; Schall, M.; Sterk, H.

1996-01-01

41

1H, 13C NMR, FT-IR, ESI-MS and PM5 semiempirical study of new lasalocid ester with 3-(methylthio)-1-propanol and its complexes with monovalent cations  

NASA Astrophysics Data System (ADS)

A new ester of lasalocid with 3-(methylthio)-1-propanol (Las10) has been synthesised and its complexation of monovalent cations has been studied by ESI mass spectrometry as well as the 1H, 13C NMR and FT-IR spectroscopic methods. The ESI-MS spectra show that Las10 forms stable 1:1 complexes with Li +, Na +, K +, Rb + and Cs + cations. The FT-IR spectrum of Las10 in acetonitrile solution indicates that this molecule exists in keto and enol equilibrium, in which the keto form is predominant. It is demonstrated that the cations have no influence on this keto-enol equilibrium. The results of the PM5 semiempirical calculations are in agreement with the spectroscopic data and allow visualisation of the structure of Las10 and its complexes with the cations studied.

Pankiewicz, Rados?aw; Schroeder, Grzegorz; Brzezinski, Bogumi?

2007-03-01

42

Molecular structure and vibrational IR spectra of the 2- hydroxypyridine 2(1H)- pyridinone system and its thio and seleno analogs: density functional theory versus conventional ab initio calculations  

Microsoft Academic Search

The molecular parameters (optimized geometries, rotational constants, dipole moments) and vibrational IR spectra (harmonic wavenumbers, absolute intensities) of the 2-hydroxypyridine2(1H)-pyridinone (2OHP2OP) system and its thio (2SHP2SP) and seleno analogs (2SeHP2SeP) are predicted by density functional theory (DFT) with the Becke3-LYP functionals (DFT(B3-LYP) method) using a valence split double-? basis set augmented by polarization functions on all atoms. The results are

Józef S. Kwiatkowski; Jerzy Leszczynski

1996-01-01

43

The 1H(11B,n)11C reaction as a practical low background monoenergetic neutron source in the 10 MeV region  

Microsoft Academic Search

Neutron source properties of the 1H(11B,n)11C reaction were measured for incident 11B energies between 50 and 64 MeV by detecting the neutrons at angles of 0° to 40°. Neutron were produced with high monochromaticity in the range of several MeV to 12 MeV. In addition, the room background is very low because they were collimated to a forward cone according

Satoshi Chiba; Motoharu Mizumoto; Kazuo Hasegawa; Yoshimaro Yamanouti; Masayoshi Sugimoto; Yukinobu Watanabe; Manfred Drosg

1989-01-01

44

The /sup 1/H(/sup 7/Li,n)/sup 7/Be reaction as a neutron source in the MeV range  

SciTech Connect

Neutron production in the MeV range by the /sup 1/H(/sup 7/Li,n)/sup 7/Be reaction is attractive for two reasons: (1) emission of neutrons only into a narrow forward cone is very profitable in low-background experiments and (2) the neutron production cross section is very high, especially at lower energies where it reaches 1b/sr. General characteristics of the source are described and the limitations in practical applications are discussed.

Drosg, M.

1981-08-01

45

EPR, 1H, 31P ENDOR, and IR study of Cu(II) and Ni(II)(O,O-dimethyldithiophosphate)(N,N-dimethyldithiocarbamate) complexes  

NASA Astrophysics Data System (ADS)

Polycrystalline samples of Cu(Me 2dtp)(Me 2dtc) and Ni(Me 2dtp)(Me 2dtc) complexes are studied by means of EPR, ENDOR, and vibrational normal coordinate analysis. On the basis of EPR and ENDOR experimental results, the spin density distribution on 1H and 31P nuclei of the mixed ligand and parent copper dithiophosphate and dithiocarbamate complexes is compared. Comparison between vibrational spectra and normal coordinate analysis data on Ni(Me 2dtp)(Me 2dtc), Ni(Me 2dtp) 2 and Ni(Me 2dtc) 2 enabled the conclusion that the structure of the NiS 4 fragment in the mixed complex is retained close to that in the bis-chelate complexes.

Iliev, V.; Alexiev, V.

1995-06-01

46

Vector and tensor analyzing powers of the {sup 1}H (d(vector sign),{gamma}){sup 3}He capture reaction  

SciTech Connect

Precise measurements of the deuteron vector analyzing power A{sub y}{sup d} and the tensor analyzing power A{sub yy} of the {sup 1}H (d(vector sign),{gamma}){sup 3}He capture reaction have been performed at deuteron energies of 29 MeV and 45 MeV. The data have been compared to theoretical state-of-the-art calculations available today. Due to the large sensitivity of polarization observables and the precision of the data light could be shed on small effects present in the dynamics of the reaction.

Klechneva, T. [Departement fuer Physik und Astronomie, Universitaet Basel (Switzerland); St. Petersburg Nuclear Physics Institute, Gatchina (Russian Federation); Carasco, C.; Hauger, M.; Jourdan, J.; Krusche, B.; Muehry, H.; Normand, Ch.; Rohe, D.; Sick, I.; Testa, G.; Warren, G.; Woehrle, H.; Zeier, M. [Departement fuer Physik und Astronomie, Universitaet Basel (Switzerland); Goussev, I.; Seliverstov, D. [St. Petersburg Nuclear Physics Institute, Gatchina (Russian Federation)

2006-03-15

47

Probing the Reaction Pathway of Dehydrogenation of the LiNH2 + LiH Mixture Using In Situ 1H NMR Spectroscopy  

SciTech Connect

Using variable temperature in situ 1H NMR spectroscopy on a mixture of LiNH2 + LiH that was mechanically activated using high energy ball milling, the dehydrogenation of the LiNH2 + LiH to Li2NH + H2 was investigated. The analysis indicates NH3 release at a temperature as low as 300C and rapid reaction between NH3 and LiH at ~ 1500C. The transition from NH3 release to H2 appearance accompanied by disappearance of NH3 confirms unambiguously the two-step elementary reaction pathway proposed by other workers.

Hu, Jian Zhi; Kwak, Ja Hun; Yang, Zhenguo; osborn, william; Markmaitree, Tippawan; Shaw, Leonard D.

2008-06-15

48

Cross sections for ?-ray production in the ^193Ir(n,xn?) reactions^*  

NASA Astrophysics Data System (ADS)

Discrete ?-ray spectra have been measured for nuclei populated in ^193Ir(n,xn?) reactions, with x ? 11, as a function of incident neutron energy using the ``white'' neutron source at the Los Alamos Neutron Science Center's (LANSCE) WNR facility. The energy of the incident neutrons was determined using the time-of-flight technique. The data were taken using the GEANIE spectrometer comprised of 26 high-purity Ge detectors with 20 BGO escape-suppression shields. The absolute cross sections for emission of more than 150 ?-rays from the ^183-193Ir isotopes were determined for neutron energies 1 MeV < En < 200 MeV. Comparison with model calculations, using the GNASH reaction model, was made up to En = 30 MeV incident neutron energies. The total ^193Ir(n,n^')^193mIr cross section for the production of the 80-keV isomer, from threshold up to En = 20 MeV incident neutron energies, was determined using a combination of experimental data and nuclear reaction modeling. ^*This work was performed under the auspices of the U.S. Department of Energy by the University of California, Los Alamos National Laboratory under contract No. W-7405-ENG-36 and Lawrence Livermore National Laboratory under contract No. W-7405-ENG-48.

Fotiades, N.; Nelson, R. O.; Devlin, M.; Chadwick, M. B.; Talou, P.; Becker, J. A.; Bernstein, L. A.; Garrett, P. E.; Younes, W.

2003-10-01

49

The model of 1,3-dipolar cycloaddition reaction of 4,5-dihydro-1 H-imidazole 3-oxide derivatives with alkynes  

NASA Astrophysics Data System (ADS)

The influence of solvents and different structural factors on the rate of 1,3-dipolar cycloaddition reaction of the 4,5-dihydro-1 H-imidazole 3-oxide derivatives with alkynes have been studied. Nitrones and alkynes have been ranged by their relative activity in this reaction. Using the DFT calculation with the triple zets basis set, the energy profile of the reaction has been plotted, and the structures and energy characteristics of the transition states have been determined. The mechanism of this reaction has been shown to be concerted and asynchronous. The validity of the used computational approach for the detailed investigation of 1,3-dipolar cycloaddition of nitrones has been demonstrated.

Popov, Sergey A.; Romanenko, Galina V.; Reznikov, Vladimir A.

2008-01-01

50

Reactions and photochemistry of transition metals with hydrogen and methane via matrix isolation FT-IR spectroscopy. [FT-IR (Fourier transform infrared)  

Microsoft Academic Search

The reactions of transition and main group metals, including Ca, Sc, Ti, V, Cr, Mo, Zn, Ga and Ge, with molecular hydrogen have been investigated using FT-IR matrix isolation spectroscopy. The reactions of gallium with methane in Ar, Kr and pure methane matrices have been studied. All the above metals (except Ge) encounter an energy barrier and require photoexcitation to

Xiao

1991-01-01

51

Bond energy of IrO+: guided ion-beam and theoretical studies of the reaction of Ir+ (5F) with O2.  

PubMed

The kinetic-energy dependence of the Ir(+) + O2 reaction is examined using guided ion-beam mass spectrometry. The cross section for IrO(+) formation from ground state Ir(+)((5)F) is unusual, and several means are used to interpret the kinetic energy dependence for IrO(+) formation. In analogy with recent observations for the analogous Re(+) and Os(+) systems, we believe the cross section is most accurately analyzed assuming there are two features. This analysis yields a threshold leading to D0(Ir(+)-O) = 4.26 ± 0.09 eV, with the higher energy feature having a threshold 0.72 ± 0.25 eV higher in energy. This bond energy, which is consistent with much less precise values determined in the literature, can be combined with literature information to suggest that D0(IrO) = 4.25 ± 0.44 eV and IE(IrO) = 8.96 ± 0.45 eV. The nature of the bonding for IrO(+) and IrO2(+) is discussed and analyzed primarily using theoretical calculations at the B3LYP/def2-TZVPPD level of theory. Bond energies for ground state IrO(+), identified as (5)?, are calculated at this level as well as BP86 and CCSD(T,full) levels using several different basis sets. BP86 theoretical bond energies are higher than the experimental value, whereas B3LYP and CCSD(T,full) values are slightly lower, especially after estimated spin-orbit corrections. Potential energy surfaces for the reaction of Ir(+) with O2 are also calculated at the B3LYP/def2-TZVPPD level of theory and reveal that ground state Ir(+)((5)F) inserts into O2 by forming several different Ir(+)(O2) complexes. These can then couple along additional surfaces to form low-lying states of the dioxide IrO2(+). The very interesting parallel behavior of the Re, Os, and Ir heavy metal systems is explored in terms of adiabatic and nonadiabatic behavior, although no unambiguous explanation is evident. PMID:23898975

Armentrout, P B; Li, Feng-Xia

2013-08-22

52

Vibrational (FT-IR and FT-Raman), electronic (UV-Vis), NMR ((1)H and (13)C) spectra and reactivity analyses of 4,5-dimethyl-o-phenylenediamine.  

PubMed

The structure of 4,5-dimethyl-o-phenylenediamine (C8H12N2, DMPDA) was investigated on the basis of spectroscopic data and theoretical calculations. The sterochemical structure was determined by FT-IR, FT-Raman, UV, (1)H and (13)C NMR spectra. An experimental study and a theoretical analysis were associated by using the B3LYP method with Gaussian09 package program. FT-IR and FT-Raman spectra were recorded in the region of 4000-400cm(-1) and 4000-10cm(-1), respectively. The vibrational spectra were calculated by DFT method and the fundamental vibrations were assigned on the basis of the total energy distribution (TED), calculated with scaled quantum mechanics (SQM) method with Parallel Quantum Solutions (PQS) program. The UV absorption spectrum of the compound that dissolved in ethanol solution were recorded in the range of 190-400nm. Total density of state (TDOS) and partial density of state (PDOS) of the DMPDA in terms of HOMOs and LUMOs were calculated and analyzed. Chemical shifts were reported in ppm relative to tetramethylsilane (TMS) for (1)H and (13)C NMR spectra. The compound was dissolved in dimethyl sulfoxide (DMSO). Also, (1)H and (13)C chemical shifts calculated using the gauge independent atomic orbital (GIAO) method. Mullikan atomic charges and other thermo-dynamical parameters were investigated with the help of B3LYP (DFT) method using 6-311++G(**) basis set. On the basis of the thermodynamic properties of the title compound at different temperatures have been carried out, revealing the correlations between heat capacity (C), entropy (S), enthalpy changes (H) and temperatures. The optimized bond lengths, bond angles, chemical shifts and vibrational wavenumbers showed the best agreement with the experimental results. PMID:24813280

Atac, Ahmet; Karaca, Caglar; Gunnaz, Salih; Karabacak, Mehmet

2014-09-15

53

FT-IR, UV-vis, 1H and 13C NMR spectra and the equilibrium structure of organic dye molecule disperse red 1 acrylate: A combined experimental and theoretical analysis  

NASA Astrophysics Data System (ADS)

This study reports the characterization of disperse red 1 acrylate compound by spectral techniques and quantum chemical calculations. The spectroscopic properties were analyzed by FT-IR, UV-vis, 1H NMR and 13C NMR techniques. FT-IR spectrum in solid state was recorded in the region 4000-400 cm -1. The UV-vis absorption spectrum of the compound that dissolved in methanol was recorded in the range of 200-800 nm. The 1H and 13C NMR spectra were recorded in CDCl 3 solution. The structural and spectroscopic data of the molecule in the ground state were calculated using density functional theory (DFT) employing B3LYP exchange correlation and the 6-311++G(d,p) basis set. The vibrational wavenumbers were calculated and scaled values were compared with experimental FT-IR spectrum. A satisfactory consistency between the experimental and theoretical spectra was obtained and it shows that the hybrid DFT method is very useful in predicting accurate vibrational structure, especially for high-frequency region. The complete assignments were performed on the basis of the experimental results and total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. Isotropic chemical shifts were calculated using the gauge-invariant atomic orbital (GIAO) method. A study on the electronic properties were performed by timedependent DFT (TD-DFT) and CIS(D) approach. To investigate non linear optical properties, the electric dipole moment ?, polarizability ?, anisotropy of polarizability ? ? and molecular first hyperpolarizability ? were computed. The linear polarizabilities and first hyperpolarizabilities of the studied molecule indicate that the compound can be a good candidate of nonlinear optical materials.

Cinar, Mehmet; Coruh, Ali; Karabacak, Mehmet

2011-12-01

54

FT-IR, UV-vis, 1H and 13C NMR spectra and the equilibrium structure of organic dye molecule disperse red 1 acrylate: a combined experimental and theoretical analysis.  

PubMed

This study reports the characterization of disperse red 1 acrylate compound by spectral techniques and quantum chemical calculations. The spectroscopic properties were analyzed by FT-IR, UV-vis, (1)H NMR and (13)C NMR techniques. FT-IR spectrum in solid state was recorded in the region 4000-400 cm(-1). The UV-vis absorption spectrum of the compound that dissolved in methanol was recorded in the range of 200-800 nm. The (1)H and (13)C NMR spectra were recorded in CDCl(3) solution. The structural and spectroscopic data of the molecule in the ground state were calculated using density functional theory (DFT) employing B3LYP exchange correlation and the 6-311++G(d,p) basis set. The vibrational wavenumbers were calculated and scaled values were compared with experimental FT-IR spectrum. A satisfactory consistency between the experimental and theoretical spectra was obtained and it shows that the hybrid DFT method is very useful in predicting accurate vibrational structure, especially for high-frequency region. The complete assignments were performed on the basis of the experimental results and total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. Isotropic chemical shifts were calculated using the gauge-invariant atomic orbital (GIAO) method. A study on the electronic properties were performed by timedependent DFT (TD-DFT) and CIS(D) approach. To investigate non linear optical properties, the electric dipole moment ?, polarizability ?, anisotropy of polarizability ?? and molecular first hyperpolarizability ? were computed. The linear polarizabilities and first hyperpolarizabilities of the studied molecule indicate that the compound can be a good candidate of nonlinear optical materials. PMID:21958518

Cinar, Mehmet; Coruh, Ali; Karabacak, Mehmet

2011-12-01

55

The Davis-Beirut Reaction: N1,N2-Disubstituted-1 H-Indazolones via 1,6-Electrophilic Addition to 3-Alkoxy-2H-Indazoles  

PubMed Central

A variety of electrophiles (anhydrides, acid chlorides, carbonochloridates, sulfonyl chlorides, and alkyl bromides) react with 3-methoxy-2H-indazole (1a), benzoxazin[3,2-b]indazole (1d), and oxazolino[3,2-b]indazole (1e) – substrates available by the Davis-Beirut reaction – to yield a diverse set of N1,N2-disubstituted-1H-indazolones. With certain electrophiles, an AERORC (Addition of the Electrophile, Ring Opening, and Ring Closure) process on indazole 1d results in indazoloindazolone formation. An intriguing aspect of these N1,N2-disubstituted-1H-indazolones is that they are poised for diversification through, for example, azide-alkyne cycloaddition chemistry reported here.

Conrad, Wayne E.; Fukazawa, Ryo; Haddadin, Makhluf J.; Kurth, Mark J.

2011-01-01

56

Fluorophenylantimony carboxylates(II): synthetic and spectroscopic studies (UV, IR, 1H, 19F and 13C NMR) of pentafluorophenylantimony(V) di- and tetracarboxylates  

Microsoft Academic Search

Pentafluorophenylantimony(V) di- and tetracarboxylates of the molecular formula C6F5SbX2L2 (when X=L=OCOR (R=?CH3, ?CH2Cl, ?CHCl2, ?CCl3, ?CF3, ?CH2OC6H3Cl2-2,4, ?CH2OC6H2Cl3-2,4,5) and when X=Cl; L=?OCOCH3, ?OCOCHCl2) have been synthesized by the metathetical reaction of pentafluorophenylantimony(V) tetrachloride and (dibromide)dichloride with corresponding sodium salt of carboxylic acids in appropriate molar ratio using 15-crown-5 as phase transfer catalyst. The van’t Hoff factor ‘i’ and molar conductance

Sanjeev K Shukla; Ashok Ranjan; A. K Saxena

2002-01-01

57

Equilibrium and 1 H NMR Kinetic Study of the Reactions of Dichlorido [S-Methyl-L-Cysteine(N,S)]Platinum(II) Complex with Some Relevant Biomolecules  

Microsoft Academic Search

The formation equilibria of the [Pt(SMC)(H2O)2]+ complex with some biologically relevant ligands such as L-methionine (L-met) and glutathione (GSH) were studied. The stoichiometry\\u000a and stability constants of the formed complexes are reported, and the concentration distribution of the various complex species\\u000a has been evaluated as a function of pH. The reaction between [PtCl2(SMC)] and guanosine-5?-monophosphate (5?-GMP) was studied by 1H

Tanja Soldatovi?; Predrag ?anovi?; Radivoje Nikoli?; Ratomir Jeli?; Živadin D. Bugar?i?

2009-01-01

58

Measurements of GnE/GnM from the 2H(e-->,en-->)1H Reaction to Q2=1.45 (GeV/c)2.  

PubMed

We report new measurements of the ratio of the electric form factor to the magnetic form factor of the neutron, G(n)(E)/G(n)(M), obtained via recoil polarimetry from the quasielastic 2H(e-->,e(')n-->)1H reaction at Q2 values of 0.45, 1.13, and 1.45 (GeV/c)(2) with relative statistical uncertainties of 7.6% and 8.4% at the two higher Q2 points, which points have never been achieved in polarization measurements. PMID:14525355

Madey, R; Semenov, A Yu; Taylor, S; Plaster, B; Aghalaryan, A; Crouse, E; MacLachlan, G; Tajima, S; Tireman, W; Yan, Chenyu; Ahmidouch, A; Anderson, B D; Arenhövel, H; Asaturyan, R; Baker, O K; Baldwin, A R; Barkhuff, D; Breuer, H; Carlini, R; Christy, E; Churchwell, S; Cole, L; Danagoulian, S; Day, D; Eden, T; Elaasar, M; Ent, R; Farkhondeh, M; Fenker, H; Finn, J M; Gan, L; Garrow, K; Gasparian, A; Gueye, P; Howell, C R; Hu, B; Jones, M K; Kelly, J J; Keppel, C; Khandaker, M; Kim, W-Y; Kowalski, S; Lai, A; Lung, A; Mack, D; Manley, D M; Markowitz, P; Mitchell, J; Mkrtchyan, H; Opper, A K; Perdrisat, C; Punjabi, V; Raue, B; Reichelt, T; Reinhold, J; Roche, J; Sato, Y; Savvinov, N; Semenova, I A; Seo, W; Simicevic, N; Smith, G; Stepanyan, S; Tadevosyan, V; Tang, L; Ulmer, P E; Vulcan, W; Watson, J W; Wells, S; Wesselmann, F; Wood, S; Yan, Chen; Yang, S; Yuan, L; Zhang, W-M; Zhu, H; Zhu, X

2003-09-19

59

Role of cluster size and substrate in the gas phase CC bond coupling reactions of allyl halides mediated by Agn+ and Agn-1H+ cluster cations  

NASA Astrophysics Data System (ADS)

Previous studies have demonstrated that the silver hydride cluster cation Ag4H+ promotes CC bond coupling of allylbromide [G.N. Khairallah, R.A.J. O'Hair, Angewandte Chemie International Edition 44 (2005) 728]. Here the influence of both the nature and the size of the silver cluster cation and the substrate on CC bond coupling are examined. Thus each of the cations Ag2H+, Ag4H+, Ag3+, and Ag5+ were allowed to react with three different halides: allyl chloride, allyl bromide and allyl iodide. No CC bond coupling is observed in the reactions of the cluster cations with allyl chloride. There are four main reaction sequences that result in CC bond coupling for allyl bromide and allyl iodide mediated by Agn+ and Agn-1H+ clusters: (i) A sequence involving the reactions of silver cluster cations with two molecules of C3H5X: Agn+ --> Agn(C3H5X)+ --> AgnX2+. This only occurs in the cases of: n = 3 and X = I; n = 5 and X = Br. (ii) A sequence involving the reactions of silver cluster cations with two molecules of C3H5X via an organometallic intermediate: Agn+ --> Agn-1(C3H5)+ --> Agn-1X+. This only occurs in the cases of: n = 5 and X = Br and I. (iii) A sequence involving the reactions of silver hydride cluster cations with three molecules of C3H5X: Agn-1H+ --> Agn-1X+ --> Agn-1X(C3H5X)+ --> Ag(C3H5)2+ and Agn-1X3+. This only occurs in the cases of: n = 5 and X = Br and I. (iv) A sequence involving the reactions of silver hydride cluster cations with three molecules of C3H5X via an organometallic intermediate: Agn-1H+ --> Agn-1X+ --> Agn-3(C3H5)+ --> Ag(C3H5)2+ and Agn-3X+. This only occurs in the cases of: n = 5 and X = I.

Wang, Farrah Qiuyun; Khairallah, George N.; O'Hair, Richard A. J.

2009-06-01

60

Spectroscopic and structural studies of quinoline derivatives—II. Forrier transform i.r. spectroscopy. 1. Rotational isomerism in 3-ethoxycarbonyl-4(1H)-quinolone and some of its substituted derivatives,  

NASA Astrophysics Data System (ADS)

Rotational isomerism associated with internal rotation about the ring carbon(3)-ester carbonyl carbon single bond in a series of 3-ethoxycarbonyl-4(1H)-quinolones have been investigated spectroscopically in the solid state using Fourier transform i.r. and laser Raman spectroscopy. Particular attention is given to the 1700, 1300 and 1100 cm -1 spectral regions related primarily to the vibrations of the CO 2C 2H 5 group. Within these regions rotational isomerism appeared in the compounds examined. The conformational changes are discussed and evidence is reported for occurrence of the unsubstituted compound 1 itself in the solid state at ambient temperature as an equilibrium mixture of both the s-trans ( 1a) and s-cis ( 1b) rotamers (this is in contrast to previous findings), and of its Bz-substituted derivatives.

Mirek, Julian; Urbanek, Zbigniew H.

61

Molecular structure, spectroscopic (FT-IR, FT-Raman, 13C and 1H NMR, UV), polarizability and first-order hyperpolarizability, HOMO and LUMO analysis of 4'-methylbiphenyl-2-carbonitrile.  

PubMed

In the present study, the molecular structure, vibrational and electronic transition, isotropic chemical shifts analysis of 4'-methylbiphenyl-2-carbonitrile were presented using experimental techniques (FT-IR, FT-Raman, NMR and UV) and quantum chemical calculations. FT-IR and FT-Raman spectra in solid state were observed in the region 4000-400cm(-1) and 3500-50cm(-1), respectively. The ultraviolet absorption spectrum of studied compound that dissolved in ethanol was examined in the range of 200-400nm. The (1)H and (13)C NMR spectra were recorded in DMSO solution. To determine lowest-energy molecular conformation of the title molecule, the selected torsion angle is varied every 10° and molecular energy profile is calculated from 0° to 360°. The molecular structure and spectroscopic data of the molecule in the ground state were computed by density functional theory (DFT) using 6-31++G(d,p) basis set. The complete assignments of all vibrational modes were performed on the basis of the total energy distributions (TED) of the vibrational modes, computed with scaled quantum mechanics (SQM) method. (13)C and (1)H isotropic chemical shifts were computed using the gauge-invariant atomic orbital (GIAO) method. Moreover, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies, absorption wavelength were performed by time-dependent DFT approach. The dipole moment, linear polarizability and first hyperpolarizability values were also computed. The linear polarizabilities and first hyper polarizabilities of the studied molecule indicate that the compound is a good candidate of nonlinear optical materials. Comparison of the calculated frequencies, NMR chemical shifts, absorption wavelengths with the experimental values revealed that DFT method produces good results. PMID:22185952

Karabacak, Mehmet; Yilan, Erkan

2012-02-15

62

Characterization of 40 kDa poly(ethylene glycol) polymers by proton transfer reaction QTOF mass spectrometry and 1H-NMR spectroscopy.  

PubMed

Several electrospray mass spectrometry (ESI-MS) techniques have been described during the past years to enable the characterization work of large poly(ethylene glycol)s (PEGs) and PEGylated proteins. The proton transfer reaction ESI-MS method utilizes amines to charge reduce the electrospray envelope of PEGs, hence PEG molecules are aminated instead of protonated. This method simplifies the mass spectrum of large PEGs, and enables the interpretation of the charge state of the observable envelopes (R ? 3,000 (FWHM) measured at the (M + 6H)(6+) ion from 40 K PEG compound 7,324.19). Hence, deconvolution of the MS data can be performed and relative molecular masses of the individual chain lengths of the PEGs can be calculated. However, as the poly-dispersity of PEGs may vary from batch to batch and from sample to sample, it was of interest to examine if the method could distinguish between these kinds of different material. Therefore, sample materials of each intermediate obtained at five synthetic steps during synthesis of a 40 kDa PEG molecule were collected. These four intermediates, starting material and the target molecule were examined by (1)H-NMR spectroscopy and ESI-MS using a proton stripping base. The study revealed that the charge-stripping ESI-MS method is able to differentiate between even small changes in the structure of the polymeric molecules only when the analysis is assisted by (1)H-NMR spectroscopy. A proper characterization of polymer molecules requires besides relative molecular mass, also poly-dispersity and end-group characterization. No end-group information is obtained based on MS data. Examination of the PEG polymers by (1)H-NMR spectroscopy provides the needed information. In addition, the (1)H-NMR spectra clearly distinguishes the examined polymers. PMID:22466162

Malmstrøm, Joan

2012-05-01

63

A determination of the vector and tensor analyzing powers in low energy {sup 1}H(d,{gamma}){sup 3}He reaction  

SciTech Connect

Full angular distributions of the vector and tensor analyzing powers have been measured for {sup 1}H(d,{gamma}){sup 3}He in the energy range 20 <, E{sub d} 330 keV. A vapor condensed heavy ice target was bombarded by a 330 keV beam using Low Energy Beam Facility and Intense Polarized lon Source at TUNL. They rays were detected in two large volume HPGe crystals. We have extracted functional energy dependence of analyzing powers at each measured angle, i.e. 0{degrees}, 30{degrees}, 60{degrees}, 90{degrees}, 120{degrees}, and 135{degrees}. The results will be compared with preliminary calculations based on the Refined Resonating Group Model (RRGM). It is expected that measurement of polarization observables for this reaction will provide new insights into the mechanism of low energy capture reaction e.g. the role of meson exchange currents, Coulomb effects, etc.

Ma, L.; Karwowski, H.J.; Ludwig, E.J.

1995-10-01

64

Design, synthesis, structural characterization by IR, (1) H, (13) C, (15) N, 2D-NMR, X-ray diffraction and evaluation of a new class of phenylaminoacetic acid benzylidene hydrazines as pfENR inhibitors.  

PubMed

Recent studies have revealed that plasmodial enoyl-ACP reductase (pfENR, FabI), one of the crucial enzymes in the plasmodial type II fatty acid synthesis II (FAS II) pathway, is a promising target for liver stage malaria infections. Hence, pfENR inhibitors have the potential to be used as causal malarial prophylactic agents. In this study, we report the design, synthesis, structural characterization and evaluation of a new class of pfENR inhibitors. The search for inhibitors began with a virtual screen of the iResearch database by molecular docking. Hits obtained from the virtual screen were ranked according to their Glide score. One hit was selected as a lead and modified to improve its binding to pfENR; from this, a series of phenylamino acetic acid benzylidene hydrazides were designed and synthesized. These molecules were thoroughly characterized by IR, (1) H, (13) C, (15) N, 2D-NMR (COSY, NOESY, (1) H-(13) C, (1) H-(15) N HSQC and HMBC), and X-ray diffraction. NMR studies revealed the existence of conformational/configurational isomers around the amide and imine functionalities. The major species in DMSO solution is the E, E form, which is in dynamic equilibrium with the Z, E isomer. In the solid state, the molecule has a completely extended conformation and forms helical structures that are stabilized by strong hydrogen bond interactions, forming a helical structure stabilized by N-H…O interactions, a feature unique to this class of compounds. Furthermore, detailed investigation of the NMR spectra indicated the presence of a minor impurity in most compounds. The structure of this impurity was deduced as an imidazoline-4-one derivative based on (1) H-(13) C and (1) H-(15) H HMBC spectra and was confirmed from the NOESY spectra. The molecules were screened for in vitro activity against recombinant pfENR enzyme by a spectrophotometric assay. Four molecules, viz. 17, 7, 10, and 12 were found to be active at 7, 8, 10, and 12 ?m concentration, respectively, showing promising pfENR inhibitory potential. A classification model was derived based on a binary QSAR approach termed recursive partitioning (RP) to highlight structural characteristics that could be tuned to improve activity. PMID:23398677

Samal, Ramanuj P; Khedkar, Vijay M; Pissurlenkar, Raghuvir R S; Bwalya, Angela Gono; Tasdemir, Deniz; Joshi, Ramesh A; Rajamohanan, P R; Puranik, Vedavati G; Coutinho, Evans C

2013-06-01

65

IR spectroscopy study of the kinetics of the gas-phase reaction between methanol and boron trichloride  

NASA Astrophysics Data System (ADS)

We present the results of a Fourier transform IR spectroscopy study of the kinetics of the gas-phase reaction between methanol and boron trichloride. From spectral data on the kinetics of the process, we determined the rate constant for the reaction of CH3OH and BCl3. The studies were conducted on a setup consisting of a chemical reactor, optically and structurally combined with a commercial AF-3 Fourier transform IR spectrometer.

Balashov, A. A.; Vagin, V. A.; Viskovatykh, A. V.; Kapralova, G. A.; Kradeckiy, V. V.; Khorokhorin, A. I.; Chaikin, A. M.

2013-03-01

66

Background defining during the imine formation reaction in FT-IR liquid cell.  

PubMed

Imine formation is a very important chemical reaction because of its relevance to biological process. Therefore, it is crucial to follow whole reaction process in detail. The current work performed to monitor the whole imination reaction in real time in liquid cell by FT-IR spectroscopy. The complex spectral futures due to solvent, unreacted reagents, acid catalysis and other additives are eliminated by defining a background at the beginning or at any time during the reaction. This procedure also makes it possible to monitor the changes in the concentration of each component in the liquid cell. The consumption of the functional groups of the reagents results in absorbance due to the direct difference spectra while the appearance of functional groups is monitored as percentage transmittance. The concentration changes in the cell arising from the reaction gives the product spectra without having to isolate it from the mixture. It is also possible to see the intermediates appearing and disappearing during the reaction. This report also illustrates a brief application of the technique by time dependence of the peak highs in absorption (ABS) mode. PMID:16095956

Namli, Hilmi; Turhan, Onur

2006-05-01

67

Time-resolved IR observation of a photocatalytic reaction of pivalic acid on platinized titanium dioxide  

NASA Astrophysics Data System (ADS)

Photodegradation of pivalic acid [(CH3)3CCOOH] on a Pt/TiO2 photocatalyst was studied by time-resolved IR spectroscopy in the microsecond-to-millisecond time region. A vibrational band due to t-butyl radical species, as a reaction intermediate, was observed at 1456 cm-1 along with decrease of reactant, bridge-adsorbed pivalate, and product formation. The product did not have vibrational bands in the CC double bond stretch region, suggesting that the main product was isobutane instead of isobutene, which was the main product in the photoreaction of pivalate on the rutile TiO2 (1 1 0) single crystal.

Maeda, Akihiro; Ishibashi, Taka-aki

2013-06-01

68

Kinetic study of the reaction CH (X 2Pi) + H2 yields CH2 (X 3B1) + H in the temperature range 372 to 675 K  

NASA Technical Reports Server (NTRS)

The kinetics of the reversible reaction CH (X 2Pi) + H2 yields CH2 (X 3B1) + H at 372-675 K and total pressure 100 torr (mainly Ar) is investigated experimentally. The ground-state CH radicals are produced by photolysis of CHBr3 using 10-mJ 266-nm laser pulses (repetition rate 10 Hz) and monitored by measuring the fluorescence induced by a 429.8-nm dye laser, in the apparatus described by Berman et al. (1982) and Berman and Lin (1984). The results are presented in tables and graphs and characterized. The absolute rate constants for the forward and reverse reactions are determined, and their temperature dependence is given by Arrhenius expressions and formulas obtained in transition-state-theory calculations. The heat of formation of CH2 at 0 K is estimated (assuming that the recombination reaction CH2 + H has zero activation energy) as 92.6 + or - 0.5 kcal/mol.

Zabarnick, S.; Fleming, J. W.; Lin, M. C.

1986-01-01

69

Aza-Diels-Alder reaction between N-aryl-1-oxo-1H-isoindolium ions and tert-enamides: Steric effects on reaction outcome  

PubMed Central

Summary The synthesis of 5-substituted 6,6a-dihydroisoindolo[2,1-a]quinolin-11(5H)-ones via [4 + 2] imino-Diels–Alder cyclization from N-aryl-3-hydroxyisoindolinones and N-vinyl lactams under Lewis acid-catalysed anhydrous conditions is reported. Reactions of N-(2-substituted-aryl)-3-hydroxyisoindolinones with N-vinylpyrrolidone under identical conditions resulted in the formation of 2-(2-substitued-aryl)-3-(2-(2-oxopyrrolidin-1-yl)vinyl)isoindolin-1-one analogues indicating steric hinderance as the cause of deviation. The probable mechanism of the reaction based on the results from X-ray crystallography and molecular modelling is discussed.

Chou, Ting-Yi; ALJaroudi, Zainab; Ellis, Bobby D; Cameron, T Stanley

2014-01-01

70

Time-resolved 1H and 13C NMR spectroscopy for detailed analyses of the Azotobacter vinelandii mannuronan C-5 epimerase reaction.  

PubMed

AlgE2, AlgE4, and AlgE6 are members of a family of mannuronan C-5 epimerases encoded by Azotobacter vinelandii, and are active in the biosynthesis of alginate, where they catalyze the post-polymerization conversion of beta-D-mannuronic acid residues into alpha-L-guluronic acid residues. To study the kinetics and mode of action of these enzymes, homopolymeric mannuronan and other alginate samples with various composition were epimerized by letting the enzymatic reaction take place in an NMR tube. Series of 1H NMR spectra were recorded to obtain a time-resolved picture of the epimerization progress and the formation of specific monomer sequences. Starting from mannuronan, guluronic acid contents of up to 82% were introduced by the enzymes, and the product specificity, substrate selectivity, and reaction rates have been investigated. To obtain direct information of the GulA-block formation, similar experiments were performed using a 13C-1-enriched mannuronan as substrate. The NMR results were found to be in good agreement with data obtained by a radioisotope assay based on 3H-5-labeled substrates. PMID:11985894

Hartmann, Martin; Duun, Anne Sissel; Markussen, Sidsel; Grasdalen, Hans; Valla, Svein; Skjåk-Braek, Gudmund

2002-03-15

71

1H, 13C NMR, FT-IR, ESI MS and PM5 studies of a new 3,6,9-trioxadecylamide of monensin A and its complexes with Li +, Na + and K + cations  

NASA Astrophysics Data System (ADS)

A new 3,6,9-trioxadecylamide of monensin A (M-AM4) has been synthesised and its ability to form complexes with Li +, Na + and K + cations has been studied by ESI mass spectrometry, 1H and 13C NMR, FT-IR spectroscopy and PM5 semiempirical method. The ESI MS data indicate that M-AM4 forms complexes with Li +, Na + and K + of exclusively 1:1 stoichiometry which are stable up to cv = 70 V. The formation of the M-AM4-Na + is strongly favoured. Above cv = 70 the fragmentation process is observed. The spectroscopic studies show that the structures of the M-AM4 and its complexes with the cations of 1:1 stoichiometry are stabilized by intramolecular hydrogen bonds in which the OH groups are always involved. The C dbnd O amide group is engaged in the complexation process of each cation. The M-AM4-K + complex can also assume a structure in which the C dbnd O amide group does not participate in the complexation but the complexes of such structure do not dominate.

?owicki, Daniel; Huczy?ski, Adam; Brzezinski, Bogumil; Bartl, Franz

2011-03-01

72

Spectroscopic (IR, Raman, UV, 1H and 13C NMR) and microbiological studies of Fe(III), Ni(II), Cu(II), Zn(II) and Ag(I) picolinates  

NASA Astrophysics Data System (ADS)

The FT-IR, Raman spectra of picolinic acid as well as Fe(III), Zn(II), Cu(II), Ni(II) and Ag(I) picolinates were registered, assigned and compared. Some regularities in the spectra of studied picolinates within the regions: 1650-1340 cm -1 [ ?(CC) ar, ?as(COO -), ?s(COO -)]; 1300-1020 cm -1 [ ?(CH)]; 780-620 cm -1 [ ?(CH), ?(CCC)] were found. 1H and 13C NMR spectra for picolinic acid, Zn(II) and Ag(I) picolinates were recorded and studied as well. Moreover the UV spectra of picolinic and picolinates were registered and compared. The influence of Ag(I), Zn(II), Ni(II), Cu(II) and Fe(III) on the electronic system of picolinic acid was investigated. The microbiological activity of picolinates against two species of bacteria: Escherichia coli, Bacillus subtilis as well as two species of yeasts: Saccharomyces cerevisiae and Hansenula anomala was also studied.

Kalinowska, M.; Borawska, M.; ?wis?ocka, R.; Piekut, J.; Lewandowski, W.

2007-05-01

73

Syntheses and biological activities of octahydro-1H-cyclopenta[d]pyrimidine derivatives.  

PubMed

Various nitromethylene derivatives were synthesized regioselectively. Compounds 8a-f were obtained by the reaction of 1-((5-chloropyridin-2-yl)methyl)-2-(nitromethylene)-octahydro-1H-cyclopenta[d]-pyrimidine (3) with primary amines and formaldehyde. The synthesized compounds were identified by 1H NMR, HRMS (EI), and IR, and preliminary bioassays indicated that most of them showed moderate insecticidal activities against Aphis craccivora. The relationship between hydrophobicity and biological activity was also discussed. PMID:17199325

Tian, Zhongzhen; Jiang, Zhaoxing; Li, Zhong; Song, Gonghua; Huang, Qingchun

2007-01-10

74

The adsorption and reaction of normal alkanes on the Ir(110)-(1 × 2) surface  

NASA Astrophysics Data System (ADS)

Previous studies of the adsorption and reaction of ethane and propane on the Ir(110)-(1 × 2) surface have been extended to the normal isomers of butane, pentane, hexane and heptane. At low coverages, each of these alkanes undergoes dissociative chemisorption at 125-130 K. At higher coverages, molecular adsorption occurs as well. Thermal desorption spectra of hydrogen are similar in many respects for the dissociative adsorption of all six of these paraffins, and both desorption-limited and reaction-limited adstates are observed. The latter are associated with the dehydrogenation of hydrocarbon fragments on the surface. Ethane, butane and hexane form high temperature adstates, the associated fragments of which are low in hydrogen content, while those for propane, pentane and heptane contain relatively more hydrogen. This difference may be explained in terms of a model for dehydrogenation which has been proposed previously [T.S. Wittrig, P.D. Szuromi and W.H. Weinberg, J. Chem. Phys. 76, (1982) 3305] in understanding the reaction of other hydrocarbons on this surface.

Szuromi, P. D.; Weinberg, W. H.

1985-01-01

75

Guided ion beam and theoretical study of the reactions of Ir+ with H2, D2, and HD.  

PubMed

We present the kinetic energy dependence of reactions of the late third-row transition metal cation Ir(+) with H(2), D(2), and HD measured using a guided ion beam tandem mass spectrometer. A flow tube ion source produces Ir(+) ions in its electronic ground state term and primarily in the ground spin-orbit level. Corresponding state-specific reaction cross sections are obtained. The kinetic energy dependence of the cross sections for forming IrH(+) and IrD(+) are analyzed to give a 0 K bond dissociation energy of D(0)(Ir(+)-H) = 3.12 +/- 0.06 eV. Ab initio calculations at the B3LYP/HW+/6-311+G(3p), BHLYP/HW+/6-311+G(3p), and QCISD(T)/HW+/6-311+G(3p) levels performed here show reasonable agreement with the experimental bond energies and with the previous theoretical values available. Theory also provides the electronic structures of these species and the reactive potential energy surfaces. We also compare this third-row transition metal system with those of the first-row and second-row congeners Co(+) and Rh(+). We find that Ir(+) has a stronger M(+)-H bond, which can be explained by the lanthanide contraction and relativistic effects that alter the relative size of the valence s and d orbitals. Results from reactions with HD provide insight into the reaction mechanisms and indicate that Ir(+) reacts largely via an insertion mechanism, in contrast with the lighter group 9 metal ions Co(+) and Rh(+) which react via direct mechanisms. PMID:16851979

Li, Feng-Xia; Zhang, Xiao-Guang; Armentrout, P B

2005-05-01

76

A novel one-pot pseudo-five-component condensation reaction towards bifunctional diazepine-tetrazole containing compounds: synthesis of 1H-tetrazolyl-1H-1,4-diazepine-2,3-dicarbonitriles and 1H-tetrazolyl-benzo[b][1,4]diazepines.  

PubMed

A novel and efficient method has been developed for the one-pot synthesis of bifunctional diazepine-tetrazole containing compounds. 1H-Tetrazolyl-1H-1,4-diazepine-2, 3-dicarbonitrile and 1H-tetrazolyl-benzo[b][1,4]diazepine derivatives were synthesized in good yields using 2,3-diaminomaleonitrile or an aromatic diamine, ketones, trimethylsilyl azide, and an isocyanide in the presence of p-toluenesulfonic acid as a catalyst in methanol at room temperature. PMID:22592603

Mofakham, Hamid; Shaabani, Ahmad; Mousavifaraz, Sajjad; Hajishaabanha, Fatemeh; Shaabani, Shabnam; Ng, Seik Weng

2012-05-01

77

Platinum-monolayer Electrocatalysts: Palladium Interlayer on IrCo Alloy Core Improves Activity in Oxygen-reduction Reaction  

SciTech Connect

We describe the synthesis and electrocatalytic properties of a new low-Pt electrocatalyst consisting of an IrCo core, a Pd interlayer, and a surface Pt monolayer, emphasizing the interlayer's role in improving electrocatalytic activity for the oxygen-reduction reaction on Pt in HClO{sub 4} solution. We prepared the IrCo alloys by decomposing, at 800 C, hexacyanometalate, KCoIr(CN){sub 6}, adsorbed on the carbon surfaces. The synthesis of Ir{sub 3}Co/C involved heating a mix of metal salts and carbon in hydrogen at 500 C. Thereafter, we placed a palladium and/or platinum monolayer on them via the galvanic displacement of an underpotentially deposited copper monolayer. The electrocatalysts were characterized using structural- and electrochemical-techniques. For PtML/PdML/IrCo/C, we observed a Pt mass activity of 1.18 A/mg{sub (Pt)} and the platinum-group-metals mass of 0.16 A/mg{sub (Pt, Pd, Ir)}. In comparison, without a Pd interlayer, i.e., Pt{sub ML}/IrCo/C, the activities of 0.15 A/mg{sub (Pt)} and 0.036 A/mg{sub (Pt, Pd, Ir)} were considerably lower. We consider that the palladium interlayer plays an essential role in achieving high catalytic activity by adjusting the electronic interaction of the platinum monolayer with the IrCo core, so that it accelerates the kinetics of adsorption and desorption of the intermediates of oxygen reduction. A similar trend was observed for Pt{sub ML}/Pd{sub ML} and Pt{sub ML} deposited on Ir{sub 3}Co/C alloy core. We used density functional theory to interpret the observed phenomena.

Gong, K.; Chen, W.-F.; Sasaki, K.; Su, D.; Vukmirovic, M.B.; Zhou, W.; Izzo, E.L.; Perez-Acosta, C.; Hirunsit, P.; Balbuena, P.B.; Adzic, R.R.

2010-11-15

78

Infrared study on the formation of isocyanate in the NO and CO reaction on supported IR catalyst  

Microsoft Academic Search

An infrared study on the formation of isocyanate in the NO + CO reaction on supported Ir catalyst was conducted to elucidate the mechanism of ammonia formation during catalytic treatment of automobile exhaust gases and to develop a new catalytic route for ammonium isocyanate and isocyanic acid. On reduced iridium supported on alumina, silica, titanium dioxide, or magnesium oxide, the

F. Solymosi; J. Rasko

1980-01-01

79

Characterization of yellow pigments formed on reaction of 2-(1 H-pyrrolyl)carboxylic acids with pyruvic acid in garlic greening model systems  

Microsoft Academic Search

Two new pyrrole derivatives 2-(1H-pyrrol-1-yl)succinic acid (P-Asp) and 2-(1H-pyrrol-1-yl)pentanedioic acid (P-Glu) were synthesized to study their effect on garlic greening, the structures of which are similar to that of a previously proposed pigment precursor for garlic greening. The puree of freshly harvested garlic bulbs turned green after being soaked in solutions of the two compounds. Also, it was found that

Dan Hu; Jian Zhang; Tuo Zhang; Jing Dong; Xiaojing Leng; Guanghua Zhao

2010-01-01

80

Excitation functions of 186,187,188,189,190,192Ir formed in proton-induced reactions on highly enriched 192Os up to 66 MeV  

NASA Astrophysics Data System (ADS)

Cross sections of proton-induced nuclear reactions on highly enriched 192Os were measured up to 66 MeV by using the stacked-foil irradiation technique. Excitation functions are presented for the reactions 192Os(p,n) 192Ir, 192Os(p,3n) 190Ir, 192Os(p,4n) 189Ir, 192Os(p,5n) 188Ir, 192Os(p,6n) 187Ir and 192Os(p,7n) 186Ir. No earlier experimental cross-section data could be found in the literature except for the 192Os(p,n) 192Ir process. Our new experimental results are compared with theoretical predictions by means of the theoretical model code ALICE/ASH. Integral thick-target yield calculations were also performed for the 192Os(p,n) 192Ir and 192Os(p,3n) 190Ir reactions to evaluate the 190Ir contamination level, as a function of energy, in the case of 192Ir productions.

Szelecsényi, F.; Vermeulen, C.; Steyn, G. F.; Kovács, Z.; Aardaneh, K.; van der Walt, T. N.

2010-10-01

81

Reinvestigating the reaction of 1H-pyrazol-5-amines with 4,5-dichloro-1,2,3-dithiazolium chloride: a route to pyrazolo[3,4-c]isothiazoles and pyrazolo[3,4-d]thiazoles.  

PubMed

The reaction of Appel salt 1 with 1H-pyrazol-5-amines 2 gives main products N-(4-chloro-5H-1,2,3-dithiazol-5-ylidene)-1H-pyrazol-5-amines 3, and 6H-pyrazolo[3,4-c]isothiazole-3-carbonitriles 5, together with several minor side products. When the pyrazoles are N-1 methylated, the product ratio 3:5 can be modified by adjusting the pH of the reaction medium: acidic conditions favor formation of the dithiazolylidenes 3, while basic conditions favor formation of pyrazolo[3,4-c]isothiazoles 5. Furthermore, thermolysis of N-(4-chloro-5H-1,2,3-dithiazol-5-ylidene)-1H-pyrazol-5-amines 3 gives 1H-pyrazolo[3,4-d]thiazole-5-carbonitriles 4. Single crystal X-ray crystallography supports the structure of 4,6-dimethyl-6H-pyrazolo[3,4-c]isothiazole-3-carbonitrile (5a) and helps resolve a previous incorrect structural assignment of 1H-pyrazolo[3,4-d]thiazole-5-carbonitriles 4. PMID:24734990

Koyioni, Maria; Manoli, Maria; Manolis, Manos J; Koutentis, Panayiotis A

2014-05-01

82

Spectroscopy of A˜190 Ir-Pt-Au Nuclei Near Stability from Complete and Incomplete Fusion Reaction  

NASA Astrophysics Data System (ADS)

High-spin states of 194, 195Au, 195Pt and 193Ir have been studied using an in-beam ?-ray spectroscopic technique following the reaction of 7Li on an 192Os target at 44 MeV. The emitted ? rays were observed using an array of 14 Compton-suppressed HPGe detectors. Several bands in these nuclei have been identified and extended up to high-spin states. The ? and t emission channels leading to 193Ir and 195Pt, respectively, are strongly enhanced which may be explained by incomplete fusion reaction; the t and ? fragments from the break-up of weakly bound 7Li nucleus fusion with 192Os target.

Fang, Y. D.; Zhang, Y. H.; Zhou, X. H.; Liu, M. L.; Wang, J. G.; Guo, Y. X.; Lei, X. G.; Hua, W.; Ma, F.; Wang, S. C.; Gao, B. S.; Li, S. C.; Wu, X. G.; He, C. Y.; Zheng, Y.; Wang, Z. M.; Shi, Y.; Xu, F. R.

2013-11-01

83

Reaction of benzoyl chlorides with Huisgen's zwitterion: synthesis of functionalized 2,5-dihydro-1 H-pyrroles and tetrasubstituted furans  

Microsoft Academic Search

The 1:1 intermediate generated by the addition of alkyl(aryl) isocyanides to dimethyl acetylenedicarboxylate is trapped by benzoyl chloride to yield functionalized 2,5-dihydro-1H-pyrroles. The presence of electron-withdrawing groups at the para position of benzoyl chloride leads to tetrasubstituted furans. The structures of these products were confirmed by single-crystal X-ray diffraction studies.

Issa Yavari; Ako Mokhtarporyani-Sanandaj; Loghman Moradi; Anvar Mirzaei

2008-01-01

84

Experimental study of the A(e,e{sup '}pi{sup +}) reaction on {sup 1}H, {sup 2}H, {sup 12}C, {sup 27}Al, {sup 63}Cu, and {sup 197}Au  

SciTech Connect

Cross sections for the {sup 1}H(e,e{sup '}pi{sup +})n process on {sup 1}H, {sup 2}H, {sup 12}C, {sup 27}Al, {sup 63}Cu, and {sup 197}Au targets were measured at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) to extract nuclear transparencies. Data were taken from Q{sup 2}=1.1-4.7 GeV{sup 2} for a fixed center-of-mass energy of W=2.14 GeV. The ratio of sigma{sub L} and sigma{sub T} was extracted from the measured cross sections for {sup 1}H, {sup 2}H, {sup 12}C, and {sup 63}Cu targets at Q{sup 2}=2.15 and 4.0 GeV{sup 2}, allowing for additional studies of the reaction mechanism. In this article, we present the experimental setup and the analysis of the data in detail, including systematic uncertainty studies. Differential cross sections and nuclear transparencies as a function of the pion momentum at different values of Q{sup 2} are presented. Our results are consistent with the predicted early onset of color transparency in mesons. Global features of the data are discussed and the data are compared with model calculations for the {sup 1}H(e,e{sup '}pi{sup +})n reaction from nuclear targets.

Qian, X.; Gao, H.; Kramer, K. [Triangle Universities Nuclear Laboratory, Duke University, Durham, North Carolina (United States); Horn, T. [University of Maryland, College Park, Maryland (United States); Physics Division, TJNAF, Newport News, Virginia (United States); Clasie, B.; Seely, J. [Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, Massachusetts (United States); Arrington, J.; El Fassi, L.; Zheng, X. [Argonne National Laboratory, Argonne, Illinois (United States); Asaturyan, R.; Mkrtchyan, H.; Navasardyan, T.; Tadevosyan, V. [Yerevan Physics Institute, Yerevan (Armenia); Benmokhtar, F. [University of Maryland, College Park, Maryland (United States); Boeglin, W.; Markowitz, P. [Florida International University, Miami, Florida (United States); Bosted, P.; Bruell, A.; Chudakov, E.; Ent, R. [Physics Division, TJNAF, Newport News, Virginia (United States)

2010-05-15

85

Remarkable performance of Ir1/FeO(x) single-atom catalyst in water gas shift reaction.  

PubMed

High specific activity and cost effectiveness of single-atom catalysts hold practical value for water gas shift (WGS) reaction toward hydrogen energy. We reported the preparation and characterization of Ir single atoms supported on FeO(x) (Ir1/FeO(x)) catalysts, the activity of which is 1 order of magnitude higher than its cluster or nanoparticle counterparts and is even higher than those of the most active Au- or Pt-based catalysts. Extensive studies reveal that the single atoms accounted for ?70% of the total activity of catalysts containing single atoms, subnano clusters, and nanoparticles, thus serving as the most important active sites. The Ir single atoms seem to greatly enhance the reducibility of the FeO(x) support and generation of oxygen vacancies, leading to the excellent performance of the Ir1/FeO(x) single-atom catalyst. The results have broad implications on designing supported metal catalysts with better performance and lower cost. PMID:24090210

Lin, Jian; Wang, Aiqin; Qiao, Botao; Liu, Xiaoyan; Yang, Xiaofeng; Wang, Xiaodong; Liang, Jinxia; Li, Jun; Liu, Jingyue; Zhang, Tao

2013-10-16

86

Mechanisms and reaction pathways for simultaneous oxidation of NOx and SO? by ozone determined by in situ IR measurements.  

PubMed

Ozone (O3) oxidation combined with wet scrubbing is a promising method for the simultaneous removal of SO2 and NOx in flue gas. In this study, the O3 oxidation processes of NO and SO2, as well as their coexistence, were investigated using an in situ IR spectrometer. Experimental results showed that the O3 concentration and the reaction temperature played critical roles in the O3 oxidation process of NO. Around 80°C, when inlet molar ratio of O3/NO was less than 1, NO was mainly oxidized to NO2, while when the ratio was greater than 1, NO would be further oxidized to NO3, N2O5, and HNO3. NO3 was the key intermediate product for the formation of N2O5 and HNO3. However, the subsequent reactions of NO3 were temperature dependence. With the increase of reaction temperature above 100°C, the concentration of NO2 increased whereas the concentrations of N2O5 and HNO3 decreased. The oxidation of SO2 by O3 was negligible and SO2 had little influence on the oxidation of NO in the simultaneous oxidation of NO and SO2. Finally, based on the in situ IR results, the oxidation mechanism is discussed and the reaction pathways are proposed. PMID:24801895

Sun, Chenglang; Zhao, Nan; Zhuang, Zhuokai; Wang, Haiqiang; Liu, Yue; Weng, Xiaole; Wu, Zhongbiao

2014-06-15

87

Reaction kinetics of solid-state cyclization of enalapril maleate investigated by isothermal FT-IR microscopic system.  

PubMed

To investigate the reaction kinetics of the solid-state degradation process of enalapril maleate, a Fourier transform infrared microspectroscope equipped with thermal analyzer (thermal FT-IR microscopic system) was used. The isothermal stability study was conducted at 120-130 degrees C for 1-2 h and changes in the three-dimensional plots of the IR spectra of enalapril maleate with respect to heating time were observed. The study indicates that the bands at 1649, 1728, and 1751 cm(-1) assigned to intact enalapril maleate gradually reduced in peak intensity with heating time. However, the peak intensities at 1672 and 1738 cm(-1) (due to enalapril diketopiperazine (DKP) formation) and at 3250 cm(-1) (corresponding to water formation) gradually increased with heating time. The solid-state diketopiperazine formation and the degradation process of enalapril maleate via intramolecular cyclization were found to be simultaneous. The isothermal decomposition curves were sigmoidal and were characterized by induction and acceleration periods, indicating the presence of autocatalytic solid-state decompositions. Moreover, the power-law equation (n = 1/4) was found to provide the best fit to the kinetics of decomposition. This isothermal FT-IR microscopic system was easily used to investigate the degradation of enalapril maleate and the concomitant formation of DKP. The solid-state reaction of enalapril maleate required an activation energy of 195+/-12 kJ/mol to undergo the processes of decomposition and intramolecular cyclization. PMID:11310665

Wang, S L; Lin, S Y; Chen, T F

2001-04-01

88

An FT-IR study on Diels Alder reactions catalysed by heteropoly acid containing sol gel silica  

NASA Astrophysics Data System (ADS)

Following the general trend of using heterogeneous catalysts whenever possible, the replacement of traditional homogeneous Lewis acid catalysts for the Diels-Alder reaction is currently considered in the literature. In this contribution, we report the successful application of sol-gel derived tungstophosphoric acid-silica composites as catalysts in the reaction of 1,3-cyclohexadiene and 2-propenal. The reaction was monitored by in situ FT-IR spectroscopy following the changes in the fine structure of the ?(C?O) band. The catalytic activity of the sol-gel immobilised heteropoly acids seems to be comparable with that of more conventional sol-gel silica-aluminas and their selectivity is even better because Broensted acid sites are destroyed upon calcination of the dry gel.

Kukovecz, Á.; Kónya, Z.; Kiricsi, I.

2001-05-01

89

Infrared spectra of XC[triple bond]IrX(3) and CX(2)=IrX(2) prepared by reactions of laser-ablated iridium atoms with halomethanes.  

PubMed

Small iridium high oxidation-state complexes with carbon-iridium multiple bonds are identified in the product matrix infrared spectra from reactions of laser-ablated Ir atoms with tetra-, tri- and dihalomethanes. In contrast to the previously studied Rh case, Ir carbyne complexes (XC[triple bond]IrX(3)) are generated in reactions of tetrahalomethanes, and their short Ir-C bond lengths of 1.725-1.736 A are appropriate for the carbon-metal triple bonds. DFT calculations also show that the Ir carbynes with an Ir-F bond have unusual square planar structures, similar to the recently discovered Ru planar complexes. Diminishing preference for the carbyne complexes leads to methylidene product absorptions in the tri- and dihalomethane spectra, marking a limit for generation of small metal carbynes. The insertion complexes, on the other hand, are not observed in this study, suggesting that X migration from C to Ir following initial C-X insertion is swift. PMID:20442951

Cho, Han-Gook; Andrews, Lester

2010-06-21

90

Improved 192,194,195,196Pt(n,?) and 192Ir(n,?) astrophysical reaction rates  

NASA Astrophysics Data System (ADS)

192Pt is produced solely by the slow neutron capture (s) nucleosynthesis process and hence an accurate (n,?) reaction rate for this nuclide would allow its use as an important calibration point near the termination of the s-process nucleosynthesis flow. For this reason, we have measured neutron capture and total cross sections for 192,194,195,196,natPt in the energy range from 10 eV to several hundred keV at the Oak Ridge Electron Linear Accelerator. Measurements on the other Pt isotopes were, in part, necessitated by the fact that only a relatively small 192Pt sample of modest enrichment was available. Astrophysical 192,194,195,196Pt(n,?) reaction rates, accurate to approximately 3%-5%, were calculated from these data. No accurate reaction rates have been published previously for any of these isotopes. At s-process temperatures, previously recommended rates are larger (by as much as 35%) and have significantly different shapes as functions of temperature than our new rates. We used our new Pt results, together with 191,193Ir(n,?) data, to calibrate nuclear statistical model calculations and hence obtain an improved rate for the unmeasured s-process branching-point isotope 192Ir.

Koehler, P. E.; Guber, K. H.

2013-09-01

91

Preignition reactions of AP-HTPB propellants studied by IR spectrometry. [Ammonium Perchlorate-Hydroxyl Terminated PolyButadiene  

NASA Technical Reports Server (NTRS)

IR absorption spectrometry was used to follow the disappearance of NH and CH bonds during the pyrolysis of a polymer film containing 30 weight percent ammonium perchlorate (AP). The remaining 70 weight percent consisted of a mixture of 92.5 weight percent hydroxyl-terminated polybutadiene (HTPB) and 7.5 weight percent isophrone diisocyanate (IPDI). The results indicate that polymer decomposition is induced by products of AP decomposition, and that about 2.5 CH bonds disappear for each NH bond that disappears. The diffusion process occurring in the later stages of the reaction is analyzed in an attempt to account for the unexpectedly low activation energy.

Law, R. J.; Baer, A. D.; Ryan, N. W.

1977-01-01

92

Bimetallic IrNi Core Platinum Monolayer Shell Electrocatalysts for the Oxygen Reduction Reaction  

SciTech Connect

We synthesized a low-Pt content electrocatalyst consisting of a Pt monolayer placed on carbon-supported thermally treated IrNi core-shell structured nanoparticles using galvanic displacement of a Cu monolayer deposited at underpotentials. The Pt mass activity of the Pt{sub ML}/IrNi/C electrocatalyst obtained in a scale-up synthesis is approximately 3 times higher than that of the commercial Pt/C electrocatalyst. The electronic and geometrical effects of the IrNi substrate on the Pt monolayer result in its higher catalytic activity than that of Pt nanoparticles. The structure and composition of the core-shell nanoparticles were verified using transmission electron microscopy and in situ X-ray absorption spectroscopy, while a potential cycling test was employed to confirm the stability of the electrocatalyst. Our experimental results, supported by the density functional calculations using a sphere-like model, demonstrate an effective way of using Pt that can resolve key problems of cathodic oxygen reduction hampering fuel cell commercialization.

Kuttiyiel K. A.; Sasaki, K.; Choi, Y.M.; Su, D.; Liu, P.; Adzic, R.R.

2012-01-01

93

Fluorescence labeling method for aryl halides with 4-(4,5-diphenyl-1H-imidazol-2-yl)phenylboronic acid based on Suzuki coupling reaction.  

PubMed

For the first time, fluorescence labeling methods for aryl halides with a fluorescent arylboronic acid was developed on the basis of a Suzuki coupling reaction. 4-(4,5-diphenyl-lH-imidazol-2-yl)phenylboronic acid (DPA) was used as a fluorescence labeling reagent. In order to explore its analytical performance, the reaction conditions were optimized using simple bromobenzene derivatives. The reactivity was then investigated with chloro- and iodobenzene derivatives, and also bromobenzene derivatives with different position of substituents. The order of reactivity with DPA: iodobenzene > bromobenzene more more than chlorobenzene derivatives, and p- > m- > o-substituted bromobenzenes. The detection limits of bromobenzene, 4-bromotoluene, and 4-bromoanisole ranged from 0.2 to 1.4 pmol/injection at a signal-to-noise ratio, (S/N) of 3. The applicability of the method to biological samples was also evaluated using clofibrate as the analyte. The reaction was found not only to proceed well but also to be selective for clofibrate even in the presence of plasma components. The method allowed the sensitive detection of clofibrate in human plasma with the detection limit of 170 pmol/mL (260 fmol/injection) at a S/N = 3. The proposed method is highly selective and sensitive and thus would be useful for labeling of aryl halides that do not have other functional groups that could be labeled by currently available fluorescent labeling reagents. PMID:15794562

Kuroda, Naotaka; Sugihara, Sumika; Sugihara, Yohko; Wada, Mitsuhiro; Kishikawa, Naoya; Ohba, Yoshihito; Nakashima, Kenichiro

2005-02-25

94

Quantum mechanical and spectroscopic (FT-IR, 13C, 1H NMR and UV) investigations of 2-(5-(4-Chlorophenyl)-3-(pyridin-2-yl)-4,5-dihydropyrazol-1-yl)benzo[d]thiazole by DFT method  

NASA Astrophysics Data System (ADS)

The electronic, NMR, vibrational, structural properties of a new pyrazoline derivative: 2-(5-(4-Chlorophenyl)-3-(pyridine-2-yl)-4,5-dihydropyrazol-1-yl)benzo[d]thiazole has been studied using Gaussian 09 software package. Using VEDA 4 program we have reported the PED potential energy distribution of normal mode of vibrations of the title compound. We have also reported the 1H and 13C NMR chemical shifts of the title compound using B3LYP level of theory with 6-311++G(2d,2p) basis set. Using time dependent (TD-DFT) approach electronic properties such as HOMO and LUMO energies, electronic spectrum of the title compound has been studied and reported. NBO analysis and MEP surface mapping has also been calculated and reported using ab initio methods.

Diwaker

2014-07-01

95

An Efficient One-Pot Green Protocol for the Synthesis of 5-Unsubstituted 3,4-Dihydropyrimidin-2(1H)-Ones Using Recyclable Amberlyst 15 DRY as a Heterogeneous Catalyst via Three-Component Biginelli-Like Reaction.  

PubMed

An environmentally benign green protocol for the synthesis of 5-unsubstituted 3,4-dihydropyrimidin-2(1H)-ones using Amberlyst 15 DRY as a recyclable catalyst has been developed. The use of resinous, nontoxic, thermally stable, and inexpensive Amberlyst 15 DRY, as a recyclable heterogeneous catalyst, makes the process simple with negligible chemical waste. Among the various solid acid catalysts Amberlyst 15 DRY was found to be the most efficient catalyst with regard to reaction time, yield, and ease of work-up procedure. PMID:24052845

Jetti, Srinivasa Rao; Verma, Divya; Jain, Shubha

2012-01-01

96

Charged pion form factor between Q2=0.60 and 2.45 GeV2. I. Measurements of the cross section for the 1H(e,e'pi+)n reaction  

Microsoft Academic Search

Cross sections for the reaction 1H(e,e'pi+)n were measured in Hall C at Thomas Jefferson National Accelerator Facility (JLab) using the high-intensity Continuous Electron Beam Accelerator Facility (CEBAF) to determine the charged pion form factor. Data were taken for central four-momentum transfers ranging from Q2=0.60 to 2.45 GeV2 at an invariant mass of the virtual photon-nucleon system of W=1.95 and 2.22

H. P. Blok; T. Horn; G. M. Huber; E. J. Beise; D. Gaskell; D. J. Mack; V. Tadevosyan; J. Volmer; D. Abbott; K. Aniol; H. Anklin; C. Armstrong; J. Arrington; K. Assamagan; S. Avery; O. K. Baker; B. Barrett; C. Bochna; W. Boeglin; E. J. Brash; H. Breuer; C. C. Chang; N. Chant; M. E. Christy; J. Dunne; T. Eden; R. Ent; H. Fenker; E. Gibson; R. Gilman; K. Gustafsson; W. Hinton; R. J. Holt; H. Jackson; S. Jin; M. K. Jones; C. E. Keppel; P. H. Kim; W. Kim; P. M. King; A. Klein; D. Koltenuk; V. Kovaltchouk; M. Liang; J. Liu; G. J. Lolos; A. Lung; D. J. Margaziotis; P. Markowitz; A. Matsumura; D. McKee; D. Meekins; J. Mitchell; T. Miyoshi; H. Mkrtchyan; B. Mueller; G. Niculescu; I. Niculescu; Y. Okayasu; L. Pentchev; C. Perdrisat; D. Pitz; D. Potterveld; V. Punjabi; L. M. Qin; P. Reimer; J. Reinhold; J. Roche; P. G. Roos; A. Sarty; I. K. Shin; G. R. Smith; S. Stepanyan; L. G. Tang; V. Tvaskis; K. Vansyoc; D. Van Westrum; S. Vidakovic; W. Vulcan; G. Warren; S. A. Wood; C. Xu; C. Yan; W.-X. Zhao; X. Zheng; B. Zihlmann

2008-01-01

97

Adsorption and oxidation of formaldehyde on a polycrystalline Pt film electrode: An in situ IR spectroscopy search for adsorbed reaction intermediates  

PubMed Central

Summary As part of a mechanistic study of the electrooxidation of C1 molecules we have systematically investigated the dissociative adsorption/oxidation of formaldehyde on a polycrystalline Pt film electrode under experimental conditions optimizing the chance for detecting weakly adsorbed reaction intermediates. Employing in situ IR spectroscopy in an attenuated total reflection configuration (ATR-FTIRS) with p-polarized IR radiation to further improve the signal-to-noise ratio, and using low reaction temperatures (3 °C) and deuterium substitution to slow down the reaction kinetics and to stabilize weakly adsorbed reaction intermediates, we could detect an IR absorption band at 1660 cm?1 characteristic for adsorbed formyl intermediates. This assignment is supported by an isotope shift in wave number. Effects of temperature, potential and deuterium substitution on the formation and disappearance of different adsorbed species (COad, adsorbed formate, adsorbed formyl), are monitored and quantified. Consequences on the mechanism for dissociative adsorption and oxidation of formaldehyde are discussed.

Behm, R Jurgen

2014-01-01

98

Multivariate data analysis as a tool to investigate the reaction kinetics of intramolecular cyclization of enalapril maleate studied by isothermal and non-isothermal FT-IR microscopy  

Microsoft Academic Search

In this paper, the use of multivariate data analysis approach to investigate the kinetics of solid-state reaction monitored via FT-IR thermal microscopy is discussed. The solid-state degradation of enalapril maleate was monitored non-isothermally at temperature range from 25 to 200°C and isothermally at various temperatures (115, 120, 125, 130, and 135°C) for a few hours. The collected FT-IR spectra were

Effendi Widjaja; Geok Hong Lim; Pui Shan Chow; Selvi Tan

2007-01-01

99

Palladium-catalysed cross-coupling reaction of ultra-stabilised 2-aryl-1,3-dihydro-1H-benzo[d]1,3,2-diazaborole compounds with aryl bromides: A direct protocol for the preparation of unsymmetrical biaryls  

PubMed Central

Summary There has been a significant interest in organoboron compounds such as arylboronic acids, arylboronate esters and potassium aryltrifluoroborate salts because they are versatile coupling partners in metal-catalysed cross-coupling reactions. On the other hand, their nitrogen analogues, namely, 1,3,2-benzodiazaborole-type compounds have been studied extensively for their intriguing absorption and fluorescence characteristics. Here we describe the first palladium-catalysed Suzuki–Miyaura cross-coupling reaction of easily accessible and ultra-stabilised 2-aryl-1,3-dihydro-1H-benzo[d]1,3,2-diazaborole derivatives with various aryl bromides. Aryl bromides bearing electron-withdrawing, electron-neutral and electron-donating substituents are reacted under the catalytic system furnishing unsymmetrical biaryl products in isolated yields of up to 96% in only 10 minutes.

Sithebe, Siphamandla

2014-01-01

100

A Study of Ethanol Reactions over Pt\\/CeO 2 by Temperature-Programmed Desorption and in Situ FT-IR Spectroscopy: Evidence of Benzene Formation  

Microsoft Academic Search

The reaction of ethanol over unreduced and H2-reduced 1 wt% Pt\\/CeO2 has been investigated primarily by temperature-programmed desorption (TPD) and in situ Fourier transform infrared spectroscopy (FT-IR). Steady state reactions have been conducted to provide information regarding the kinetics of the above reaction. Characterisation of the catalyst has been achieved through the use of XPS and titration of surface metal

Anna Yee; Scott J. Morrison; Hicham Idriss

2000-01-01

101

Influence of brachytherapy ( sup 192 Ir afterloading) on cell-mediated immune reactions in patients with stage I endometrial cancer  

SciTech Connect

The influence of radiation therapy on cell-mediated immune reactions in cancer patients seems to depend on source, dose, and area of irradiation, as well as on the variables reflected by the patient population investigated. In the present study we demonstrated that brachytherapy ({sup 192}Ir afterloading), applied to patients with inoperable stage I endometrial cancer, has no immediate or sustained effect on lymphocyte function. Both lymphocyte mitogen response and natural killer cell (NK) activity are not significantly changed in terms of baseline values compared with test results during and after therapy. Brachytherapy, as used in this study, has no influence on cell-mediated immunity in patients with endometrial cancer stage I.

Gerstner, G.J.; Kucera, H.; Kudlacek, S.; Micksche, M. (Vienna Univ. Medical School (Austria))

1989-11-01

102

Time-Resolved O3 Chemical Chain Reaction Kinetics Via High-Resolution IR Laser Absorption Methods  

NASA Technical Reports Server (NTRS)

Excimer laser photolysis in combination with time-resolved IR laser absorption detection of OH radicals has been used to study O3/OH(v = 0)/HO2 chain reaction kinetics at 298 K, (i.e.,(k(sub 1) is OH + 03 yields H02 + 02 and (k(sub 2) is H02 + 03 yields OH + 202). From time-resolved detection of OH radicals with high-resolution near IR laser absorption methods, the chain induction kinetics have been measured at up to an order of magnitude higher ozone concentrations ([03] less than or equal to 10(exp 17) molecules/cu cm) than accessible in previous studies. This greater dynamic range permits the full evolution of the chain induction, propagation, and termination process to be temporally isolated and measured in real time. An exact solution for time-dependent OH evolution under pseudo- first-order chain reaction conditions is presented, which correctly predicts new kinetic signatures not included in previous OH + 03 kinetic analyses. Specifically, the solutions predict an initial exponential loss (chain "induction") of the OH radical to a steady-state level ([OH](sub ss)), with this fast initial decay determined by the sum of both chain rate constants, k(sub ind) = k(sub 1) + k(sub 2). By monitoring the chain induction feature, this sum of the rate constants is determined to be k(sub ind) = 8.4(8) x 10(exp -14) cu cm/molecule/s for room temperature reagents. This is significantly higher than the values currently recommended for use in atmospheric models, but in excellent agreement with previous results from Ravishankara et al.

Kulcke, Axel; Blackmon, Brad; Chapman, William B.; Kim, In Koo; Nesbitt, David J.

1998-01-01

103

Noise-induced spatiotemporal patterns in a bistable reaction-diffusion system: Photoelectron emission microscopy experiments and modeling of the CO oxidation reaction on Ir(111)  

NASA Astrophysics Data System (ADS)

We use photoelectron emission microscopy (PEEM) measurements to study the spatiotemporal patterns obtained for the CO oxidation reaction on Ir(111) as a function of the noise strength we superpose on the CO and the oxygen fractions of the constant total reactant gas flux. The investigations are focused on the bistable regime this reaction displays including its monostable vicinity. Simultaneously we analyze numerically the underlying reaction-diffusion (RD) equations in two spatial dimensions. For intrinsic and/or small strength of the external noise we find transitions from the locally stable to the globally stable branch via slow nucleation and growth of islands of the globally stable state: oxygen or CO , respectively. With increasing noise strength the number of islands as well as their growth rate increases. These phenomena are very well reproduced by numerical calculations of the RD model. For sufficiently large noise strength we observe bursts from CO rich to oxygen rich and back as well as switching between the two states. While such phenomena are also obtained from the model calculations, their experimentally observed spatial scales were not satisfactorily reproduced using the same approach as for the lower noise strengths.

Hoffmann, Patrick; Wehner, Stefan; Schmeisser, Dieter; Brand, Helmut R.; Küppers, Jürgen

2006-05-01

104

Reactions of laser-ablated Co, Rh, and Ir with CO: Infrared spectra and density functional calculations of the metal carbonyl molecules, cations and anions in solid neon  

SciTech Connect

Laser ablation produces metal atoms, cations, and electrons for reaction with CO during condensation in excess neon at 4 K. Infrared spectra are observed for the metal carbonyls, cations, and anions, which are identified from isotopic shifts ({sup 13}CO, C{sup 18}O) and splittings using mixed isotopic precursors. Density functional calculations with pseudopotentials for Rh and Ir predict the observed carbonyl stretching frequencies within 1--2%. This characterization of the simple RhCO{sup +}, RhCO, and RhCO{sup {minus}} (and Ir) species over a 350 cm{sup {minus}1} range provides a scale for comparison of larger catalytically active Rh and Ir carbonyl complexes in solution and on surfaces to estimate charge on the metal center. This work provides the first spectroscopic characterization of Rh and Ir carbonyl cations and anions except for the stable tetracarbonyl anions in solution.

Zhou, M.; Andrews, L.

1999-09-30

105

Application of an enhanced luminol chemiluminescence reaction using 4-[4,5-di(2-pyridyl)-1H-imidazol-2-yl]phenylboronic acid to photographic detection of horseradish peroxidase on a membrane.  

PubMed

Photographic detection of horseradish peroxidase (HRP) on a membrane by the luminol-hydrogen peroxide-HRP chemiluminescence reaction using 4-[4,5-di(2-pyridyl)-1H-imidazol-2-yl]phenylboronic acid (DPPA) as an enhancer is described. The method is based on the long-lived chemiluminescence emission obtained by using DPPA. Under the optimum conditions, as little as 0.10 ng (ca. 2.3 fmol) and 0.20 ng (ca. 4.6 fmol) per spot of HRP on a membrane were detected as visible spots with exposure time of 60 and 10 min, respectively, by using an instant photographic film and a camera luminometer. The proposed method was highly sensitive and was successfully applied to the detection of HRP conjugates as an alternative to the colorimetric method using a chromogenic substrate in a commercially available assay kit of Western blotting. PMID:11312543

Kuroda, N; Murasaki, N; Wada, M; Nakashima, K

2001-01-01

106

Spectroscopic (FT-IR, FT-Raman and 1H and 13C NMR) and theoretical in MP2/6-311++G(d,p) and B3LYP/6-311++G(d,p) levels study of benzenesulfonic acid and alkali metal benzenesulfonates.  

PubMed

The FT-IR, FT-Raman and NMR ((1)H and (13)C) spectra of benzenesulfonic acid as well as lithium, sodium, potassium, rubidium and caesium benzenesulfonates were registered, assigned and compared. The molecular structures of ligand and alkali metal salts were discussed. On the basis of quantum mechanical calculations in MP2/6-311++G(d,p) and B3LYP/6-311++G(d,p) levels the geometric parameters, infrared spectra, NMR spectra, the magnetic and geometric aromaticity indices for acid and alkali metal benzenesulfonates and benzoates were obtained. The effect of alkali metal ions on the electronic charge distribution of benzenesulfonic acid was studied and compared with the alkali metal benzoates and benzoic acid. PMID:22406243

?widerski, G; Kalinowska, M; ?wis?ocka, R; Wojtulewski, S; Lewandowski, W

2013-01-01

107

IR Characterization of BiPropellant Reaction Control Engines During Auxiliary Propulsion Systems Tests at NASA's White Sands Test Facility In Las Cruces, New Mexico  

Microsoft Academic Search

This paper describes the application of a FLIR Systems A40M infrared (IR) digital camera for thermal monitoring of a Liquid Oxygen (LOX) and Ethanol bi-propellant Reaction Control Engine (RCE) during Auxiliary Propulsion System (APS) testing at the National Aeronautics & Space Administration's (NASA) White Sands Test Facility (WSTF) near Las Cruces, New Mexico. Typically, NASA has relied mostly on the

Elizabeth Holleman

108

Ir-catalyzed preparation of SF5-substituted potassium aryl trifluoroborates via C-H borylation and their application in the Suzuki-Miyaura reaction.  

PubMed

The preparation of new pentafluorosulfanyl-substituted potassium aryltrifluoroborates via Ir-catalyzed C-H borylation is reported. The utility of these novel building blocks was demonstrated in the Suzuki-Miyaura cross-coupling reaction, giving access to 3,5-disubstituted pentafluorosulfanylbenzenes. PMID:24090251

Joliton, Adrien; Carreira, Erick M

2013-10-18

109

Glycyl-histidyl-lysine (GHK) is a quencher of alpha,beta-4-hydroxy-trans-2-nonenal: a comparison with carnosine. insights into the mechanism of reaction by electrospray ionization mass spectrometry, 1H NMR, and computational techniques.  

PubMed

Histidine-containing oligopeptides are currently studied as detoxifying agents against cytotoxic alpha,beta-unsaturated aldehydes (prototype: 4-hydroxy-2-nonenal, HNE), electrophilic end products formed by decomposition of omega-6 polyunsaturated fatty acids, associated with severe pathologies such as diabetes, nephropathy, retinopathy, and neurodegenerative diseases. This study evaluated the quenching reaction against HNE of the endogenous tripeptide l-glycyl- l-histidyl- l-lysine (GHK), an oligopeptide discovered to be a growth-modulating factor and also a strong activator of wound healing. We first evaluated the HNE consumption (50 microM, HPLC-UVDAD method) in the presence of GHK (1 mM) in physiomimetic conditions (phosphate buffer, pH 7.4) and confirmed GHK/HNE adduct formation by mass spectrometric analysis (ESI-MS/MS) and (1)H NMR analyses. These results indicated that GHK was an effective quencher of HNE, although significantly less potent than the reference compound carnosine, and that HNE modulation by GHK can contribute to the satisfactory outcome of the wound-healing process. In the second part of the study, we investigated the quenching reaction between GHK and HNE, in parallel to carnosine, using (1)H NMR and computational analyses. At a mechanistic level, this explained the different reactivity of the two peptides: (i) The greater stability of the macrocyclic intermediate HNE/carnosine was compared to HNE/GHK. (ii) GHK in solution has a quasi-folded conformation due to the interaction of four intramolecular hydrogen bonds, three of which need to be broken for the transition state to form (energy barrier, approximately 20 kcal/mol). By contrast, carnosine, with an extended conformation and only one hydrogen bond, requires less energy to reach the transition state ( approximately 7 kcal/mol). (iii) The different stereoelectronic features of the transition state lead to the intramolecular Michael reaction, that is, the favorable superimposition of carnosine highest occupied molecular orbital and the HNE lowest unoccupied molecular orbital, in relation to the unfavorable orbital configuration of GHK. The overall findings provide interesting and useful insights into the mechanisms of interaction of both GHK and carnosine with HNE and illustrate the utility of computational studies for defining the (optimal) chemical and structural parameters for an optimal quenching of alpha,beta-unsaturated aldehydes. PMID:17672515

Beretta, Giangiacomo; Artali, Roberto; Regazzoni, Luca; Panigati, Monica; Facino, Roberto Maffei

2007-09-01

110

Cross sections and tensor analyzing powers A_yy of the reaction ^1H(|vec|d,pp)n in SCRE geometries at E_d=19 MeV  

SciTech Connect

We measured the cross sections and tensor analyzing powers of the 1H({approx}d,pp)n breakup reaction at Ed=19 MeV in four symmetric constant relative energy (SCRE) configurations. The data are compared with theoretical predictions from three different approaches: one based on high precision (semi)phenomenological potentials alone or combined with model three-nucleon forces, another on chiral forces up to next-to-next-to-leading order (NNLO) in the chiral expansion. In both cases, the Coulomb interaction is not included. In addition, a comparison to predictions based on CD Bonn including the Lambda excitation and the Coulomb force is presented. In all cases the measured cross sections are significantly below the theoretical values whereas the magnitude of the tensor analyzing powers agree within the error bars in three of the four cases. The apparent discrepancies in the breakup cross sections are similar to the known differences for the space-star breakup. This adds to the data base of unsolved low-energy discrepancies.

J. Ley; C. Dueweke; A. Emmerich; A. Imig; H. Paez gen. Schieck; J. Golak; H. Witala; Evgeny Epelbaum; A. Deltuva; A. C. Fonseca; W. Gloeckle; Ulf-G. Meissner; A. Nogga; P. U. Sauer

2006-02-01

111

Charged pion form factor between $Q^2$=0.60 and 2.45 GeV$^2$. I. Measurements of the cross section for the ${^1}$H($e,e'\\pi^+$)$n$ reaction.  

SciTech Connect

DOI: http://dx.doi.org/10.1103/PhysRevC.78.045202
Cross sections for the reaction 1H(e,e'pi+)n were measured in Hall C at Thomas Jefferson National Accelerator Facility (JLab) using the high-intensity Continuous Electron Beam Accelerator Facility (CEBAF) to determine the charged pion form factor. Data were taken for central four-momentum transfers ranging from Q2=0.60 to 2.45 GeV2 at an invariant mass of the virtual photon-nucleon system of W=1.95 and 2.22 GeV. The measured cross sections were separated into the four structure functions sigmaL,sigmaT,sigmaLT, and sigmaTT. The various parts of the experimental setup and the analysis steps are described in detail, including the calibrations and systematic studies, which were needed to obtain high-precision results. The different types of systematic uncertainties are also discussed. The results for the separated cross sections as a function of the Mandelstam variable t at the different values of Q2 are presented. Some global featu

Blok, Henk; Horn, Tanja; Huber, Garth; Beise, Elizabeth; Gaskell, David; Mack, David; Tadevosyan, Vardan; Volmer, Jochen; Abbott, David; Aniol, Konrad; Anklin, Heinz; Armstrong, Christopher; Arrington, John; Assamagan, Ketevi; Avery, Steven; Baker, O.; Barrett, Robert; Bochna, Christopher; Boeglin, Werner; Brash, Edward; Breuer, Herbert; Chang, C.; Chang, C.C.; Chant, Nicholas; Christy, Michael; Dunne, James; Eden, Thomas; Ent, Rolf; Fenker, Howard; Gibson, Edward; Gilman, Ronald; Gustafsson, Kenneth; Hinton, Wendy; Holt, Roy; Jackson, Harold; uk Jin, Seong; Jones, Mark; Keppel, Cynthia; Kim, pyunghun; Kim, Wooyoung; King, Paul; Klein, Andreas; Koltenuk, Douglas; Kovaltchouk, Vitali; Liang, Meihua; Liu, Jinghua; Lolos, George; Lung, Allison; Margaziotis, Demetrius; Markowitz, Pete; Matsumura, Akihiko; McKee, David; Meekins, David; Mitchell, Joseph; Miyoshi, Toshinobu; Mkrtchyan, Hamlet; Mueller, Robert; Niculescu, Gabriel; Niculescu, Maria-Ioana; Okayasu, Yuichi; Pentchev, Lubomir; Perdrisat, Charles; Pitz, David; Potterveld, David; Punjabi, Vina; Qin, Liming; Reimer, Paul; Reinhold, Joerg; Roche, Julie; Roos, Philip; Sarty, Adam; Shin, Ilkyoung; Smith, Gregory; Stepanyan, Stepan; Tang, Liguang; Tvaskis, Vladas; van der Meer, Rob; Vansyoc, Kelley; Van Westrum, Derek; Vidakovic, Sandra; Vulcan, William; Warren, Glen; Wood, Stephen; Xu, C.; Yan, Chen; Zhao, Wenxia; Zheng, Xiaochao; Zihlmann, Benedikt

2008-10-01

112

Synthesis, characterization, and antimicrobial evaluation of carbostyril derivatives of 1H-pyrazole.  

PubMed

A new series of 12 derivatives of 4-pyrazolyl-N-arylquinoline-2,5-dione (4a-l) were synthesized by one pot base catalyzed cyclocondensation reaction of 1-aryl-5-chloro-3-methyl-1H-pyrazole-4-carbaldehyde (1a-c), Meldrum's acid (2) and 3-arylamino-5,5-disubstitutedcyclohex-2-enone (3a-d). All the compounds were characterized by elemental analysis, FT-IR, (1)H NMR and (13)C NMR spectral data and were screened, against six bacterial pathogens, namely Bacillus subtilis, Clostridium tetani, Streptococcus pneumoniae, Salmonella typhi, Vibrio cholerae, Escherichia coli and antifungal activity, against two fungal pathogens Aspergillus fumigatus and Candida albicans, using broth microdilution MIC (minimum inhibitory concentration) method. Some of the compounds were found to be equipotent or more potent than commercial drugs, against most of the employed strains, as evident from the screening data. PMID:23960745

Thumar, Nilesh J; Patel, Manish P

2011-04-01

113

Visible-light-induced, Ir-catalyzed reactions of N-methyl-N-((trimethylsilyl)methyl)aniline with cyclic ?,?-unsaturated carbonyl compounds  

PubMed Central

Summary N-Methyl-N-((trimethylsilyl)methyl)aniline was employed as reagent in visible-light-induced, iridium-catalyzed addition reactions to cyclic ?,?-unsaturated carbonyl compounds. Typical reaction conditions included the use of one equivalent of the reaction substrate, 1.5 equivalents of the aniline and 2.5 mol % (in MeOH) or 1.0 mol % (in CH2Cl2) [Ir(ppy)2(dtbbpy)]BF4 as the catalyst. Two major reaction products were obtained in combined yields of 30–67%. One product resulted from aminomethyl radical addition, the other product was a tricyclic compound, which is likely formed by attack of the intermediately formed ?-carbonyl radical at the phenyl ring. For five-membered ?,?-unsaturated lactone and lactam substrates, the latter products were the only products isolated. For the six-membered lactones and lactams and for cyclopentenone the simple addition products prevailed.

Lenhart, Dominik

2014-01-01

114

Visible-light-induced, Ir-catalyzed reactions of N-methyl-N-((trimethylsilyl)methyl)aniline with cyclic ?,?-unsaturated carbonyl compounds.  

PubMed

N-Methyl-N-((trimethylsilyl)methyl)aniline was employed as reagent in visible-light-induced, iridium-catalyzed addition reactions to cyclic ?,?-unsaturated carbonyl compounds. Typical reaction conditions included the use of one equivalent of the reaction substrate, 1.5 equivalents of the aniline and 2.5 mol % (in MeOH) or 1.0 mol % (in CH2Cl2) [Ir(ppy)2(dtbbpy)]BF4 as the catalyst. Two major reaction products were obtained in combined yields of 30-67%. One product resulted from aminomethyl radical addition, the other product was a tricyclic compound, which is likely formed by attack of the intermediately formed ?-carbonyl radical at the phenyl ring. For five-membered ?,?-unsaturated lactone and lactam substrates, the latter products were the only products isolated. For the six-membered lactones and lactams and for cyclopentenone the simple addition products prevailed. PMID:24778745

Lenhart, Dominik; Bach, Thorsten

2014-01-01

115

Mid-IR band gap engineering of CdxPb1-xS nanocrystals by mechanochemical reaction  

NASA Astrophysics Data System (ADS)

Composition-tunable ternary CdxPb1-xS nanocrystals (NCs) are very important materials for remote sensing and detecting in the infrared (IR) wavelength region. They are, however, almost exclusively prepared by wet chemical routes which lead to surface-capped nanoparticles. The surface capping molecules could move their absorption peaks from mid-IR to near IR wavelength region. However, surface clean CdxPb1-xS nanocrystals (NCs) would demonstrate intrinsic optical spectrum in the mid-IR region. Herein, we present a physical mechanical alloying (MA) process being applied to prepare tens of grams of surface clean CdxPb1-xS nanocrystals within the composition range of x = 0.0 to 0.4. The average particle size is smaller than 9 nm. The as-milled nanocrystals are chemically homogenous. The CdxPb1-xS nanocrystals show a continuous lattice contraction with Cd content. There is an exponential indirect band gap-composition relationship. This MA method shows the ability to continuously and precisely tune the band gap energies of ternary CdxPb1-xS semiconductor nanocrystals from mid-IR region (2638 nm) to NIR wavelength region (1240 nm) through chemical composition.

Tan, Guo-Long; Liu, Limin; Wu, Weibing

2014-06-01

116

Multivariate data analysis as a tool to investigate the reaction kinetics of intramolecular cyclization of enalapril maleate studied by isothermal and non-isothermal FT-IR microscopy.  

PubMed

In this paper, the use of multivariate data analysis approach to investigate the kinetics of solid-state reaction monitored via FT-IR thermal microscopy is discussed. The solid-state degradation of enalapril maleate was monitored non-isothermally at temperature range from 25 to 200 degrees C and isothermally at various temperatures (115, 120, 125, 130, and 135 degrees C) for a few hours. The collected FT-IR spectra were subjected to self-modeling curve resolution (SMCR) in order to elucidate the pure component spectral estimates. Subsequently, the relative contributions from the observed species could be obtained by projecting the pure component spectral estimates onto the collected FT-IR spectra. Accordingly, the conversion factors from enalapril maleate to diketopiperazine were calculated and were fitted to various solid-state reaction models. The activation energy values (E(a)) calculated from seven nucleation models were ranging from 176.4 to 193.9 kJ/mol. This multivariate data analysis approach proves to be an effective tool for analyzing the kinetic spectroscopic data having a high degree of overlap between original compound and its degradation product since the information from the whole spectral range is used. PMID:17949952

Widjaja, Effendi; Lim, Geok Hong; Chow, Pui Shan; Tan, Selvi

2007-12-01

117

Reactions of the allenylidenes trans-[IrCl[=C=C=C(ph)R](PiPr3)2] with electrophiles: generation of butatriene-, carbene-, and carbyne- iridium complexes.  

PubMed

The allenylidenciridium(I) complexes trans-[IrX(=C=C-CPh2)(PiPr3)2] (X = Cl: 1; X = I: 2) react with excess methyl iodide by C-C coupling and elimination of HI to give the eta2-butatriene compounds trans-[IrX-(eta2-CH2=C=C=CPh2)(PiPr3)2] (3, 4), of which 3 (X = Cl) was characterized by X-ray crystallography. Treatment of 1 and 5 (containing C=C=C(Ph)tBu as the allenylidene ligand) with HCI leads to the formation of the six-coordinate hydridoiridium(III) complexes [IrHCl2[= C=C=C(Ph)R](PiPr3)2] (6, 7) by oxidative addition at the metal center. In contrast, the reactions of 1 and 5 with both CF3CO2H and CF3SO3H afford the four-coordinate vinylcarbene compounds trans-[IrCl[=C(X)-CH=C(Ph)R[(PiPr3)2] (8-10). For X= CF3CO2, in nitromethane a dissociation of the C-X bond occurs and the cationic iridium carbynes trans-[IrCl[=C-CH=C(Ph)R](PiPr3)2]+ are generated. Upon addition of NaBPh4, the stable carbyne complexes 11b (R= Ph) and 12b (R = tBu) with BPh4 as the counterion were isolated in almost quantitative yields. The X-ray crystal structure analysis of 6 reveals that the chloro ligands are cis and the phosphane ligands trans disposed. PMID:11757655

Ilg, K; Werner, H

2001-11-01

118

Iminophosphines: synthesis, formation of 2,3-dihydro-1 H-benzo[1,3]azaphosphol-3-ium salts and N-(pyridin-2-yl)-2-diphenylphosphinoylaniline, coordination chemistry and applications in platinum group catalyzed Suzuki coupling reactions and hydrosilylations  

Microsoft Academic Search

The aprotic and protic bi- and multidentate iminophosphines 2-Ph2PC6H4N?CR1R2 (R1=H, R2=Ph=2a; R1=Me R2=Ph=2b; R1=H, R2=2-thienyl=2c; R1=H, R2=C6H4-2-PPh2=2d; R1=H, R2=C6H4-2-OH=2e, R1=H, R2=C6H4-2-OH-3-But=2f; R1=H, R2=CH2C(O)Me=2g) have been prepared by the acid catalyzed condensation of 2-(diphenylphosphino)aniline with the corresponding aldehyde–ketone. Iminophosphine 2d can be reduced with sodium cyanoborohydride to give the corresponding amino-diphosphine 2-Ph2PC6H4N(H)CH2C6H4-2-PPh2 (2h). In the presence of a stoichiometric quantity of

Simon Doherty; Julian G Knight; Tom H Scanlan; Mark R. J Elsegood; William Clegg

2002-01-01

119

A tandem synthesis of functionalized azet-2(1H)-ones and azet-2(1H)-thiones.  

PubMed

Highly functionalized azet-2(1H)-ones and azet-2(1H)-thiones are obtained via a copper-catalyzed tandem reaction of readily available terminal alkynes, sulfonyl azides, and heterocummulenes in moderate to good yields. PMID:24043583

Yavari, Issa; Nematpour, Manijeh; Bayat, Mohammad J

2013-11-01

120

Reaction between isocyanides and dialkyl acetylenedicarboxylates in the presence of 2,4-dihydro-3 H-pyrazol-3-ones. One-pot synthesis of highly functionalized 7-oxo-1 H,7 H-pyrazolo[1,2- a]pyrazoles  

Microsoft Academic Search

The reactive 1:1 intermediate produced in the reaction between isocyanides and dialkyl acetylenedicarboxylates was trapped by 2,4-dihydro-3H-pyrazol-3-ones to yield highly functionalized 7-oxo-1H,7H-pyrazolo[1,2-a]pyrazoles in fairly good yields.

Mehdi Adib; Mohammad Hosein Sayahi; Behnaz Aghaaliakbari; Hamid Reza Bijanzadeh

2005-01-01

121

Esterification of cellulose with acyl-1 H -benzotriazole  

Microsoft Academic Search

For the first time, the acylation of cellulose was realized by activation of carboxylic acid with 1H-benzotriazole. The reaction could be carried out under mild conditions. The acyl-1H-benzotriazole reacts with cellulose leading to cellulose acetate, butyrate, caproate, benzoate, myristate, and stearate with\\u000a DS values between 1.07 and 1.89. The reaction proceeds completely homogeneously in dimethyl sulfoxide (DMSO)\\/TBAF × 3H2O (tetrabutylammonium fluoride trihydrate)

Matilde C. V. Nagel; Thomas Heinze

2010-01-01

122

Improvement of Anode Oxidation Reaction of a Fuel Cell Using Ammonium Formate with Pt-Ir Catalysts  

NASA Astrophysics Data System (ADS)

We have first attempted to develop high performance and safe fuel cells using ammonium formate as solid (powder) fuel. This solid fuel has potential to realize safe portability compared with liquid fuel such as methanol from the viewpoint of toxicity and flammability. In order to make use of some advantages of ammonium formate, we have investigated oxidation characteristics of ammonium formate toward Pt electrode. From cyclic voltammograms, ammonium formate has high activity to be oxidized with a Pt electrode. We have found that oxidation of ammonium formate can be improved by additional Ir catalysts with Pt catalysts. There is a high potentiality that ammonium formate is useful as solid (powder) fuel for polymer electrolyte membrane (PEM) fuel cells. This new fuel will be driving force to develop safe fuel cells for PEM.

Ohyama, Kazutoshi; Sugino, Takashi; Nitta, Tomohiro; Kimura, Chiharu; Aoki, Hidemitsu

123

On the faradaic selectivity and the role of surface inhomogeneity during the chlorine evolution reaction on ternary Ti-Ru-Ir mixed metal oxide electrocatalysts.  

PubMed

The faradaic selectivity of the chlorine evolution reaction (CER) and oxygen evolution reaction (OER) on the industrially important Ti-Ru-Ir mixed metal oxide is discussed. Absolute evolution rates as well as volume fractions of Cl2 and O2 were quantified using differential electrochemical mass spectrometry (DEMS), while the catalyst surface redox behavior was analyzed using cyclic voltammetry. The spatial inhomogeneity of the surface catalytic reaction rate was probed using Scanning Electrochemical Microscopy (SECM). Although the nature of the competition between electrochemical discharging of chloride ions and water molecules remains elusive on a molecular scale, new insights into the spatial reactivity distribution of the CER and OER were obtained. Oxidation of water is the initial step in corrosion and concomitant deactivation of the oxide electrodes; however, at the same time the nature of interaction between the oxide surface and water is used as a rational indicator of selectivity and catalytic activity. An experimental procedure was established that would allow the study of selectivity of a variety of different catalyst materials using polycrystalline electrode surfaces. PMID:24752521

Zeradjanin, Aleksandar R; Menzel, Nadine; Schuhmann, Wolfgang; Strasser, Peter

2014-07-21

124

A novel one-pot three-(in situ five-)component condensation reaction: an unexpected approach for the synthesis of tetrahydro-2,4-dioxo-1H-benzo[b][1,5]diazepine-3-yl-2-methylpropanamide derivatives.  

PubMed

A novel and efficient method has been developed for the synthesis of tetrahydro-2,4-dioxo-1H-benzo[b][1,5]diazepine-3-yl-2-methylpropanamide derivatives using an aromatic diamine, Meldrum's acid, and an isocyanide in CH(2)Cl(2) at ambient temperature in high yields without using any catalyst or activation. The procedure provides an alternative method for the synthesis of benzo[b][1,5]diazepine derivatives. These compounds have closely related ring systems such as triflubazam, clobazam, and 1,5-benzodiazepines, which have a broad spectrum of biological activities. PMID:19719182

Shaabani, Ahmad; Rezayan, Ali Hossein; Keshipour, Sajjad; Sarvary, Afshin; Ng, Seik Weng

2009-08-01

125

DFT calculations of XPS/NEXAFS and IR spectra to elucidate the reaction products of acetonitrile with Si(0 0 1)-2 × 1  

NASA Astrophysics Data System (ADS)

NEXAFS data [S. Rangan et al., Phys. Rev. B 71 (2005) 165319] and FTIR data [M.P. Schwartz, R.J. Hamers, Surf. Sci. 601 (2007) 945] apparently do not converge in the identification of the reaction products of acetonitrile (CH 3CN) with Si(0 0 1)-2 × 1 at room temperature. Using DFT calculations of core-excited/core-ionized spectra and of IR vibrational frequencies and intensities, we show the consistency of the body of experimental data. Three species are present on the surface in equivalent amounts, a C dbnd N moiety, a pendent C tbnd N and a C dbnd C dbnd N ketenimine submitted to a strong twist imposed by the Si bond directionality. More generally, the paper shows the usefulness of spectroscopic data simulations in the elucidation of complex surface chemistry problems.

Carniato, S.; Rochet, F.; Gallet, J.-J.; Bournel, F.; Dufour, G.; Mathieu, C.; Rangan, S.

2007-12-01

126

Proton transfer reaction from some C H acids to N-bases in polar aprotic solvents  

NASA Astrophysics Data System (ADS)

The deprotonation reactions of dimethyl (4-nitrophenyl)malonate and 4-bromophenyl-4-nitrophenylcyanomethane by tris[2-(2-methoxyethoxy)ethyl]amine, tributylamine and cryptand 222 were studied in polar aprotic solvents such as DMSO and acetonitrile by the kinetic, FT-IR and 1H NMR spectroscopic methods. The mechanisms of the proton transfer reactions are discussed.

Schroeder, Grzegorz; L??ska, Bogus l?awa; Bartl, Franz; Ró?alski, Bartosz; Brzezinski, Bogumi?

1999-03-01

127

Reaction of guaiazulene with o-formylbenzoic acid in diethyl ether (or methanol) in the presence of hexafluorophosphoric acid: comparative studies on 1H and 13C NMR spectral properties of 3-guaiazulenylmethylium- and 3-guaiazulenium-ion structures  

Microsoft Academic Search

Reaction of guaiazulene (1) with o-formylbenzoic acid (2) in diethyl ether in the presence of hexafluorophosphoric acid at 25°C for 90min gives the corresponding monocarbenium-ion compound, [2-(carboxy)phenyl](3-guaiazulenyl)methylium hexafluorophosphate (3), quantitatively, which upon treatment with aq NaHCO3 leads to 3-(3-guaiazulenyl)-2-benzofuran-1(3H)-one (5) in 96% isolated yield. Similarly, reaction of 1 with 2 in methanol under the same conditions as the above reaction

Shin-ichi Takekuma; Kazutaka Sonoda; Chika Fukuhara; Toshie Minematsu

2007-01-01

128

Divergent synthesis of 2,3-dihydro-1H-pyrroles, 3-alkyl-1H-pyrroles and 3-alkenyl-1H-pyrroles from 2,4-pentadienenitriles and isocyanides.  

PubMed

An efficient and divergent one-pot synthesis of 2,3-dihydro-1H-pyrroles, 3-alkyl-1H-pyrroles and 3-alkenyl-1H-pyrroles from readily accessible 2,4-pentadienenitriles with isocyanide based on reaction condition selection has been described. The reaction of 2,4-pentadienenitriles with ethyl isocyanoacetate undergoes a formal [2 + 3] annulation either to generate 2,3-dihydro-1H-pyrroles in the presence of DBU (0.3 equiv.) in EtOH at room temperature or to give 3-alkyl-1H-pyrroles in the presence of DBU (2.0 equiv.) in EtOH under reflux. Moreover, the 2,3-dihydro-1H-pyrroles could be converted to 3-alkenyl-1H-pyrroles with DDQ as an oxidant. PMID:24943054

Xin, Xiaoqing; Liu, Xu; Zhang, Dingyuan; Zhang, Rui; Liang, Yongjiu; Han, Fushe; Dong, Dewen

2014-07-01

129

Photochemical parameters of atmospheric source gases: accurate determination of OH reaction rate constants over atmospheric temperatures, UV and IR absorption spectra  

NASA Astrophysics Data System (ADS)

The emissions of halogenated (Cl, Br containing) organics of both natural and anthropogenic origin contribute to the balance of and changes in the stratospheric ozone concentration. The associated chemical cycles are initiated by the photochemical decomposition of the portion of source gases that reaches the stratosphere. Reactions with hydroxyl radicals and photolysis are the main processes dictating the compound lifetime in the troposphere and release of active halogen in the stratosphere for a majority of halogen source gases. Therefore, the accuracy of photochemical data is of primary importance for the purpose of comprehensive atmospheric modeling and for simplified kinetic estimations of global impacts on the atmosphere, such as in ozone depletion (i.e., the Ozone Depletion Potential, ODP) and climate change (i.e., the Global Warming Potential, GWP). The sources of critically evaluated photochemical data for atmospheric modeling, NASA/JPL Publications and IUPAC Publications, recommend uncertainties within 10%-60% for the majority of OH reaction rate constants with only a few cases where uncertainties lie at the low end of this range. These uncertainties can be somewhat conservative because evaluations are based on the data from various laboratories obtained during the last few decades. Nevertheless, even the authors of the original experimental works rarely estimate the total combined uncertainties of the published OH reaction rate constants to be less than ca. 10%. Thus, uncertainties in the photochemical properties of potential and current atmospheric trace gases obtained under controlled laboratory conditions still may constitute a major source of uncertainty in estimating the compound's environmental impact. One of the purposes of the presentation is to illustrate the potential for obtaining accurate laboratory measurements of the OH reaction rate constant over the temperature range of atmospheric interest. A detailed inventory of accountable sources of instrumental uncertainties related to our FP-RF experiment proves a total uncertainty of the OH reaction rate constant to be as small as ca. 2-3%. The high precision of kinetic measurements allows reliable determination of weak temperature dependences of the rate constants and clear resolution of the curvature of the Arrhenius plots for the OH reaction rate constants of various compounds. The results of OH reaction rate constant determinations between 220 K and 370 K will be presented. Similarly, the accuracy of UV and IR absorption measurements will be highlighted to provide an improved basis for atmospheric modeling.

Orkin, V. L.; Khamaganov, V. G.; Martynova, L. E.; Kurylo, M. J.

2012-12-01

130

Preparation on oligostilbenes of isorhapontigenin by oxidative coupling reaction.  

PubMed

Four new compounds 1-4 were obtained from an oxidative coupling reaction of (E)-isorhapontigenin using FeCl(3) as oxidant. Their structures and stereochemistry were determined on the basis of spectroscopic evidence [UV, IR, MS, (1)H-, (13)C-NMR, NOE and 2D NMR], and their possible formation mechanisms were also discussed, respectively. PMID:14758010

Yao, Chun-Suo; Zhou, Li-Xin; Lin, Mao

2004-02-01

131

Initial electron donor and acceptor in isolated Photosystem II reaction centers identified with femtosecond mid-IR spectroscopy  

PubMed Central

Despite the apparent similarity between the plant Photosystem II reaction center (RC) and its purple bacterial counterpart, we show in this work that the mechanism of charge separation is very different for the two photosynthetic RCs. By using femtosecond visible-pump–mid-infrared probe spectroscopy in the region of the chlorophyll ester and keto modes, between 1,775 and 1,585 cm–1, with 150-fs time resolution, we show that the reduction of pheophytin occurs on a 0.6- to 0.8-ps time scale, whereas P+, the precursor state for water oxidation, is formed after ?6 ps. We conclude therefore that in the Photosystem II RC the primary charge separation occurs between the “accessory chlorophyll” ChlD1 and the pheophytin on the so-called active branch.

Groot, Marie Louise; Pawlowicz, Natalia P.; van Wilderen, Luuk J. G. W.; Breton, Jacques; van Stokkum, Ivo H. M.; van Grondelle, Rienk

2005-01-01

132

On the road from formamide ices to nucleobases: IR-spectroscopic observation of a direct reaction between cyano radicals and formamide in a high-energy impact event.  

PubMed

The formamide-based synthesis of nucleic acids is considered as a nonaqueous scenario for the emergence of biomolecules from inorganic matter. In the current study, we scrutinized the chemical composition of formamide ices mixed with an FeNi meteorite material treated with laser-induced dielectric breakdown plasma created in nitrogen buffer gas. These experiments aimed to capture the first steps of those chemical transformations that may lead to the formation of nucleobases during the impact of an extraterrestrial icy body containing formamide on an early Earth atmosphere. High-resolution FT-IR spectroscopy combined with quantum chemical calculations was used to analyze the volatile fraction of the products formed during such an event. We have found that the spectrum of the evaporated formamide ices is dominated by the spectral signatures of the dimeric form of formamide. Upon exposure to laser sparks, new well-defined bands appear in the spectrum centered at ~820, ~995, and ~1650 cm(-1). On the basis of quantum chemical calculations, these bands can be assigned to the absorptions of 2-amino-2-hydroxy-acetonitrile and to 2-amino-2-hydroxy-malononitrile, which are formed in a direct reaction between formamide and CN(•) radicals upon the high-energy impact event. We also show that there is an exergonic reaction route via these intermediates leading to diaminomaleonitrile, which is generally considered to play a key role in the synthesis of nucleobases. PMID:23193998

Ferus, Martin; Civiš, Svatopluk; Mládek, Arnošt; Šponer, Ji?í; Juha, Libor; Šponer, Judit E

2012-12-26

133

FT-IR study of the ring-retaining products from the reaction of OH radicals with phenol, o-, m-, and p-cresol  

NASA Astrophysics Data System (ADS)

The ring-retaining products of the OH-initiated degradation of phenol and o-, m-, and p-cresol in the presence of NO x have been investigated and their formation yields determined. The experiments were carried out in a large volume reactor at (298±2) K and 1000 mbar total pressure of synthetic air using FT-IR spectroscopy for the analysis of reactants and products. The products observed and their respective molar yields were: from phenol: 1,2-dihydroxybenzene (80.4±12.1)%, 1,4-benzoquinone (3.7±1.2)% and 2-nitrophenol (5.8±1.0)%; from o-cresol: 3-methyl-1,2-dihydroxybenzene (73.4±14.6)%, methyl-1,4-benzoquinone (6.8±1.0)% and 6-methyl-2-nitrophenol (6.8±1.5)%; from m-cresol: 3-methyl-1,2-dihydroxybenzene (68.6±13.4)%, 4-methyl-1,2-dihydroxybenzene (9.7±2.7)%, methyl-1,4-benzoquinone (11.3±2.5)%, 5-methyl-2-nitrophenol (4.4±1.5)% and 3-methyl-2-nitrophenol (4.3±1.6)% and from p-cresol: 4-methyl-1,2-dihydroxybenzene (64.1±11.3)% and 4-methyl-2-nitrophenol (7.6±2.2)%. Reaction pathways leading to the observed products are proposed and potential ramifications for the atmospheric reaction mechanisms of aromatic hydrocarbons are considered.

Olariu, Romeo Iulian; Klotz, Björn; Barnes, Ian; Becker, Karl Heinz; Mocanu, Raluca

134

Two new neutral copper(II) complexes with dipicolinic acid and 3-amino-1H-1,2,4-triazole formed under different reaction conditions: synthesis, characterization, molecular structures and DNA-binding studies.  

PubMed

Two Cu(II) complexes, [Cu?(?-atr)(pydc)?(H?O)?]·5H?O (1) and [Cu(atr)(pydc) (H?O)]·H?O (2), with pyridine-2,6-dicarboxylic acid (H?pydc) and 3-amino-1H-1,2,4-triazole (atr), have been synthesized and characterized. The interaction ability of the both complexes with native calf thymus DNA (CT-DNA) has been monitored as a function of the metal complex-DNA molar ratio. UV-vis spectrophotometry, circular dichroism (CD), thermal denaturation studies, cyclic voltammetry (CV) and viscosity measurements. The intrinsic binding constants K(b) of complexes 1 and 2, with CT-DNA obtained from UV-vis absorption studies were 4.7 (±0. 1) × 10(4) and 9.5 (±0. 1) × 10(4) M(-1), respectively. Further investigation of interaction mode was performed using viscosity, cyclic voltammetry and T(m) of CT-DNA studies as well as CD study, indicating complexes bind to DNA via an intercalation mode. PMID:24177363

Tabatabaee, Masoumeh; Bordbar, Maryam; Ghassemzadeh, Mitra; Tahriri, Mozhgan; Tahrir, Marjan; Mehri Lighvan, Zohreh; Neumüller, Bernhard

2013-12-01

135

Structural elucidation of impurities in 5-n-butyl-4-{4-[2-(1H-tetrazole-5-yl)-1H-pyrrol-1-yl]phenylmethyl}-2,4-dihydro-2-(2,6-dichlorophenyl)-3H-1,2,4-triazol-3-one (Ib), a novel nonpeptide angiotensin AT1 receptor antagonist.  

PubMed

5-n-butyl-4-{4-[2-(1H-tetrazole-5-yl)-1H-pyrrol-1-yl]phenylmethyl}-2,4-dihydro-2-(2,6-dichlorophenyl)-3H-1,2,4-triazol-3-one (Ib), a new nonpeptide angiotensin AT1-receptor antagonist, has been observed to play a positive role in the treatment of hypertension in preclinical tests. Four process impurities of Ib were detected by LC-UV and LC/ESI-MS, and the impurities isolated by preparative HPLC chromatography were characterized by LC-MS/MS, high resolution MS (HRMS), NMR and IR analyses. The structures of impurities were confirmed as 5-n-butyl-4-{4-[2-chloro-5-(1H-tetrazole-5-yl)-1H-pyrrol-1-yl]phenylmethyl}-2,4-dihydro-2-(2,6-dichlorophenyl)-3H-1,2,4-triazol-3-one (I), 5-n-butyl-4-{4-[2-bromo-5-(1H-tetrazole-5-yl)-1H-pyrrol-1-yl]phenylmethyl}-2,4-dihydro-2-(2,6-dichlorophenyl)-3H-1,2,4-triazol-3-one (II), 5-n-butyl-4-{4-[4-chloro-2-(1H-tetrazole-5-yl)-1H-pyrrol-1-yl]phenylmethyl}-2,4-dihydro-2-(2,6-dichlorophenyl)-3H-1,2,4-triazol-3-one (III) and 5-n-butyl-4-{4-[4-bromo-2-(1H-tetrazole-5-yl)-1H-pyrrol-1-yl]phenylmethyl}-2,4-dihydro-2-(2,6-dichlorophenyl)-3H-1,2,4-triazol-3-one (IV), respectively. All of the four impurities were produced as the by-products of the bromination reaction by NBS (N-bromosuccinimide) in the synthesis of Ib. PMID:22516679

Gao, Ting; Liu, Yaxuan; Ji, Yibing; Wu, Xiaoming; Xu, Jinyi

2012-07-01

136

Synthesis of multifunctionalized 1,2,3,4-tetrahydropyridines, 2,3-dihydropyridin-4(1H)-ones, and pyridines from tandem reactions initiated by [5+1] cycloaddition of N-formylmethyl-substituted enamides to isocyanides: mechanistic insight and synthetic application.  

PubMed

Tandem reactions for the efficient synthesis of multifunctionalized 1,2,3,4-tetrahydropyridines, 2,3-dihydropyridin-4(1H)-ones, and pyridine derivatives have been developed and reaction mechanisms have been investigated. Synthetic cascades are initiated by the Zn(OTf)2-mediated [5+1] cycloaddition of N-formylmethyl-substituted tertiary enamides to isocyanides, thus leading to the versatile heterocyclic enamino imine intermediates. Interception of the intermediates by diastereoselective reduction of imine functionality with Me4NBH(OAc)3 afforded 1,6-disubstituted trans-3-hydroxy-4-arylamino- or -alkylamino-1,2,3,4-tetrahydropyridines, whereas acylation of the imino group followed by acidic hydrolysis produced 1,6-disubstituted 3-acyloxy-2,3-dihydropyridin-4(1H)-ones. Aerobic oxidation led to the aromatization followed by intermolecular acyl-group transfer from the pyridinium nitrogen to the 3-hydroxy moiety, thereby yielding substituted 3-acyloxy-4-aminopyridines. Synthetic potentials of the resulting products have been demonstrated by expedient and highly stereoselective synthesis of cis,cis-4,5-dihydroxy-2-phenylpiperidine and trans,trans-4-amino-5-hydroxy-2-phenylpiperidine compounds, which are important in medicinal chemistry, through simple and practical reduction reactions. PMID:24194465

Lei, Chuan-Hu; Wang, De-Xian; Zhao, Liang; Zhu, Jieping; Wang, Mei-Xiang

2013-12-01

137

The Cl + H2 --> HCl + H reaction induced by IR + UV irradiation of Cl2 in solid para-H2: quantum model simulation.  

PubMed

Recent experimental investigations by the group of D. T. Anderson (Kettwich, S. C.; Raston, P. L.; Anderson, D. T. J. Phys. Chem. A 2009, 113, DOI 10.1021/jp811206a) show that the reaction Cl + H(2) --> HCl + H in the para-H(2) crystal can be induced by infrared (IR) + ultraviolet (UV) coirradiations causing vibrational pre-excitation of the molecular reactant, H(2)(v=1), and generation of the atomic reactant, Cl((2)P(3/2)), by near-resonant photodissociation of a matrix-isolated Cl(2) molecule in the C (1)Pi(u) state, respectively. The corresponding reaction probability P(v=1) for the reactants Cl + H(2)(v=1) is approximately 0.15; this is approximately 25 times larger than P(v=0) for Cl + H(2)(v=0) (as initiated by pure UV irradiation). We present a simple three-step quantum model which accounts for some important parts of the experimental results and allows predictions for other scenarios, for example, UV photodissociation of the Cl(2) molecule by a laser pulse. The first step, vibrational pre-excitation of H(2), yields the molecular initial state which is described using the Einstein model of the para-H(2) crystal. The second step, photodissociation of Cl(2), generates the Cl((2)P(3/2)) atom approaching H(2)(v=1). In the third step, Cl reacts with H(2)(v=1) much more efficiently than with H(2)(v=0) close to threshold. The ultrashort time domains (approximately 100 fs) of steps 2 plus 3 support one- and then two-dimensional models of photodissociation of Cl(2) by short laser pulses and of the subsequent reaction of the system Cl-H-H embedded in frozen environments. The widths of the corresponding wave function describing the translational motion of the reactants is revealed as a significant parameter which is determined not only by the duration of the laser pulse but, even more importantly, by the width of the Gaussian-type distribution of the center of mass of the H(2) molecule in its Einstein cell. As a consequence, the resulting P(v) are quite robust versus variations of the UV pulse durations, allowing extrapolations to continuous wave irradiation. Quantum dynamics simulations of the reaction reveal that the experimental results are due to energetic and dynamical effects. PMID:19378981

Korolkov, M V; Manz, J; Schild, A

2009-07-01

138

Two-Dimensional Fourier Transform Infrared (FT-IR) Correlation Spectroscopy Study of the Imidization Reaction from Polyamic Acid to Polyimide.  

PubMed

The mechanism of the thermal imidization of solid-state polyamic acid was studied using Fourier transform infrared (FT-IR) spectroscopy using the two-dimensional correlation spectroscopy method. It is assumed that two isomers exist in a polyamic acid segment: one is called the para-segment, which favors imidization reaction, the other is the meta-segment, which is not in favor for imidization unless the temperature is high enough. The results show that the imidization process differs for the two states of polyamic acid segments. The para-segment is more sensitive to the heat environment for the formation of imide ring, and it will take several intermediate steps to complete the ring closure at the aid of the solvent. As for the meta-segment, the ring will be closed before the imide formation due to the powerful energy provided in the high-temperature environment, and the ever-increasing chain rigidity and the loss of solvent during the heating process make this path the only option to continue the imidization process. PMID:25014721

Xu, Yuan; Zhang, Qinghua

2014-06-01

139

Ir/IrSi3/Si Schottky-Barrier Infrared Detector  

NASA Technical Reports Server (NTRS)

Quantum efficiency increased. Proposed Schottky-barrier infrared detector has double metallic layer of Ir and IrSi3 instead of single metallic layer of Ir, IrSi, or IrSi3. Offers advantages of both relatively high infrared absorption in thin film of Ir and stability and reproducibility of layer of IrSi3 in contact with Si. Also serves as barrier to chemical reactions between Ir overlayer and Si substrate. Detectors used to form focal-plane array integrated with charge-coupled-device-addressing and image-processing circuitry.

Lin, True-Lon

1991-01-01

140

Preparation, GIAO NMR Calculations and Acidic Properties of Some Novel 4,5-dihydro-1H-1,2,4-triazol-5-one Derivatives with Their Antioxidant Activities  

PubMed Central

Six novel 3-alkyl(aryl)-4-(p-nitrobenzoylamino)-4,5-dihydro-1H-1,2,4-triazol-5- ones (2a-f) were synthesized by the reactions of 3-alkyl(aryl)-4-amino-4,5-dihydro-1H- 1,2,4-triazol-5-ones (1a-f) with p-nitrobenzoyl chloride and characterized by elemental analyses and IR, 1H-NMR, 13C-NMR and UV spectral data. The newly synthesized compounds 2 were titrated potentiometrically with tetrabutylammonium hydroxide in four non-aqueous solvents such as acetone, isopropyl alcohol, tert-butyl alcohol and N,N-dimethylformamide, and the half-neutralization potential values and the corresponding pKa values were determined for all cases. Thus, the effects of solvents and molecular structure upon acidity were investigated. In addition, isotropic 1H and 13C nuclear magnetic shielding constants of compounds 2 were obtained by the gauge-including-atomic-orbital (GIAO) method at the B3LYP density functional level. The geometry of each compound has been optimized using the 6-311G basis set. Theoretical values were compared to the experimental data. Furthermore, these new compounds and five recently reported 3-alkyl-4-(2-furoylamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones (3a–c,e,f) were screened for their antioxidant activities.

Yuksek, Haydar; Alkan, Muzaffer; Cakmak, Ismail; Ocak, Zafer; Bahceci, Sule; Calapoglu, Mustafa; Elmastas, Mahfuz; Kolomuc, Ali; Aksu, Havva

2008-01-01

141

[15N,1H]\\/[13C,1H]-TROSY for simultaneous detection of backbone 15N–1H, aromatic 13C–1H and side-chain 15N–1H2 correlations in large proteins  

Microsoft Academic Search

This paper describes a [15N,1H]\\/[13C,1H]-TROSY experiment for the simultaneous acquisition of the heteronuclear chemical shift correlations of backbone amide 15N–1H groups, side chain 15N–1H2 groups and aromatic 13C–1H groups in otherwise highly deuterated proteins. The 15N–1H and 13C–1H correlations are extracted from two subspectra of the same data set, thus preventing possible spectral overlap of aromatic and amide protons in

Konstantin Pervushin; Daniel Braun; César Fernández; Kurt Wüthrich

2000-01-01

142

FT-IR, FT-Raman, molecular structure, first order hyperpolarizability, HOMO and LUMO analysis, MEP and NBO analysis of 3-(adamantan-1-yl)-4-(prop-2-en-1-yl)-1H-1,2,4-triazole-5(4H)-thione, a potential bioactive agent.  

PubMed

The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of 3-(adamantan-1-yl)-4-(prop-2-en-1-yl)-1H-1,2,4-triazole-5(4H)-thione have been investigated experimentally and theoretically using Gaussian09 software package. Potential energy distribution of normal modes vibrations was done using GAR2PED program. The HOMO and LUMO analysis are used to determine the charge transfer within the molecule. The stability of the molecule arising from hyperconjugative interaction and charge delocalization has been analyzed using NBO analysis. The calculated geometrical parameters are in agreement with the XRD data. The calculated first hyperpolarizability is high and the title compound is an attractive candidate for further studies in nonlinear optical applications. To estimate the chemical reactivity of the molecule, the molecular electrostatic potential is calculated for the optimized geometry of the molecule. PMID:24878436

Rosline Sebastian, S H; Attia, Mohamed I; Almutairi, Maha S; El-Emam, Ali A; Panicker, C Yohannan; Van Alsenoy, Christian

2014-11-11

143

Measurements of the neutron electric to magnetic form factor ratio G{sub En}/G{sub Mn} via the {sup 2}H(e{yields},e{sup '}n{yields}){sup 1}H reaction to Q{sup 2}=1.45 (GeV/c){sup 2}  

SciTech Connect

We report values for the neutron electric to magnetic form factor ratio, G{sub En}/G{sub Mn}, deduced from measurements of the neutron's recoil polarization in the quasielastic {sup 2}H(e{yields},e{sup '}n{yields}){sup 1}H reaction, at three Q{sup 2} values of 0.45, 1.13, and 1.45 (GeV/c){sup 2}. The data at Q{sup 2}=1.13 and 1.45 (GeV/c){sup 2} are the first direct experimental measurements of G{sub En} employing polarization degrees of freedom in the Q{sup 2}>1 (GeV/c){sup 2} region and stand as the most precise determinations of G{sub En} for all values of Q{sup 2}.

Plaster, B. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); California Institute of Technology, Pasadena, California 91125 (United States); Semenov, A.Yu.; Semenova, I.A. [Kent State University, Kent, Ohio 44242 (United States); Joint Institute for Nuclear Research, Dubna RU-141980 (Russian Federation); Aghalaryan, A.; Asaturyan, R.; Mkrtchyan, H.; Stepanyan, S.; Tadevosyan, V. [Yerevan Physics Institute, Yerevan 375036 (Armenia); Crouse, E.; Finn, J.M.; Perdrisat, C.; Roche, J. [College of William and Mary, Williamsburg, Virginia 23187 (United States); MacLachlan, G.; Opper, A.K. [Ohio University, Athens, Ohio 45701 (United States); Tajima, S.; Churchwell, S.; Howell, C.R. [Duke University and TUNL, Durham, North Carolina 27708 (United States); Tireman, W. [Kent State University, Kent, Ohio 44242 (United States); Northern Michigan University, Marquette, Michigan 49855 (United States); Ahmidouch, A. [North Carolina A and T State University, Greensboro, North Carolina 27411 (United States); Anderson, B. D. [Kent State University, Kent, Ohio 44242 (United States)] (and others)

2006-02-15

144

Poly(ethylene glycol) (PEG-400) as an alternative reaction solvent for the synthesis of some new 1-(4-(4'-chlorophenyl)-2-thiazolyl)-3-aryl-5-(2-butyl-4-chloro-1H-imidazol-5yl)-2-pyrazolines and their in vitro antimicrobial evaluation.  

PubMed

Several 1-(4-(4'-chlorophenyl)-2-thiazolyl)-3-aryl-5-(2-butyl-4-chloro-1H-imidazol-5yl)-2-pyrazoline derivatives were prepared by the base catalyzed treatment of appropriate chalcones with 4-(4'-chlorophenyl)-2-hydrazino-thiazole in poly (ethylene glycol) (PEG-400) as an alternative reaction solvent. All the synthesized compounds were tested for their antimicrobial activities against Escherichia coli (MTCC 2939), Salmonella typhi (MTCC 98), Staphylococcus aureus (MTCC 96), Bacillus subtilis (MTCC 441), Aspergillus niger (MTCC 281), Trichoderma viridae (MTCC 167), Penicillium chrysogenum (MTCC 160), Fusarium moniliforme (MTCC 156) and Candida albicans (MTCC 183). Most of the compounds showed potent antibacterial and antifungal activity. PMID:19896247

Dawane, Bhaskar S; Konda, Shankaraiah G; Mandawad, Gajanan G; Shaikh, Baseer M

2010-01-01

145

Synthesis and antimicrobial activity of some new N-substituted quinoline derivatives of 1H-pyrazole.  

PubMed

A new series of 32 derivatives of 4-pyrazolyl-N-(hetero)arylquinoline 5a-p and 6a-p were synthesized by a one-pot base-catalyzed cyclocondensation reaction of 1-phenyl-3-(hetero)aryl-pyrazole-4-carbaldehyde 1a-h, malononitrile 2, and 3-(hetero)aryl-5,5-disubstitutedcyclohex-2-enone 3a-b or 4a-b, respectively. All the synthesized compounds were characterized by elemental analysis, FT-IR, (1) H-NMR, and (13) C-NMR spectral data. All the synthesized compounds were screened, against six bacterial pathogens, namely Bacillus subtilis, Clostridium tetani, Streptococcus pneumoniae, Salmonella typhi, Vibrio cholerae, Escherichia coli, and antifungal activity, against two fungal pathogens Aspergillus fumigatus and Candida albicans, using broth microdilution MIC method. Some of the compounds were found to be more or equipotent against most of the employed strains than commercially available drugs as evident from the screening data. PMID:21290425

Thumar, Nilesh J; Patel, Manish P

2011-02-01

146

Dioxygenases without requirement for cofactors and their chemical model reaction: compulsory order ternary complex mechanism of 1H-3-hydroxy-4-oxoquinaldine 2,4-dioxygenase involving general base catalysis by histidine 251 and single-electron oxidation of the substrate dianion.  

PubMed

1H-3-Hydroxy-4-oxoquinaldine 2,4-dioxygenase (Hod) is a cofactor-less dioxygenase belonging to the alpha/beta hydrolase fold family, catalyzing the cleavage of 1H-3-hydroxy-4-oxoquinaldine (I) and 1H-3-hydroxy-4-oxoquinoline (II) to N-acetyl- and N-formylanthranilate, respectively, and carbon monoxide. Bisubstrate steady-state kinetics and product inhibition patterns of HodC, the C69A protein variant of Hod, suggested a compulsory-order ternary-complex mechanism, in which binding of the organic substrate precedes dioxygen binding, and carbon monoxide is released first. The specificity constants, k(cat)/K(m,A) and k(cat)/K(m,O)()2, were 1.4 x 10(8) and 3.0 x 10(5) M(-1) s(-1) with I and 1.2 x 10(5) and 0.41 x 10(5) M(-1) s(-1) with II, respectively. Whereas HodC catalyzes formation of the dianion of its organic substrate prior to dioxygen binding, HodC-H251A does not, suggesting that H251, which aligns with the histidine of the catalytic triad of the alpha/beta hydrolases, acts as general base in catalysis. Investigation of base-catalyzed dioxygenolysis of I by electron paramagnetic resonance (EPR) spectroscopy revealed formation of a resonance-stabilized radical upon exposure to dioxygen. Since in D(2)O spectral properties are not affected, exchangeable protons are not involved, confirming that the dianion is the reactive intermediate that undergoes single-electron oxidation. We suggest that in the ternary complex of the enzyme, direct single-electron transfer from the substrate dianion to dioxygen may occur, resulting in a radical pair. Based on the estimated spin distribution within the radical anion (observed in the model reaction of I), radical recombination may produce a C4- or C2-hydroperoxy(di)anion. Subsequent intramolecular attack would result in the 2,4-endoperoxy (di)anion that may collapse to the reaction products. PMID:15533053

Frerichs-Deeken, Ursula; Ranguelova, Kalina; Kappl, Reinhard; Hüttermann, Jürgen; Fetzner, Susanne

2004-11-16

147

Bis(3-pyridyl)methylvinylsilane ( L1) and 1,2-di(3-quinolyl) dimethyl disilane ( L2): Synthesis and complexation reactions. Anion controlled solid state structures of cationic Ag(I)– L1 complex  

Microsoft Academic Search

3-Bromopyridine and 3-bromoquinoline on reaction with n-butyllithium give lithiated products which on reaction with dichloromethylvinylsilane and 1,2-dichlorodimethyldisilane at ?78°C result in the ligands bis(3-pyridyl)methylvinylsilane (L1) and 1,2-di(3-quinolyl)dimethyl disilane (L2). The complexation reactions of both these ligands with Ag(I), Pd(II) and Cu(II) have been explored. The 1H, 13C{1H} and 29Si{1H}NMR and IR spectra of both the ligands and their metal complexes

Neetu Rani; G. K. Rao; Ajai K. Singh

2009-01-01

148

Theoretical investigation for the cycle reaction of N2O (x1?+) with CO (1?+) catalyzed by IrO(n)+ (n = 1, 2) and utilizing the energy span model to study its kinetic information.  

PubMed

The mechanisms of the reactions between N(2)O and CO catalyzed by IrO(n)(+) (n = 1, 2) have been investigated using B3LYP and CCSD(T) levels of theory. Spin inversion among three reaction profiles corresponding to the quintet, triplet, and singlet multiplicities was discussed by using spin-orbit coupling (SOC) calculations. The probability of electron hopping in the vicinity of the (MECP) has been calculated by the Landau-Zener-type model. The single P(1)(ISC) and double P(2)(ISC) passes estimated at MECP1(#) (SOC = 198.61 cm(-1)) are approximately 0.11 and 0.20, respectively. Important analysis and explanations were done using molecular orbital theory and natural bonding orbital (NBO). The energetic span (?E) model coined by Kozuch was applied in this cycle. The turnover frequency (TOF)-determining transition state (TDTS) and TDI (TOF-determining intermediate) were confirmed. Finally, TOF(IrO(+))/TOF(IrO(2)(+)) = 0.38 at 298 K. PMID:21882822

Nian, JingYan; Wang, YongCheng; Ma, WeiPeng; Ji, DaFang; Wang, CuiLan; La, MaoJi

2011-10-13

149

Computational study of the reaction of C6F6 with [IrMe(PEt3)3]: identification of a phosphine-assisted C-F activation pathway via a metallophosphorane intermediate.  

PubMed

Density functional theory calculations have been used to model the reaction of C6F6 with [IrMe(PEt3)3], which proceeds with both C-F and P-C bond activation to yield trans-[Ir(C6F5)(PEt3)2(PEt2F)], C2H4, and CH4 (Blum, O.; Frolow, F.; Milstein, D. J. Chem. Soc., Chem. Commun. 1991, 258). Using a model species, trans-[IrMe(PH3)2(PH2Et)], a low-energy mechanism involving nucleophilic attack of the electron-rich Ir metal center at C6F6 with displacement of fluoride has been identified. A novel feature of this process is the capture of fluoride by a phosphine ligand to generate a metallophosphorane intermediate [Ir(C6F5)(Me)(PH3)2(PH2EtF)]. These events occur in a single step via a 4-centered transition state, in a process that we have termed "phosphine-assisted C-F activation". Alternative mechanisms based on C-F activation via concerted oxidative addition or electron-transfer processes proved less favorable. From the metallophosphorane intermediate the formation of the final products can be accounted for by facile ethyl group transfer from phosphorus to iridium followed by beta-H elimination of ethene and reductive elimination of methane. The interpretation of phosphine-assisted C-F activation in terms of nucleophilic attack is supported by the reduced activation barriers computed with the more electron-rich model reactant trans-[IrMe(PMe3)2(PMe2Et)] and the higher barriers found with lesser fluorinated arenes. Reactivity patterns for a range of fluoroarenes indicate the dominance of the presence of ortho-F substituents in promoting phosphine-assisted C-F activation, and an analysis of the charge distribution and transition state geometries indicates that this process is controlled by the strength of the Ir-aryl bond that is being formed. PMID:18950169

Erhardt, Stefan; Macgregor, Stuart A

2008-11-19

150

Characterization of heroin samples by 1H NMR and 2D DOSY 1H NMR.  

PubMed

Twenty-four samples of heroin from different illicit drug seizures were analyzed using proton Nuclear Magnetic Resonance ((1)H NMR) and two-dimensional diffusion-ordered spectroscopy (2D DOSY) (1)H NMR. A careful assignment and quantification of (1)H signals enabled a comprehensive characterization of the substances present in the samples investigated: heroin, its main related impurities (6-acetylmorphine, acetylcodeine, morphine, noscapine and papaverine) and cutting agents (caffeine and acetaminophen in nearly all samples as well as lactose, lidocaine, mannitol, piracetam in one sample only), and hence to establish their spectral signatures. The good agreement between the amounts of heroin, noscapine, caffeine and acetaminophen determined by (1)H NMR and gas chromatography, the reference method in forensic laboratories, demonstrates the validity of the (1)H NMR technique. In this paper, 2D DOSY (1)H NMR offers a new approach for a whole characterization of the various components of these complex mixtures. PMID:24378299

Balayssac, Stéphane; Retailleau, Emmanuel; Bertrand, Geneviève; Escot, Marie-Pierre; Martino, Robert; Malet-Martino, Myriam; Gilard, Véronique

2014-01-01

151

Quantitative analysis of hydrogen peroxide by 1H NMR spectroscopy.  

PubMed

A technique utilizing 1H NMR spectroscopy has been developed to measure the concentration of hydrogen peroxide from 10(-3) to 10 M. Hydrogen peroxide produces a peak at around 10-11 ppm, depending upon the interaction between solvent molecules and hydrogen peroxide molecules. The intensity of this peak can be monitored once every 30 s, enabling the measurement of changes in hydrogen peroxide concentration as a function of time. 1H NMR has several advantages over other techniques: (1) applicability to a broad range of solvents, (2) ability to quantify hydrogen peroxide rapidly, and (3) ability to follow reactions forming and/or consuming hydrogen peroxide as a function of time. As an example, this analytical technique has been used to measure the concentration of hydrogen peroxide as a function of time in a study of hydrogen peroxide decomposition catalyzed by iron(III) tetrakispentafluorophenyl porphyrin. PMID:15756600

Stephenson, Ned A; Bell, Alexis T

2005-03-01

152

Efficient synthesis of 5,6,7-trisubstituted 1 H-pyrrolizines  

Microsoft Academic Search

Crystalline phosphorus ylides are obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine, dialkyl acetylenedicarboxylates and strong NH-acids, such as 2-pyrrolylglyoxalate or N-benzyl-2-pyrrolylglyoxamate. These phosphoranes undergo a smooth intramolecular Wittig reaction in boiling toluene to produce 5,6,7-trisubstituted 1H-pyrrolizine derivatives in quantitative yields. Dynamic NMR effects are observed in the 1H NMR spectra of stabilized ylides 6a and 6d

Issa Yavari; Mehdi Adib

2001-01-01

153

Ion chemistry of 1H-1,2,3-triazole.  

PubMed

A combination of experimental methods, photoelectron-imaging spectroscopy, flowing afterglow-photoelectron spectroscopy and the flowing afterglow-selected ion flow tube technique, and electronic structure calculations at the B3LYP/6-311++G(d,p) level of density functional theory (DFT) have been employed to study the mechanism of the reaction of the hydroxide ion (HO-) with 1H-1,2,3-triazole. Four different product ion species have been identified experimentally, and the DFT calculations suggest that deprotonation by HO- at all sites of the triazole takes place to yield these products. Deprotonation of 1H-1,2,3-triazole at the N1-H site gives the major product ion, the 1,2,3-triazolide ion. The 335 nm photoelectron-imaging spectrum of the ion has been measured. The electron affinity (EA) of the 1,2,3-triazolyl radical has been determined to be 3.447 +/- 0.004 eV. This EA and the gas-phase acidity of 2H-1,2,3-triazole are combined in a negative ion thermochemical cycle to determine the N-H bond dissociation energy of 2H-1,2,3-triazole to be 112.2 +/- 0.6 kcal mol-1. The 363.8 nm photoelectron spectroscopic measurements have identified the other three product ions. Deprotonation of 1H-1,2,3-triazole at the C5 position initiates fragmentation of the ring structure to yield a minor product, the ketenimine anion. Another minor product, the iminodiazomethyl anion, is generated by deprotonation of 1H-1,2,3-triazole at the C4 position, followed by N1-N2 bond fission. Formation of the other minor product, the 2H-1,2,3-triazol-4-ide ion, can be rationalized by initial deprotonation of 1H-1,2,3-triazole at the N1-H site and subsequent proton exchanges within the ion-molecule complex. The EA of the 2H-1,2,3-triazol-4-yl radical is 1.865 +/- 0.004 eV. PMID:17960930

Ichino, Takatoshi; Andrews, Django H; Rathbone, G Jeffery; Misaizu, Fuminori; Calvi, Ryan M D; Wren, Scott W; Kato, Shuji; Bierbaum, Veronica M; Lineberger, W Carl

2008-01-17

154

Real time observations of surface reactions during aSi:H deposition or H 2 plasma annealing by using FT-IR-ATR  

Microsoft Academic Search

The hydrogen bonding features of reacting film surfaces during a-Si:H deposition, H2 or D2 plasma treatments, have been investigated by employing a real-time, in-situ Fourier-transform infrared attenuated total reflection (FT-IR-ATR) technique. It is shown that SiHx (x ? 2) bonds are the predominant surface products during the a-Si:H deposition. They are decreased by H2 plasma annealing while SiH bonds are

Y. Miyoshi; Y. Yoshida; S. Miyazaki; M. Hirose

1996-01-01

155

XRD, Raman and FT-IR spectroscopic observations of nanosized TiO 2 synthesized by the sol–gel method based on an esterification reaction  

Microsoft Academic Search

Ti(IV)-isopropoxide was hydrolyzed with water molecules generated “in situ” by an esterification between carboxylic acid and alcohol providing excellent control of the hydrolysis and condensation rate. Raman and FT-IR spectra of the TiO2–acetate precursor suggested that the organic ligand is chemically bound to the titanium. With heating of the TiO2–acetate precursor up to 320°C, the surface area increased from 3

M. Ivanda; S Popovi?; M Goti?

1999-01-01

156

Organo-niobate Ionic Liquids: Synthesis, Characterization and Application as Acid Catalyst in Pechmann Reactions  

PubMed Central

The combinations of 1-butyl-3-methylimidazolium chloride with NbCl5 yielded ionic mixtures with different melting point temperatures and acidity depending on the niobium molar fraction. The mixtures were characterized by thermal (DSC) and spectroscopic (FT-IR and 1H NMR) analysis. The Pechmann reactions of different phenols with ethylacetoacetate, producing coumarins, was used as model to evaluate the catalytic behavior of these mixtures as acid Lewis catalyst. These reactions were carried out using acidic mixtures of 60 mol%.

Soares, Valerio C. D.; Alves, Melquizedeque B.; Souza, Ernesto R.; Pinto, Ivana O.; Rubim, Joel C.; Andrade, Carlos Kleber Z.; Suarez, Paulo A. Z.

2007-01-01

157

C-H Bond activation and C-C bond formation in the reaction of 2,5-dimethylthiophene with TpMe2Ir compounds.  

PubMed

The bulky 2,5-dimethylthiophene (2,5-Me2T) reacts at 60 degrees C with TpMe2Ir(C2H4)2 to give a mixture of two TpMe2Ir(III) hydride products, 3 and 4, that contain in addition a thienyl (3) or a thienyl-derived ligand (4). For the generation of 3 only sp2 C-H activation is needed, but the formation of 4 requires also the activation of an sp3 C-H bond and the formation of a new C-C bond (between vinyl and thienyl fragments). In the presence of 2,5-Me2T, compound 4 reacts further to produce a complex thiophenic structure (5, characterized by X-ray methods) that derives formally from two molecules of 2,5-Me2T and a vinyl fragment. Compounds 3-5 can be readily protonated by [H(OEt2)2][BAr'4](Ar'= 3,5-C6H3(CF3)2), with initial generation of carbene ligands (in the case of 3 and 5) as a consequence of H+ attack at the beta-carbon of the Ir-thienyl unit. Free, substituted thiophenes, derived from the original 2,5-Me2T, may be isolated in this way. PMID:15824780

Paneque, Margarita; Poveda, Manuel L; Carmona, Ernesto; Salazar, Verónica

2005-04-21

158

Isotope effects of reactions in quantum solids initiated by IR + UV lasers: quantum model simulations for Cl((2)P(3/2)) + X(2)(?) ? XCl + X in X(2) matrices (X = H, D).  

PubMed

Six isotope effects (i)-(vi) are discovered for the reactions Cl + H(2)(?) ? HCl + H in solid para-H(2) ( 1 ) versus Cl + D(2)(?) ? DCl + D in ortho-D(2) ( 2 ), by means of quantum reaction dynamics simulations, within the frame of our simple model ( J. Phys. Chem. A 2009 , 113 , 7630 . ). Experimentally, the reactions may be initiated for ? = 0 and ? ? 1, by means of "UV only" photodissociation of the matrix-isolated precursor, Cl(2), or by "IR + UV" coirradiation ( Kettwich , S. C. , Raston , P. L. , and Anderson , D. T. J. Phys. Chem. A 2009 , 113 , 7621 . ), respectively. Specifically, (i) various shape and Feshbach reaction resonances correlate with vibrational thresholds of reactants and products, due to the near-thermoneutrality and low barrier of the system. The energetic density of resonances increases as the square root of mass, from M(X) = M(H) to M(D). (ii) The state selective reaction ( 1 ), ? = 1, is supported by a shape resonance, whereas this type of resonance is absent in ( 2 ), ? = 1. As a consequence, time-resolved measurements should monitor different three-step versus direct error-function type evolutions of the formation of the products. (iii) The effective barrier is lower for reaction 1 , ? = 0, enhancing the tunneling rate, as compared to that for reaction 2 , ? = 0. (iv) For reference, the reaction probabilities P versus total energy E(tot) in the gas exhibit sharp resonance peaks or zigzag behaviors of the reaction probability P versus total energy, near the levels of resonances ( Persky , A. and Baer , M. J. Chem. Phys . 1974 , 60 , 133 . ). These features tend to be washed out and broadened for reaction 1 , and even more so for reaction 2 . For comparison, they disappear for reactions in classical solids. (v) The slopes of P versus E(tot) below the potential barrier increase more steeply for reaction 1 , ? = 0, than for reaction 2 , ? = 0. This enhances the tunneling rate of the heavier isotopomer, reaction 2 , ? = 0, compared to that for reaction 1 . (vi) For a given value of the UV frequency, the translational energy E(trans) increases with mass M(X). Again, this effect supports tunneling of the heavier isotopomer. The isotope effects (i)-(iii), (iv)-(v), and (vi) may be classified as energetic, translational amplitude, and kinematic, respectively. Specifically, the effects (iv)-(v) are due to a systematic decrease of the amplitudes of translational motions of the reactant molecules, from quasi infinite in the gas via still rather large values of para-H(2)(?) and smaller values for ortho-D(2)(?) to very small values in classical solids. These isotope effects are special phenomena in quantum solids, which do not occur, neither in the gas phase nor in classical solids. Quantitative predictions, e.g., for the effects of increasing UV frequency on the ratio of reactions probabilities for the UV only versus IR + UV experiments, must account for the interplay of various isotope effects, e.g., (vi) combined with the antagonistic effects (iii) versus (iv) and (v). PMID:20533845

Korolkov, M V; Manz, J; Schild, A

2010-09-16

159

Spectral pattern recognition of in situ FT-IR spectroscopic reaction data using minimization of entropy and spectral similarity (MESS): application to the homogeneous rhodium catalyzed hydroformylation of isoprene.  

PubMed

An improved algorithm using minimization of entropy and spectral similarity (MESS) was tested to recover pure component spectra from in situ experimental Fourier transform infrared (FT-IR) reaction spectral data, which were collected from a homogeneous rhodium catalyzed hydroformylation of isoprene. The experimental spectra are complicated and highly overlapping because of the presence of multiple intermediate products in this reaction system. The traditional entropy minimization method fails to resolve real reaction mixture spectra, but MESS can successfully reconstruct pure component spectra of unknown intermediate products for real reaction systems by the addition of minimization of spectral similarity. The quantitative measure of spectral similarity between two spectra was given by their inner products. The results indicate that MESS is a stable and useful algorithm for spectral pattern recognition of highly overlapped experimental reaction spectra. Comparison is also made between MESS, entropy minimization, simple-to-use interactive self-modeling mixture analysis (SIMPLISMA), interactive principle component analysis (IPCA), and orthogonal projection approach-alternating least squares (OPA-ALS). PMID:14658672

Chen, Li; Chew, Wee; Garland, Marc

2003-05-01

160

IR Windstreaks  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Windstreaks are features caused by the interaction of wind and topographic landforms. The raised rims and bowls of impact craters causes a complex interaction such that the wind vortex in the lee of the crater can both scour away the surface dust and deposit it back in the center of the lee. If you look closely, you will see evidence of this in a darker 'rim' enclosing a brighter interior.

This infrared image shows windstreaks in the region between Gordii Dorsum and Amazonis Mensa.

Image information: IR instrument. Latitude -15.8, Longitude 215 East (145 West). 97 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

2005-01-01

161

In situ attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectroscopy monitoring of 1,2-butylene oxide polymerization reaction by using iterative concentration-guided classical least squares.  

PubMed

There has been rapid growth in the application of in situ optical spectroscopy techniques for reaction and process monitoring recently in both academia and industry. Vibrational spectroscopies such as mid-infrared, near-infrared spectroscopy, and Raman spectroscopy have proven to be versatile and informative. Accurate determination of concentrations, based on highly overlapped spectra, remains a challenge. As an example, 1,2-butylene oxide (BO) polymerization, an important industrial reaction, initiated by propylene glycol (PG) and catalyzed by KOH, is studied in this work in a semi-batch fashion by using in situ attenuated total reflectance Fourier transform infrared spectroscopy (ATR FT-IR) monitoring. The weak BO absorbance, the constantly changing interference from the product oligomers throughout the course of the reaction, and the change in BO spectral features with system polarity posed challenges for quantitative spectral analysis based on conventional methods. An iterative concentration-guided classical least-squares (ICG-CLS) method was developed to overcome these challenges. Taking advantage of the concentration-domain information, ICG-CLS enabled the estimation of the pure oligomer product spectra at different stages of the semi-batch process, which in turn was used to construct valid CLS models. The ICG-CLS algorithm provides an in situ calibration method that can be broadly applied to reactions of known order. Caveats in its applications are also discussed. PMID:23876733

Chen, Xiaoyun; Pell, Randy; Sarsani, Sagar; Cramm, Brian; Villa, Carlos; Dixit, Ravindra

2013-08-01

162

Kinetics of free radicals generated by IR laser photolysis. IV. Intersystem crossings and reactions of C2(X 1?+g) and C2(a 3?u) in the gaseous phase  

NASA Astrophysics Data System (ADS)

Rate coefficients (300 K) for the removal of C2(X 1?+g) and C2(a 3?u), hereafter referred to as 1C2 and 3C2 respectively, by H2, NO, and a number of hydrocarbons are reported as well as rate coefficients for intersystem crossing between 1C2 and 3C2 induced by collisions with N2, CO2, CF4, Ar, Kr, and Xe. C2 molecules are produced via ir photolysis of C2H3CN or C2HCl3, and their concentrations are monitored by laser induced fluorescence. We find that collisionally induced intersystem crossing is significant only when it is spin allowed or involves heavy collision partners (e.g., Kr, Xe). 1C2 reacts more rapidly with NO than does 3C2, and excited CN molecules in the A and B states are formed predominantly in reactions of 3C2. 1C2 reactions result (mainly) in ground state CN, as expected from adiabatic state correlations. Radiationless transitions between the X and B states of CN, induced by collisions with Ar, are observed. It is suggested that both 1C2 and 3C2 are removed by hydrocarbons mainly via chemical reactions, and 1C2 reacts more rapidly than 3C2 for every case that we have measured. With the 3C2+H2 reaction, molecular orbital correlation diagrams show that there are barriers in the entrance channel, thereby rationalizing the small rate coefficient for this reaction, compared to the allowed 1C2+H2 reaction. Similar correlations may explain the smaller reactivity of 3C2, compared to 1C2, toward hydrocarbons in general.

Reisler, H.; Mangir, M. S.; Wittig, C.

1980-09-01

163

IR Spectra of Isocyanic Acid (HNCO) and its Reaction Product with Ammonia: Possible Identification of the 4.6 and 6.8 Micron Absorption Features of Several Protostellar Objects  

NASA Astrophysics Data System (ADS)

Strong absorption features are found at 4.6 microns (2170 cm-1) and 6.8 microns (1470 cm-1) in the spectra of several protostellar objects (e.g. W33A, NGC 7538 IRS9, RAFGL 7009S). Ices with similar features may have been present in the early solar system. Realistic candidates responsible for the 6.8 micron band include CH3OH, and/or ions such as CO3=, HCO3-, and NH4+. The 4.6 micron feature is due to the absorption of the cyanate ion (OCN-). We have synthesized and obtained the infrared spectrum of pure, solid HNCO and measured its intrinsic band strength. We have also investigated the IR spectrum of HNCO covered with a layer of H2O and NH3 at low temperatures ( 10K). During warm-up to 100K, an acid-base reaction occurs and new peaks develop around 1470 cm-1 and 2170 cm-1 which are due to NH4+ and OCN- ions, respectively. Irradiation of solid HNCO shows evidence of OCN- formation at low temperatures. The conditions under which NH4OCN converts into urea ((NH2)2CO) will be discussed. Ammonium cyanate is a good candidate for the source of the 4.6 and 6.8 micron interstellar features and may also exist in cometary ices.

Lowenthal, M. S.; Khanna, R. K.; Moore, M. H.

2000-10-01

164

Electronic, infrared, mass, 1H NMR spectral studies of the charge-transfer complexes of sulphonamide drugs with ?-acceptors in acetonitrile  

NASA Astrophysics Data System (ADS)

The rapid interaction between sulphonamides (sulphamethoxazole (SMZ), sulphaguanidine (SGD), sulphaquinoxaline sodium (SQX) and sulphadimidine sodium (SDD)) as n-electron donors with the 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone (chloranilic acid, p-CLA) as ?-acceptors resulted in the formation of 1:1 charge-transfer complexes as the final products with the formula [(drug) (acceptor)]. The final products of the reactions have been isolated and characterized using FT-IR, 1H NMR, mass spectroscopy and elemental analyses as well as photometric measurements and thermogravimetric analysis (TG). The stoichiometry and apparent formation constants of the complexes formed were determined by applying the conventional spectrophotometric molar ratio method.

Frag, Eman Y.; Mohamed, Gehad G.

2010-08-01

165

Conformational changes in the extrinsic manganese stabilizing protein can occur upon binding to the photosystem II reaction center: an isotope editing and FT-IR study.  

PubMed

Photosystem II catalyzes the light-driven oxidation of water and reduction of plastoquinone in oxygenic photosynthesis. The manganese stabilizing protein (MSP) of photosystem II is an extrinsic subunit that plays an important role in catalytic activity. This subunit can be extracted and re-bound to the photosystem II reaction center. Extraction is associated with decreased stability of manganese binding by the enzyme and by loss in high rates of oxygen evolution activity; reconstitution reverses these phenomena. Since little is known about the assembly of complex membrane proteins, we have employed isotope editing and vibrational spectroscopy to obtain information about any changes in secondary structure that occur in MSP upon functional reconstitution to photosystem II. The spectroscopic data obtained are consistent with substantial changes in conformation when MSP binds to photosystem II; approximately 30-40% of the peptide backbone undergoes a change in secondary structure. These conclusions were reached by comparing different aliquots, before and after binding, of the same 13[C]MSP sample. Analysis of amide I band line shapes through Fourier deconvolution and nonlinear regression suggests that binding of MSP to photosystem II is associated with a decrease in random structure and an increase in beta-sheet content. We conclude that binding of MSP to the reaction center can induce folding of MSP. Our results also indicate that, in solution, MSP can sample a variety of conformational states, which differ in hydrogen bonding of the peptide backbone. PMID:9548950

Hutchison, R S; Betts, S D; Yocum, C F; Barry, B A

1998-04-21

166

Hydrophobization of epoxy nanocomposite surface with 1H,1H,2H,2H-perfluorooctyltrichlorosilane for superhydrophobic properties  

NASA Astrophysics Data System (ADS)

Nature inspires the design of synthetic materials with superhydrophobic properties, which can be used for applications ranging from self-cleaning surfaces to microfluidic devices. Their water repellent properties are due to hierarchical (micrometer- and nanometre-scale) surface morphological structures, either made of hydrophobic substances or hydrophobized by appropriate surface treatment. In this work, the efficiency of two surface treatment procedures, with a hydrophobic fluoropolymer, synthesized and deposited from 1H,1H,2H,2H-perfluorooctyltrichlorosilane (PFOTS) is investigated. The procedures involved reactions from the gas and liquid phases of the PFOTS/hexane solutions. The hierarchical structure is created in an epoxy nanocomposite surface, by filling the resin with alumina nanoparticles and micron-sized glass beads and subsequent sandblasting with corundum microparticles. The chemical structure of the deposited fluoropolymer was examined using XPS spectroscopy. The topography of the modified surfaces was characterized using scanning electron microscopy (SEM), and atomic force microscopy (AFM). The hydrophobic properties of the modified surfaces were investigated by water contact and sliding angles measurements. The surfaces exhibited water contact angles of above 150° for both modification procedures, however only the gas phase modification provided the non-sticking behaviour of water droplets (sliding angle of 3°). The discrepancy is attributed to extra surface roughness provided by the latter procedure.

Psarski, Maciej; Marczak, Jacek; Celichowski, Grzegorz; Sobieraj, Grzegorz B.; Gumowski, Konrad; Zhou, Feng; Liu, Weimin

2012-10-01

167

Synthesis of 3,4-Dihydropyrimidin-2(1H)-Ones and Their Corresponding 2(1H)Thiones Using Trichloroacetic Acid as a Catalyst under Solvent-Free Conditions  

PubMed Central

Trichloroacetic acid was found to be a convenient catalyst for the synthesis of 3,4-dihydropyrimidin-2-(1H)-ones and their corresponding 2(1H)-thiones through a one-pot three-component reaction of aldehydes, alkyl acetoacetate, and urea or thiourea at 70°C under solvent-free conditions.

Karimi-Jaberi, Zahed; Moaddeli, Mohammad Sadegh

2012-01-01

168

Global sampling of the photochemical reaction paths of bromoform by ultrafast deep-UV through near-IR transient absorption and ab initio multiconfigurational calculations  

NASA Astrophysics Data System (ADS)

Ultrafast deep-ultraviolet through near infrared (210-950 nm) transient absorption spectroscopy complemented by ab initio multiconfigurational calculations offers a global description of the photochemical reaction pathways of bromoform following 255-nm excitation in methylcyclohexane and acetonitrile solutions. Photoexcitation of CHBr3 leads to the ground-state iso-CHBr3 product in a large quantum yield (~35%), formed through two different mechanisms: concerted excited-state isomerization and cage-induced isomerization through the recombination of the nascent radical pair. These two processes take place on different time scales of tens of femtoseconds and several picoseconds, respectively. The novel ultrafast direct isomerization pathway proposed herein is consistent with the occurrence of a conical intersection between the first excited singlet state of CHBr3 and the ground electronic state of iso-CHBr3. Complete active space self-consistent field calculations characterize this singularity in the vicinity of a second order saddle point on the ground state which connects the two isomer forms. For cage-induced isomerization, both the formation of the nascent radical pair and its subsequent collapse into ground-state iso-CHBr3 are directly monitored through the deep-ultraviolet absorption signatures of the radical species. In both mechanisms, the optically active (i.e., those with largest Franck-Condon factors) C-Br-Br bending and Br-Br stretching modes of ground-state iso-CHBr3 have the largest projection on the reaction coordinate, enabling us to trace the structural changes accompanying vibrational relaxation of the non-equilibrated isomers through transient absorption dynamics. The iso-CHBr3 photoproduct is stable in methylcyclohexane, but undergoes either facile thermal isomerization to the parent CHBr3 structure through a cyclic transition state stabilized by the polar acetonitrile medium (~300-ps lifetime), and hydrolysis in the presence of water.

Pal, S. K.; Mereshchenko, A. S.; Butaeva, E. V.; El-Khoury, P. Z.; Tarnovsky, A. N.

2013-03-01

169

Photochemical Properties of trans-1-Chloro-3,3,3-trifluoropropene (trans-CHCl?CHCF3): OH Reaction Rate Constant, UV and IR Absorption Spectra, Global Warming Potential, and Ozone Depletion Potential.  

PubMed

Measurements of the rate constant for the gas-phase reactions of OH radicals with trans-1-chloro-3,3,3-trifluoropropene (trans-CHCl?CHCF3) were performed using a flash photolysis resonance-fluorescence technique over the temperature range 220-370 K. The reaction rate constant exhibits a noticeable curvature of the temperature dependence in the Arrhenius plot, which can be represented by the following expression: kt-CFP (220-370 K) = 1.025 × 10(-13) × (T/298)(2.29)?exp(+384/T) cm(3 )molecule(-1)?s(-1). The room-temperature rate constant was determined to be kt-CFP (298 K) = (3.29 ± 0.10) × 10(-13) cm(3)?molecule(-1)?s(-1), where the uncertainty includes both two standard errors (statistical) and the estimated systematic error. For atmospheric modeling purposes, the rate constant below room temperature can be represented by the following expression: kt-CFP (220-298 K) = (7.20 ± 0.46) × 10(-13)?exp[-(237 ± 16)/T]?cm(3)?molecule(-1)?s(-1). There was no difference observed between the rate constants determined at 4 kPa (30 Torr) and 40 kPa (300 Torr) at both 298 and 370 K. The UV and IR absorption cross sections of this compound were measured at room temperature. The atmospheric lifetime, global warming potential, and ozone depletion potential of trans-CHCl?CHCF3 were estimated. PMID:24955760

Orkin, Vladimir L; Martynova, Larissa E; Kurylo, Michael J

2014-07-17

170

Impedance study of electrochromism in anodic Ir oxide films  

Microsoft Academic Search

The aim of this work is to analyse voltammetric and impedance behavior of the hydrated Ir oxide film grown on Ir by 10 Hz potential pulsing in 0.5 mol dm?3 H2SO4 (AIROF). The solid-solution type Ir(+III)\\/Ir(+IV) redox reaction has been manifested in two-peak cyclic voltammograms both in 0.5 mol dm?3 H2SO4 and 1 mol dm?3 NaOH solutions, but with different

L. Sziráki; L. Bóbics

2002-01-01

171

IRS Enrolled Actuaries File.  

National Technical Information Service (NTIS)

The file contains names, addresses, and IRS enrollment number for actuaries who are eligible to practice before the IRS. These actuaries are professionals who are eligible to perform actuarial services under the Employee Retirement Income Security Act of ...

1991-01-01

172

IR Hot Wave  

Microsoft Academic Search

The IR Hot Wave{trademark} furnace is a breakthrough heat treatment system for manufacturing metal components. Near-infrared (IR) radiant energy combines with IR convective heating for heat treating. Heat treatment is an essential process in the manufacture of most components. The controlled heating and cooling of a metal or metal alloy alters its physical, mechanical, and sometimes chemical properties without changing

2010-01-01

173

A heteroleptic cyclometalated iridium(III) fluorophenylpyridine complex from partial defluorohydrogenation reaction: synthesis, photophysical properties and mechanistic insights.  

PubMed

In this paper, a C-F bond activation reaction of a chloro-bridged iridium(III) dimer (dfppy)(2)Ir(?-Cl)(2)Ir(dfppy)(2) (1) (dfppy denotes 2-(4,6-difluorophenyl)pyridyl) in the presence of sodium methoxide has been reported, leading to the formation of a heteroleptic cyclometalated iridium(III) fluorophenylpyridine complex 2. HPLC-mass analysis confirmed the release of formaldehyde in the product mixture. When sodium benzyloxide was used as the base, complex 2 was also generated with the release of a benzaldehyde derivative. Complex 2 has been fully characterized by (1)H-NMR, (19)F-NMR and X-ray crystallographic methods, confirming the partial loss of one of the fluorine atoms on one of the cyclometalated phenylpyridyl ligands. Photophysical studies of complex 2 show that it has a similar absorption spectrum to that of Ir(III)(dfppy)(3). However, the emission spectrum shows a red shift maximum emission band at 478 nm due to the loss of a single fluorine atom, highlighting the critical effect of fluorine on the photoluminescence of these Ir(III) complexes. Finally, intensive mechanistic studies including HPLC-mass analysis, (1)H-NMR, and (19)F-NMR studies demonstrate that the formation of complex 2 should involve a critical ?-hydride elimination of Ir(III)-alkoxide intermediate and the participation of Ir-hydride and/or Ir-fluoride intermediates. PMID:23348919

Li, Liang; Wu, Feng; Zhang, Songlin; Wang, Dawei; Ding, Yuqiang; Zhu, Zhenzhong

2013-04-01

174

Guanine binding of a cytotoxic platinum–acridin-9-ylthiourea conjugate monitored by 1-D 1H and 2-D [ 1H, 15N] NMR spectroscopy: Hydrolysis is not the rate-determining step  

Microsoft Academic Search

The reaction of [PtCl(en)(ACRAMTU)](NO3)2 (PT-ACRAMTU, 1; ACRAMTU=1-[2-(acridin-9-ylamino)ethyl]-1,3-dimethylthiourea, en=ethane-1,2-diamine) and the [15N]-en labeled analogue, 1?, with 2?-deoxyguanosine (dG) was studied by 1H NMR and two-dimensional [1H,15N] HSQC (heteronuclear single quantum coherence) spectroscopy. Reactions were performed in phosphate buffered solution at 37°C at various ratios and total concentrations of reactants. The 1H NMR data suggest that the hydrolyzed form of the drug,

Rajsekhar Guddneppanavar; Marcus W. Wright; Alyssa K. Tomsey; Ulrich Bierbach

2006-01-01

175

Syntheses of vanadyl and zinc(II) complexes of 1-hydroxy-4,5,6-substituted 2(1H)-pyrimidinones and their insulin-mimetic activities.  

PubMed

Control of the glucose level in the blood plasma has been achieved in vitro and in vivo by administration of vanadium and zinc in form of inorganic salts. It has been shown that elements are poorly absorbed in their inorganic forms and required high doses which have been associated with undesirable side effects. Many researchers, therefore, have focused on metal complexes that were prepared from VOSO(4) or ZnSO(4) and low-molecular-weight bidentate ligands. Seven kinds of 1-hydroxy-4,6-disubstituted and 1-hydroxy-4,5,6-trisubstituted-2(1H)-pyrimidinones were synthesized by reaction of N-benzyloxyurea and beta-diketones and subsequent removal of the protecting group. Six kinds of 1-hydroxy-4-(substituted)amino-2(1H)-pyrimidinones were synthesized by the substitution reaction of 1-benzyloxy-4-(1',2',4'-triazol-1'-yl)-2(1H)-pyrimidinone with various alkyl amines or amino acids. Treatment with VOSO(4) and ZnSO(4) or Zn(OAc)(2) afforded vanadyl(IV) and zinc(II) complexes which were characterized by means of (1)H NMR, IR, EPR, and UV-vis spectroscopies, and combustion analysis. The in vitro insulin-mimetic activity of these complexes was evaluated from 50% inhibitory concentrations (IC(50)) on free fatty acid (FFA) release from isolated rat adipocytes treated with epinephrine. Vanadyl complexes of 4,6-disubstituted-2(1H)-pyrimidinones showed higher insulin-mimetic activities than those of 4,5,6-trisubstituted ones. On the other hand, Zn(II) complexes showed lower insulin-mimetic activities than VOSO(4) and ZnSO(4) as positive controls. It was found that the balance of the hydrophilicity and/or hydrophobicity is important for higher insulin-mimetic activity. The in vivo insulin-mimetic activity was evaluated with streptozotocin (STZ)-induced diabetic rats. Blood glucose levels were lowered from hyperglycemic to normal levels after the treatment with bis(1,2-dihydro-4,6-dimethyl-2-oxo-1-pyrimidinolato)oxovanadium(IV) by daily intraperitoneal injections. The improvement in glucose tolerance was also confirmed by an oral glucose tolerance test. PMID:16387366

Yamaguchi, Mika; Wakasugi, Kei; Saito, Ryota; Adachi, Yusuke; Yoshikawa, Yutaka; Sakurai, Hiromu; Katoh, Akira

2006-02-01

176

Stereoselective ?-Fluorination of N-Acyloxazolidinones at Room Temperature within 1 h.  

PubMed

A direct ?-fluorination of N-acyloxazolidinones based on the unique reactivity of group IVa metal enolates has been developed. The reaction is an experimentally simple, low-cost, quick, and energy-efficient alternative for asymmetric ?-fluorination of N-acyloxazolidinones. Preliminary studies have shown compatibility with alkyl, alkenyl, and alkynyl, aromatic, and several heteroaromatic substituents. High diastereoselectivities have been achieved with most substrates tested, and the reaction is typically complete within 1 h at ambient temperature. PMID:24926887

Alvarado, Joseph; Herrmann, Aaron T; Zakarian, Armen

2014-07-01

177

Aromatic derivatives of 2,3-dihydro-1H-1,5-benzodiazepine  

SciTech Connect

The formation of 2,2,4-trisubstituted 2,3-dihydro-1H-1,5-benzodiazepines in the reactions of acetylarenes with 4-ethoxy- and 3,5-dimethyl-1,2-phenylenediamine was studied. The effect of the substituents on the individual stages of the reactions is discussed. A quantum-chemical calculation of the relative nucleophilicity of 1,2-phenylenediamine, 2,3-diaminopyridine, and 3,4-diaminofurazan was undertaken.

Orlov, V.D.; Desenko, S.M.; Kiroga, Kh.

1987-09-01

178

Practical choice of 1H- 1H decoupling schemes in through-bond 1H-{X} HMQC experiments at ultra-fast MAS  

NASA Astrophysics Data System (ADS)

Three 1H- 1H homonuclear dipolar decoupling schemes for 1H indirect detection measurements at very fast MAS are compared. The sequences require the following conditions: (i) being operable at very fast MAS, (ii) a long T2' value, (iii) a large scaling factor, (iv) a small number of adjustable parameters, (v) an acquisition window, (vi) a low rf-power requirement, and (vii) a z-rotation feature. To satisfy these conditions a modified sequence named TIlted Magic-Echo Sandwich with zero degree sandwich pulse (TIMES 0) is introduced. The basic elements of TIMES 0 consist of one sampling window and two phase-ramped irradiations, which realize alternating positive and negative 360° rotations of 1H magnetization around an effective field tilted with an angle ? from the B0 axis. The TIMES 0 sequence benefits from very large chemical shift scaling factors at ultra-fast MAS that reach ?cs = 0.90 for ? = 25° at ?r = 80 kHz MAS and only four adjustable parameters, resulting in easy setup. Long ?T2' values, where T2' is a irreversible proton transverse relaxation time, greatly enhance the sensitivity in 1H-{ 13C} through-bond J-HMQC (Heteronuclear Multiple-Quantum Coherence) measurements with 1H- 1H decoupling during magnetization transfer periods. Although similar sensitivity can be obtained with through-space D-HMQC sequences, in which 13C- 1H dipolar interactions are recoupled, J-HMQC experiments incorporating 1H- 1H decoupling benefit from lower t1-noise, more uniform excitation of both CH, CH 2 and CH 3 moieties, and easier identification of through-bond connectivities.

Nishiyama, Yusuke; Lu, Xingyu; Trébosc, Julien; Lafon, Olivier; Gan, Zhehong; Madhu, P. K.; Amoureux, Jean-Paul

2012-01-01

179

Atmospheric chemistry of CF3CF2CHO: absorption cross sections in the UV and IR regions, photolysis at 308 nm, and gas-phase reaction with OH radicals (T = 263-358 K).  

PubMed

The relative importance in the atmosphere of UV photolysis of perfluoropropionaldehyde, CF3CF2CHO, and reaction with hydroxyl (OH) radicals has been investigated in this work. First, the forbidden n ? ?* transition of the carbonyl chromophore was characterized between 230 and 380 nm as a function of temperature (269–298 K) and UV absorption cross sections, ??, were determined in those ranges. In addition, IR absorption cross sections were determined between 4000 and 500 cm–1. Pulsed laser photolysis (PLP) of CF3CF2CHO coupled to Fourier transform infrared (FTIR) was employed to determine the overall photolysis quantum yield, ??, at 308 nm and 298 K. ??=308 nm was pressure dependent, ranging from (0.94 ± 0.14) at 75 Torr to (0.30 ± 0.01) at 760 Torr. This dependence is characterized by the Stern–Volmer parameters ?0?=308 nm = (1.19 ± 0.34) and KSV = (1.22 ± 0.52) × 10(–19) cm3 molecule–1. End products of the photodissociation of CF3CF2CHO were measured and quantified by FTIR spectroscopy. Furthermore, the rate coefficients for the OH + CF3CF2CHO reaction, k1, were determined as a function of temperature (T = 263–358 K) by PLP-LIF. At room temperature the rate coefficient is k1(T = 298 K) = (5.57 ± 0.07) × 10(–13) cm3 molecule–1 s–1, whereas the temperature dependence is described by k1(T) = (2.56 ± 0.32) × 10(–12) exp{?(458 ± 36)/T} cm3 molecule–1 s–1. On the basis of our results, photolysis of CF3CF2CHO in the actinic region could be an important removal process for CF3CF2CHO in the atmosphere. The formation of the primary products in the UV photolysis of CF3CF2CHO is also discussed. PMID:24299449

Antiñolo, María; Jiménez, Elena; González, Sergio; Albaladejo, José

2014-01-01

180

Infrared, 1H and 13C NMR spectra, structural charcterization and DFT calculations of novel adenine-cyclodiphosp(V)azane derivatives.  

PubMed

Adenine tetrachlorocyclodiphospha(V)zane derivatives (III(a-c)) were prepared by the reaction of hexachlorocyclodiphospha(V)zane derivatives (I(a-c)) and adenine (II) as precursors. The synthesized compound's and their structures (III(a-c)) were firmly characterized (based on the presence of an inversion center) using FT-IR (4000-200 cm(-1)), UV-vis. (190-800 nm), (1)H, (13)C NMR and Mass spectral measurements in addition to C, H, N, P elemental analysis. The compounds (III(a-c)) were found to be a 1:2 molar ratio of (I(a-c)) and adenine (II) adducts, respectively. Confident and complete vibrational assignments are proposed for nearly all fundamental vibrations, along with detailed interpretation for all observed signals in both (1)H and (13)C NMR spectra of the investigated phospha(V)zanes (III(a-c)). In addition, unconstrained geometry optimization of III(a-c) were carried out by means of DFT-B3LYP/3-21G(d) calculations to provide new insight into the structural parameters and molecular geometries of compounds III(a-c). The results are reported herein and compared with similar molecules whenever appropriate. PMID:21937263

Mohamed, Tarek A; Zoghaib, Wajdi M; Shaaban, Ibrahim A; Farag, Rabei S; Alajhaz, Abd Elnasser M A

2011-12-01

181

Structural and spectroscopic characterization of 2-mesityl-1H-benzo[d]imidazol-3-ium chloride: A combined experimental and theoretical analysis  

NASA Astrophysics Data System (ADS)

The title molecular salt, 2-mesityl-1H-benzo[d]imidazol-3-ium chloride (C16H17N2+·Cl?), was synthesized unexpectedly from the reaction of N-[(1E)-mesitylmethylene]benzene-1,2-diamine and CoCl2·6H2O, and characterized by elemental analysis, 1H NMR and FT-IR spectroscopies, and single-crystal X-ray diffraction technique. In addition, quantum chemical calculations employing density functional theory (DFT) method with the 6-311++G(d,p) basis set were performed to study the molecular, spectroscopic and some electronic structure properties of the title compound, and the results were compared with the experimental findings. The computational result shows that the optimized geometry can well reproduce the crystal structural parameters. The intermolecular proton transfer process between the ionic (C16H17N2+·Cl?) and nonionic forms (C16H16N2·HCl) of the title salt is investigated and found to be almost barierless with an energy value of 0.20 kcal mol-1. The NLO properties of the compound are bigger than those of urea.

Özdemir, Nam?k

2012-06-01

182

Green chemistry approaches to the synthesis of 5-alkoxycarbonyl-4-aryl-3,4- dihydropyrimidin-2(1H)-ones by a three-component coupling of one-pot condensation reaction: comparison of ethanol, water, and solvent-free conditions.  

PubMed

A general and practical green chemistry route to the Biginelli cyclocondensation reaction using cerium(III) chloride as the catalyst (25% mol) is described under three different sets of reaction conditions. This method provides an efficient and much improved modification of original Biginelli reaction reported in 1893, in terms of high yields, short reaction times, and simple work-up procedure, and it has the ability to tolerate a wide variety of substitutions in all three components, which is lacking in existing procedures. PMID:12530887

Bose, D Subhas; Fatima, Liyakat; Mereyala, Hari Babu

2003-01-24

183

Synthesis of 2,3-dihydronaphtho[2,3-d][1,3]thiazole-4,9-diones and 2,3-dihydroanthra[2,3-d][1,3]thiazole-4,11-diones and novel ring contraction and fusion reaction of 3H-spiro[1,3-thiazole-2,1'-cyclohexanes] into 2,3,4,5-tetrahydro-1H-carbazole-6,11-diones.  

PubMed

Treatment of N-substituted 2-(methylamino)naphthoquinones 3 and -anthracene-1,4-diones 4 with S2Cl2 and DABCO in chlorobenzene gave the corresponding 2,3-dihydronaphtho[2,3-d][1,3]thiazole-4,9-diones 1 and 2,3-dihydroanthra[2,3-d][1,3]thiazole-4,11-diones 2 by triethylamine addition, in high to moderate yields. The DABCO replacement for N-ethyldiisopropylamine in the reaction of anthracene-1,4-diones 4 led unexpectedly to the corresponding 2-thioxo-2,3-dihydroanthra[2,3-d][1,3]thiazole-4,11-diones 10. The reaction of 3H-spiro[1,3-thiazole-2,1'-cyclohexanes] 1d, 2d with Et3N in chlorobenzene under reflux yielded 2,3,4,5-tetrahydro-1H-carbazole-6,11-diones 15, 16, i.e., ring contraction and fusion products. A plausible mechanism was proposed for the formation of the products. PMID:23616798

Konstantinova, Lidia S; Lysov, Kirill A; Souvorova, Ljudmila I; Rakitin, Oleg A

2013-01-01

184

Reaction of H[sub 2] with IrHCl[sub 2]P[sub 2] (P = P[sup i]Pr[sub 3] or P[sup t]Bu[sub 2]Ph). Stereoelectronic control of the stability of molecular H[sub 2] transition metal complexes  

SciTech Connect

IrHCl[sub 2]P[sub 2] (P = P[sup i]Pr[sub 3]) reacts rapidly with H[sub 2] at 25[degrees]C to set up an equilibrium where H[sub 2] binds trans to the original hydride ligand (trans-2). A second slower reaction forms IrH(H[sub 2])Cl[sub 2]P[sub 2] (cis-2), where the cis disposition of the chlorides, and also H cis to H[sub 2], was established by neutron diffraction. This molecule (unlike trans-2), shows rapid site exchange between coordinated H and H[sub 2]. cis-2 can be induced to lose HCL to form Ir(H)[sub 2]ClP[sub 2]. The structure of Ir(H)[sub 2]Cl(P[sup t]Bu[sub 2]Ph)[sub 2], an analog of 3, was shown by neutron diffraction to have a planar H[sub 2]IrCl in a Y shape, with Cl at the base of the Y and a H-Ir-H angle of only 73[degree]. ECP ab initio calculations of IrH[sub 2]Cl(PH[sub 3])[sub 2] show that the Y shape with a H-Ir-H angle close to the experimental value has the minimum energy. They also show that the trans-2 isomer of IrH(H[sub 2])Cl[sub 2](PH[sub 3])[sub 2] is less stable than the cis-2 isomer by 10.3 kcal/mol. The Ir-H[sub 2] interaction is stronger in cis-2. The rotational barrier has been calculated in the two isomers as 2.3 (trans) and 6.5 (cis) kcal/mol. In agreement with the experimental structure, the H-H bond is found to eclipse preferentially the Ir-H bond in cis-2. 74 refs., 12 figs., 5 tabs.

Albinati, A. (Universita de Milano (Italy)); Bakhmutov, V.I.; Gusev, D.G.; Caulton, K.G.; Clot, E.; Eckert, J.; Eisenstein, O.; Grushin, V.V.; Hauger, B.E.; Klooster, W.T. (and others)

1993-08-11

185

A practical, metal-free synthesis of 1H-indazoles.  

PubMed

The synthesis of 1H-indazoles is achieved from o-aminobenzoximes by the selective activation of the oxime in the presence of the amino group. The reaction occurs with a variety of substituted o-aminobenzoximes using a slight excess of methanesulfonyl chloride and triethylamine at 0-23 degrees C and is amenable to scale-up. The synthesis of 1H-indazoles under these conditions is extremely mild compared with previous synthetic approaches and affords the desired compounds in good to excellent yields. PMID:18229936

Counceller, Carla M; Eichman, Chad C; Wray, Brenda C; Stambuli, James P

2008-03-01

186

Cross-linking reaction of waterborne polyurethane adhesives containing different amount of ionic groups with hexamethoxymethyl melamine  

Microsoft Academic Search

Two series of cross-linkable waterborne polyurethane (WBPU) adhesives were synthesized by a conventional prepolymer process using 2,2-bis(hydroxymethyl) propionic acid (DMPA) (13.85 and 25.00mol%) and hexamethoxymethyl melamine (HMMM) as a hydrophilic agent and cross-linking agent, respectively. Using infrared (IR) and 1H NMR spectroscopy analysis, the cross-linking reaction between DMPA (carboxyl acid salt group) and HMMM (methoxy group) was identified, and it

Mohammad Mizanur Rahman; Eun-Young Kim; Ji Yun Kwon; Hye-Jin Yoo; Han-Do Kim

2008-01-01

187

The reaction of diethyl bromomalonate with p-tert-butylthia-calix[4]arene: an approach to asymmetrical derivatives.  

PubMed

New dissymmetric and asymmetric p-tert-butylthiacalix[4]arene derivatives were prepared as a result of the reaction of p-tert-butylthiacalix[4]arene with diethyl bromomalonate in the presence of different alkali metals (Cs, K and Na) in refluxing acetone for 7 days. The structures of the prepared compounds were investigated by IR, (1)H-NMR and MALDI-TOF mass spectroscopy. PMID:19471195

Omran, Omran Abdellah

2009-01-01

188

(1) H NMR spectra part 31: (1) H chemical shifts of amides in DMSO solvent.  

PubMed

The (1) H chemical shifts of 48 amides in DMSO solvent are assigned and presented. The solvent shifts ?? (DMSO-CDCl3 ) are large (1-2?ppm) for the NH protons but smaller and negative (-0.1 to -0.2?ppm) for close range protons. A selection of the observed solvent shifts is compared with calculated shifts from the present model and from GIAO calculations. Those for the NH protons agree with both calculations, but other solvent shifts such as ??(CHO) are not well reproduced by the GIAO calculations. The (1) H chemical shifts of the amides in DMSO were analysed using a functional approach for near (???3 bonds removed) protons and the electric field, magnetic anisotropy and steric effect of the amide group for more distant protons. The chemical shifts of the NH protons of acetanilide and benzamide vary linearly with the ? density on the ?N and ?C atoms, respectively. The C=O anisotropy and steric effect are in general little changed from the values in CDCl3 . The effects of substituents F, Cl, Me on the NH proton shifts are reproduced. The electric field coefficient for the protons in DMSO is 90% of that in CDCl3 . There is no steric effect of the C=O oxygen on the NH proton in an NH…O=C hydrogen bond. The observed deshielding is due to the electric field effect. The calculated chemical shifts agree well with the observed shifts (RMS error of 0.106?ppm for the data set of 257 entries). Copyright © 2014 John Wiley & Sons, Ltd. PMID:24824670

Abraham, Raymond J; Griffiths, Lee; Perez, Manuel

2014-07-01

189

One-step synthesis of pyrido[1,2-a]benzimidazole derivatives by a novel multicomponent reaction of chloroacetonitrile, malononitrile, aromatic aldehyde, and pyridine.  

PubMed

Polysubstituted pyrido[1,2-a]benzimidazole derivatives are efficiently produced in moderate yields in a novel one-pot, four-component reaction from pyridine or 3-picoline, chloroacetonitrile, malononitrile, and aromatic aldehyde in refluxing acetonitrile. The mechanism of this novel reaction was believed involving the formation of polysubstituted benzenes with subsequent substitution and annulation reaction of pyridine. All pyrido[1,2-a]benzimidazoles, polysubstituted benzenes, polysubstituted indoles, and some key reaction intermediates are characterized by (1)H and (13)C NMR, MS, IR spectra, and elemental analysis as well as X-ray crystallography. PMID:19072237

Yan, Chao Guo; Wang, Qi Fang; Song, Xiao Kai; Sun, Jing

2009-01-16

190

Infrared (IR) image synthesis method of IR real background and modeled IR target  

NASA Astrophysics Data System (ADS)

An infrared (IR) image synthesis method is proposed for the synthesis of a real IR background and modeled IR target, used as IR signatures, as well as a band-transformation between short wave IR (SWIR), middle wave IR (MWIR), and long wave IR (LWIR) in an IR imaging system simulation. IR target images are created by the RadThermIR software, an IR signature prediction software. Individual radiances for IR signatures, corresponding to the max/min temperatures of a real IR background and modeled IR target image, are calculated with Planck's law. First, an IR background of an arbitrary wavelength band is transformed to one of the other wavelength bands with the temperature-radiance characteristics. And then, after adjusting the gray levels of the arbitrary IR target signatures based on their radiances for the wavelength band of the transformed IR background, these IR target and background signatures can be synthesized as one image for a specific wavelength band. The experimental results show that the modeled IR target images, such as a modeled helicopter and F16, can be synthesized on the IR background images of three IR wavelength bands. And we confirmed that IR background images of the three IR wavelength bands can diversely be synthesized with the modeled IR targets as the setting temperature of the target and background, the target distance, and the field of view (FOV) arbitrarily.

Kim, Young-Choon; Bae, Tae-Wuk; Kwon, Hyuk-Ju; Kim, Byoung-Ik; Ahn, Sang-Ho

2014-03-01

191

Synthesis of trans-1,3-diaryl-2-(5-methylisoxazol-3-yl)-2,3-dihydro-1H-naphtho[1,2-e][1,3]oxazines via bismuth(III)-catalyzed one-pot pseudo-four component reaction.  

PubMed

An expeditious, straightforward and efficient synthesis of diversely naphtho[1,2-e][1,3]oxazines via one-pot condensation reaction of ?- naphthol, 3-amino-5-methylisoxazole and arylaldehydes catalyzed by bismuth(III) trifluoromethanesulfonate is described. The reaction preferentially afforded 1,3-trans oxazines. PMID:23090419

Shafiee, Mehdi; Khosropour, Ahmad Reza; Mohammadpoor-Baltork, Iraj; Moghadam, Majid; Tangestaninejad, Shahram; Mirkhani, Valiollah; Khavasi, Hamid Reza

2012-11-01

192

Catalytic Activity of Platinum Monolayer on Iridium and Rhenium Alloy Nanoparticles for the Oxygen Reduction Reaction  

SciTech Connect

A new type of electrocatalyst with a core?shell structure that consists of a platinum monolayer shell placed on an iridium? rhenium nanoparticle core or platinum and palladium bilayer shell deposited on that core has been prepared and tested for electrocatalytic activity for the oxygen reduction reaction. Carbon-supported iridium? rhenium alloy nanoparticles with several different molar ratios of Ir to Re were prepared by reducing metal chlorides dispersed on Vulcan carbon with hydrogen gas at 400 °C for 1 h. These catalysts showed specific electrocatalytic activity for oxygen reduction reaction comparable to that of platinum. The activities of PtML/PdML/Ir2Re1, PtML/Pd2layers/Ir2Re1, and PtML/Pd2layers/Ir7Re3 catalysts were, in fact, better than that of conventional platinum electrocatalysts, and their mass activities exceeded the 2015 DOE target. Our density functional theory calculations revealed that the molar ratio of Ir to Re affects the binding strength of adsorbed OH and, thereby, the O2 reduction activity of the catalysts. The maximum specific activity was found for an intermediate OH binding energy with the corresponding catalyst on the top of the volcano plot. The monolayer concept facilitates the use of much less platinum than in other approaches. The results with the PtML/PdML/Ir2Re electrocatalyst indicate that it is a promising alternative to conventional Pt electrocatalysts in low-temperature fuel cells.

Karan, Hiroko I.; Sasaki, Kotaro; Kuttiyiel, Kurian; Farberow, Carrie A.; Mavrikakis, Manos; Adzic, Radoslav R.

2012-05-04

193

WebSpectra: Problems in NMR and IR Spectroscopy  

NSDL National Science Digital Library

From the University of California at Los Angeles's Chemistry Department, WebSpectra provides chemistry students with a searchable library of Nuclear Magnetic Resonance (NMR) and Infrared (IR) spectroscopy problems. According to the makers of this innovative site, "Interpretation of spectra is a technique that requires practice - this site provides 1H NMR and 13C NMR, DEPT, COSY and IR spectra of various compounds for students to interpret." A set of instructional documents are entitled Solving Spectral Problems, Overview of NMR Spectroscopy, Notes on NMR Solvents, Types of NMR Spectra, Introduction to IR Spectra, and a Table of IR Absorptions. A wide variety of compounds and their spectra are available for interpretation and have been organized in categories from Beginning to Advanced. Spectrum for each compound may be magnified 16X by clicking on peaks. This is an outstanding learning tool for students coming to grips with interpreting NMR and IR spectra.

194

Web Spectra: Problems in NMR and IR spectroscopy  

NSDL National Science Digital Library

This site was established to provide chemistry students with a library of spectroscopy problems. Interpretation of spectra is a technique that requires practice - this site provides 1H NMR and 13 C NMR, DEPT, COSY and IR spectra of various compounds for students to interpret. Hopefully, these problems will provide a useful resource to better understand spectroscopy.

Merlic, Craig A.

2008-02-29

195

Deproto-metallation using a mixed lithium-zinc base and computed CH acidity of 1-aryl 1H-benzotriazoles and 1-aryl 1H-indazoles.  

PubMed

1-Aryl-1H-benzotriazoles and -1H-indazoles were synthesized, and their deproto-metallation using the base prepared by mixing LiTMP with ZnCl2·TMEDA (1/3 equiv.) was studied. In the indazole series, reactions occurring at the 3 position were followed by ring opening, and functionalization of the substrate was only found possible (on the sulfur ring) using 2-thienyl as aryl group. In the benzotriazole series, either mono- or bis-deprotonation (depending on the amount of base employed) was achieved with phenyl, 4-methoxyphenyl and 2-thienyl as aryl group, and bis-deprotonation in the case of 4-chlorophenyl and 4-trifluoromethylphenyl. The experimental results were analyzed with the help of the CH acidities of the substrates, determined in THF solution using the DFT B3LYP method. PMID:24445663

Nagaradja, Elisabeth; Chevallier, Floris; Roisnel, Thierry; Dorcet, Vincent; Halauko, Yury S; Ivashkevich, Oleg A; Matulis, Vadim E; Mongin, Florence

2014-03-01

196

The hydrogen-bonded 2-pyridone dimer model system. 1. Combined NMR and FT-IR spectroscopy study.  

PubMed

2-Pyridone (PD), converting to 2-hydroxypyridine (HP) through a lactam-lactim isomerization mechanism, can form three different cyclic dimers by hydrogen bond formation: (PD)(2), (PD-HP), and (HP)(2). We investigate the complexation chemistry of pyridone in dichloromethane-d(2) using a combined NMR and Fourier transform infrared (FT-IR) approach. Temperature-dependent (1)H NMR spectra indicate that at low temperatures (<200 K) pyridone in solution predominantly exists as a cyclic (PD)(2) dimer, in exchange with PD monomers. At higher temperatures a proton exchange mechanism sets in, leading to a collapse of the doublet of (15)N labeled 2-pyridone. Linear FT-IR spectra indicate the existence of several pyridone species, where, however, a straightforward interpretation is hampered by extensive spectral overlap of many vibrational transitions in both the fingerprint and the NH/OH stretching regions. Two-dimensional IR correlation spectroscopy applied on concentration-dependent and temperature-dependent data sets reveals the existence of the (PD)(2) cyclic dimer, of PD-CD(2)Cl(2) solute-solvent complexes, and of PD-PD chainlike dimers. Regarding the difference in effective time scales of the NMR and FT-IR experiments, milliseconds vs (sub)picoseconds, the cyclic dimers (PD-HP) and (HP)(2), and the chainlike conformations HP-PD, may function as intermediates in reaction pathways through which the protons exchange between PD units in cyclic (PD)(2). PMID:20593823

Szyc, ?ukasz; Guo, Jing; Yang, Ming; Dreyer, Jens; Tolstoy, Peter M; Nibbering, Erik T J; Czarnik-Matusewicz, Bogus?awa; Elsaesser, Thomas; Limbach, Hans-Heinrich

2010-07-29

197

Lipoatrophic diabetes in Irs1?/?/Irs3?/? double knockout mice  

PubMed Central

Based on the phenotypes of knockout mice and cell lines, as well as pathway-specific analysis, the insulin receptor substrates IRS-1, IRS-2, IRS-3, and IRS-4 have been shown to play unique roles in insulin signal transduction. To investigate possible functional complementarity within the IRS family, we generated mice with double knockout of the genes for IRS-1/IRS-3 and IRS-1/IRS-4. Mice with a combined deficiency of IRS-1 and IRS-4 showed no differences from Irs1?/? mice with respect to growth and glucose homeostasis. In contrast, mice with a combined deficiency of IRS-1 and IRS-3 developed early-onset severe lipoatrophy associated with marked hyperglycemia, hyperinsulinemia, and insulin resistance. However, in contrast to other models of lipoatrophic diabetes, there was no accumulation of fat in liver or muscle. Furthermore, plasma leptin levels were markedly decreased, and adenovirus-mediated expression of leptin in liver reversed the hyperglycemia and hyperinsulinemia. The results indicate that IRS-1 and IRS-3 play important complementary roles in adipogenesis and establish the Irs1?/?/Irs3?/? double knockout mouse as a novel model of lipoatrophic diabetes.

Laustsen, Palle G.; Michael, M. Dodson; Crute, Barbara E.; Cohen, Shmuel E.; Ueki, Kohjiro; Kulkarni, Rohit N.; Keller, Susanna R.; Lienhard, Gustav E.; Kahn, C. Ronald

2002-01-01

198

Synthesis and biological evaluation of some 2-(3,5-dimethyl-1H-pyrazol-1-yl)-1-arylethanones: Antibacterial, DNA photocleavage, and anticancer activities.  

PubMed

In continuation of our efforts to find new biologically active agents, regioselective synthesis of a series of 2-(3,5-dimethyl-1H-pyrazol-1-yl)-1-arylethanones 4a-k has been achieved under facile, extremely mild and greener reaction conditions with excellent yields. Moreover, one pot multicomponent reaction has also been reinvestigated under previously reported solvent conditions to prepare 4a-b and found that the reaction generates significant amount of side products. The chemical structures of 4a-k were established on the basis of a combined use of IR, NMR ((1)H, (13)C) spectroscopy, mass spectrometry and elemental analysis. All the compounds were evaluated for their antibacterial, DNA photocleavage and anticancer activities. Among all, 2-(3,5-dimethyl-1H-pyrazol-1-yl)-1-(naphth-2-yl)ethanone 4j displayed good inhibitory profile against Escherichia coli and Staphylococcus aureus which was about 50% and 25% of the Ampicillin (standard drug), respectively. The compounds, 4a and 4f showed relatively moderate inhibition against Psuedomonas aeruginosa and E. coli. In DNA photocleavage study, compounds 4c and 4d were found to be highly active and completely degraded both forms of DNA (SC and OC), even at a very low concentration of 1 ?g (4c) under irradiation of UV light. However, 4h and 4f resulted in complete DNA degradation at 30 ?g concentration. Moreover, 4h showed fluorescence at 15 ?g concentration and increased the intensity of both bands of DNA (SC and OC) as compared to control. On the other hand, to valorize the biological potential, the compounds were screened for their cytotoxic activity on colon (HCT116 and HT29), prostate (DU145), ovarian (SKOV3) and lung (A549) cancer cell lines. The compound 4j was found to be cytotoxic to all the cancer cell lines, except SKOV3, with more selectivity towards the colon cancer cell lines (HCT116, HT29) and A549 lung cancer cell line. On A549 lung cancer cell line, 4j and 4k exhibited similar potency as carboplatin in inhibiting cell viability. PMID:24849271

Kumar, Vinod; Kaur, Kamalneet; Karelia, Deepkamal N; Beniwal, Vikas; Gupta, Girish Kumar; Sharma, Arun K; Gupta, Akhilesh Kumar

2014-06-23

199

Low-lying positive parity states in 195Ir following double neutron capture  

Microsoft Academic Search

Multiple neutron capture reactions have been studied on 193Ir targets and gamma and electron spectroscopy performed. Double neutron capture events were separated from all others and a level scheme of 195Ir deduced. Gamma-ray energies and multipolarities are tabulated. A neutron capture cross-section for the reaction 194Ir(n, gamma) of 1500+\\/-290b has been determined and the neutron binding energy of 195Ir measured

G. G. Colvin; H. G. Börner; P. Geltenbort; F. Hoyler; S. A. Kerr; K. Schreckenbach; J. A. Cizewski

1987-01-01

200

Fluorescence and IR characterization of epoxy cured with aliphatic amines  

Microsoft Academic Search

Cure reactions of the stoichiometric mixtures of diglycidyl ether of bisphenol A (DGEBA) and two very low molecular weight aliphatic polyether diamines (PED) were studied by using fluorescence and mid- and near-IR spectroscopic techniques. As the cure proceeded, the primary amine groups in PED are converted to the secondary and the tertiary amines. Near-IR spectral analysis was used to calculate

Andrés Rigail-Cedeño; Chong Sook Paik Sung

2005-01-01

201

A simple and clean procedure for the synthesis of polyhydroacridine and quinoline derivatives: reaction of Schiff base with 1,3-dicarbonyl compounds in aqueous medium  

Microsoft Academic Search

A clean and simple synthesis of benzo[c]acridine, benzo[a]acridine, pyrido[2,3-c]acridine and benzo[f]quinoline derivatives was accomplished in good to excellent yields via the reaction of Schiff base with 1,3-dicarbonyl compounds in aqueous medium catalyzed by TEBA. The structures were characterized by 1H NMR, IR and elemental analysis, and confirmed by X-ray diffraction study.

Xiang-Shan Wang; Mei-Mei Zhang; Zhao-Sen Zeng; Da-Qing Shi; Shu-Jiang Tu; Xian-Yong Wei; Zhi-Min Zong

2005-01-01

202

Synthesis and characterization of 2,2?-(pyridine-2,6-diyl)bis(1H-benzo[d]imidazol-3-ium) 2,4,6-trimethylbenzenesulfonate chloride by experimental and theoretical methods  

NASA Astrophysics Data System (ADS)

The title molecular salt (2), 2,2?-(pyridine-2,6-diyl)bis(1H-benzo[d]imidazol-3-ium) 2,4,6-trimethylbenzenesulfonate chloride (C19H15N52+·C9H11O3S-·Cl-), was synthesized unexpectedly from the reaction of 2,6-bis(benzimidazol-2-yl)pyridine (1) with 2-mesitylenesulfonyl chloride. Spectroscopic techniques (FT-IR, NMR and UV-vis.) were used to characterize compounds 1 and 2. Solid-state structure of compound 2 was identified by X-ray crystallography. Theoretical characterization of the spectroscopic properties of compounds 1 and 2 was achieved using the density functional theory (DFT) method with the 6-311G(d,p) basis set, and the results were checked against the experimental data. Electronic absorption spectra of the compounds have also been obtained.

Özdemir, Nam?k; Dayan, Osman; Yava?o?lu, Melek Tercan; Çetinkaya, Bekir

2014-10-01

203

Synthesis and characterization of 2,2'-(pyridine-2,6-diyl)bis(1H-benzo[d]imidazol-3-ium) 2,4,6-trimethylbenzenesulfonate chloride by experimental and theoretical methods.  

PubMed

The title molecular salt (2), 2,2'-(pyridine-2,6-diyl)bis(1H-benzo[d]imidazol-3-ium) 2,4,6-trimethylbenzenesulfonate chloride (C19H15N5(2+)·C9H11O3S(-)·Cl(-)), was synthesized unexpectedly from the reaction of 2,6-bis(benzimidazol-2-yl)pyridine (1) with 2-mesitylenesulfonyl chloride. Spectroscopic techniques (FT-IR, NMR and UV-vis.) were used to characterize compounds 1 and 2. Solid-state structure of compound 2 was identified by X-ray crystallography. Theoretical characterization of the spectroscopic properties of compounds 1 and 2 was achieved using the density functional theory (DFT) method with the 6-311G(d,p) basis set, and the results were checked against the experimental data. Electronic absorption spectra of the compounds have also been obtained. PMID:24825668

Ozdemir, Nam?k; Dayan, Osman; Yava?o?lu, Melek Tercan; Cetinkaya, Bekir

2014-10-15

204

Synthesis of a rare 3D copper cyanide compound based on 3-(5-(pyridin-4-yl)-1H-1,2,4-triazol-3-yl)pyridine via the transformation of acetonitrile to inorganic cyanide  

NASA Astrophysics Data System (ADS)

One-pot solvothermal treatments of acetonitrile, water, LiOH, Cu(CH3COO)2·H2O and 3-(5-(pyridin-4-yl)-1H-1,2,4-triazol-3-yl)pyridine (HL) yielded a rare copper cyanide coordination polymer, [Cu2(L) (CN)]n (1). The existence of a cyanide group in compound 1 may be due to the decomposition of acetonitrile at the relatively high temperature (160 °C) and autogenous pressure of the reaction. Compound 1 has been characterized by single-crystal X-ray diffraction, XRPD, IR, and elemental analysis. Compound 1 is a 3D copper cyanide coordination polymer, and a ({6.8.10}2{6.8^3.10^2}) topology in 1 is created. In addition, the optical and catalytic properties have been investigated.

Yang, Linyan; Xin, Liangliang; Tian, Jinlei; Du, Peiyao; Wei, Xiaohua; Liao, Shengyun; Zhang, Yanping; Lv, Rui; Gu, Wen; Liu, Xin

2014-05-01

205

Density functional theory investigations on the catalytic mechanisms of hydrazine decompositions on Ir(1 1 1)  

Microsoft Academic Search

The mechanisms of hydrazine decompositions on Ir(111) have been investigated by using slab model based on periodic density functional theory (DFT). In order to shed light on the elementary radical reaction processes of hydrazine decomposition on Ir-based catalysts, three possible reaction pathways are considered. Through computational modeling we have investigated the adsorption characteristics, geometrical structures, activation energies, and reaction mechanisms.

Ping-Xia Zhang; Yang-Gang Wang; Yan-Qiang Huang; Tao Zhang; Guo-Shi Wu; Jun Li

2011-01-01

206

Synthesis of 3-(1-Methyl-1H-imidazol-2-ylthio)propanoic Acid and (E)-3-(1-Methyl-1H-imidazol-2-ylthio)acrylic Acid  

PubMed Central

The syntheses of 3-(1-methyl-1H-imidazol-2-ylthio)acrylic acid and 3-(1-methyl-1H-imidazol-2-ylthio)propanoic acid, mitochondria-targeted prodrugs of the antioxidant methimazole, are described. The method of Fan et al. (Fan et al., Synthesis 2006, 2286) for the reaction of phenols with propiolic acid and propiolate esters was modified to synthesize (E)-3-(1-methyl-1H-imidazol-2-ylthio)acrylic acid. The intermediate tert-butyl (E)-3-(1-methyl-1H-imidazol-2-ylthio)acrylate was prepared by the reaction of tert-butyl propiolate with methimazole; the use of tert-butyl propiolate rather than methyl propiolate gave tert-butyl (E)-3-(1-methyl-1H-imidazol-2-ylthio)acrylate as the predominant isomer. Acid hydrolysis of the intermediate ester afforded the target compound. 3-(1-Methyl-1H-imidazol-2-ylthio)propanoic acid was synthesized from 3-bromopropanoic acid and methimazole under conditions that gave preferential substitution on sulfur and minimized substitution on nitrogen.

Hattan, Christopher M.; Shojaie, Jalil; Lau, Serrine S.; Anders, M. W.

2014-01-01

207

Microcavity array IR photodetector  

SciTech Connect

An original microcavity array IR photodetector is proposed and the sensitivity and response time of its pixels are calculated. A photosensitive element represents a composite silicon microcavity made of two optically coupled closed waveguides on a dielectric substrate whose resonance wave depends on its temperature. This dependence is used to detect IR radiation which heats an absorbing element and the composite microcavity thermally coupled with this element. It is shown that for a spatial resolution of 45 {mu}m, the time response is 30 ms and the sensitivity is 10{sup -3} K at the IR radiation power of {approx} 4.7 x 10{sup -8} W element{sup -1}. (photodetectors)

Esman, A K; Kuleshov, V K; Zykov, G L [B.I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, Minsk (Belarus)

2009-12-31

208

Quantification of taurine in energy drinks using (1)H NMR.  

PubMed

The consumption of so called energy drinks is increasing, especially among adolescents. These beverages commonly contain considerable amounts of the amino sulfonic acid taurine, which is related to a magnitude of various physiological effects. The customary method to control the legal limit of taurine in energy drinks is LC-UV/vis with postcolumn derivatization using ninhydrin. In this paper we describe the quantification of taurine in energy drinks by (1)H NMR as an alternative to existing methods of quantification. Variation of pH values revealed the separation of a distinct taurine signal in (1)H NMR spectra, which was applied for integration and quantification. Quantification was performed using external calibration (R(2)>0.9999; linearity verified by Mandel's fitting test with a 95% confidence level) and PULCON. Taurine concentrations in 20 different energy drinks were analyzed by both using (1)H NMR and LC-UV/vis. The deviation between (1)H NMR and LC-UV/vis results was always below the expanded measurement uncertainty of 12.2% for the LC-UV/vis method (95% confidence level) and at worst 10.4%. Due to the high accordance to LC-UV/vis data and adequate recovery rates (ranging between 97.1% and 108.2%), (1)H NMR measurement presents a suitable method to quantify taurine in energy drinks. PMID:24094700

Hohmann, Monika; Felbinger, Christine; Christoph, Norbert; Wachter, Helmut; Wiest, Johannes; Holzgrabe, Ulrike

2014-05-01

209

Photo-polymeriable chitosan derivative prepared by Michael reaction of chitosan and polyethylene glycol diacrylate (PEGDA).  

PubMed

N-Alkyled photo-polymeriable chitosan derivative (PEGDA-CS) was synthesized by Michael reaction of chitosan and polyethylene glycol diacrylate (PEGDA) under mild reaction conditions. The chemical structure and physical properties of PEGDA-CS were characterized by FT-IR, (1)H NMR, XRD and TG techniques. The degree of substitution (DS) of PEGDA-CS could be calculated from (1)H NMR. PEGDA-CS exhibited good solubility in distilled water. XRD analysis showed that PEGDA-CS was amorphous. TG results demonstrated that thermal stability of the derivate was lower than that of chitosan. Antimicrobial test showed that PEGDA-CS had the antimicrobial activity on Escherichia coli. It could photopolymerize under ultraviolet light with 2959 as initiator. PMID:19720075

Ma, Guiping; Zhang, Xiaodan; Han, Jing; Song, Guoqiang; Nie, Jun

2009-12-01

210

Novel 1H low field nuclear magnetic resonance applications for the field of biodiesel  

PubMed Central

Background Biodiesel production has increased dramatically over the last decade, raising the need for new rapid and non-destructive analytical tools and technologies. 1H Low Field Nuclear Magnetic Resonance (LF-NMR) applications, which offer great potential to the field of biodiesel, have been developed by the Phyto Lipid Biotechnology Lab research team in the last few years. Results Supervised and un-supervised chemometric tools are suggested for screening new alternative biodiesel feedstocks according to oil content and viscosity. The tools allowed assignment into viscosity groups of biodiesel-petrodiesel samples whose viscosity is unknown, and uncovered biodiesel samples that have residues of unreacted acylglycerol and/or methanol, and poorly separated and cleaned glycerol and water. In the case of composite materials, relaxation time distribution, and cross-correlation methods were successfully applied to differentiate components. Continuous distributed methods were also applied to calculate the yield of the transesterification reaction, and thus monitor the progress of the common and in-situ transesterification reactions, offering a tool for optimization of reaction parameters. Conclusions Comprehensive applied tools are detailed for the characterization of new alternative biodiesel resources in their whole conformation, monitoring of the biodiesel transesterification reaction, and quality evaluation of the final product, using a non-invasive and non-destructive technology that is new to the biodiesel research area. A new integrated computational-experimental approach for analysis of 1H LF-NMR relaxometry data is also presented, suggesting improved solution stability and peak resolution.

2013-01-01

211

Synthesis and Characterization of Carbazolide-Based Iridium PNP Pincer Complexes. Mechanistic and Computational Investigation of Alkene Hydrogenation: Evidence for an Ir(III)/Ir(V)/Ir(III) Catalytic Cycle.  

PubMed

New carbazolide-based iridium pincer complexes ((carb)PNP)Ir(C2H4), 3a, and ((carb)PNP)Ir(H)2, 3b, have been prepared and characterized. The dihydride, 3b, reacts with ethylene to yield the cis-dihydride ethylene complex cis-((carb)PNP)Ir(C2H4)(H)2. Under ethylene this complex reacts slowly at 70 °C to yield ethane and the ethylene complex, 3a. Kinetic analysis establishes that the reaction rate is dependent on ethylene concentration and labeling studies show reversible migratory insertion to form an ethyl hydride complex prior to formation of 3a. Exposure of cis-((carb)PNP)Ir(C2H4)(H)2 to hydrogen results in very rapid formation of ethane and dihydride, 3b. DFT analysis suggests that ethane elimination from the ethyl hydride complex is assisted by ethylene through formation of ((carb)PNP)Ir(H)(Et)(C2H4) and by H2 through formation of ((carb)PNP)Ir(H)(Et)(H2). Elimination of ethane from Ir(III) complex ((carb)PNP)Ir(H)(Et)(H2) is calculated to proceed through an Ir(V) complex ((carb)PNP)Ir(H)3(Et) which reductively eliminates ethane with a very low barrier to return to the Ir(III) dihydride, 3b. Under catalytic hydrogenation conditions (C2H4/H2), cis-((carb)PNP)Ir(C2H4)(H)2 is the catalyst resting state, and the catalysis proceeds via an Ir(III)/Ir(V)/Ir(III) cycle. This is in sharp contrast to isoelectronic (PCP)Ir systems in which hydrogenation proceeds through an Ir(III)/Ir(I)/Ir(III) cycle. The basis for this remarkable difference is discussed. PMID:24746026

Cheng, Chen; Kim, Bong Gon; Guironnet, Damien; Brookhart, Maurice; Guan, Changjian; Wang, David Y; Krogh-Jespersen, Karsten; Goldman, Alan S

2014-05-01

212

IRS1/A0484  

NSDL National Science Digital Library

The insulin receptor substrate 1 (IRS1, also known as A0484) is a docking and adaptor protein that is multiply phosphorylated by a variety of protein kinases and is the major substrate of the insulin and insulin-like growth factor receptors (IGFRs).

2009-04-14

213

Integrated IR sensors  

Microsoft Academic Search

Integrated infrared (IR) sensors which exploit modular avionics concepts can provide features such as operational flexibility, enhanced stealthiness, and ease of maintenance to meet the demands of tactical, airborne sensor systems. On-board, tactical airborne sensor systems perform target acquisition, tracking, identification, threat warning, missile launch detection, and ground mapping in support of situation awareness, self-defense, navigation, target attack, weapon support,

Michael Tom; Edward Trujillo

1994-01-01

214

Synthesis of 5(and 6)-nitro-4-methyl-2,3-dihydro-1h-1,5-benzo-2-diazepinones  

Microsoft Academic Search

The reaction of 4-nitro-o-phenylenediamine (I) with acetoacetic ester at room temperature under acid catalysis gives ethyl 3-(2-amino-5-nitrophenylamino)crotonate (II), which is readily cyclized to 7-nitro-4-methyl-2,3-dihydro-1H-1,5-benzo-2-diazepinone (III) on heating with alkaline agents. The reaction of I with acetoacetic ester in refluxing xylene gives isomeric 8-nitro-4-methyl-2,5-dihydro-1H-1,5-benzo-2-diazepinone (IVa) or 8-nitro-4-methyl-2,3-dihydro-1H-1,5-benzo-2-diazepinone (IVb), which are readily interconverted. The synthesis of IV is complicated by the side

A. N. Kost; Z. F. Solomko; V. A. Budylin; T. S. Semenova

1972-01-01

215

Synthesis and structure characterization of new 1,2,4-oxadiazolo[4,5-d]-1,5-benzothiazepines derivatives containing 2-phenyl-1,2,3-triazole through 1,3-dipolar cycloaddition reaction  

Microsoft Academic Search

Reaction of 1,5-benzothiazepines, containing 2-phenyl-1,2,3-triazole 2a–d, with aryl nitrile oxides in CH2 Cl2 at room temperature leads to a series of novel 1,2,4-oxadiazolo[4,5-d]-1,5-benzothiazepine derivatives 3a-l in good yields. The products were characterized by IR, 1H NMR, MS, elemental analyses, X-ray and their spectrum characters were discussed.

De-Bao Yang; Fang-Ming Liu; Feng Xu; Chun Yang; Jia-Wei Ye; Song-Wei Shen; Ying-Lei Zhou; Wei Li

2008-01-01

216

Sulfur-containing hyperbranched polymeric photoinitiator end-capped with benzophenone and tertiary amine moieties prepared via simultaneous double thiol-ene click reactions used for UV curing coatings  

Microsoft Academic Search

A series of sulfur-containing hyperbranched polymeric photoinitiators end-capped with benzophenone (BP) and tertiary amine moieties (B\\/A-HPIs) were synthesized via the simultaneous double thiol-ene click reactions of thiolated hyperbranched polymer with both dimethylaminoethyl acrylate and 3-(4-benzoylphenoxy)propyl acrylate. The molecular structures were characterized by 1H NMR and FT-IR spectroscopy. From the UV–vis spectra, B\\/A-HPIs showed the stronger n-?* absorption at ?340nm with

Han Xie; Lihua Hu; Yong Zhang; Wenfang Shi

2011-01-01

217

One-pot synthesis of 3,4-dihydropyrimidin-2(1 H)-ones using boric acid as catalyst  

Microsoft Academic Search

A simple effective synthesis of 3,4-dihydropyrimidin-2(1H)-one derivatives, using boric acid as catalyst, from aromatic aldehydes, 1,3-dicarbonyl compounds and urea in glacial acetic acid is described. Compared with the classical Biginelli reaction conditions, this new method has the advantage of excellent yields (86–97%) and short reaction time (0.5–2 h).

Shujang Tu; Fang Fang; Chunbao Miao; Hong Jiang; Youjian Feng; Daqing Shi; Xiangshan Wang

2003-01-01

218

Crystal structure, spectroscopic properties and density functional theory study of (Z)-1-[(2,4-dimethoxyphenylamino)methylene]naphthalen-2(1 H)-one  

NASA Astrophysics Data System (ADS)

The Schiff base (Z)-1-[(2,4-dimethoxyphenylamino)methylene]naphthalen-2(1 H)-one was synthesized from the reaction of 2-hydroxy-1-naphthaldehyde with 2,4-dimethoxyaniline. The title compound has been characterized by FT-IR, UV-Vis and, X-ray single-crystal techniques. The present X-ray investigation shows that the compound exists in the keto-amine tautomeric form. Molecular geometry and vibrational frequencies of the compound in the ground state have been calculated using the density functional theory (DFT) with 6-311G(d, p) basis set and compared with the experimental data. The calculated results show that the optimized geometry is compatible with the crystal structure and the theoretical vibrational frequencies are in good agreement with the experimental values. Besides, molecular electrostatic potential (MEP), frontier molecular orbital analysis (HOMO-LUMO) and non-linear optical (NLO) properties of the compound were investigated using the same theoretical calculations.

Kargili, Hakan; Alpaslan, Gökhan; Macit, Mustafa; Erdönmez, Ahmet; Büyükgüngör, Orhan

2014-02-01

219

Novel approach to 3,4-dihydro-2(1H)-quinolinone derivatives via cyclopropane ring expansion.  

PubMed

N-(1'-Alkoxy)cyclopropyl-2-haloanilines are transformed to 3,4-dihydro-2((1)H)-quinolinones via palladium-catalyzed cyclopropane ring expansion. The reaction tolerates a variety of functional groups such as ester, nitrile, ether, and ketone groups. PMID:19193029

Tsuritani, Takayuki; Yamamoto, Yuhei; Kawasaki, Masashi; Mase, Toshiaki

2009-03-01

220

A simple route for the synthesis of novel N-alkyl-2-(alkylthio)-1H-imidazole derivatives.  

PubMed

Novel N-alkyl-2-(alkylthio)-1H-imidazole derivatives were synthesized in a single step by an efficient and simple method in high yields. Readily available starting materials, mild reaction conditions, operational simplicity and novelty are the key advantages of this method. Besides their novel structures, these compounds may have important biological activities and industrial applications. PMID:23456639

Kianmehr, Ebrahim; Shamsaei Zafarghandi, Narges; Ghanbari, Mohammad

2013-05-01

221

Studies of antimicrobial activity of N-alkyl and N-acyl 2-(4-thiazolyl)- 1H-benzimidazoles  

Microsoft Academic Search

Various N-alkyl and N-acyl derivatives of 2-(4-thiazolyl)-1H-benzimidazole, an anthelmintic and systemic fungicide, were synthesized by polymer-supported reactions and screened for their antifungal and antibacterial potency to establish structure-activity relationships.

N. S Pawar; D. S Dalal; S. R Shimpi; P. P Mahulikar

2004-01-01

222

Studies of antimicrobial activity of N-alkyl and N-acyl 2-(4-thiazolyl)-1H-benzimidazoles.  

PubMed

Various N-alkyl and N-acyl derivatives of 2-(4-thiazolyl)-1H-benzimidazole, an anthelmintic and systemic fungicide, were synthesized by polymer-supported reactions and screened for their antifungal and antibacterial potency to establish structure-activity relationships. PMID:14757482

Pawar, N S; Dalal, D S; Shimpi, S R; Mahulikar, P P

2004-02-01

223

Gold-catalyzed tandem [3,3]-propargyl ester rearrangement leading to (E)-1H-inden-1-ones.  

PubMed

An efficient method for the synthesis of (E)-1H-inden-1-ones using gold-catalyzed tandem [3,3]-propargyl ester rearrangement followed by Michael addition under mild reaction conditions has been developed. The resulting products are important frameworks found in numerous natural products and pharmaceutically active compounds, as well as being valuable intermediates in organic synthesis. PMID:24328090

Wang, Li-Jing; Zhu, Hai-Tao; Wang, An-Qi; Qiu, Yi-Feng; Liu, Xue-Yuan; Liang, Yong-Min

2014-01-01

224

Diagnostic performance 1 h after simulation training predicts learning.  

PubMed

Although simulation training improves post-training performance, it is unclear how well performance soon after simulation training predicts longer term outcomes (i.e., learning). Here our objective was to assess the predictive value of performance 1 h post-training of performance 6 weeks later. We trained 84 first year medical students a simulated case of chest pain due to aortic stenosis. They then received training on a case of acute onset dyspnea due to pulmonary embolism, after which we evaluated diagnostic performance on their trained murmur followed by novel murmur. We repeated the evaluation of diagnostic performance on the same murmurs 6 weeks later. One hour post-training 88.1 % of students identified the training murmur, compared to 60.7 % for the novel murmur. Six weeks after training the corresponding results were 89.3 and 65.5 %, respectively (p < 0.0001 for both time periods). The probability of students diagnosing their training murmur 6 weeks post-training if they diagnosed this after 1 h (positive predictive value) was 0.89 [0.87, 0.93], and the probability of misdiagnosing their trained murmur 6 weeks post-training if they misdiagnosed this after 1 h (negative predictive value) was 0.10 [0.01, 0.40]. The corresponding positive and negative predictive values for the novel murmur were 0.69 [0.55, 0.80] and 0.39 [0.24, 0.57], respectively. Students who successfully diagnosed a cardiac murmur 1 h after simulation training were very likely to recognize the same murmur 6 weeks later, suggesting that we can use performance 1 h post-training as a learning outcome. PMID:23184437

Consoli, Anna; Fraser, Kristin; Ma, Irene; Sobczak, Matthew; Wright, Bruce; McLaughlin, Kevin

2013-12-01

225

{ital In situ} study of interface reactions of ion beam sputter deposited (Ba{sub 0.5}Sr{sub 0.5})TiOâ films on Si, SiOâ, and Ir  

Microsoft Academic Search

(Ba{sub 0.5},Sr{sub 0.5})TiOâ (BST) thin films were deposited on MgO, Si, SiOâ and Ir surfaces by ion beam sputter deposition in oxygen at 700&hthinsp;°C. {ital In situ} spectroscopic ellipsometry (SE) has been used to investigate the evolution of the BST films on different surfaces during both deposition and postannealing processes. First, the optical constants of the BST films in the

Y. Gao; A. H. Mueller; E. A. Irene; O. Auciello; A. Krauss; J. A. Schultz

1999-01-01

226

In situ study of interface reactions of ion beam sputter deposited (Ba{sub 0.5}Sr{sub 0.5})TiOâ films on Si, SiOâ, and Ir  

Microsoft Academic Search

Ba{sub 0.5},Sr{sub 0.5}TiOâ (BST) thin films were deposited on MgO, Si, SiOâ and Ir surfaces by ion beam sputter deposition in oxygen at 700 {sup o}C. In situ spectroscopic ellipsometry (SE) has been used to investigate the evolution of the BST films on different surfaces during both deposition and postannealing processes. First, the optical constants of the BST films in

Y. Gao; H. Mueller; E. A. Irene; O. Auciello; A. R. Krauss; J. A. Schultz; Ionwerks

1999-01-01

227

Synthesis, molecular structure and spectral analysis of ethyl 4-[(3,5-dinitrobenzoyl)-hydrazonomethyl]-3,5-dimethyl-1H-pyrrole-2-carboxylate: a combined experimental and quantum chemical approach.  

PubMed

A new hydrazone, ethyl 4-[(3,5-dinitrobenzoyl)-hydrazonomethyl]-3,5-dimethyl-1H-pyrrole-2-carboxylate (PDNBAH) has been synthesized and characterized by FT-IR, (1)H NMR, UV-visible spectroscopy. All the quantum chemical calculations have been performed by density functional theory (DFT), using B3LYP functional and 6-31G(d,p) as basis set. The calculated and experimental wavenumber analyses confirm the existence of dimer of PDNBAH. The calculated binding energies of dimer using DFT and Bader's atoms in molecules (AIM) theory are -14.32 and -15.41 kcal/mol respectively. The intermolecular hydrogen bond energy of dimer due to the involvement of intermolecular hetero-nuclear double hydrogen bonds (N-H···O=C) through pyrrolic N-H and C=O of ester is also calculated to be equal to -12.29 kcal/mol using AIM calculation. The strength and the nature of hydrogen bonding and weak interactions in dimer have been analyzed by AIM theory in detail. The presence of resonance assisted hydrogen bonds (RAHB) has been confirmed by calculated ellipticity parameters using AIM calculation. The calculated thermodynamic parameters show that the reaction is non spontaneous at room temperature. The local reactivity descriptors show that C(13) is most reactive site for nucleophilic attack. PMID:22208959

Singh, R N; Verma, Divya; Kumar, Amit; Baboo, Vikas

2012-03-01

228

Future of Interoperability (IR) Research  

NASA Technical Reports Server (NTRS)

This presentation provides a forum for discussion about the work presented by the Interoperability (IR) focus area and the future of interoperability research. Of particular interest will be the direction IR research should take in future years

Cate, Karen; Allen, Bonnie Danette

2011-01-01

229

Synthesis, structural, theoretical studies and biological activities of 3-(arylamino)-2-phenyl-1H-inden-1-one derivative  

NASA Astrophysics Data System (ADS)

Five derivatives of 2-phenyl-1H-indene-1-one have been prepared and fully characterized. Spectroscopic techniques such as FT-IR, 1H NMR, mass spectrometry, and elemental analysis were used to investigate the chemical structures and physical properties of the prepared compounds. The optimized structures and the distribution of the frontier molecular orbital were obtained using density functional theory (DFT) at B3LYP/6-311++G(d,p) level of theory. Additionally, the UV spectral properties of the indene compounds were corroborated by frontier orbital (HOMO and LUMO) calculations. Intramolecular charge transfer (ICT) peak has been observed in the UV spectra of the compounds and theoretically confirmed by the HOMO and LUMO analysis. The potential use of these compounds as antibacterial agents was investigated. The results show that indene-1-one derivatives have an antibacterial activity for both gram-negative (Pseudomonas aeruginosa) and gram-positive (Methicillin Resistant Staphylococcus aureus) bacteria.

El-Sheshtawy, Hamdy S.; Abou Baker, Ahmed M.

2014-06-01

230

Osmium(IV) complexes with 1H- and 2H-indazoles: Tautomer identity versus spectroscopic properties and antiproliferative activity  

PubMed Central

A one-pot synthesis of osmium(IV) complexes with two different tautomers of indazole, 1H-indazole and 2H-indazole, namely (H2ind)[OsIVCl5(2H-ind)] (1) and (H2ind)[OsIVCl5(1H-ind)] (2) is reported. Both compounds have been comprehensively characterized by NMR spectroscopy, ESI (electrospray ionization) mass spectrometry, electronic absorption spectroscopy, IR spectroscopy, cyclic voltammetry and tested for antiproliferative activity in vitro in three human cancer cell lines, CH1 (ovarian carcinoma), A549 (non-small cell lung cancer) and SW480 (colon carcinoma), as well as in vivo in a Hep3B SCID mouse xeno-transplantation model. 2H-Indazole tautomer stabilization in 1 has been confirmed by X-ray diffraction.

Buchel, Gabriel E.; Stepanenko, Iryna N.; Hejl, Michaela; Jakupec, Michael A.; Keppler, Bernhard K.; Heffeter, Petra; Berger, Walter; Arion, Vladimir B.

2012-01-01

231

Compounds of L(+)-ascorbic acid with dimethylthallium(III), dimethyltin(IV), and dibutyltin(IV): Synthesis, solid-state spectroscopy (CP\\/MAS 13C NMR and IR), and multi-NMR behavior in aqueous solution  

Microsoft Academic Search

Reaction of L(+)-ascorbic acid (H2Asc) with TlMe2OOCCH3, SnMe2O, and SnBu2Cl2 (in this last case, in the presence of Et3N) afforded [TlMe2(HAsc)]·12C3H8O, [SnMe2(Asc)], and [SnBu2(Asc)], respectively. The new compounds were studied in the solid state by CP\\/MAS 13C NMR and IR spectroscopy, and in aqueous solution by 1H, 13C, 205Tl, and 119Sn NMR spectroscopy. The thallium compound behaves as a salt.

José S. Casas; María V. Castaño; María S. García-Tasende; Teresa Pérez-Alvarez; Agustín Sánchez; José Sordo

1996-01-01

232

Experimental and computational studies on ( Z )-1-((4-phenylamino)phenylamino)-methylene)naphthalen-2(1 H )-one  

Microsoft Academic Search

The Schiff base compound (Z)-1-((4-phenylamino)phenylamino)methylene)naphthalen-2(1H)-one has been synthesized and characterized by IR, UV–Vis, and X-ray single-crystal determination. Molecular geometry from\\u000a X-ray experiment of the title compound in the ground state have been compared using the Hartree–Fock (HF) and density functional\\u000a method (B3LYP) with 6?31G(d,p) basis set. Calculated results show that density functional theory DFT and HF can well reproduce\\u000a the

Gökhan Alpaslan; Mustafa Macit; Ahmet Erdönmez; Orhan Büyükgüngör

2011-01-01

233

Evaluation of a 1H-13C NMR Spectral Library  

Microsoft Academic Search

A simple database of 13C\\/1H-13C spectral lists for 11 673 natural products was created in standard commercial database format. Over 50% of the spectra were predicted using HOSE code descriptors derived from the 50% of spectra having experimental values. Prediction errors obtained by prediction of and comparison to the experimental spectra revealed an exponentially decaying dependence between the average absolute

S. K. Smith; Jamieson M. Cobleigh; V. Svetnik

2001-01-01

234

?-Oxido-bis-[hydridotris(tri-methyl-phosphane-?P)iridium(III)](Ir--Ir) bis-(tetra-fluorido-borate) dihydrate  

PubMed Central

The title compound, [Ir2H2O(C3H9P)6](BF4)2·2H2O, was isolated from the reaction between [Ir(COD)(PMe3)3]BF4 and H2 in water (COD is cyclo­octa-1,5-diene). The asymmetric unit consists of one IrIII atom bonded to three PMe3 groups, one hydride ligand and half an oxide ligand, in addition to a BF4 ? counter-ion and one water molecule of hydration. The single oxide ligand bridging two IrIII atoms is disordered across an inversion center with each O atom having a 50% site occupancy. Each IrIII atom has three PMe3 groups occupying facial positions, with the half-occupancy O atoms, a hydride ligand and an Ir—Ir bond completing the coordination sphere. The Ir—Ir distance is 2.8614?(12)?Å, comparable to other iridium(III) metal–metal bonds. Two water mol­ecules hydrogen bond to two BF4 ? anions in the unit cell.

Merola, Joseph; Husebo, Trang Le

2014-01-01

235

Preparation and characterization of water-soluble chitosan derivative by Michael addition reaction.  

PubMed

The efficient procedure to prepare novel water-soluble chitosan derivative was established by Michael addition reaction to introduce sodium allylsulfonate into the chitosan at mild condition. The chemical structure of the chitosan derivative was characterized by FT-IR, (1)H NMR and Elemental analysis. The degree of substitution (DS) was calculated by Elemental analysis. The chitosan derivative exhibited an excellent solubility in the distilled water. The physical properties were analyzed by XRD and TG. The XRD study indicated that the crystallinity of chitosan derivative decreased. The thermal analysis showed that chitosan derivative had lower thermal stability than chitosan. PMID:20837054

Jiang, Mingyan; Wang, Kemin; Kennedy, John F; Nie, Jun; Yu, Qiang; Ma, Guiping

2010-12-01

236

Synthesis, crystal structure and herbicidal activity of mimics of intermediates of the KARI reaction.  

PubMed

Two mimics of the intermediate in the reaction catalyzed by ketol-acid reductoisomerase (KARI) were synthesized. Their structures were established on the basis of elemental analyses, IR, 1H NMR and GC/mass detector. The crystal structure of compound 2 was found to be a substituted dioxane, formed by the condensation of two molecules. The two compounds showed some herbicidal activity on the basis of tests using rape root and barnyard grass growth inhibition. However, the herbicidal effect was weaker in greenhouse tests. PMID:15751008

Wang, Bao-Lei; Duggleby, Ronald G; Li, Zheng-Ming; Wang, Jian-Guo; Li, Yong-Hong; Wang, Su-Hua; Song, Hai-Bin

2005-04-01

237

Stable Ir/SiO2 catalyst for selective hydrogenation of crotonaldehyde  

NASA Astrophysics Data System (ADS)

Vapor-phase selective hydrogenation of crotonaldehyde was conducted over Ir/SiO2 catalysts to investigate the effects of Ir loading on the catalytic behaviors. The catalysts were characterized by X-ray powder diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), CO chemisorption, temperature-programmed reduction (TPR), diffuse reflectance infrared Fourier transform spectra of CO adsorption (CO-DRIFTS), NH3 temperature-programmed desorption (NH3-TPD), and temperature-programmed oxidation (TPO). It was found that the particle size of Ir in the catalyst increased with Ir loading, being 2.1, 3.9 and 6.7 nm for the 1Ir/SiO2, 3Ir/SiO2 and 5Ir/SiO2 catalyst, respectively. The Ir species on the Ir/SiO2 catalysts consisted of Ir0 and Ir?+, but the average valence of Ir species decreased with increasing Ir loading. Also, catalytic testing results revealed that the reactivity of the catalyst increased with Ir loading. Interestingly, it was found that the reaction underwent an induction period, with the conversion of crotonaldehyede and the selectivity to crotyl alcohol gradually increasing during the reaction, and eventually reaching a steady state. The highest selectivity (77.6%) to crotyl alcohol was obtained over the 3Ir/SiO2 catalyst, and the conversion increased gradually to 15.6%. The catalytic behavior of these stable catalysts could be attributed to the proper Ir particle size, the existence of Ir0 and Ir?+ species on the surface, and high amount of surface acid sites in these catalysts.

Hong, Xiao; Li, Bo; Wang, Yuejuan; Lu, Jiqing; Hu, Gengshen; Luo, Mengfei

2013-04-01

238

Asymmetric organocatalytic synthesis of 4,6-bis(1H-indole-3-yl)-piperidine-2 carboxylates.  

PubMed

We developed an asymmetric organocatalytic synthesis of 4,6-bis(1H-indole-3-yl)-piperidine-2-carboxylates using 10 mol% of a chiral phosphoric acid. The products, which are novel bisindole-piperidine-amino acid hybrids, can be obtained in one step from 3-vinyl indoles with imino esters in dichloromethane at room temperature after 1 h of reaction time. A variety of these compounds could be synthesized in up to 70% yield and 99% ee, and they were experimentally and computationally analyzed regarding their relative and absolute stereochemistry. PMID:24733144

Zhong, Sabilla; Nieger, Martin; Bihlmeier, Angela; Shi, Min; Bräse, Stefan

2014-05-28

239

Antitumor Activity of 6-(cyclohexylamino)-1, 3-dimethyl-5(2-pyridyl)furo[2,3-d]pyrimidine-2,4(1H,3H)-dione and Its Ti(IV), Zn(II), Fe(III), and Pd(II) Complexes on K562 and Jurkat Cell Lines  

PubMed Central

(6-(cyclohexylamino)-1,3-dimethyl-5(2-pyridyl)furo[2,3-d]pyrimidine-2,4(1H,3H)-dione) abbreviated as CDP was synthesized and characterized. Ti(IV), Zn(II), Fe(III), and Pd(II) metal complexes of this ligand are prepared by the reaction of salts of Ti(IV), Zn(II), Fe(III), and Pd(II) with CDP in acetonitrile. Characterization of the ligand and its complexes was made by microanalyses, FT-IR, 1H NMR, 13C NMR, and UV-Visible spectroscopy. All complexes were characterized by several techniques using elemental analysis (C, H, N), FT-IR, electronic spectra, and molar conductance measurements. The elemental analysis data suggest the stoichiometry to be 1:1 [M:L] ratio formation. The molar conductance measurements reveal the presence of 1:1 electrolytic nature complexes. These new complexes showed excellent antitumor activity against two kinds of cancer cells that are K562 (human chronic myeloid leukemia) cells and Jurkat (human T lymphocyte carcinoma) cells.

Shabani, Fahmideh; Ghammamy, Shahriar; Mehrani, Khayroallah; Teimouri, Mohammad Bagher; Soleimani, Masoud; Kaviani, Saeid

2008-01-01

240

Alkaloid-fullerene systems through photocycloaddition reactions.  

PubMed

The photocycloaddition of tertiary amines to ¿60fullerene (C(60)) is an interesting and useful reaction. We wished to extend the applications of this type of reaction through an investigation of the photoaddition of alkaloids to C(60) for the purpose of synthesizing novel and complex photoadducts that are difficult to obtain by usual methods. Irradiation of tazettine (2) or gramine (3) with C(60) in toluene leads to formation of one monoadduct (6 or 7), whereas scandine (1a) or 10-hydroxyscandine (1b) reacts with C(60) photochemically to give two products, the expected ¿6,6 monoadduct (5a, 5b) and a new type of monoadduct with a bis-¿6, 6 closed structure (4a, 4b). These new structures were characterized by UV-vis, FT-IR, (1)H NMR, (13)C NMR, (1)H-(1)H COSY, ROESY, HMQC (heteronuclear multiple-quantum coherence), and HMBC (heteronuclear multiple-bond connectivity) spectroscopy. The techniques of time-of-flight secondary ion MS (TOF-SIMS) and field desorption MS (FD-MS) were used for the mass determination. (3)He NMR analysis of the product mixture from photoaddition of 1a to C(60) containing a (3)He atom ((3)He@C(60)) led to two peaks at -9.091 and -11.090 ppm relative to gaseous (3)He, consistent with formation of a ¿6, 6-closed monoadduct and a bis-¿6,6 closed adduct. Presumably, the bis-¿6, 6 closed adducts are formed by an intramolecular ¿2 + 2 cycloaddition of the vinyl group to the adjacent 6,6-ring junction of C(60) after the initial photocycloaddition. PMID:10864768

Guo, L W; Gao, X; Zhang, D W; Wu, S H; Wu, H M; Li, Y J; Wilson, S R; Richardson, C F; Schuster, D I

2000-06-16

241

Cinchona alkaloid derivative-catalyzed enantioselective synthesis via a Mannich-type reaction and antifungal activity of ?-amino esters bearing benzoheterocycle moieties.  

PubMed

An efficient synthesis of highly functionalized chiral ?-amino ester derivatives containing benzothiophene and benzothiazole moieties is developed by a Mannich-type reaction using a cinchona alkaloid-derived thiourea catalyst. The desired products were obtained in good yields and high enantioselectivities (~86% yield, >99% ee) using to the optimized reaction conditions. The synthesized compounds were characterized by 1H-NMR, 13C-NMR, IR, and HREI-MS analyses. The bioassays identified that compound 5dr has excellent antifungal activity, with a 60.53% inhibition rate against F. oxysporum, higher than that of the commercial agricultural fungicide hymexazol, whose inhibition rate was 56.12%. PMID:24694652

Xiao, Han; Wu, Fang; Shi, Li; Chen, Zhiwei; Su, Shihu; Tang, Chenghao; Wang, Hongtao; Li, Zhining; Li, Meichuan; Shi, Qingcai

2014-01-01

242

Experimental and computational studies on the tautomerism of N-substituted 3-amino-5-oxo-4-phenyl-1H-pyrazolo-1-carboxamides with antibacterial activity  

NASA Astrophysics Data System (ADS)

The tautomerism of N-substituted 3-amino-5-oxo-4-phenyl-1H-pyrazolo-1-carboxamides with antibacterial activity is studied with X-ray crystallography, IR, 1H and 13C NMR (including NOESY spectra) and quantum chemical calculations. It is found that the form with the keto group at position 5 is the preferred one in the crystalline state and in DMSO, although some fraction with the corresponding hydroxy group also occurs in both states. This finding was related to the antibacterial activity of the studied compounds as the energetic stabilization of the keto group may determine their proper hydrogen bond interactions with the bacterial enzyme.

Kaczor, Agnieszka A.; Wróbel, Tomasz; Karczmarzyk, Zbigniew; Wysocki, Waldemar; Mendyk, Ewaryst; Poso, Antti; Matosiuk, Dariusz; Pitucha, Monika

2013-11-01

243

Generation and characterization of a 4?-electron three-membered ring 1H-diazirine: An elusive intermediate in nitrile imine-carbodiimide isomerization.  

PubMed

The photolysis at 222 nm of 5-methyltetrazole isolated in a cryogenic argon matrix leads to formation of methyl nitrile imine as primary product. Subsequent irradiation at 328 nm induces transformation of the nitrile imine into 4?-electron three-membered-ring 3-methyl-1H-diazirine, which photorearranges to give methyl carbodiimide. These products were characterized by IR spectroscopy and theoretical calculations. For the first time, a 1H-diazirine was captured as intermediate in the photoisomerization of nitrile imines into carbodiimides. PMID:24605983

Nunes, Cláudio M; Araujo-Andrade, Cuauhtémoc; Fausto, Rui; Reva, Igor

2014-04-18

244

Synthesis and antibacterial activity of 4-benzoyl-1-(4-carboxy-phenyl)-5-phenyl-1 H -pyrazole-3-carboxylic acid and derivatives  

Microsoft Academic Search

A new 1H-pyrazole-3-carboxylic acid 2, along with hydrazono-pyridazinone 3, a by-product, and its derivatives 4–7 were synthesized and the structures confirmed by infrared (IR) and 1H and 13C nuclear magnetic resonance (NMR) data. These new compounds were evaluated for their antibacterial activities against Gram-positive\\u000a and Gram-negative bacteria using the tube dilution method. The minimal inhibitory concentrations (MICs) experiments revealed\\u000a that

?shak Bildirici; Ahmet ?ener; Ekrem Atalan; Abdulhamit Battal; Hasan Genç

2009-01-01

245

Probing degradation in complex engineering silicones by 1H multiple quantum NMR  

SciTech Connect

Static {sup 1}H Multiple Quantum Nuclear Magnetic Resonance (MQ NMR) has recently been shown to provide detailed insight into the network structure of pristine silicon based polymer systems. The MQ NMR method characterizes the residual dipolar couplings of the silicon chains that depend on the average molecular weight between physical or chemical constraints. Recently, we have employed MQ NMR methods to characterize the changes in network structure in a series of complex silicone materials subject to numerous degradation mechanisms, including thermal, radiative, and desiccative. For thermal degradation, MQ NMR shows that a combination of crosslinking due to post-curing reactions as well as random chain scissioning reactions occurs. For radiative degradation, the primary mechanisms are via crosslinking both in the network and at the interface between the polymer and the inorganic filler. For samples stored in highly desiccating environments, MQ NMR shows that the average segmental dynamics are slowed due to increased interactions between the filler and the network polymer chains.

Maxwell, R S; Chinn, S C; Giuliani, J; Herberg, J L

2007-09-05

246

1H NMR study of hydrogen abstraction in model compound mimics of polymers.  

PubMed

Small molecules representing common synthetic polymers were subjected to photochemically induced hydrogen abstraction by benzophenone. Reactions were monitored using (1) H NMR to query the factors that influence preferential abstraction of protons in unique chemical environments. Differences in bond dissociation energies do not fully explain the observed hydrogen abstraction preferences. To that end, we identify contributions to abstraction from prereactive complexation, radical stability, steric effects and charge transfer effects. Using representative small molecule model compounds in lieu of polymeric materials is a novel approach to understanding photochemical reaction in polymers; however, it cannot probe the contributions of macromolecular effects--e.g. polymer rigidity or side chain and backbone mobility--to preferential hydrogen abstraction. PMID:24256104

Lancaster, Jeffrey R; Smilowitz, Rachael; Turro, Nicholas J; Koberstein, Jeffrey T

2014-01-01

247

1 H and 13 C NMR observation of the reaction of acetic acid with titanium isopropoxide  

Microsoft Academic Search

Hydrogen and carbon NMR spectroscopy have been used to investigate the chemical modification process of titanium isopropoxide by acetic acid. The spectra confirm the belief that the titanium isopropoxide exchanges isopropyl groups with modifying acetate groups to form a molecule with approximate stoichiometry Ti(OiPr)2(OAc)2. This stoichiometry results even when enough acetic acid is present in solution to allow for significantly

Dunbar P Birnie III; Norbert J. Bendzko

1999-01-01

248

Rational design, synthesis and QSAR study of vasorelaxant active 3-pyridinecarbonitriles incorporating 1H-benzimidazol-2-yl function.  

PubMed

A variety of 2-alkoxy-4-aryl-6-(1H-benzimidazol-2-yl)-3-pyridinecarbonitriles 4a-r were prepared via either regioselective reaction of 3-aryl-1-(1H-benzimidazol-2-yl)-2-propen-1-ones 3 with malononitrile or ylidenemalononitriles 6 with 2-acetyl-1H-benzimidazoles 1 in the presence of sodium alkoxide in the corresponding alcohol. All the synthesized compounds showed significant vasodilation properties using isolated thoracic aortic rings of rats pre-contracted with norepinephrine hydrochloride standard technique. Compounds 4d, 4p, 4l, and 4f exhibited remarkable activity compared with prazosin hydrochloride, which was used as a reference standard in the present study. QSAR studies revealed a good predictive and statistically significant 3 descriptor model (r(2) = 0.913, radjusted(2)=0.8808, rprediction(2)=0.7911). PMID:23454530

Nofal, Zeinab M; Srour, Aladdin M; El-Eraky, Wafaa I; Saleh, Dalia O; Girgis, Adel S

2013-05-01

249

Graphite catalyzed solvent free synthesis of dihydropyrimidin-2(1H)-ones/thiones and their antidiabetic activity.  

PubMed

A solvent free three component condensation reaction between an aldehyde, ethyl acetoacetate and urea catalyzed by graphite, a green catalyst is described for the synthesis of dihydropyrimidin-2(1H)-ones. This protocol is scalable and the catalyst is reusable. This method is also applied for the synthesis of dihydropyrimidin-2(1H)-thiones. ?-Amylase, a key enzyme in carbohydrate metabolism is generally targeted for management of type 2 diabetes. The therapeutic potential of the dihydropyrimidinones and dihydropyrimidinthiones to inhibit ?-amylase activity was evaluated by in vitro assay. Of the synthesized compounds 3,4-dihydropyrimidin-2(1H)-thione (1k) demonstrated highest inhibition of ?-amylase activity. PMID:24835627

Dhumaskar, Kashinath L; Meena, Surya Nandan; Ghadi, Sanjeev C; Tilve, Santosh G

2014-07-01

250

Increased NOE enhancement in 1H decoupled 31P MRS.  

PubMed

1H decoupling using the WALTZ-4 decoupling scheme is a popular means of improving spectral resolution in 31P NMR spectroscopy. At the same time, sensitivity in the proton decoupled 31P spectra is enhanced by the nuclear Overhauser effect. The authors show that when using WALTZ-4 decoupling in a uniform decoupler RF field, the degree of sensitivity enhancement is critically dependent on whether the decoupling interval contains an odd or an even number of WALTZ decoupling elements. This effect is demonstrated both in phantoms and in vivo. PMID:8598817

van Sluis, R; Payne, G S; Leach, M O

1995-12-01

251

Biotransformation and toxicokinetics of the insect repellent IR3535® in male and female human subjects after dermal exposure.  

PubMed

The absorption and excretion of the insect repellent IR3535(®) was studied in human subjects (five males and five females) after dermal application of approx. 3g of a formulation containing 20% IR3535(®), i.e. the amounts of IR3535(®) applied were between 1.94 and 3.4 mmol/person (418-731 mg/person). Blood and urinary concentrations of IR3535(®) and its only metabolite, IR3535(®)-free acid, were determined over time. In plasma, concentrations of the parent compound IR3535(®) were at or below the limit of quantification (0.037 ?mol/L). IR3535(®)-free acid peaked in plasma samples 2-6h after dermal application. Cmax mean values were 5.7 ?mol/L in males, 3.0 ?mol/L in females and 4.2 ?mol/L in all volunteers. Mean AUC values were 41.6, 24.5 and 33.9 ?molL(-1)h in males, females and all subjects, respectively. In urine samples from all human subjects, both IR3535(®) and IR3535(®)-free acid were detectable, however, only very small amounts of IR3535(®) were found. Concentrations of IR3535(®)-free acid were several thousand-fold higher than the parent compound and peaked at the first two sampling points (4h and 8h after dermal application). Overall, IR3535(®) and IR3535(®)-free acid excreted with urine over 48 h representing 13.3 ± 3.05% of the dose applied. Since IR3535(®) is rapidly and extensively metabolized, and IR3535(®)-free acid has a low molecular weight and high water solubility, it is expected that urinary excretion of IR3535(®)-free acid and IR3535(®) represents the total extent of absorption of IR3535(®) in humans. Based on the results of this study, the skin penetration rate of IR3535(®) is 13.3% in humans after dermal application. PMID:23402938

Broschard, Thomas H; Bohlmann, Anja M; Konietzny, Stefan; Schauer, Ute M D; Dekant, Wolfgang

2013-04-26

252

Synthesis, crystal structure, insecticidal activity and DFT study on the geometry and vibration of O-(E)-1-{1-[(6-chloropyridin-3-yl)methyl]-5-methyl-1H-1,2,3-triazol-4-yl}ethyleneamino-O-ethyl-O-phenylphosphorothioate.  

PubMed

The title compound, O-(E)-1-{1-[(6-chloropyridin-3-yl)methyl]-5-methyl-1H-1,2,3-triazol-4-yl}ethyleneamino-O-ethyl-O-phenylphosphorothioate, has been synthesized via the condensation reaction of 1-{1-[(6-chloropyridin-3-yl)methyl]-5-methyl-1H-1,2,3-triazol-4-yl}ethanone oxime and O-ethyl-O-phenylphosphorochloridothioate in the presence of NaOH powder in refluxing EtOH. Its structure was characterized by (1)H NMR, FTIR, Raman, elemental analysis and X-ray single crystal diffraction. The results of preliminary bioassays indicated that the title compound displays good insecticidal activity. Density functional (DFT) calculations have been carried out for the title compound by using the Becke-Lee-Yang-Parr's three-parameter hybrid functional (B3LYP) method at 6-31G and 6-31G basis sets. The calculated results show that the predicted geometry can well reproduce the structural parameters. The vibrational wave numbers of the title compound were calculated at same level. Predicted vibrational frequencies have been assigned and compared with experimental IR and Raman spectra and they are supported each other. PMID:18555740

Shi, De-Qing; Zhu, Xiao-Fei; Song, Yuan-Zhi

2008-12-01

253

Integrated IR sensors  

NASA Astrophysics Data System (ADS)

Integrated infrared (IR) sensors which exploit modular avionics concepts can provide features such as operational flexibility, enhanced stealthiness, and ease of maintenance to meet the demands of tactical, airborne sensor systems. On-board, tactical airborne sensor systems perform target acquisition, tracking, identification, threat warning, missile launch detection, and ground mapping in support of situation awareness, self-defense, navigation, target attack, weapon support, and reconnaissance activities. The use of sensor suites for future tactical aircraft such as US Air Force's multirole fighter require a blend of sensor inputs and outputs that may vary over time. It is expected that special-role units of these tactical aircraft will be formed to conduct tasks and missions such as anti-shipping, reconnaissance, or suppression of enemy air defenses.

Tom, Michael; Trujillo, Edward

1994-06-01

254

Suzuki Cross-Coupling Reactions: Synthesis of Unsymmetrical Biaryls in the Organic Laboratory  

NASA Astrophysics Data System (ADS)

An organic chemistry laboratory experiment in which unsymmetrical biaryl alcohols are synthesized in a two-step process is described. In the first step, an aryl boronic acid is coupled with p-bromoacetaldehyde or p-bromoacetophenone. The carbonyl group of the product is reduced with sodium borohydride in the second step. The products of both reactions are solids that can be easily purified by recrystallization. The primary purpose in implementing this experiment was to give students additional exposure to transition-metal-catalyzed reactions. The experiment provides an opportunity to discuss a number of topics, including the palladium-catalyzed cross-coupling mechanism, reactions that permit the formation of C-C bonds in an aqueous environment, the reduction of carbonyl groups with metal hydrides, and atropisomerism. The students can use IR and 1H NMR spectroscopy to determine the structure of their products, and so this laboratory also allows them to improve their spectral interpretation skills.

Callam, Christopher S.; Lowary, Todd L.

2001-07-01

255

1H NMR aided elucidation of products derived from photodegradation of ethyl 3-azido-4,6-difluorobenzoate in 2,2,2-trifluoroethanol  

Microsoft Academic Search

The major products formed upon photolysis of ethyl 3-azido-4,6-difluorobenzoate in 2,2,2-trifluoroethanol-d3 has been elucidated by 1H NMR analysis of the product mixture. Among the products formed and structurally elucidated was a hitherto unreported product formed during photolysis of aryl azides, namely azoxybenzene 19. The structural assignments of the major components of the reaction mixture were aided by comparison with 1H

Magne O. Sydnes; Masaki Kuse; Issei Doi; Minoru Isobe

2009-01-01

256

Molecular structure of 2-chloromethyl-1H-benzimidazole hydrochloride: Single crystal, spectral, biological studies, and DFT calculations  

NASA Astrophysics Data System (ADS)

In the present work, structural studies on 2-chloromethyl-1H-benzimidazole hydrochloride have been performed extensively by X-ray crystallography, 1H NMR, FT-IR, UV/vis, and elemental analysis. The title compound crystallizes in a monoclinic space group P21/c with a = 7.1982 (3) Å, b = 9.4513 (5) Å, c = 14.0485 (7) Å and ? = 102.440 (3)° forming an infinite chain structure parallel to " b" axis through the intermolecular hydrogen bond. Optimized geometrical structure, harmonic vibrational frequencies, natural bonding orbital (NBO) and frontier molecular orbitals (FMO) were obtained by DFT/B3LYP method combined with 6-31G(d) basis set. TD-DFT calculations help to assign the electronic transitions. The 1H NMR chemical shifts were computed at the B3LYP/6-311 + G(2d,p) level of theory in different solvents by applying GIAO method using the polarizable continuum model (PCM). The title compound was screened for its antibacterial activity referring to Tetracycline as a standard antibacterial agent.

Abdel Ghani, Nour T.; Mansour, Ahmed M.

2012-02-01

257

4-Methyl-5-phenyl-1H-pyrazol-3-ol  

PubMed Central

The title compound, C10H10N2O, crystallizes with two independent mol­ecules in the asymmetric unit, having closely comparable geometries. The dihedral angles between the 1H-pyrazole and benzene rings in the two mol­ecules are 39.57?(14) and 41.95?(13)°. The two mol­ecules are each connected to neighbouring mol­ecules by pairs of inter­molecular O—H?N hydrogen bonds, forming dimers with R 2 2(8) ring motifs. These dimers are further linked into R 4 4(10) ring motifs by inter­molecular N—H?O hydrogen bonds, forming chains along [101]. The crystal structure is further stabilized by a C—H?? inter­action.

Shahani, Tara; Fun, Hoong-Kun; Ragavan, R. Venkat; Vijayakumar, V.; Sarveswari, S.

2010-01-01

258

Solvent 1H NMRD of copper(II) complexes  

NASA Astrophysics Data System (ADS)

Solvent 1H nuclear magnetic relaxation dispersion (NMRD) between 0.01 and 100 MHz of solutions containing a square pyramidal copper(II) complex in water and ethyleneglycol have been measured between 5 and 39°C. The data have been interpreted in terms of decreasing rotational correlation time with decreasing temperature and upon passing from water to ethyleneglycol; simultaneously the metal nucleus-unpaired electron hyperfine coupling becomes increasingly significant. The NMRD data of the copper derivative of a protein of MW 30000 in water at 25°C are similar to those of the small complex in ethyleneglycol at somewhat lower temperatures. A fitting of the data with the available theory is presented.

Banci, Lucia; Bertini, Ivano; Luchinat, Claudio

1985-07-01

259

1H NMR visibility of mammalian glycogen in solution.  

PubMed

High-resolution 1H NMR spectra of rabbit liver glycogen in 2H2O were obtained at 500 MHz, and several resonances were assigned by comparison with the chemical shifts of alpha-linked diglucose molecules. The NMR relaxation times T1 and T2 of glycogen in 2H2O were determined to be 1.1 and 0.029 s, respectively. The measured natural linewidth of the carbon-1 proton (12 +/- 2 Hz) is in excellent agreement with that calculated from T2. The visibility measurements made by digesting glycogen and comparing glucose and glycogen signal intensities demonstrate that in spite of the very high molecular weight, all of the proton nuclei in glycogen contribute to the NMR spectrum. The result is not unexpected, since 100% NMR visibility was previously observed from the carbon nuclei of glycogen, due to the rapid intramolecular motions. PMID:2308928

Zang, L H; Rothman, D L; Shulman, R G

1990-03-01

260

Liver Metabolite Concentrations Measured with 1H MR Spectroscopy  

PubMed Central

Purpose: To determine the feasibility of measuring choline and glycogen concentrations in normal human liver in vivo with proton (hydrogen 1 [1H]) magnetic resonance (MR) spectroscopy. Materials and Methods: Signed consent to participate in an institutional review board–approved and HIPAA-compliant study was obtained from 46 subjects (mean age, 46 years ± 17 [standard deviation]; 24 women) consecutively recruited during 285 days. Navigator-gated MR images were used to select 8-mL volumes for point-resolved spectroscopy (PRESS) with a 35-msec echo time. Line widths were minimized with fast breath-hold B0 field mapping and further manual shimming. Navigator-gated spectra were recorded with and without water suppression to determine metabolite concentrations with water signals as an internal reference. In three subjects, echo time was varied to determine the glycogen and choline T2. Linear regression analysis was used to examine relations between choline, hepatic lipid content, body mass index, glycogen content, and age. Results: Choline concentrations could be determined in 46 of 48 studies and was found to be 8.6 mmol per kilogram of wet weight ± 3.1 (range, 3.8–17.6; n = 44). Twenty-seven spectra in 25 individuals with narrow line widths and low lipid content were adequate for quantitation of glycogen. The glycogen (glucosyl unit) concentration was 38.1 mmol/kg wet weight ± 14.4. The T2 of combined glycogen peaks in the liver of three subjects was 36 msec ± 8. Choline levels showed a weak but significant correlation with glycogen (r2 = 0.15; P < .05) but not with lipid content. Conclusion: Navigator-gated and gradient-echo shimmed PRESS 1H MR spectroscopy may allow quantification of liver metabolites that are important for understanding and identifying disorders of glucose and lipid metabolism. © RSNA, 2012 Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12112344/-/DC1

Pettigrew, Roderic I.; Gharib, Ahmed M.

2012-01-01

261

Ionic Liquid Promoted Eco-friendly and Efficient Synthesis of 2,3-Dihydroquinazolin-4(1 H )-ones  

Microsoft Academic Search

Summary.  2,3-Dihydroquinazolin-4(1H)-ones were efficiently synthesised by the reaction of isatoic anhydride, a primary amine or ammonium acetate, and different\\u000a aromatic aldehydes in 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF4) without using any acidic catalyst. Also a bis-derivative of the title compound as a polyheterocyclic system was synthesised\\u000a successfully in high yield.

Minoo Dabiri; Peyman Salehi; Mostafa Baghbanzadeh

2007-01-01

262

Novel multicomponent one-pot synthesis of tetrahydro-1H-1,5-benzodiazepine-2-carboxamide derivatives.  

PubMed

A new approach to the design of multicomponent reactions is introduced. As a result, the novel one-pot synthesis of 2,3,4,5-tetrahydro-1 H-1,5-benzodiazepine-2-carboxamide derivatives using an aromatic diamine, a linear or cyclic ketone, an isocyanide, and water in the presence of a catalytic amount of p-toluenesulfonic acid at ambient temperature in high yields is described. PMID:18553983

Shaabani, Ahmad; Maleki, Ali; Mofakham, Hamid

2008-01-01

263

Synthesis, determination of p K a values and GIAO NMR calculations of some new 3-alkyl-4-( p-methoxybenzoylamino)-4,5-dihydro-1 H-1,2,4-triazol-5-ones  

Microsoft Academic Search

3-Alkyl-4-amino-4,5-dihydro-1H-1,2,4-triazol-5-ones (2) reacted with p-methoxybenzoyl chloride to afford the corresponding 3-alkyl-4-(p-methoxybenzoylamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones (3). Five newly synthesized compounds have been characterized by elemental analyses, IR, 1H NMR, 13C NMR and UV spectral data. The newly synthesized compounds 3 were titrated potentiometrically with tetrabutylammonium hydroxide in four non-aqueous solvents such as acetonitrile, isopropyl alcohol, tert-butyl alcohol and N,N-dimethylformamide, and the half-neutralization potential values

Haydar Yüksek; Muzaffer Alkan; ?ule Bahçeci; Ismail Cakmak; Zafer Ocak; Haci Baykara; Ozlem Akta?; Elif A?yel

2008-01-01

264

60 MHz 1H NMR spectroscopy for the analysis of edible oils?  

PubMed Central

We report the first results from a new 60 MHz 1H nuclear magnetic resonance (NMR) bench-top spectrometer, Pulsar, in a study simulating the adulteration of olive oil with hazelnut oil. There were qualitative differences between spectra from the two oil types. A single internal ratio of two isolated groups of peaks could detect hazelnut oil in olive oil at the level of ?13%w/w, whereas a whole-spectrum chemometric approach brought the limit of detection down to 11.2%w/w for a set of independent test samples. The Pulsar’s performance was compared to that of Fourier transform infrared (FTIR) spectroscopy. The Pulsar delivered comparable sensitivity and improved specificity, making it a superior screening tool. We also mapped NMR onto FTIR spectra using a correlation-matrix approach. Interpretation of this heat-map combined with the established annotations of the NMR spectra suggested a hitherto undocumented feature in the IR spectrum at ?1130 cm?1, attributable to a double-bond vibration.

Parker, T.; Limer, E.; Watson, A.D.; Defernez, M.; Williamson, D.; Kemsley, E. Kate

2014-01-01

265

Cure process and reaction-induced phase separation in a diepoxy–diamine\\/PMMA blend. Monitoring by steady-state fluorescence and FT-IR (near and medium range)  

Microsoft Academic Search

Poly(methyl methacrylate), PMMA, was chosen as an additive for an epoxy system based on the cured product of (a) diglycidyl ether of bisphenol A labeled with 5-dimethylaminonaphthalene-1-(2-aminoethyl) sulfonamide and (b) 1,5-diamino-2-methylpentane. Fourier transformed infrared spectroscopy (near, FT-NIR, and medium, FT-MIR, ranges) and steady-state fluorescence spectroscopy were used to monitor the epoxy cure reaction and the induced phase separation. The PMMA

D. Olmos; J. González-Benito

2006-01-01

266

Bi- and tri-metallic Rh and Ir complexes containing click derived bis- and tris-(pyrazolyl-1,2,3-triazolyl) N-N' donor ligands and their application as catalysts for the dihydroalkoxylation of alkynes.  

PubMed

A series of bi-topic and tri-topic pyrazolyl-1,2,3-triazolyl donor ligands (; = 1,X-bis((4-((1H-pyrazol-1-yl)methyl)-1H-1,2,3-triazol-1-yl)methyl)benzene (X = 2, 3 and 4; o-C6H4(PyT)2, m-C6H4(PyT)2 and p-C6H4(PyT)2) and = 1,3,5-tris((4-((1H-pyrazol-1-yl)methyl)-1H-1,2,3-triazol-1-yl)methyl)benzene, 1,3,5-C6H3(PyT)3) were conveniently synthesised in 'one pot' reactions using the Cu(i) catalysed 'click' reaction. Rh(i), Ir(i), Rh(iii) and Ir(iii) complexes with ligands of the general formulae C6H6-n[(PyT)M(CO)2]n[BAr]n (M = Rh, Ir; n = 2, 3; ; ) and C6H6-n[(PyT)MCp*Cl]n[BAr]n (M = Rh, Ir; n = 2, 3; ; ) were synthesised and fully characterised. In solution each of the bi- or tri-metallic complexes and exists as a mixture of two (, ) or three ( and ) diastereomers due to the presence of a chiral centre at each metal centre in these complexes. The solid state structures of complexes and were determined by single crystal X-ray crystallography and showed that each bidentate arm of these multitopic ligands coordinates to the Rh or Ir centre in a bidentate fashion via the pyrazolyl-N2 and 1,2,3-triazolyl N3' donors. The intermetallic distances in these solid state structures vary from 8.66 Å to 15.17 Å. These complexes were assessed as catalysts for the dihydroalkoxylation of alkynes using the cyclisation of 2-(5-hydroxypent-1-ynyl)benzyl alcohol, , to a mixture of two spiroketals, 2,3,4,5-tetrahydro-spirol[furan-2,3'-isochroman], , and 3',4',5',6'-tetrahydro-spiro[isobenzofuran-1(3H),2'(2H)pyran], , as the model reaction. The Rh(i) complexes (), with the highest TOF of 2052 h(-1) for complex , were the most active catalysts when compared with the other complexes under investigation here. The Ir(i) complexes () were moderately active as catalysts for the same transformation. No significant enhancement in catalytic reactivity was observed with the Rh(i) series bi- and trimetallic complexes () when compared with their monometallic analogues. The bi- and trimetallic Ir(i) complexes () were much more efficient as catalysts for this transformation than their monometallic analogues, suggesting some intermetallic cooperativity. Rh(iii), , and Ir(iii), , complexes were not active as catalysts for this transformation. PMID:24699761

Vuong, Khuong Q; Wong, Chin M; Bhadbhade, Mohan; Messerle, Barbara A

2014-04-23

267

Brain creatine depletion in vegetarians? A cross-sectional 1H-magnetic resonance spectroscopy (1H-MRS) study.  

PubMed

The present cross-sectional study aimed to examine the influence of diet on brain creatine (Cr) content by comparing vegetarians with omnivores. Brain Cr content in the posterior cingulate cortex was assessed by proton magnetic resonance spectroscopy (1H-MRS). Dietary Cr intake was assessed by 3 d food recalls. Vegetarians had lower dietary Cr intake than omnivores (0.03 (sd 0.01) v. 1.34 (sd 0.62) g/d, respectively; P= 0.005). However, vegetarians and omnivores had comparable brain total Cr content (5.999 (sd 0.811) v. 5.917 (sd 0.665) IU, respectively; P= 0.77). In conclusion, dietary Cr did not influence brain Cr content in healthy individuals, suggesting that in normal conditions brain is dependent on its own Cr synthesis. PMID:24290771

Yazigi Solis, Marina; de Salles Painelli, Vítor; Giannini Artioli, Guilherme; Roschel, Hamilton; Concepción Otaduy, Maria; Gualano, Bruno

2014-04-14

268

Infrared Assisted Production of 3,4-Dihydro-2(1H)-pyridones in Solvent-Free Conditions  

PubMed Central

A green approach for the synthesis of a set of ten 4-aryl substituted-5-alcoxy carbonyl-6-methyl-3,4-dihydro-2(1H)-pyridones using Meldrum’s acid has been devised, the absence of solvent and the activation with infrared irradiation in addition to a multicomponent protocol are the main reaction conditions. The transformations proceeded with moderated yields (50–75%) with a reasonable reaction rate (3 h). It is worth noting that two novel molecules of the new class of the bis-3,4-dihydropyridones were also obtained. In addition, a comparison without the use of infrared irradiation was performed.

Noguez, M. Olivia; Marcelino, Vanessa; Rodriguez, Hortensia; Martin, Osnieski; Martinez, Joel O.; Arroyo, Gabriel A.; Perez, Francisco J.; Suarez, Margarita; Miranda, Rene

2011-01-01

269

Hydrate layers on ice particles and superheated ice: a {sup 1}H NMR microimaging study  

SciTech Connect

Recent observations on the interaction of methane gas with ice surfaces have led to the suggestion that the resulting hydrate layer prevents the encapsulated ice from melting at its usual temperature. This would require ice to exist in a superheated state. The authors have examined the product of the gas-solid reaction with {sup 1}H NMR imaging. The imaging experiments show that the hydrate-encapsulated ice is able to melt at its usual melting point. As a possible alternative model, the authors suggest that a considerable amount of ice inside the hydrate layer can be converted to hydrate and liquid water under isothermal and constant volume conditions, the hydrate layer acting as an insulating, semipermeable layer that insulates processes inside the hydrate layer from external bulk temperature and pressure measurements.

Moudrakovski, I.L.; Ratcliffe, C.I.; McLaurin, G.E.; Simard, B.; Ripmeester, J.A. [National Research Council of Canada, Ottawa, Ontario (Canada). Steacie Inst. for Molecular Sciences] [National Research Council of Canada, Ottawa, Ontario (Canada). Steacie Inst. for Molecular Sciences

1999-07-01

270

1H NMR spectroscopic identification of a glue sniffing biomarker.  

PubMed

Organic solvent abuse typically involves sniffing organic solvents to experience the mind-altering conditions they induce. In Republic of Korea, organic solvent abuse is a serious social problem, especially among teenagers. Several studies have addressed the effects of organic solvent abuse on mind and body, but there are no simple methods by which such abuse can be positively identified. In this report, we describe a method for analyzing toluene metabolites (toluene is the main ingredient of glue) in glue-sniffers' urine using (1)H NMR spectroscopy. Toluene is a commonly used solvent in the rubber, paint, plastics, leather, printing, and chemical industries. Inhaled toluene is metabolized to hippuric acid in the liver and excreted in the urine. Hippuric acid is known as a good biomarker for biological monitoring of toluene exposure. We have scanned hippuric acid and other toluene metabolites by NMR spectroscopy and performed statistical multivariate analysis of the data. Based on this analysis, we sought to determine parameters by which glue-sniffing (toluene inhalation) behavior may be verified. We also demonstrate the use of a pattern recognition method for accurate and efficient analysis of NMR data. In comparison to conventional methods, such as mass spectroscopy coupled with liquid chromatography or gas chromatography, nuclear magnetic resonance spectroscopy has several advantages, including simple sample preparation, non-destructive sampling, accuracy, short acquisition time, and reproducibility in the determination of urinary hippuric acid. PMID:21316881

Kwon, Bobae; Kim, Siwon; Kim, Sosun; Lee, Dong-Kye; Park, Yu-Jin; Kim, Myung-Duck; Lee, Jae-Shin; Kim, Suhkmann

2011-06-15

271

3-hydroxy-2(1H)-pyridinone chelating agents  

DOEpatents

Disclosed is a series of improved metal chelating agents, which are highly effective upon both injection and oral administration; several of the most effective are of low toxicity. These chelating agents incorporate within their structure 1-hydroxy-2-pyridinone (1,2-HOPO) and 3-hydroxy-2-pyridinone (3,2-HOPO) moieties with a substituted carbamoyl group ortho to the hydroxy or oxo groups of the hydroxypyridinone ring. The electron-withdrawing carbamoyl group increases the acidity of the hydroxypyridinones. In the metal complexes of said chelating agents, the amide protons form very strong hydrogen bonds with its adjacent HOPO oxygen donor, making these complexes very stable at physiological conditions. The terminal N-substituents provides a certain degree of lipophilicity to said 3,2-HOPO, increasing oral activity. Also disclosed is a method of making the chelating agents and a method of producing a known compound, 3-hydroxy-1-alkyl-2(1H)pyridinone, used as a precursor to the chelating agent, safely and in large quantities.

Raymond, Kenneth N. (Berkeley, CA) [Berkeley, CA; Xu, Jide (Berkeley, CA) [Berkeley, CA

1997-01-01

272

/sup 1/H NMR studies of spin-labeled oligonucleotides  

SciTech Connect

Structural determinations of oligonucleotides and their complexes using distance measurements based on NOE data are limited due to the relatively short distances available from this technique (less than or equal to 5 A). Extension of NMR measurements to longer distances would greatly augment the information currently obtainable. Effects over a range of approx.20 A can be observed by the incorporation of a paramagnetic spin label at a unique site into an oligomer by establishing a linewidth gradient with an r/sup -6/ dependence on the electron-proton distance. They have therefore synthesized a nonpalindromic oligonucleotide duplex with the sequence /sup 5'/CCACGG./sup 5'/CCGTGG as well as the two corresponding oligonucleotides containing 4-hydroxy-2,2,6,6-tetramethylpiperidinyloxy (TEMPO) attached by a phosphodiester linkage to the 5'terminus. The /sup 1/H NMR spectra obtained at 500 MHz of the spin-labeled duplexes have been analyzed and the resonances assigned. The extent of line broadening for the nucleotide resonances of the labeled duplexes has been measured and correlated to the distance between the label and the average proton position based on the crystal structure of B-DNA. This study suggests that it is feasible to acquire information over longer distances for the determination of solution structures of oligonucleotides and oligonucleotide:ligand complexes by distance geometry algorithms.

Oppenheimer, N.J.; Marschner, T.M.; Levenson, C.H.; Keller, T.J.

1986-05-01

273

3-hydroxy-2(1H)-pyridinone chelating agents  

DOEpatents

Disclosed is a series of improved metal chelating agents, which are highly effective upon both injection and oral administration; several of the most effective are of low toxicity. These chelating agents incorporate within their structure 1-hydroxy-2-pyridinone (1,2-HOPO) and 3-hydroxy-2-pyridinone (3,2-HOPO) moieties with a substituted carbamoyl group ortho to the hydroxy or oxo groups of the hydroxypyridinone ring. The electron-withdrawing carbamoyl group increases the acidity of the hydroxypyridinones. In the metal complexes of the chelating agents, the amide protons form very strong hydrogen bonds with its adjacent HOPO oxygen donor, making these complexes very stable at physiological conditions. The terminal N-substituents provides a certain degree of lipophilicity to the 3,2-HOPO, increasing oral activity. Also disclosed is a method of making the chelating agents and a method of producing a known compound, 3-hydroxy-1-alkyl-2(1H)pyridinone, used as a precursor to the chelating agent, safely and in large quantities. 2 figs.

Raymond, K.N.; Xu, J.

1997-04-29

274

1H NMR metabolomics study of age profiling in children  

PubMed Central

Metabolic profiling of urine provides a fingerprint of personalized endogenous metabolite markers that correlate to a number of factors such as gender, disease, diet, toxicity, medication, and age. It is important to study these factors individually, if possible to unravel their unique contributions. In this study, age-related metabolic changes in children of age 12 years and below were analyzed by 1H NMR spectroscopy of urine. The effect of age on the urinary metabolite profile was observed as a distinct age-dependent clustering even from the unsupervised principal component analysis. Further analysis, using partial least squares with orthogonal signal correction regression with respect to age, resulted in the identification of an age-related metabolic profile. Metabolites that correlated with age included creatinine, creatine, glycine, betaine/TMAO, citrate, succinate, and acetone. Although creatinine increased with age, all the other metabolites decreased. These results may be potentially useful in assessing the biological age (as opposed to chronological) of young humans as well as in providing a deeper understanding of the confounding factors in the application of metabolomics.

Gu, Haiwei; Pan, Zhengzheng; Xi, Bowei; Hainline, Bryan E.; Shanaiah, Narasimhamurthy; Asiago, Vincent; Nagana Gowda, G. A.; Raftery, Daniel

2014-01-01

275

Synthesis and Dynamic NMR Spectroscopic Study of Dialkyl 4-Ethoxy-1-(1-naphthyl)-5-oxo-4,5-dihydro-1 H -pyrrole-2,3-dicarboxylates  

Microsoft Academic Search

Summary. Protonation of the reactive 1:1 intermediate produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates with ethyl 2-(1-naphthylamino)-2-oxoacetate, leads to a vinylphosphonium salt, which undergoes intramolecular Wittig reaction to produce dialkyl 4-ethoxy-1-(1-naphthyl)-5-oxo-4,5-dihydro-1 H-pyrrole-2,3-dicarboxylates in excellent yields. A dynamic NMR effect is observed in the 1H NMR spectra of the title compounds as a result of restricted rotation around the

Issa Yavari; Mehdi Adib; Shahrzad Abdolmohammadi; Mansoreh Aghazadeh

2003-01-01

276

Automated amino acid side-chain NMR assignment of proteins using 13 C- and 15 N-resolved 3D [ 1 H, 1 H]-NOESY  

Microsoft Academic Search

ASCAN is a new algorithm for automatic sequence-specific NMR assignment of amino acid side-chains in proteins, which uses\\u000a as input the primary structure of the protein, chemical shift lists of 1HN, 15N, 13C?, 13C? and possibly 1H? from the previous polypeptide backbone assignment, and one or several 3D 13C- or 15N-resolved [1H,1H]-NOESY spectra. ASCAN has also been laid out for

Francesco Fiorito; Torsten Herrmann; Fred F. Damberger; Kurt Wüthrich

2008-01-01

277

? decay of the ?h11/2 isomer in Ir164  

NASA Astrophysics Data System (ADS)

The ?-decay branch of the ?h11/2 isomer in Ir164 has been identified using the GREAT spectrometer. The Ir164 nuclei were produced using the 92Mo(78Kr,p5n )164Ir reaction and separated in flight using the recoil ion transport unit (RITU) gas-filled separator. The measured ?-decay energy of 6880±10 keV allowed the excitation of the ?h11/2 state in Re160 to be deduced as 166±14 keV. The half-life of Ir164 was measured with improved precision to be 70±10?s and an ?-decay branching ratio of 4±2% was determined. Improved half-life and branching ratio measurements were also obtained for Ir165, but no evidence was found for the ground-state decays of either Ir164 or Ir165.

Drummond, M. C.; O'Donnell, D.; Page, R. D.; Joss, D. T.; Capponi, L.; Cox, D. M.; Darby, I. G.; Donosa, L.; Filmer, F.; Grahn, T.; Greenlees, P. T.; Hauschild, K.; Herzan, A.; Jakobsson, U.; Jones, P. M.; Julin, R.; Juutinen, S.; Ketelhut, S.; Leino, M.; Lopez-Martens, A.; Mistry, A. K.; Nieminen, P.; Peura, P.; Rahkila, P.; Rinta-Antila, S.; Ruotsalainen, P.; Sandzelius, M.; Sarén, J.; Say??, B.; Scholey, C.; Simpson, J.; Sorri, J.; Thornthwaite, A.; Uusitalo, J.

2014-06-01

278

Synthesis, crystal structure, HF and DFT calculations of 1-(2-chlorobenzyl)-N-(1-(2-chlorobenzyl)-4,5-dihydro-1H-imidazol-2-yl) -1H-benzimidazol-2-amine  

SciTech Connect

The titled compound (1), has been synthesized and characterized by IR and {sup 1}H-NMR spectroscopy, and single crystal X-ray diffraction. The compound crystallizes in the triclinic space group P-1. The crystal structure is stabilized by C-H-{pi} and aromatic {pi}-{pi} interactions. There are also intramolecular N-H-N and C-H-N hydrogen bonds in the molecule. The use of quantum chemical calculations to characterise and optimise the choice of material is illustrated by ab initio treatments. Vibrational frequencies and LUMO-HOMO energy difference of 1 have also been investigated by Density functional theory (DFT) and Hartree-Fock (HF) calculations. Calculated frequencies are in good agreement with the corresponding experimental data.

Yueksektepe, Cigdem, E-mail: yuksekc@yahoo.com [Cankiri Karatekin University, Department of Physics, Faculty of Science (Turkey); Caliskan, Nezihe [Ondokuz Mayis University, Department of Physics, Faculty of Arts and Sciences (Turkey); Genc, Murat [Adiyaman University, Department of Chemistry, Faculty of Arts and Sciences (Turkey); Servi, Sueleyman [Firat University, Department of Chemistry, Faculty of Science (Turkey)

2010-12-15

279

Oxidation of CO by NO on planar and faceted Ir(210).  

PubMed

Oxidation of CO by pre-adsorbed NO has been studied on planar Ir(210) and nanofaceted Ir(210) with average facet sizes of 5 nm and 14 nm by temperature programmed desorption (TPD). Both surfaces favor oxidation of CO to CO(2), which is accompanied by simultaneous reduction of NO with high selectivity to N(2). At low NO pre-coverage, the temperature (T(i)) for the onset of CO(2) desorption as well as CO(2) desorption peak temperature (T(p)) decreases with increasing CO exposure, and NO dissociation is affected by co-adsorbed CO. At high NO pre-coverage, T(i) and T(p) are independent of CO exposure, and co-adsorbed CO has no influence on dissociation of NO. Moreover, at low NO pre-coverage, planar Ir(210) is more active than faceted Ir(210) for oxidation of CO to CO(2): T(i) and T(p) are much lower on planar Ir(210) than that on faceted Ir(210). In addition, faceted Ir(210) with an average facet size of 5 nm is more active for oxidation of CO to CO(2) than faceted Ir(210) with an average facet size of 14 nm, i.e., oxidation of CO by pre-adsorbed NO on faceted Ir(210) exhibits size effects on the nanometer scale. In comparison, at low O pre-coverage planar Ir(210) is more active than faceted Ir(210) for oxidation of CO to CO(2) but no evidence has been found for size effects in oxidation of CO by pre-adsorbed oxygen on faceted Ir(210) for average facet sizes of 5 nm and 14 nm. The TPD data indicate the same reaction pathway for CO(2) formation from CO + NO and CO + O reactions on planar Ir(210). The adsorption sites of CO, NO, O, CO + O, and CO + NO on Ir are characterized by density functional theory. PMID:22713063

Chen, Wenhua; Bartynski, Robert A; Kaghazchi, Payam; Jacob, Timo

2012-06-14

280

IR, NMR and dielectric characterization of a novel tetramic acid  

NASA Astrophysics Data System (ADS)

The structure of the N-acetyl-3-hexanoyl tetramic acid has been elucidated by IR and NMR spectroscopy. The IR spectra showed absorption bands for the CO group of the ?-dicarbonyl system CO-CH-CO ?; C(OH)DC-CO as well as for the carbon-carbon double bond thus verifying the proposed structure. The 1H and 13C NMR spectra confirm the existence of enolic "internal" and "external" tautomers. The interconversion of "internal" tautomers seems to be faster than that of the "external" ones. The Thermally Stimulated Depolarization Currents (TSDC) spectrum in the temperature range 10-340 K revealed the presence of two predominant relaxation mechanisms, which are tentatively discussed in terms of the relaxation of tautomeric transformations under the influence of the applied electric field.

Vassilikou-Dova, A.; Kalogeras, I. M.; Petroliagi, M.; Igglessi-Markopoulou, O.; Markopoulos, J.

281

Optical/IR from ground  

NASA Technical Reports Server (NTRS)

Optical/infrared (O/IR) astronomy in the 1990's is reviewed. The following subject areas are included: research environment; science opportunities; technical development of the 1980's and opportunities for the 1990's; and ground-based O/IR astronomy outside the U.S. Recommendations are presented for: (1) large scale programs (Priority 1: a coordinated program for large O/IR telescopes); (2) medium scale programs (Priority 1: a coordinated program for high angular resolution; Priority 2: a new generation of 4-m class telescopes); (3) small scale programs (Priority 1: near-IR and optical all-sky surveys; Priority 2: a National Astrometric Facility); and (4) infrastructure issues (develop, purchase, and distribute optical CCDs and infrared arrays; a program to support large optics technology; a new generation of large filled aperture telescopes; a program to archive and disseminate astronomical databases; and a program for training new instrumentalists)

Strom, Stephen; Sargent, Wallace L. W.; Wolff, Sidney; Ahearn, Michael F.; Angel, J. Roger; Beckwith, Steven V. W.; Carney, Bruce W.; Conti, Peter S.; Edwards, Suzan; Grasdalen, Gary

1991-01-01

282

Electrochemical and spectroelectrochemical studies of (TPP)(Ir(CO)/sub 3/)/sub 2/) in nonaqueous media  

SciTech Connect

A modified method for the synthesis of (TPP)(Ir(CO)/sub 3/)/sub 2/ from (Ir(CO)/sub 3/Cl)/sub 2/ and (TPP)H/sub 2/ where TPP is the dianion of tetraphenylporphyrin was developed and gives a much higher percent yield. Electrochemical and spectroelectrochemical studies of (TPP)(Ir(CO)/sub 3/)/sub 2/ indicate that this binuclear Ir(I) complex undergoes two reversible reductions at the porphyrin /pi/-ring system. Three irreversible oxidations are observed in benzonitrile containing 0.2 M tetrabutylammonium perchlorate, while in CH/sub 2/Cl/sub 2/, only two irreversible oxidations are recorded. The first oxidation occurs at one of the two Ir(I) centers of (TPP)(Ir(CO)/sub 3/)/sub 2/ and is followed by a rapid chemical reaction that leads to the generation of ((TPP)Ir)/sup +/ClO/sub 4//sup /minus// or a solvated form of this species in solution. An overall mechanism for the electrochemical conversion of binuclear (TPP)(Ir(CO)/sub 3/)/sub 2/ to monomeric ((TPP)Ir)/sup +/ClO/sub 4//sup /minus// and the additional reactions of this species are reported. Comparisons are also made between electrochemical properties of binuclear (TPP)(Ir(CO)/sub 3/)/sub 2/ and the binuclear Rh(I) analogue (TPP)(Rh(CO)/sub 2/)/sub 2/.

Kadish, K.M.; Deng, Y.J.; Yao, C.L.; Anderson, J.E.

1988-09-01

283

CCD and IR array controllers  

NASA Astrophysics Data System (ADS)

A family of controllers has bene developed that is powerful and flexible enough to operate a wide range of CCD and IR focal plane arrays in a variety of ground-based applications. These include fast readout of small CCD and IR arrays for adaptive optics applications, slow readout of large CCD and IR mosaics, and single CCD and IR array operation at low background/low noise regimes as well as high background/high speed regimes. The CCD and IR controllers have a common digital core based on user- programmable digital signal processors that are used to generate the array clocking and signal processing signals customized for each application. A fiber optic link passes image data and commands to VME or PCI interface boards resident in a host computer to the controller. CCD signal processing is done with a dual slope integrator operating at speeds of up to one Megapixel per second per channel. Signal processing of IR arrays is done either with a dual channel video processor or a four channel video processor that has built-in image memory and a coadder to 32-bit precision for operating high background arrays. Recent developments underway include the implementation of a fast fiber optic data link operating at a speed of 12.5 Megapixels per second for fast image transfer from the controller to the host computer, and supporting image acquisition software and device drivers for the PCI interface board for the Sun Solaris, Linux and Windows 2000 operating systems.

Leach, Robert W.; Low, Frank J.

2000-08-01

284

Mitochondrial OXPHOS Functions in R1H Rhabdomyosarcoma and Skeletal Muscles of the Rat  

Microsoft Academic Search

The aim of the study was to determinate mitochondrial oxidative phosphorylation (OXPHOS) functions in rat rhabdomyosarcoma\\u000a R1H (R1H) and rat skeletal muscles. For that purpose skinned fiber technique and multiple substrate inhibitor titration were\\u000a adapted to tumor samples. In our animal tumor model (R1H) functional abnormalities of OXPHOS were found compared to skeletal\\u000a muscles. In R1H the state 3 respiration

Thomas Kuhnt; Tanja Pelz; Xiaoying Qu; Gabriele Hänsgen; Jürgen Dunst; Frank Norbert Gellerich

2007-01-01

285

Liver X receptors alpha gene (NR1H3) promoter polymorphisms are associated with systemic lupus erythematosus in Koreans  

PubMed Central

Introduction Liver X receptors are established sensors of lipid and cholesterol homeostasis. Recent studies have reported that these receptors are involved in the regulation of inflammation and immune responses. We attempted to identify single nucleotide polymorphisms (SNPs) of the NR1H3 gene associated with the susceptibility to systemic lupus erythematosus (SLE). Methods SNPs were genotyped using SNaPSHOT assay in 300 Korean patients with SLE and 217 normal controls (NC), and in replication samples (160 SLE patients and 143 NC). Also, the functional effects of NR1H3 gene promoter polymorphisms were analyzed using a luciferase assay, real-time polymerase chain reaction, B cell proliferation assay and an electrophoretic mobility shift assay. Results We identified five polymorphisms: -1851 T?>?C (rs3758673), -1830 T?>?C (rs3758674), -1003 G?>?A (new), -840 C?>?A (rs61896015) and -115 G?>?A (rs12221497). There was a significant and reproducible difference in the -1830 T?>?C, -1003 G?>?A and -115 G?>?A polymorphisms between the SLE and the NC. Luciferase activity of the structure containing -1830 C was less enhanced compared to the structure containing -1830 T in basal, GW3965 and T0901317 treated Hep3B cells (P?=?0.009, P?=?0.034 and P <0.001, respectively). Proliferation of the -1830 TC type was increased compared to the -1830 TT type in basal, GW3965 and T0901317 treated B cells from SLE patients (P?=?0.011, P?=?0.040 and P?=?0.017, respectively). Transcription factor GATA-3 preferentially bound the -1830 T allele in the promoter. Conclusions NR1H3 genetic polymorphisms may be associated with disease susceptibility and clinical manifestations of SLE. Specifically, -1830 T?>?C polymorphism within NR1H3 promoter region may be involved in regulation of NR1H3 expression.

2014-01-01

286

Simple Approaches for Estimating Vicinal 1H- 1H Coupling-Constants and for Obtaining Stereospecific Resonance Assignments in Leucine Side Chains  

NASA Astrophysics Data System (ADS)

An approach for deriving stereospecific ?-methyl assignments and ? 2 dihedral angle constraints for leucine residues, based on easily recognized patterns of 1H- 1H spin-spin coupling constants and intraresidue nuclear-Overhauser-effect spectroscopy (NOESY) cross-peak intensities, is described. The approach depends on resolved H ? and/or ?-methyl resonances and on initially obtaining stereospecific assignments for H ?2 and H ?3. As part of the overall strategy, a method is presented for obtaining qualitative or, in favorable cases, semiquantitative estimates of vicinal 1H- 1H coupling constants from peak intensities measured in a short-mixing-time 1H- 1H total correlation spectroscopy (TOCSY) experiment. This method of estimating 1H- 1H spin-spin coupling constants is generally applicable to all side-chain types. The approach is illustrated for several leucine residues within uniformly 15N-labeled and 15N/ 13C-double-labeled isolated light-chain variable domain of the anti-digoxin antibody 26-10. Estimates of 3J?? and 3J?? coupling constants are derived from a three-dimensional (3D) 13C-edited TOCSY-heteronuclear multiple-quantum coherence (HMQC) spectrum. These data are combined with information from 3D 15N-edited NOESY and 3D 13C-edited NOESY spectra to yield stereospecific H ?2, H ?3, and ?-methyl assignments, as well as constraints on ? (1) and ? 2 dihedral angles. Although the overall approach is illustrated using 3D 15N-edited and 13C-edited data, it is equally applicable to analysis of two-dimensional 1H- 1H NOESY and TOCSY spectra.

Constantine, K. L.; Friedrichs, M. S.; Mueller, L.

287

The reaction of nitro-1,2-diaminobenzenes with the [ReO] 3+ core: isolation of oxo-free rhenium(V) complexes  

Microsoft Academic Search

The reaction of 2 equiv. of 3-nitro-1,2-diaminobenzene (H2L1) with trans-ReOCl3(PPh3)2 in ethanol gave the oxo-free rhenium(V) complex [ReCl(PPh3)(L1)2] (1) in good yield. IR, 1H NMR and X-ray crystallographic results indicate that the diamine ligand L1 coordinates in a dianionic bidentate diamido form to the metal, and that the complex has the unusual skew-trapezoidal bipyramidal geometry. With 4-nitro-1,2-diaminobenzene (H2L2) as ligand

Giuliano Bandoli; Alessandro Dolmella; Thomas I. A. Gerber; Joanne Perils; Jan G. H. du Preez

2000-01-01

288

The partial (1)H NMR spectra of Al-OH and molecular H(2)O in hydrous aluminosilicate glasses: Component-Resolved analysis of (27)Al-(1)H cross polarization and (1)H spin-echo MAS NMR spectra.  

PubMed

The Component-Resolved methodology was applied to (1)H spin-echo and (27)Al-(1)H cross polarization (CP) MAS NMR data of aluminosilicate glasses. The method was able to resolve two components with different T2 relaxation rates, hydroxyl groups (OH) and molecular water (H(2)O(mol)), from the spin-echo data and to determine partial spectra and the relative abundances of OH and H(2)O(mol). The algorithm resolved two to three components with different (27)Al-(1)H CP dynamics from the (27)Al-(1)H cross polarization data; the obtained partial NMR spectra for Al-OH are in excellent agreement with those obtained previously from the difference spectra between spectra with various contact times and confirm previous quantitative results and models for the Al-OH, Si-OH and H(2)O(mol) speciation (Malfait and Xue, 2010). PMID:20418075

Malfait, Wim J; Xue, Xianyu

2010-01-01

289

Bicyclization of Isocyanides with Alkenoyl Bis(ketene dithioacetals): Access to 6,7-Dihydro-1H-indol-4(5H)-ones.  

PubMed

The tandem [3 + 2] cycloaddition/intramolecular imidoyl anion trapping strategy has been successfully applied for the synthesis of 6,7-dihydro-1H-indol-4(5H)-ones from alkenoyl bis(ketene dithioacetals) and tosylmethyl isocyanide. The reaction proceeded smoothly under mild reaction conditions to afford bicyclization products in high to excellent yields in a single step. PMID:24846440

Li, Yifei; Xu, Xianxiu; Shi, Hui; Pan, Ling; Liu, Qun

2014-06-20

290

Catalytic ethanolysis of soybean oil with immobilized lipase from Candida antarctica and 1H NMR and GC quantification of the ethyl esters (biodiesel) produced  

Microsoft Academic Search

The catalytic ethanolysis of soybean oil with commercial immobilized lipase type B from Candida antarctica to yield ethyl esters (biodiesel) has been investigated. Transesterification was monitored with respect to the following parameters: quantity of biocatalyst, reaction time, amount of water added and turnover of lipase. The highest yields of biodiesel (87% by 1H NMR; 82.9% by GC) were obtained after

Isac G. Rosset; Maria Cecília H. Tavares; Elisabete M. Assaf; André Luiz M. Porto

2011-01-01

291

Cu(OTf) 2: a reusable catalyst for high-yield synthesis of 3,4-dihydropyrimidin-2(1 H)-ones  

Microsoft Academic Search

Copper(II) triflate catalyzes efficiently the three-component condensation reaction of an aldehyde, ?-ketoester and urea in acetonitrile to afford the corresponding 3,4-dihydropyrimidin-2(1H)-ones in high yields. The catalyst exhibited remarkable reusable activity.

A. S. Paraskar; G. K. Dewkar; A. Sudalai

2003-01-01

292

Rh(III)-Catalyzed Oxidative Coupling of 1,2-Disubstituted Arylhydrazines and Olefins: A New Strategy for 2,3-Dihydro-1H-Indazoles.  

PubMed

A rhodium(III)-catalyzed oxidative olefination of 1,2-disubstituted arylhydrazines with alkenes via sp(2) C-H bond activation followed by an intramolecular aza-Michael reaction is described. This strategy allows the direct and efficient construction of highly substituted 2,3-dihydro-1H-indazole scaffolds. PMID:24754303

Han, Sangil; Shin, Youngmi; Sharma, Satyasheel; Mishra, Neeraj Kumar; Park, Jihye; Kim, Mirim; Kim, Minyoung; Jang, Jinbong; Kim, In Su

2014-05-01

293

Guanine binding of a cytotoxic platinum-acridin-9-ylthiourea conjugate monitored by 1-D 1H and 2-D [1H,15N] NMR spectroscopy: hydrolysis is not the rate-determining step.  

PubMed

The reaction of [PtCl(en)(ACRAMTU)](NO(3))(2) (PT-ACRAMTU, 1; ACRAMTU=1-[2-(acridin-9-ylamino)ethyl]-1,3-dimethylthiourea, en=ethane-1,2-diamine) and the [(15)N]-en labeled analogue, 1', with 2'-deoxyguanosine (dG) was studied by (1)H NMR and two-dimensional [(1)H,(15)N] HSQC (heteronuclear single quantum coherence) spectroscopy. Reactions were performed in phosphate buffered solution at 37 degrees C at various ratios and total concentrations of reactants. The (1)H NMR data suggest that the hydrolyzed form of the drug, [Pt(H(2)O)(en)(ACRAMTU)](3+) (1a), forms at a rate (k(1)) similar to that observed in classical platinum chloroam(m)ines but to only a minor extent ( approximately 15%). Attempts to detect and characterize 1'a by two-dimensional NMR spectroscopy, however, were unsuccessful, and 1' and dG( *) were the only species observed in the HSQC spectra. Reaction of the putative aqua intermediate 1a with dG to yield [Pt(en)(dG-N7)(ACRAMTU)](3+) (dG( *)) is slow and is highly dependent on the initial concentrations of the reactants. This unusual observation is consistent with a mechanism in which a second-order term becomes rate-determining (k(2)

Guddneppanavar, Rajsekhar; Wright, Marcus W; Tomsey, Alyssa K; Bierbach, Ulrich

2006-05-01

294

Complete 1H NMR spectral analysis of ten chemical markers of Ginkgo biloba  

PubMed Central

The complete and unambiguous 1H NMR assignments of ten marker constituents of Ginkgo biloba are described. The comprehensive 1H NMR profiles (fingerprints) of ginkgolide A, ginkgolide B, ginkgolide C, ginkgolide J, bilobalide, quercetin, kaempferol, isorhamnetin, isoquercetin, and rutin in DMSO-d6 were obtained through the examination of 1D 1H NMR and 2D 1H,1H-COSY data, in combination with 1H iterative Full Spin Analysis (HiFSA). The computational analysis of discrete spin systems allowed a detailed characterization of all the 1H NMR signals in terms of chemical shifts (?H) and spin-spin coupling constants (JHH), regardless of signal overlap and higher order coupling effects. The capability of the HiFSA-generated 1H fingerprints to reproduce experimental 1H NMR spectra at different field strengths was also evaluated. As a result of this analysis, a revised set of 1H NMR parameters for all ten phytoconstituents was assembled. Furthermore, precise 1H NMR assignments of the sugar moieties of isoquercetin and rutin are reported for the first time.

Napolitano, Jose G.; Lankin, David C.; Chen, Shao-Nong; Pauli, Guido F.

2013-01-01

295

Silver(I) and copper(I) bis(pyridine-2-carbaldehyde-imine) triflate complexes studied in solution by 1H, 1H-{109Ag}, INEPT 15N and INEPT 109Ag NMR  

Microsoft Academic Search

The reactions of the neutral pyridine-imine, 6-R-py-2-CH=N-R' (NN'), donor ligands with [M(O{3}SCF{3})] [M = Ag(I) or Cu(I)] yield ionic complexes, consisting of a [M(NN'){2}]}+{ cation and a O{3}SCF{3}}-{ anion. }1{H NMR studies of the complexes which contain the prochiral substituent (R') i-Pr or the chiral (S)-CHMePh show that in the slow exchange limit the metal IB centres have tetrahedral geometries

G. van Koten; G. C. van Stein; B. de Bok; L. C. Taylor; K. Vrieze; C. Brevard

1984-01-01

296

Pd(ii)-catalyzed ligand controlled synthesis of methyl 1-benzyl-1H-indole-3-carboxylates and bis(1-benzyl-1H-indol-3-yl)methanones.  

PubMed

A simple change of ligand and solvent allows controlled, effective switching between cyclization-carbonylation and cyclization-carbonylation-cyclization-coupling (CCC-coupling) reactions of 2-alkynylanilines catalyzed by palladium(ii). The use of a [Pd(tfa)2(box)] catalyst in iPrOH afforded symmetrical ketones bearing two indoles in good yields; replacing the catalyst and solvent with Pd(tfa)2 and DMSO-MeOH led to the formation of methyl 1-benzyl-1H-indole-3-carboxylates in good yields. PMID:24802816

Shen, Rong; Kusakabe, Taichi; Takahashi, Keisuke; Kato, Keisuke

2014-06-11

297

IR seeker simulator and IR scene generation to evaluate IR decoy effectiveness  

NASA Astrophysics Data System (ADS)

IR decoys can be an effective countermeasure against IR guided anti ship missiles. However, it's not so easy to determine how the decoys should be deployed to get maximum effectiveness. A limitation of trials is that results are obtained for the specific trial condition only. Software tools have been developed to solve these problems. One solution uses recorded IR imagery from a decoy deployment trial, while the other solution generates IR imagery and is thus independent of trials. In the first solution, a combination of hardware and software is used that allows recording of a scene with an infrared camera, and simulating a missile seeker. A pre-processing algorithm corrects the recorded images before they are fed into the seeker algorithm of the simulated missile. To perform this correction the pre-processing uses the speed, distance to the target and field of view of the IR camera as fixed parameters and the speed and starting distance of the simulated missile as variable parameters. Modtran and the Navy Aerosol Model are used to calculate the atmospheric transmission effects in the pre-processing. The second solution generates artificial IR images that are subsequently fed into the seeker algorithm. This solution also allows variation of those parameters that are fixed when recorded IR imagery is used. Examples are among others: the signature of the target ship, the orientation, size and speed of the target ship, the type of decoy, the timing of the decoy sequence, atmospheric conditions etc. With these tools the effectiveness of decoy deployment in various scenarios can be evaluated.

de Jong, Wim; Dam, Frans A.; Kunz, Gerard J.; Schleijpen, Ric

2004-12-01

298

Synthesis and Determination of pKa Values of Some New 3,4-Disubstituted-4,5Dihydro1H-1,2,4-triazol-5-one Derivatives in Nonaqueous Solvents  

Microsoft Academic Search

Alkyl(Aryl)-4-amino-4,5-dihydro-1H-1,2,4-triazol-5-ones (2) reacted with 2-furoyl chloride and thiophene-2-carbonyl chloride to afford the corresponding 3- alkyl(aryl)-4-(2-furoylamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones (3) and 3-alkyl(aryl)- 4-(2-thienylcarbonylamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones (4), respectively. The new compounds synthesized were characterized by using IR, 1 H-NMR, 13 C-NMR and UV spectral data together with elemental analysis. In addition, to investigate the effects of solvents and molecular structure upon acidity, compounds 3 and 4 were

Haydar Yüksek; Zafer Ocak; Muzaffer Alkan; Sule Bahçeci; Mustafa Özdemir

2004-01-01

299

1H and 13C{1H} NMR spectral parameters of sulfur mustards, nitrogen mustards, and lewisites: computing and predicting of reference spectra for chemical identification.  

PubMed

The (1)H and (13)C{(1)H} chemical shifts and (1)H spin-spin couplings of sulfur mustards, nitrogen mustards, and lewisites scheduled in the Chemical Weapons Convention, and those of bis(2-chloromethyl)disulfide, were determined in CDCl(3), CD(2)Cl(2), and (CD(3))(2)CO. Accurate parameters of this kind of series can be used for evaluating the current molecular modeling programs and the chemical shift and coupling constant prediction possibilities of the programs. Several prediction tests were made with commercial programs, and the results are reported here. PMID:22374852

Haapaniemi, Esa; Mesilaakso, Markku

2012-03-01

300

CaIrO_{3}.  

PubMed

In CaIrO_{3}, electronic correlation, spin-orbit coupling, and tetragonal crystal field splitting are predicted to be of comparable strength. However, the nature of its ground state is still an object of debate, with contradictory experimental and theoretical results. We probe the ground state of CaIrO_{3} and assess the effective tetragonal crystal field splitting and spin-orbit coupling at play in this system by means of resonant inelastic x-ray scattering. We conclude that insulating CaIrO_{3} is not a j_{eff}=1/2 iridate and discuss the consequences of our finding to the interpretation of previous experiments. In particular, we clarify how the Mott insulating state in iridates can be readily extended beyond the j_{eff}=1/2 ground state. PMID:24836260

Sala, M Moretti; Ohgushi, K; Al-Zein, A; Hirata, Y; Monaco, G; Krisch, M

2014-05-01

301

3D 15N/15N/1H chemical shift correlation experiment utilizing an RFDR-based 1H/1H mixing period at 100 kHz MAS  

NASA Astrophysics Data System (ADS)

Homonuclear correlation NMR experiments are commonly used in the high-resolution structural studies of proteins. While 13C/13C chemical shift correlation experiments utilizing dipolar recoupling techniques are fully utilized under MAS, correlation of the chemical shifts of 15N nuclei in proteins has been a challenge. Previous studies have shown that the negligible 15N-15N dipolar coupling in peptides or proteins necessitates the use of a very long mixing time (typically several seconds) for effective spin diffusion to occur and considerably slows down a 15N/15N correlation experiment. In this study, we show that the use of mixing proton magnetization, instead of 15N, via the recoupled 1H-1H dipolar couplings enable faster 15N/15N correlation. In addition, the use of proton-detection under ultrafast MAS overcomes the sensitivity loss due to multiple magnetization transfer (between 1H and 15N nuclei) steps. In fact, less than 300 nL (?1.1 micromole quantity) sample is sufficient to acquire the 3D spectrum within 5 h. Our results also demonstrate that a 3D 15N/15N/1H experiment can render higher resolution spectra that will be useful in the structural studies of proteins at ultrafast MAS frequencies. 3D 15N/15N/1H and 2D radio frequency-driven dipolar recoupling (RFDR)-based 1H/1H experimental results obtained from a powder sample of N-acetyla-L-15N-valyl-L-15N-leucine at 70 and 100 kHz MAS frequencies are presented.

Nishiyama, Yusuke; Malon, Michal; Ishii, Yuji; Ramamoorthy, Ayyalusamy

2014-07-01

302

3D (15)N/(15)N/(1)H chemical shift correlation experiment utilizing an RFDR-based (1)H/(1)H mixing period at 100kHz MAS.  

PubMed

Homonuclear correlation NMR experiments are commonly used in the high-resolution structural studies of proteins. While (13)C/(13)C chemical shift correlation experiments utilizing dipolar recoupling techniques are fully utilized under MAS, correlation of the chemical shifts of (15)N nuclei in proteins has been a challenge. Previous studies have shown that the negligible (15)N-(15)N dipolar coupling in peptides or proteins necessitates the use of a very long mixing time (typically several seconds) for effective spin diffusion to occur and considerably slows down a (15)N/(15)N correlation experiment. In this study, we show that the use of mixing proton magnetization, instead of (15)N, via the recoupled (1)H-(1)H dipolar couplings enable faster (15)N/(15)N correlation. In addition, the use of proton-detection under ultrafast MAS overcomes the sensitivity loss due to multiple magnetization transfer (between (1)H and (15)N nuclei) steps. In fact, less than 300nL (?1.1micromole quantity) sample is sufficient to acquire the 3D spectrum within 5h. Our results also demonstrate that a 3D (15)N/(15)N/(1)H experiment can render higher resolution spectra that will be useful in the structural studies of proteins at ultrafast MAS frequencies. 3D (15)N/(15)N/(1)H and 2D radio frequency-driven dipolar recoupling (RFDR)-based (1)H/(1)H experimental results obtained from a powder sample of N-acetyla-l-(15)N-valyl-l-(15)N-leucine at 70 and 100kHz MAS frequencies are presented. PMID:24801998

Nishiyama, Yusuke; Malon, Michal; Ishii, Yuji; Ramamoorthy, Ayyalusamy

2014-07-01

303

Isomeric luminescent Zn(II) coordination polymers based on pyridinecarboxylate and 5-methyl-1H-tetrazole ligands  

NASA Astrophysics Data System (ADS)

Two new metal-organic frameworks, namely [Zn(nic)(mtz)]n (1) and [Zn(isonic)(mtz)]n (2) (Hnic = nicotinic acid, Hisonic = isonicotinic acid, Hmtz = 5-methyl-1H-tetrazole), have been obtained through the solvothermal reactions of Zn(NO3)2, Htmz and Hnic or Hisonic. Single crystal X-ray diffraction analysis reveals that compound 1 features a 2D layered structure with sql topology, which is further extended into a 3D supramolecular framework via weak CH…? interactions, and compound 2 is 2-fold interpenetrated 3D framework with dia topology. Luminescent investigation shows that both of them emit blue luminescence at room temperature.

An, Zhe; Gao, Jing; Zhu, Ling

2013-12-01

304

Monitoring bound HA1(H1N1) and HA1(H5N1) on freely suspended graphene over plasmonic platforms with infrared spectroscopy  

NASA Astrophysics Data System (ADS)

Infrared (IR) spectroscopy provides fingerprinting of the energy and orientation of molecular bonds. The IR signals are generally weak and require amplification. Here we present a new plasmonic platform, made of freely suspended graphene, which was coating periodic metal structures. Only monolayer thick films were needed for a fast signal recording. We demonstrated unique IR absorption signals of bound proteins: these were the hemagglutinin area (HA1) of swine influenza (H1N1) and the avian influenza (H5N1) viruses bound to their respective tri-saccharides ligand receptors. The simplicity and sensitivity of such approach may find applications in fast monitoring of binding events.

Banerjee, Amrita; Chakraborty, Sumit; Altan-Bonnet, Nihal; Grebel, Haim

2013-09-01

305

Synthesis, Characterization, Thermal Properties, and Antimicrobial Activities of 5-(Diethylamino)-2-(5-nitro-1H-benzimidazol-2-yl)phenol and Its Transition Metal Complexes.  

PubMed

Synthesis and antimicrobial activities of new metal [Co(II), Cu(II), Ni(II), and Fe(II)] complexes from 5-(diethylamino)-2-(5-nitro-1H-benzimidazol-2-yl)phenol are described. The newly synthesized ligands were characterized by IR, (1)H NMR, and LC-MS analysis, and metal-ligand complex formations were confirmed by using atomic absorption spectroscopy and elemental analysis. All complexes show significant in vitro antibacterial activities against E. coli and S. aureus strains and in vitro antifungal activity against C. albicans and A. niger strains by using serial dilution method. The antibacterial activities were expressed as the minimum inhibitory concentration (MIC) in ?g/mL. Thermal properties and electrochemical behavior of novel transition metal complexes have been studied. PMID:24052831

Padalkar, Vikas S; Patil, Vikas S; Gupta, Vinod D; Phatangare, Kiran R; Umape, Prashant G; Sekar, N

2011-01-01

306

Synthesis, Characterization, Thermal Properties, and Antimicrobial Activities of 5-(Diethylamino)-2-(5-nitro-1H-benzimidazol-2-yl)phenol and Its Transition Metal Complexes  

PubMed Central

Synthesis and antimicrobial activities of new metal [Co(II), Cu(II), Ni(II), and Fe(II)] complexes from 5-(diethylamino)-2-(5-nitro-1H-benzimidazol-2-yl)phenol are described. The newly synthesized ligands were characterized by IR, 1H NMR, and LC-MS analysis, and metal-ligand complex formations were confirmed by using atomic absorption spectroscopy and elemental analysis. All complexes show significant in vitro antibacterial activities against E. coli and S. aureus strains and in vitro antifungal activity against C. albicans and A. niger strains by using serial dilution method. The antibacterial activities were expressed as the minimum inhibitory concentration (MIC) in ?g/mL. Thermal properties and electrochemical behavior of novel transition metal complexes have been studied.

Padalkar, Vikas S.; Patil, Vikas S.; Gupta, Vinod D.; Phatangare, Kiran R.; Umape, Prashant G.; Sekar, N.

2011-01-01

307

Glycemic variability in normal glucose regulation subjects with elevated 1-h postload plasma glucose levels.  

PubMed

Subjects with normal glucose regulation (NGR), whose 1-h postload plasma glucose is ?8.6 mmol/L (155 mg/dL, NGR 1 h ? 8.6) during 75-g oral glucose tolerance test (OGTT), have an increased risk of type 2 diabetes and subclinical organ damage. And, the deficiency in islet ? cell function is responsible for glycemic disorders. The purpose of this study is to investigate glycemic variability in NGR subjects with elevated 1-h postload plasma glucose levels and its association with islet ? cell function. The 29 NGR subjects with 1-h postload plasma glucose ?8.6 mmol/L (NGR 1 h ? 8.6) and 29 age- and sex-matched NGR subjects with 1-h postload plasma glucose <8.6 mmol/L (NGR 1 h < 8.6) were recruited in the study. Insulin sensitivity (Matsuda index, ISI), insulin secretion (insulinogenic index ?I30/?G30), and integrated ? cell function measured by the oral disposition index (?I30/?G30 multiplied by the ISI) were derived from OGTT. All subjects were monitored using the continuous glucose monitoring system for consecutive 72 h. The multiple parameters of glycemic variability included the standard deviation of blood glucose (SDBG), mean blood glucose (MBG), mean of daily differences (MODD), and mean amplitude of glycemic excursions (MAGE). MAGE is considered as a gold standard of glycemic variability. Glycemic variability parameters SDBG, MBG, MODD, and MAGE in NGR 1 h ? 8.6 group were higher than those in NGR 1 h < 8.6 group (p < 0.05), and oral disposition index in NGR 1 h ? 8.6 group was lower than that in NGR 1 h < 8.6 group (p < 0.05). SDBG, MBG, MODD, MAGE, and 1-h postload plasma glucose all negatively associated with oral disposition index in the separate group (p < 0.05) and in the whole subjects (p < 0.05). After multivariate regression analysis, oral disposition index was the strongest independent contributor to MAGE and 1-h postload plasma glucose in the separate group (p < 0.05) and in the whole subjects (p < 0.05). It is concluded that NGR 1 h ? 8.6 group had higher glycemic variability and lower oral disposition index, compared with NGR 1 h < 8.6 group. Increased glycemic variability parameters and elevated 1-h postload plasma glucose consistently associated with declined oral disposition index in subjects from NGR 1 h < 8.6 to NGR 1 h ? 8.6 group. PMID:24030695

Su, Jian-Bin; Chen, Tong; Xu, Feng; Wang, Xue-Qin; Chen, Jin-Feng; Wu, Gang; Jin, Yan; Wang, Xiao-Hua

2014-06-01

308

Ab initio and density functional theory studies on vibrational spectra of 3-hydroxy-3-(2-methyl-1H-indol-3-yl)indolin-2-one  

NASA Astrophysics Data System (ADS)

Computational studies have been carried out on 3-hydroxy-3-(2-methyl-1H-indol-3-yl) indolin-2-one (HMI) using both the DFT-B3LYP/6-311+G and HF/6-311+G methods. The optimized geometry of HMI and its bonding parameters as well as IR spectra have been calculated and analyzed. It can be seen that the calculated bond lengths are in good agreement with the reported bond lengths of indole and isatins. The calculated spectra have been compared with the available experimental FT-IR spectra. From vibrational frequency analysis, it can be seen that the vibrational frequencies obtained from B3LYP method are in good agreement with the experiment, when compared to HF method and there is an excellent correlation with the 0.999 regression coefficient between the experimental and calculated vibrations for HMI. The geometrical parameters, non-linear optical properties and thermodynamic properties are calculated and reported.

Vasantha Kumar, V.; Goud, S. L.; Laxmikanth Rao, J.

2013-02-01

309

Anharmonic vibrations of N-H in Cl(-)(N-methylacetamide)1(H2O)(0-2)Ar2 cluster ions. Combined IRPD experiments and BOMD simulations.  

PubMed

Infrared Predissociation (IRPD) spectra of Cl(-)(NMA)1(H2O)0-2Ar2 combined with Born-Oppenheimer Molecular Dynamics (BOMD) IR spectra have been acquired, providing the structure and dynamics of these systems. We show that the chloride ion is bound to the hydrogen of the amide N-H group, forming a strong ionic hydrogen bond, weakening the N-H stretch, and shifting it to lower frequency. The presence of water molecules enhances the ionic hydrogen bond by binding to the amide carbonyl oxygen of NMA and shifts the N-H stretch further to lower frequency. The BOMD IR spectra can recapture all, but about 100 cm(-1), of the 600 to 700 cm(-1) shifts due to the strong N-H stretch anharmonicities observed in experiments. This residual error was found to be due to the lack of zero point energy in the classical treatment of motion in the BOMD method. PMID:23986352

Beck, Jordan P; Gaigeot, Marie-Pierre; Lisy, James M

2013-10-21

310

1H/ 2H-Dimethyl Sulfone as a Convenient Standard for Setting the Hartmann-Hahn Match in 1H- 2H CP/MAS NMR  

NASA Astrophysics Data System (ADS)

A physical mixture of powders and a molten mixture of 1H- and 2H-dimethyl sulfones were used to set the Hartmann-Hahn match in 1H- 2H CP/MAS NMR. There is no increase of spectral intensity for a mixture of powdered 1H- and 2H-sulfones compared with the MAS spectrum of pure 2H sulfone, but a considerable increase is found for the mixed melt and for bis[ tert-butyl(phenyl- d5) thiophosphoryl] disulfide. 1H- 2H CP/MAS offers increased signal intensity, shortens the accumulation time, and, in addition, provides a direct measure of the homogeneity of solids on a molecular level.

Potrzebowski, M. J.; Wasiak, J.; Ciesielski, W.; Klinowski, J.

311

Calibration of the 1H decoupling field strength and experimental evaluation of the specific RF absorption rate in 1H-decoupled human 13C-MRS.  

PubMed

For patient safety in human 1H decoupled 13C-MRS, it is absolutely necessary to evaluate the specific RF absorption rate (SAR) of the tissue exposed to 1H frequency irradiation. With the use of surface coils, the local SAR at the body surface is of most concern due to the inherent RF field inhomogeneity. An empirical procedure to spatially calibrate the decoupler power level and to evaluate the local SAR at the body surface is described. For head, liver, muscle gastrocnemius, and muscle vastus lateralis, the SAR at the body surface was estimated for an 1H/13C double surface coil setup. Optimized duty cycle values obtained with this procedure show that broad-band 1H-decoupled 13C-MR spectroscopy is clinically feasible at 1.5 T for such a coil configuration within safety guidelines. PMID:9543427

van den Bergh, A J; van den Boogert, H J; Heerschap, A

1998-04-01

312

Metallothionein 1 h tumour suppressor activity in prostate cancer is mediated by euchromatin methyltransferase 1  

PubMed Central

Metallothioneins (MTs) are a group of metal binding proteins thought to play a role in the detoxification of heavy metals. Here we showed by microarray and validation analyses that MT1h, a member of MT, is down-regulated in many human malignancies. Low expression of MT1h was associated with poor clinical outcomes in both prostate and liver cancer. We found that the promoter region of MT1h was hypermethylated in cancer and that demethylation of the MT1h promoter reversed the suppression of MT1h expression. Forced expression of MT1h induced cell growth arrest, suppressed colony formation, retarded migration, and reduced invasion. SCID mice with tumour xenografts with inducible MT1h expression had lower tumour volumes as well as fewer metastases and deaths than uninduced controls. MT1h was found to interact with euchromatin histone methyltransferase 1 (EHMT1) and enhanced its methyltransferase activity on histone 3. Knocking down of EHMT1 or a mutation in MT1h that abrogates its interaction with EHMT1 abrogated MT1h tumour suppressor activity. This demonstrates tumour suppressor activity in a heavy metal binding protein that is dependent on activation of histone methylation.

Han, Yu-Chen; Zheng, Zhong-Liang; Zuo, Ze-Hua; Yu, Yan P; Chen, Rui; Tseng, George C; Nelson, Joel B; Luo, Jian-Hua

2014-01-01

313

Synthesis and Antimicrobial Activity of 2-[2-(2,6-dichloro phenyl)amino]benzyl-3-(5-substituted phenyl-4,5-dihydro-1H-pyrazol-3-yl-amino)-6,8-dibromoquinazolin-4(3H)ones  

PubMed Central

A series of 2-[2-(2,6-dichlorophenyl)amino]benzyl-3-(5-substituted phenyl-4,5-dihydro-1H-pyrazol-3-yl-amino)-6,8-dibromoquinazolin-4(3H) ones 6a-m have been synthesized by the reaction of 2-[2-(2,6-dichlorophenyl)amino]benzyl-3-substituted phenylacrylamido-6,8-dibromoquinazolin-4(3H) ones 5a-m with hydrazine hydrate in the presence of glacial acetic acid. The chalcones 5a-m were prepared by the condensation of 2-[2-(2,6-dichlorophenyl)amino]benzyl-3-acetamido-6,8-dibromoquinazolin-4(3H)one 4 with different substituted aromatic aldehyde. The benzoxazinone 2 was synthesized from 2-[2-(2,6-dichlorophenyl)amino]phenyl acetyl chloride 1 on treatment with 3,5-dibromoanthranilic acid in pyridine, which on reaction with hydrazine hydrate and then on acetylation reaction yielded 4. The structures of these compounds have been elucidated by elemental analyses, IR, and NMR spectral data. The title compounds pyrazolyl-quinazolin-4(3H)ones 6a-m were evaluated for their antibacterial and antifungal activities in vitro.

Patel, NB; Patel, JC; Barat, GG

2010-01-01

314

Decreased Insulin Clearance in Individuals with Elevated 1-h Post-Load Plasma Glucose Levels  

PubMed Central

Reduced insulin clearance has been shown to predict the development of type 2 diabetes. Recently, it has been suggested that plasma glucose concentrations ?8.6 mmol/l (155 mg/dl) at 1 h during an oral glucose tolerance test (OGTT) can identify individuals at high risk for type 2 diabetes among those who have normal glucose tolerance (NGT 1 h-high). The aim of this study was to examine whether NGT 1 h-high have a decrease in insulin clearance, as compared with NGT individuals with 1-h post-load glucose <8.6 mmol/l (l (155 mg/dl, NGT 1 h-low). To this end, 438 non-diabetic White individuals were subjected to OGTT and euglycemic-hyperinsulinemic clamp to evaluate insulin clearance and insulin sensitivity. As compared with NGT 1 h-low individuals, NGT 1 h-high had significantly higher 1-h and 2-h post-load plasma glucose and 2-h insulin levels as well as higher fasting glucose and insulin levels. NGT 1 h-high exhibited also a significant decrease in both insulin sensitivity (P<0.0001) and insulin clearance (P?=?0.006) after adjusting for age, gender, adiposity measures, and insulin sensitivity. The differences in insulin clearance remained significant after adjustment for fasting glucose (P?=?0.02) in addition to gender, age, and BMI. In univariate analyses adjusted for gender and age, insulin clearance was inversely correlated with body weight, body mass index, waist, fat mass, 1-h and 2-h post-load glucose levels, fasting, 1-h and 2-h post-load insulin levels, and insulin-stimulated glucose disposal. In conclusion, our data show that NGT 1 h-high have a reduction in insulin clearance as compared with NGT 1 h-low individuals; this suggests that impaired insulin clearance may contribute to sustained fasting and post-meal hyperinsulinemia.

Marini, Maria Adelaide; Frontoni, Simona; Succurro, Elena; Arturi, Franco; Fiorentino, Teresa Vanessa; Sciacqua, Angela; Hribal, Marta Letizia; Perticone, Francesco; Sesti, Giorgio

2013-01-01

315

Novel Asymmetric Tetradentate Schiff Base Ligands Derived from 6-Metwia-Formyl4Hydroxy2-(1H)-Quinolone and Their Metal Complexes  

Microsoft Academic Search

Novel asymmetric, tetradentate, dibasic Schiff base ligands were synthesized by the condensation of the half-unit Schiff base ligand 3-[o-aminophenyliminomethyl]-4-hydroxy-6-methyl-2-(1H)-quinolone with acetylacetone and salicylaldehyde. Cu(II), Ni(II), UO2 (VI) and Fe(III) complexes of both ligands were prepared using different salts in the case of Cu(II) and Ni(II) cations The structures of the ligands and the complexes were elucidated by chemical analyses, IR,

Adel A. A. Emara

1999-01-01

316

Experimental and ab initio computational studies on 4-(1H-benzo[d]imidazol-2-yl)-N,N-dimethylaniline  

Microsoft Academic Search

The title molecule, 4-(1H-benzo[d]imidazol-2-yl)-N,N-dimethylaniline (C15H15N3), was prepared and characterised by H-NMR, C-NMR, IR and single-crystal X-ray diffraction. The molecular geometry, vibrational frequencies and gauge including atomic orbital (GIAO) H- and C-NMR chemical shift values of the title compound in the ground state have been calculated using the Hartree–Fock (HF) and density functional theory (DFT) methods with 6–31G(d) basis sets, and

Namik Ozdemir; Bilge Eren; Muharrem Dincer; Yunus Bekdemir

2010-01-01

317

Vibrational spectra and DFT study of anticancer active molecule 2-(4-Bromophenyl)-1H-benzimidazole by normal coordinate analysis  

NASA Astrophysics Data System (ADS)

FT-IR and FT-Raman spectra of the 2-(4-Bromophenyl)-1H-benzimidzole were recorded and analyzed in the solid phase. The optimized molecular geometry, the vibrational wavenumbers, the infrared intensities and the Raman scattering activities were calculated by using Hartree-Fock and density functional method (B3LYP) with 6-31G(d,p) basis set. The potential surface scan study was carried out for the conformation of theoretical structure. Detailed interpretation of the vibrational spectra had been carried out with the aid of the normal coordinate analysis. Chemical interpretation of hyperconjugative interaction was done by natural bond orbital analysis.

Xavier, T. S.; Rashid, Naghmana; Hubert Joe, I.

2011-01-01

318

Heterocycle-Heterocycle Strategies: (2-Nitrophenyl)isoxazole Precursors to 4-Aminoquinolines, 1H-Indoles, and Quinolin-4(1H)-ones  

PubMed Central

Reductive heterocycle-heterocycle (heterocycle ? heterocycle; H–H) transformations that give 4-aminoquinolines, 3-acylindoles, and quinolin-4(1H)-ones from 2-nitrophenyl substituted isoxazoles are reported. When this methodology is applied to 3,5-, 4,5-, and 3,4-bis-(2-nitrophenyl)isoxazoles, chemoselective heterocyclization gives quinolin-4(1H)-ones, and 4-aminoquinolines, exclusively.

Coffman, Keith C.; Palazzo, Teresa A.; Hartley, Timothy P.; Fettinger, James C.; Tantillo, Dean J.; Kurth, Mark J.

2013-01-01

319

Characterization of the conjugative transposon Tn6000 from Enterococcus casseliflavus 664.1H1 (formerly Enterococcus faecium 664.1H1).  

PubMed

Tn6000 (formerly EfcTn1) from Enterococcus casseliflavus strain 664.1H1 (previously Enterococcus faecium 664.1H1) is a tetracycline resistance-encoding conjugative transposon of the Tn916-like family of mobile genetic elements. Sequence analysis of Tn6000 shows that it has a novel modular structure, comprising fragments of diverse proven and putative mobile elements including plasmids, conjugative transposons and virulence and pathogenicity islands. PMID:20528943

Brouwer, Michael S M; Mullany, Peter; Roberts, Adam P

2010-08-01

320

Surface oxides of Ir(111) prepared by gas-phase oxygen atoms  

NASA Astrophysics Data System (ADS)

The Ir(111) surface is oxidized with gas-phase oxygen atoms under vacuum condition to achieve an oxidation level beyond its saturation coverage for chemisorption. Two surface oxides, rutile IrO2 of (100) domain and corundum Ir2O3 of (001) domain, have been grown at 550 K with different oxygen exposure of 3.6 × 105 L and 7.2 × 105 L respectively. The temperature programmed desorption (TPD) experiment of rutile IrO2(100) shows its desorption curve (at 4 K s- 1) peaks at 750 K, followed by a long tail of less pronounced desorption features. On the other hand, TPD of corundum Ir2O3(001) displays a symmetric trace, peaking at 880 K. Carbon monoxide titration experiments show that adsorbed CO reduces corundum Ir2O3(001) at 400 K, but CO does not adsorb on rutile IrO2(100) and no reduction reaction occurs. Evidently, among the two surface oxides, corundum Ir2O3(001) involves in catalysis of carbon monoxide oxidation, while rutile IrO2(100) does not. The formation of two surface oxides is also compared, we conclude that the atom arrangement favors Ir2O3(001) at the oxide/metal interface.

Chung, Wen-Hung; Tsai, Dah-Shyang; Fan, Liang-Jen; Yang, Yaw-Wen; Huang, Ying-Sheng

2012-12-01

321

MARYLAND COASTAL BAYS IR 2002  

EPA Science Inventory

The Maryland Coastal Bays Program Implementation Review (IR) summarizes the progress and challenges ahead for the Program through examination of its activities in relation to the CCMP. During the CCMP planning phase the stakeholders prioritized the actions and determined the impl...

322

IR interferometers using modern cameras  

NASA Astrophysics Data System (ADS)

Laser interferometers have been used widely in the optics and disk drive industries. Often the surface of the sample is either too curved to resolve the fringes or too rough to reflect the incident beam back into the interferometer. Illuminating at a graze incident angle effectively increases the equivalent wavelength, and hence the reflectivity, but the image of a circular aperture becomes elliptical. Lasers with a long IR wavelength seem to be the solution. However,the spatial resolution of the vidicon cameras is usually poor, and the image lag is often too long. These limit the accuracy of an IR phase-shifting interferometer. Recently, we have designed tow types of interferometers for 3.39 micrometers and 10.6 micrometers using an InSb array and a micro- bolometer array, respectively. These modern cameras have a high resolution and hence greatly extend the range of measurable material from a blank to a finished optics. Because the refractive index of the optical material at the IR wavelength is usually very high, the anti-reflection coating of the optics at IR is more critical than that at a visible wavelength. The interferometer's design, the resolution, the dependence of the fringe contrast on the sample roughness, and the measurement results of various samples are presented.

Ai, Chiayu

1997-10-01

323

IrYdium Project, The  

NSDL National Science Digital Library

The IrYdium Project, and CREATE Project, develop educational software that can be integrated flexibly into introductory chemistry courses nationwide. Our goal is to create simulation-based learning environments where college and high school students can approach chemistry more like practicing scientists and see interesting real-world applications of key concepts.

324

Mechanistic study of electrochemical oxidation of 2,5-dihydroxybenzoic acid and 3,4-dihydroxybenzaldehyde in the presence of 3-hydroxy-1H-phenalene-1-one.  

PubMed

The mechanism of the electrochemical oxidation of 2,5-dihydroxybenzoic acid and 3,4-dihydroxybenzaldehyde in the presence of 3-hydroxy-1H-phenalene-1-one as a nucleophile has been studied in water/acetonitrile (80/20 v/v) solution using cyclic voltammetry and controlled-potential coulometry methods. The results indicate that the quinones derived from oxidation of 2,5-dihydroxybenzoic acid and 3,4-dihydroxybenzaldehyde participate in Michael addition reactions with 3-hydroxy-1H-phenalene-1-one and via ECE and ECEC mechanisms convert to the different products, with good yield under controlled potential conditions, at carbon electrode. PMID:18379100

Nematollahi, Davood; Amani, Amaneh

2008-04-01

325

Interaction of cytochrome c with cytochrome oxidase: dielectric, ionic strength and /sup 1/H NMR studies  

SciTech Connect

At low ionic strength, the reaction of cytochrome c with cytochrome oxidase exhibits a hyperbolic dependence on cytochrome c concentration. Employing a Keilin Hartree particle preparation derived from Ustilago sphaerogena, whose specific activity of cytochrome oxidase is 20-fold greater than the more commonly used beef and horse heart preparations, the ionic strength and dielectric dependences of the low affinity (K/sub m/ > 10/sup -7/M) region of the interaction with various prokaryotic and eukaryotic cytochromes c were examined. In all cases, increasing the ionic strength results in a decrease in the specific activity, with the eukaryotic cytochromes c, in contrast to the prokaryotic, displaying a biphasic dependence. Decreasing the dielectric of the bulk media results in a decrease in specific activity, independently of whether the dielectric effector is methanol, dioxane or dimethylsulfoxide. /sup 1/H nuclear magnetic resonance nuclear Overhauser effects, arising from irradiation of the methionine-80 methyl group, histidine-18 C4 proton and the various heme meso protons, as a function of the ionic strength and dielectric of the bulk media, were interpreted in terms of changes in the stability of the heme crevice. Also by examining the NOE arising from irradiation of acetate in the buffer, the relationship between changes in the bulk media and the composition of the solvation sphere was followed.

Garber, E.A.E.; Margoliash, E.

1986-05-01

326

1H NMR investigations of the molecular nature of cobalt(II) ions in human saliva.  

PubMed

High-resolution (1)H NMR spectroscopy demonstrated that addition of Co(II) ions to isolated human salivary supernatants (HSSs) gave rise to its complexation by a variety of biomolecules. The relative efficacies of these complexants/chelators in this context were classifiable by the influence of added Co(II) on their line-widths and chemical shift values, and also the added Co(II) concentration-dependence of these spectral modifications. Those which were most affected by the addition of this metal ion were lactate > formate ?histidinate > succinate, this order reflecting the ability of these complexants to compete for the available Co(II) in terms of (1) thermodynamic equilibrium constants for the formation of their complexes and (2) their HSS concentrations. Since many of these HSS Co(II) complexants (particularly lactate, formate and histidine) serve as powerful ()OH scavengers, the results acquired indicate that any of this radical generated from the Co(II) source in such complexes via pseudo-Fenton reactions may be 'site-specifically' scavenged. The significance of these observations regarding the in vivo corrosion of cobalt-containing metal alloy dental prostheses (e.g., Co-Cr alloys), the availability of trace levels of this metal ion in human saliva, and cobalt toxicity, is discussed. PMID:22342562

Chang, Hubert; Tomoda, Shigetaka; Silwood, Christopher J L; Lynch, Edward; Grootveld, Martin

2012-04-01

327

Topotecan dynamics, tautomerism and reactivity--1H/13C NMR and ESI MS study.  

PubMed

Topotecan (TPT) is in clinical use as an antitumor agent, hycamtin. Because of this, it requires both biologically and chemically useful information to be available. TPT acts by binding to the covalent complex formed by nicked DNA and topoisomerase I. This has a poisonous effect since inserted into the single-strand nick and TPT inhibits its religation. We used NMR to trace TPT dynamics, tautomerism and solvolysis products in various solvents and conditions. Chemical stability was assessed in methanol and DMSO as compared to water, and the regioselectivity of the N- and O-methylation was studied using various alkylating agents. The reaction products of quaternization of the nitrogen atom and methylation of the oxygen atom were characterized by means of ESI MS, (1)H/(13)C-HMBC and -HSQCAD NMR. We have focused on the NMR characterization of TPT with an anticipation that its aggregation, tumbling properties and the intramolecular dipolar interactions will be a common feature for other compounds described in this article. These features can also be useful in tracing the interactions of this class of topoisomerase I (TopoI) poisons with DNA. Moreover, the results explained shed light on the recently disclosed problem of lack of stability of TPT in the heart tissue homogenate samples using the analytical assays developed for this class of compounds carried out in the presence of methanol. PMID:20623719

Hyz, Karolina; Kawecki, Robert; Bednarek, Elzbieta; Bocian, Wojciech; Sitkowski, Jerzy; Kozerski, Lech

2010-08-01

328

An efficient synthesis and reactions of novel indolylpyridazinone derivatives with expected biological activity.  

PubMed

Reaction of 4-anthracen-9-yl-4-oxo-but-2-enoic acid (1) with indole gave the corresponding butanoic acid 2. Cyclocondensation of 2 with hydrazine hydrate, phenyl hydrazine, semicarbazide and thiosemicarbazide gave the pyridazinone derivatives 3a-d. Reaction of 3a with POCl(3) for 30 min gave the chloropyridazine derivative 4a, which was used to prepare the corresponding carbohydrate hydrazone derivatives 5a-d. Reaction of chloropyridazine 4a with some aliphatic or aromatic amines and anthranilic acid gave 6a-f and 7, respectively. When the reaction of the pyridazinone derivative 3a with POCl(3) was carried out for 3 hr an unexpected product 4b was obtained. The structure of 4b was confirmed by its reaction with hydrazine hydrate to give hydrazopyridazine derivative 9, which reacted in turn with acetyl acetone to afford 10. Reaction of 4b with methylamine gave 11, which reacted with methyl iodide to give the trimethylammonium iodide derivative 12. The pyridazinone 3a also reacted with benzene- or 4-toluenesulphonyl chloride to give 13a-b and with aliphatic or aromatic aldehydes to give 14a-g. All proposed structures were supported by IR, (1)H-NMR, (13)C-NMR, and MS spectroscopic data. Some of the new products showed antibacterial activity. PMID:17693951

Abubshait, Samar A

2007-01-01

329

13 C– 1 H dipolar-assisted rotational resonance in magic-angle spinning NMR  

Microsoft Academic Search

A new 13C–13C recoupling mechanism which occurs under magic-angle spinning (MAS) is presented. The mechanism can basically be attributed to rotational resonance (R2), but the conventional R2 condition is modified by a recoupled 13C–1H dipolar interaction. The 13C–1H recoupling is attained by 1H rf irradiation fulfilling a rotary-resonance condition. The present method does not have the drawbacks associated with rf

K. Takegoshi; Shinji Nakamura; Takehiko Terao

2001-01-01

330

1 H Magnetic Resonance in the Study of Hepatic Encephalopathy in Humans  

Microsoft Academic Search

1H magnetic resonance (1H MR) studies of the brain in patients with liver diseases have shown several abnormalities that may be relevant for the pathogenesis of hepatic encephalopathy. 1H magnetic resonance imaging shows a typical pallidal hyperintensity on T1-weighted images. This abnormality appears to be secondary to the accumulation of manganese in basal ganglia because of portal-systemic shunting. No direct

Juan Córdoba; Francesc Sanpedro; Juli Alonso; Alex Rovira

2002-01-01

331

Reactions of Pentaborane (9) and Pentaborane Derivatives.  

National Technical Information Service (NTIS)

A number of pentaborane derivatives are prepared in their (11)B and (1)H nmr spectra recorded and correlated. Assessments of alternative preparative schemes are given. An extension of the apex to base rearrangement reaction to polyalkyl pentaboranes revea...

T. Onak G. B. Dunks I. W. Search J. R. Spielman

1966-01-01

332

Derivatives of 2,3-dihydro-1H-1,5-benzodiazepine based on substituted 1,2-phenylenediamines and acetylarenes  

SciTech Connect

Derivatives of 2,3-dihydro-1H-1,5-benzodiazepine were obtained by the reaction of 4-chloro-, 4-bromo- 3,5-dichloro-, and 4-cyano-substituted ortho-phenyl-enediamines with 4-R-acetophenones in the presence of concentrated sulfuric acid. Electron-withdrawing groups R increase the reaction rate and consequently promote the formation of a mixture of isomeric products. The structure of the compounds and the composition of their mixtures were established by PMR spectroscopy. The reaction mechanism is discussed.

Orlov, V.D.; Desenko, S.M.

1986-06-01

333

Organometallic 3-(1H-Benzimidazol-2-yl)-1H-pyrazolo[3,4-b]pyridines as Potential Anticancer Agents  

PubMed Central

Six organometallic complexes of the general formula [MIICl(?6-p-cymene)(L)]Cl, where M = Ru (11a, 12a, 13a) or Os (11b, 12b, 13b) and L = 3-(1H-benzimidazol-2-yl)-1H-pyrazolo[3,4-b]pyridines (L1–L3) have been synthesized. The latter are known as potential cyclin-dependent kinase (Cdk) inhibitors. All compounds have been comprehensively characterized by elemental analysis, one- and two-dimensional NMR spectroscopy, UV–vis spectroscopy, ESI mass spectrometry, and X-ray crystallography (11b and 12b). The multistep synthesis of 3-(1H-benzimidazol-2-yl)-1H-pyrazolo[3,4-b]pyridines (L1–L3), which was reported by other researchers, has been modified by us essentially (e.g., the synthesis of 5-bromo-1H-pyrazolo[3,4-b]pyridine-3-carboxylic acid (3) via 5-bromo-3-methyl-1H-pyrazolo[3,4-b]pyridine (2); the synthesis of 1-methoxymethyl-2,3-diaminobenzene (5) by avoiding the use of unstable 2,3-diaminobenzyl alcohol; and the activation of 1H-pyrazolo[3,4-b]pyridine-3-carboxylic acids (1, 3) through the use of an inexpensive coupling reagent, N,N?-carbonyldiimidazole (CDI)). Stabilization of the 7b tautomer of methoxymethyl-substituted L3 by coordination to a metal(II) center, as well as the NMR spectroscopic characterization of two tautomers 7b-L3 and 4b?-L3 in a metal-free state are described. Structure–activity relationships with regard to cytotoxicity and cell cycle effects in human cancer cells, as well as Cdk inhibitory activity, are also reported.

2011-01-01

334

A combined experimental and theoretical (DFT and AIM) studies on synthesis, molecular structure, spectroscopic properties and multiple interactions analysis in a novel Ethyl-4-[2-(thiocarbamoyl)hydrazinylidene]-3,5-dimethyl-1H-pyrrole-2-carboxylate and its dimer  

NASA Astrophysics Data System (ADS)

In the present work, ethyl-4-[2-(thiocarbamoyl)hydrazinylidene]-3,5-dimethyl-1H-pyrrole-2-carboxylate (3) has been synthesized and characterized by 1H NMR, UV-Vis, FT-IR and Mass spectroscopy. The formation of the compound and its properties have also been evaluated by quantum chemical calculations using DFT, B3LYP functional and 6-31G(d,p) as basis set. The calculated thermodynamic parameters show that the formation of 3 is an exothermic and spontaneous reaction at room temperature. 1H NMR chemical shifts are calculated using gauge including atomic orbitals (GIAO) approach in DMSO-d6 as solvent. Time dependent density functional theory (TD-DFT) is used to calculate the energy (E), oscillator strength (f) and wavelength absorption maxima (?max) of various electronic transitions and their nature within the molecule. NBO analysis is carried out to investigate the charge transfer or charge delocalization in various intra- and intermolecular interactions of molecular system. The vibrational analysis indicates the formation of dimer in the solid state by intermolecular heteronuclear hydrogen bonding (Nsbnd H⋯O). Topological parameters at bond critical points (BCP) are calculated to analyze the strength and nature of various types of intra and intermolecular interactions in dimer by Bader's 'Atoms in molecules' AIM theory in detail. The binding energy of intermolecular multiple interactions is calculated to be 15.54 kcal/mol, using AIM calculation. The local reactivity descriptors such as Fukui functions (fk+,fk-), local softnesses (sk+,sk-) and electrophilicity indices (?k+,?k-) analyses are performed to determine the reactive sites within molecule.

Singh, R. N.; Kumar, Amit; Tiwari, R. K.; Rawat, Poonam

2013-08-01

335

Spectroscopic and structural study of some 2,5-hexanedione bis(salicyloylhydrazone) complexes: Crystal structures of its Ni(II) and Cu(II) complexes and N-(2,5-dimethyl-1H-pyrrol-1-yl)-2-hydroxy-benzamide  

NASA Astrophysics Data System (ADS)

The reaction between 2,5-hexanedione and salicylic acid hydrazide produced two compounds: 2,5-hexanedione bis(salicyloylhydrazone) [HDSH] (ethanol insoluble) and N-(2,5-dimethyl-1H-pyrrol-1-yl)-2-hydroxybenzamide [DPH] (ethanol soluble). HDSH formed complexes with Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II) and Pd(II) which are characterized by elemental analyses, spectra (IR, 1H NMR, ESR and MS), thermal and magnetic measurements. The crystals of [Ni(HDSH-2H)(EtOH)(H2O)] and [Cu(HDSH-2H)] were solved having octahedral and square-planar geometries, respectively. The other complexes have the formulae [Co(HDSH-2H)(H2O)2], [Cu(HDSH-H)2], [Zn(HDSH-2H)(H2O)2], [Cd2(HDSH-4H)(H2O)4], [Cd2(HDSH-2H)(H2O)4Cl2]; [Hg(HDSH-2H)] and [Pd2(HDSH-4H)(H2O)4]. The obtained complexes are stable in air and non-hygroscopic. The magnetic moments and electronic spectra of the complexes provide different geometries. The ESR spectra support the mononuclear geometry for [Cu(HDSH-2H)] and [Cu(HDSH-H)2]. The thermal decomposition of the complexes revealed the coordinated waters as well as the end product which is in most cases the metal oxide. The crystal structure of N-(2,5-dimethyl-1H-pyrrol-1-yl)-2-hydroxybenzamide is solved by X-ray technique.

Jeragh, Bakir; El-Asmy, Ahmed A.

2014-08-01

336

A combined experimental and theoretical (DFT and AIM) studies on synthesis, molecular structure, spectroscopic properties and multiple interactions analysis in a novel ethyl-4-[2-(thiocarbamoyl)hydrazinylidene]-3,5-dimethyl-1H-pyrrole-2-carboxylate and its dimer.  

PubMed

In the present work, ethyl-4-[2-(thiocarbamoyl)hydrazinylidene]-3,5-dimethyl-1H-pyrrole-2-carboxylate (3) has been synthesized and characterized by (1)H NMR, UV-Vis, FT-IR and Mass spectroscopy. The formation of the compound and its properties have also been evaluated by quantum chemical calculations using DFT, B3LYP functional and 6-31G(d,p) as basis set. The calculated thermodynamic parameters show that the formation of 3 is an exothermic and spontaneous reaction at room temperature. (1)H NMR chemical shifts are calculated using gauge including atomic orbitals (GIAO) approach in DMSO-d6 as solvent. Time dependent density functional theory (TD-DFT) is used to calculate the energy (E), oscillator strength (f) and wavelength absorption maxima (?(max)) of various electronic transitions and their nature within the molecule. NBO analysis is carried out to investigate the charge transfer or charge delocalization in various intra- and intermolecular interactions of molecular system. The vibrational analysis indicates the formation of dimer in the solid state by intermolecular heteronuclear hydrogen bonding (NH···O). Topological parameters at bond critical points (BCP) are calculated to analyze the strength and nature of various types of intra and intermolecular interactions in dimer by Bader's 'Atoms in molecules' AIM theory in detail. The binding energy of intermolecular multiple interactions is calculated to be 15.54 kcal/mol, using AIM calculation. The local reactivity descriptors such as Fukui functions (f(k)(+),f(k)(-)), local softnesses (s(k)(+),s(k)(-)) and electrophilicity indices (?(k)(+),?(k)(-)) analyses are performed to determine the reactive sites within molecule. PMID:23666353

Singh, R N; Kumar, Amit; Tiwari, R K; Rawat, Poonam

2013-08-01

337

Preparation, spectroscopic properties of 1,4-di (N,N-diisopropylacetamido)-2,3(1H,4H)-quinoxalinedione (L) lanthanide complexes and the supramolecular structure of [Nd{sub 2}L{sub 2}(NO{sub 3}){sub 6}(H{sub 2}O){sub 2}].H{sub 2}O  

SciTech Connect

The reaction of lanthanide nitrate with 1,4-di (N,N-diisopropylacetamido)-2,3(1H,4H)-quinoxalinedione (L) yields six novel Ln(III) complexes ([Ln{sub 2}L{sub 2}(NO{sub 3}){sub 6}(H{sub 2}O){sub 2}].H{sub 2}O) which are characterized by elemental analysis, thermogravimetric analysis (TGA), conductivity measurements, IR, electronic and {sup 1}H NMR spectroscopies. A new quinoxalinedione-based ligand is used as antenna ligand to sensitize the emission of lanthanide cations. The lowest triplet state energy level of the ligand in the nitrate complex matches better to the resonance level of Eu(III) and Sm(III) than Tb(III) and Dy(III) ion. The f-f fluorescence is induced in the Eu{sup 3+} and Sm{sup 3+} complexes by exciting into the {pi}-{pi}* absorptions of the ligand in the UV. Furthermore, the crystal structures of a novel binuclear complex [Nd{sub 2}L{sub 2}(NO{sub 3}){sub 6}(H{sub 2}O){sub 2}].H{sub 2}O has been determined by single-crystal X-ray diffraction. The binuclear [Nd{sub 2}L{sub 2}(NO{sub 3}){sub 6}(H{sub 2}O){sub 2}].H{sub 2}O complex units are linked by the intermolecular hydrogen bonds and {pi}-{pi} interactions to form a two-dimensional (2-D) layer supramolecule. - Graphical abstract: Preparation, spectroscopic properties of 1,4-di (N,N-diisopropylacetamido)-2,3(1H,4H)-quinoxalinedione (L) lanthanide complexes and the supramolecular structure of [Nd{sub 2}L{sub 2}(NO{sub 3}){sub 6}(H{sub 2}O){sub 2}].H{sub 2}O.

Song Xueqin [College of Chemistry and Chemical Engineering, State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000 (China); School of Chemical and Biological Engineering, Lanzhou Jiaotong University, Lanzhou 730070 (China); Yu Yang [College of Chemistry and Chemical Engineering, State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000 (China); Liu Weisheng [College of Chemistry and Chemical Engineering, State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000 (China)], E-mail: liuws@lzu.edu.cn; Dou Wei; Zheng Jiangrong; Yao Junna [College of Chemistry and Chemical Engineering, State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000 (China)

2007-09-15

338

Spectroscopic and structural study of some 2,5-hexanedione bis(salicyloylhydrazone) complexes: Crystal structures of its Ni(II) and Cu(II) complexes and N-(2,5-dimethyl-1H-pyrrol-1-yl)-2-hydroxy-benzamide.  

PubMed

The reaction between 2,5-hexanedione and salicylic acid hydrazide produced two compounds: 2,5-hexanedione bis(salicyloylhydrazone) [HDSH] (ethanol insoluble) and N-(2,5-dimethyl-1H-pyrrol-1-yl)-2-hydroxybenzamide [DPH] (ethanol soluble). HDSH formed complexes with Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II) and Pd(II) which are characterized by elemental analyses, spectra (IR, (1)H NMR, ESR and MS), thermal and magnetic measurements. The crystals of [Ni(HDSH-2H)(EtOH)(H2O)] and [Cu(HDSH-2H)] were solved having octahedral and square-planar geometries, respectively. The other complexes have the formulae [Co(HDSH-2H)(H2O)2], [Cu(HDSH-H)2], [Zn(HDSH-2H)(H2O)2], [Cd2(HDSH-4H)(H2O)4], [Cd2(HDSH-2H)(H2O)4Cl2]; [Hg(HDSH-2H)] and [Pd2(HDSH-4H)(H2O)4]. The obtained complexes are stable in air and non-hygroscopic. The magnetic moments and electronic spectra of the complexes provide different geometries. The ESR spectra support the mononuclear geometry for [Cu(HDSH-2H)] and [Cu(HDSH-H)2]. The thermal decomposition of the complexes revealed the coordinated waters as well as the end product which is in most cases the metal oxide. The crystal structure of N-(2,5-dimethyl-1H-pyrrol-1-yl)-2-hydroxybenzamide is solved by X-ray technique. PMID:24747853

Jeragh, Bakir; El-Asmy, Ahmed A

2014-08-14

339

Unusual behavior in the reactivity of 5-substituted-1H-tetrazoles in a resistively heated microreactor  

PubMed Central

Summary The decomposition of 5-benzhydryl-1H-tetrazole in an N-methyl-2-pyrrolidone/acetic acid/water mixture was investigated under a variety of high-temperature reaction conditions. Employing a sealed Pyrex glass vial and batch microwave conditions at 240 °C, the tetrazole is comparatively stable and complete decomposition to diphenylmethane requires more than 8 h. Similar kinetic data were obtained in conductively heated flow devices with either stainless steel or Hastelloy coils in the same temperature region. In contrast, in a flow instrument that utilizes direct electric resistance heating of the reactor coil, tetrazole decomposition was dramatically accelerated with rate constants increased by two orders of magnitude. When 5-benzhydryl-1H-tetrazole was exposed to 220 °C in this type of flow reactor, decomposition to diphenylmethane was complete within 10 min. The mechanism and kinetic parameters of tetrazole decomposition under a variety of reaction conditions were investigated. A number of possible explanations for these highly unusual rate accelerations are presented. In addition, general aspects of reactor degradation, corrosion and contamination effects of importance to continuous flow chemistry are discussed.

Gutmann, Bernhard; Glasnov, Toma N; Razzaq, Tahseen; Goessler, Walter; Roberge, Dominique M

2011-01-01

340

Unusual behavior in the reactivity of 5-substituted-1H-tetrazoles in a resistively heated microreactor.  

PubMed

The decomposition of 5-benzhydryl-1H-tetrazole in an N-methyl-2-pyrrolidone/acetic acid/water mixture was investigated under a variety of high-temperature reaction conditions. Employing a sealed Pyrex glass vial and batch microwave conditions at 240 °C, the tetrazole is comparatively stable and complete decomposition to diphenylmethane requires more than 8 h. Similar kinetic data were obtained in conductively heated flow devices with either stainless steel or Hastelloy coils in the same temperature region. In contrast, in a flow instrument that utilizes direct electric resistance heating of the reactor coil, tetrazole decomposition was dramatically accelerated with rate constants increased by two orders of magnitude. When 5-benzhydryl-1H-tetrazole was exposed to 220 °C in this type of flow reactor, decomposition to diphenylmethane was complete within 10 min. The mechanism and kinetic parameters of tetrazole decomposition under a variety of reaction conditions were investigated. A number of possible explanations for these highly unusual rate accelerations are presented. In addition, general aspects of reactor degradation, corrosion and contamination effects of importance to continuous flow chemistry are discussed. PMID:21647324

Gutmann, Bernhard; Glasnov, Toma N; Razzaq, Tahseen; Goessler, Walter; Roberge, Dominique M; Kappe, C Oliver

2011-01-01

341

Metal substitution reaction in the cluster [( ??H) 2Fe 3( ? 3?Se)(CO) 9]. Crystal and molecular structure of [( ??H)Fe 2W( ? 3?Se)(CO) 8( ? 5?C 5H 5)  

Microsoft Academic Search

The cluster [(??H)2Fe3(?3?Se)(CO)9] has been found to react with [CPW(CO)3]2 [Cp = (?5?C5H5)] when refluxed in m-xylene. Two major products of this reaction have been isolated, one of which is the heteronuclear cluster [(??H)Fe2W(?3?Se)(CO)8Cp]. Its structure has been determined by X-ray analysis. The other product is probably [FeW2(?3?Se)(CO)7Cp2]. Its composition and structure have been proposed from the IR, 1H and

Sergei N. Konchenko; Alexander V. Virovets; Sergei V. Tkachev; Vasilii I. Alekseev; Nina V. Podberezskaya

1996-01-01

342

Oxidation of 1,4-Dihydropyridines and 3,4-Dihydropyrimidin-2(1H)-ones to Substituted Pyridines and Pyrimidinones Using Ca(OCl)2 in Aqueous Media  

Microsoft Academic Search

Abstract1,4-Dihydropyridines and 3,4-dihydropyrimidin-2(1H)-ones obtained from the Hantzsch and Biginelli reactions undergo readily oxidative dehydrogenation by using calcium hypochlorite in very short times. These calcium stimulator drugs were oxidized under reaction conditions next to the in vivo transformations at room temperature.

Fatemeh Tamaddon; Zahra Razmi

2011-01-01

343

Vista IR Camera: Conceptual Design  

Microsoft Academic Search

This paper describes the conceptual design for a near infrared camera for the Visible and Infrared Survey Telescope for Astronomy (VISTA). VISTA is a 4m class survey telescope that is being designed to perform pre-planned, ground-based astronomical surveys of the Southern sky from ESO's Cerro Paranal Observatory in Chile. The IR Surveys will be carried out in the J, H

Ian Egan; Eli Atad-Ettedgui; Mark M. Casali; Simon C. Craig; Maureen A. Ellis; Peter R. Hastings; David M. Henry; Ken Laidlaw; John Murray; Malcom Stewart; Will Sutherland

2002-01-01

344

In situ synthesis of mononuclear copper(II) complexes of the new tridentate ligand bis[(3,5-dimethyl-1H-pyrazol-1-yl)methyl]amine.  

PubMed

Two mononuclear copper complexes, {bis[(3,5-dimethyl-1H-pyrazol-1-yl-?N(2))methyl]amine-?N}(3,5-dimethyl-1H-pyrazole-?N(2))(perchlorato-?O)copper(II) perchlorate, [Cu(ClO(4))(C(5)H(8)N(2))(C(12)H(19)N(5))]ClO(4), (I), and {bis[(3,5-dimethyl-1H-pyrazol-1-yl-?N(2))methyl]amine-?N}bis(3,5-dimethyl-1H-pyrazole-?N(2))copper(II) bis(hexafluoridophosphate), [Cu(C(5)H(8)N(2))(2)(C(12)H(19)N(5))](PF(6))(2), (II), have been synthesized by the reactions of different copper salts with the tripodal ligand tris[(3,5-dimethyl-1H-pyrazol-1-yl)methyl]amine (TDPA) in acetone-water solutions at room temperature. Single-crystal X-ray diffraction analysis revealed that they contain the new tridentate ligand bis[(3,5-dimethyl-1H-pyrazol-1-yl)methyl]amine (BDPA), which cannot be obtained by normal organic reactions and has thus been captured in the solid state by in situ synthesis. The coordination of the Cu(II) ion is distorted square pyramidal in (I) and distorted trigonal bipyramidal in (II). The new in situ generated tridentate BDPA ligand can act as a meridional or facial ligand during the process of coordination. The crystal structures of these two compounds are stabilized by classical hydrogen bonding as well as intricate nonclassical hydrogen-bond interactions. PMID:21979969

Yu, Fan

2011-10-01

345

Coinhibitory receptor PD-1H preferentially suppresses CD4+ T cell-mediated immunity  

PubMed Central

T cell activation is regulated by the interactions of surface receptors with stimulatory and inhibitory ligands. Programmed death-1 homolog (PD-1H, also called VISTA) is a member of the CD28 family of proteins and has been shown to act as a coinhibitory ligand on APCs that suppress T cell responses. Here, we determined that PD-1H functions as a coinhibitory receptor for CD4+ T cells. CD4+ T cells in mice lacking PD-1H exhibited a dramatically increased response to antigen stimulation. Furthermore, delivery of a PD-1H–specific agonist mAb directly inhibited CD4+ T cell activation both in vitro and in vivo, validating a coinhibitory function of PD-1H. In a murine model of acute hepatitis, administration of a PD-1H agonist mAb suppressed CD4+ T cell–mediated acute inflammation. PD-1H–deficient animals were highly resistant to tumor induction in a murine brain glioma model, and depletion of CD4+ T cells, but not CD8+ T cells, promoted tumor formation. Together, our findings suggest that PD-1H has potential as a target of immune modulation in the treatment of human inflammation and malignancies.

Flies, Dallas B.; Han, Xue; Higuchi, Tomoe; Zheng, Linghua; Sun, Jingwei; Ye, Jessica Jane; Chen, Lieping

2014-01-01

346

Complete Genome Sequence of the Arcobacter butzleri Cattle Isolate 7h1h  

PubMed Central

Arcobacter butzleri strain 7h1h was isolated in the United Kingdom from the feces of a clinically healthy dairy cow. The genome of this isolate was sequenced to completion. Here, we present the annotation and analysis of the completed 7h1h genome, along with a comparison of this genome to the existing A. butzleri genomes.

Winstanley, Craig; Williams, Nicola J.; Yee, Emma

2013-01-01

347

Coinhibitory receptor PD-1H preferentially suppresses CD4+ T cell-mediated immunity.  

PubMed

T cell activation is regulated by the interactions of surface receptors with stimulatory and inhibitory ligands. Programmed death-1 homolog (PD-1H, also called VISTA) is a member of the CD28 family of proteins and has been shown to act as a coinhibitory ligand on APCs that suppress T cell responses. Here, we determined that PD-1H functions as a coinhibitory receptor for CD4+ T cells. CD4+ T cells in mice lacking PD-1H exhibited a dramatically increased response to antigen stimulation. Furthermore, delivery of a PD-1H-specific agonist mAb directly inhibited CD4+ T cell activation both in vitro and in vivo, validating a coinhibitory function of PD-1H. In a murine model of acute hepatitis, administration of a PD-1H agonist mAb suppressed CD4+ T cell-mediated acute inflammation. PD-1H-deficient animals were highly resistant to tumor induction in a murine brain glioma model, and depletion of CD4+ T cells, but not CD8+ T cells, promoted tumor formation. Together, our findings suggest that PD-1H has potential as a target of immune modulation in the treatment of human inflammation and malignancies. PMID:24743150

Flies, Dallas B; Han, Xue; Higuchi, Tomoe; Zheng, Linghua; Sun, Jingwei; Ye, Jessica Jane; Chen, Lieping

2014-05-01

348

The Use and Evaluation of Scaffolding, Student Centered-Learning, Behaviorism, and Constructivism to Teach Nuclear Magnetic Resonance and IR Spectroscopy in a Two-Semester Organic Chemistry Course  

ERIC Educational Resources Information Center

Since 2002, infrared spectroscopy (IR) and nuclear magnetic resonance (NMR) spectrometry have been introduced at the beginning of the first-semester organic chemistry lab course at this university. Starting in 2008, each individual student was given 20 unique homework problems that consisted of multiple-choice [superscript 1]H NMR and IR problems…

Livengood, Kimberly; Lewallen, Denver W.; Leatherman, Jennifer; Maxwell, Janet L.

2012-01-01

349

Buried object detection - EMI and IR sensors  

Microsoft Academic Search

Several sensors have been used to detect buried objects, such as GPR (ground penetrating radar) and EMI (electromagnetic induction) sensors. IR (infrared) and acoustic sensors are supportive sensors which are used with an EMI sensor or GPR. The paper focuses mainly on two sensors, a main EMI sensor and a support IR sensor. The EMI sensor's output signal and IR

S. Akgun; M. D. Azak; S. Samedov; R. Caputcu

2004-01-01

350

Irs1 and Irs2 signaling is essential for hepatic glucose homeostasis and systemic growth  

PubMed Central

Insulin receptor substrates, including Irs1 and Irs2, integrate insulin and IGF receptor signals with heterologous pathways to coordinate growth and metabolism. Since Irs2 is thought to be especially important in hepatic nutrient homeostasis, we deleted Irs1 from hepatocytes of WT mice (called LKO) or genetically insulin-resistant Irs1–/– mice (called LKO::Irs1–/–). Viable LKO::Irs1–/– mice were 70% smaller than WT or LKO mice, and 40% smaller than Irs1–/– mice. Hepatic insulin receptors were functional in all the mice, but insulin signaling via the Akt—FoxO1 pathway was reduced in Irs1–/– and LKO liver, and undetected in LKO::Irs1–/– liver; however, Gsk3? phosphorylation (Ser9) and hepatic glycogen stores were nearly normal in all of the mice. LKO and Irs1–/– mice developed insulin resistance and glucose intolerance that never progressed to diabetes, whereas LKO::Irs1–/– mice developed hyperglycemia and hyperinsulinemia immediately after birth. Regardless, few hepatic genes changed expression significantly in Irs1–/– or LKO mice, whereas hundreds of genes changed in LKO::Irs1–/– mice — including elevated levels of Pck1, G6pc, Ppargc1, Pparg, and Igfbp1. Thus, signals delivered by Irs1 or Irs2 regulate hepatic gene expression that coordinates glucose homeostasis and systemic growth.

Dong, Xiaocheng; Park, Sunmin; Lin, Xueying; Copps, Kyle; Yi, Xianjin; White, Morris F.

2006-01-01

351

In vivo CAMPATH-1H prevents graft-versus-host disease following nonmyeloablative stem cell transplantation.  

PubMed

A novel nonmyeloablative conditioning regimen was investigated in 44 patients with hematologic malignancies. The median patient age was 41 years. Many of the patients had high-risk features, including 19 patients with a previous failed transplant. Recipient conditioning consisted of CAMPATH-1H, 20 mg/day on days -8 to -4; fludarabine, 30 mg/m(2) on days -7 to -3; and melphalan, 140 mg/m(2) on day -2. Thirty-six recipients received unmanipulated granculocyte colony-stimulating factor-mobilized peripheral blood stem cells from HLA-identical siblings, and 8 received unmanipulated marrow from matched unrelated donors. GVHD prophylaxis was with cyclosporine A alone for 38 patients and cyclosporine A plus methotrexate for 6 sibling recipients. Forty-two of the 43 evaluable patients had sustained engraftment. Results of chimerism analysis using microsatellite polymerase chain reaction indicate that 18 of 31 patients studied were full-donor chimeras while the other patients were mixed chimeras in one or more lineages. At a median follow-up of 9 months (range 3 to 29 months), 33 patients remain alive in complete remission or with no evidence of disease progression. Seven patients relapsed or progressed post-transplantation, and 4 of them subsequently died. Four patients died of regimen-related complications. There were no cases of grades III-IV acute GVHD. Only 2 patients developed grade II acute GVHD, and only 1 had chronic GVHD. The estimated probability of nonrelapse mortality was 11%. Although longer follow-up is needed to establish the long-term remission rates, this study demonstrates that this nonmyeloablative preparative regimen is associated with durable engraftment, minimal toxicity, and low incidence of GVHD. PMID:11001893

Kottaridis, P D; Milligan, D W; Chopra, R; Chakraverty, R K; Chakrabarti, S; Robinson, S; Peggs, K; Verfuerth, S; Pettengell, R; Marsh, J C; Schey, S; Mahendra, P; Morgan, G J; Hale, G; Waldmann, H; de Elvira, M C; Williams, C D; Devereux, S; Linch, D C; Goldstone, A H; Mackinnon, S

2000-10-01

352

1H MRS brain measures and acute lorazepam administration in healthy human subjects.  

PubMed

The effects of acute lorazepam administration on 1H magnetic resonance spectroscopy (MRS) in vivo brain spectra were examined in the left dorsolateral prefrontal cortex (L-DLPFC) of healthy human subjects. We wanted to examine whether lorazepam administration would result in significant changes in the levels of 1H-MRS metabolites in this brain region. Ten healthy controls underwent a short echo-time 1H-MRS session immediately before, and a second one 1 h after lorazepam administration (2mg/orally). The measured 1H-metabolites included N-acetyl-aspartate, phosphocreatine+creatine, trimethylamines, myo-inositol, glutamate, and glutamine, which were expressed as absolute values and ratios. No significant differences were found after lorazepam administration for any of the measured metabolite levels or ratios (paired t-tests, p >.05). This study demonstrated that lorazepam can potentially be utilized to acutely sedate psychiatric subjects during in vivo 1H-MRS sessions, as it does not appear to produce significant changes in the 1H-MRS spectra in this specific brain region. PMID:11927179

Brambilla, Paolo; Stanley, Jeff A; Nicoletti, Mark; Harenski, Keith; Wells, Kelly Forster; Mallinger, Alan G; Keshavan, Matcheri S; Soares, Jair C

2002-04-01

353

A mixed experimental and DFT study on ethyl 4-[3-(4-dimethylamino-phenyl)-acryloyl]-3,5-dimethyl-1H-pyrrole-2-carboxylate  

NASA Astrophysics Data System (ADS)

A new pyrrole containing chalcone, ethyl 4-[3-(4-dimethylamino-phenyl)-acryloyl]-3,5-dimethyl-1H-pyrrole-2-carboxylate (EDPADPC) derived from ethyl 4-acetyl-3,5-dimethyl-1H-pyrrole-2-carboxylate and 4-dimethylamino-benzaldehyde has been characterized by spectroscopic techniques (1H NMR, UV–Visible, FT-IR) and results have been compared by means of theoretical findings. A combined experimental and theoretical vibrational analysis identified red shifts in vNH and vCO indicating the formation of dimer in the solid state. The binding energy of dimer has been evaluated as 9.89 kcal/mol and the strength and nature of hydrogen bonding have also been analyzed in detail. The DFT derived reactivity descriptors indicate that EDPADPC is suitable for the formation of new heterocyclic compounds. The first hyperpolarizability (?0) of EDPADPC has been computed and found to be 62.0226 × 10?30 indicating its use as non-linear optical (NLO) material.

Singh, R. N.; Rawat, Poonam; Sahu, Sangeeta

2014-05-01

354

MDA IR sensor technology program and applications  

NASA Astrophysics Data System (ADS)

Infrared (IR) sensors are needed for ballistic missile defense (BMD). BMD IR sensor applications extend from surveillance using ground, airborne and space-based platforms, to both endo- and exo-atmospheric interceptor seekers. Even though IRFPAs using material systems, such as HgCdTe and InSb, are adequate for most tactical military applications, certain IR systems for BMD have much more stringent requirements. With a cold dim target a long distance away, IR sensors having extended wavelengths are needed in the mid course. The requirements of BMD IR sensors with high sensitivity, large format, small pixel size and high frame rate, plus long cutoff wavelength and operating at low temperatures present great challenges to IR sensor technology. This presentation will cover the current MDA IR sensor technology development, its system application for block upgrades and advanced concepts.

Tidrow, Meimei Z.

2003-09-01

355

Combined (1)H-NMR and (1)H-(13)C HSQC-NMR to improve urinary screening in autism spectrum disorders.  

PubMed

Autism spectrum disorders (ASD) are neurodevelopmental diseases with complex genetic and environmental etiological factors. Although genetic causes play a significant part in the etiology of ASD, metabolic disturbances may also play a causal role or modulate the clinical features of ASD. The number of ASD studies involving metabolomics is increasing, and sometime with conflicting findings. We assessed the metabolomics profiling of urine samples to determine a comprehensive biochemical signature of ASD. Furthermore, to date no study has combined metabolic profiles obtained from different analytical techniques to distinguish patient with ASD from healthy individuals. We obtained (1)H-NMR spectra and 2D (1)H-(13)C HSQC NMR spectra from urine samples of patients with ASD or healthy controls. We analyzed these spectra by multivariate statistical data analysis. The OPLS-DA model obtained from (1)H NMR spectra showed a good discrimination between ASD samples and non-ASD samples (R(2)Y(cum) = 0.70 and Q(2) = 0.51). Combining the (1)H NMR spectra and the 2D (1)H-(13)C HSQC NMR spectra increased the overall quality and predictive value of the OPLS-DA model (R(2)Y(cum) = 0.84 and Q(2) = 0.71), leading to a better sensitivity and specificity. Urinary excretion of succinate, glutamate and 3-methyl-histidine differed significantly between ASD and non-ASD samples. Urinary screening of children with neurodevelopmental disorders by combining NMR spectroscopies (1D and 2D) in multivariate analysis is a better sensitive and a straightforward method that could help the diagnosis ASD. PMID:24841505

Nadal-Desbarats, Lydie; Aïdoud, Nacima; Emond, Patrick; Blasco, Hélène; Filipiak, Isabelle; Sarda, Pierre; Bonnet-Brilhault, Frédérique; Mavel, Sylvie; Andres, Christian R

2014-06-01

356

Reversal of acute cellular rejection after renal transplantation with Campath-1H.  

PubMed

Between September 2002 and February 2004, 40 kidney transplant (27 from deceased and 13 from living donors) recipients (25 male and 15 female, aged 50.3 +/- 15.1 years) were treated with Campath 1H (C 1H; 30 mg/dose IV) for biopsy-proven steroid-resistant rejection (SRR) or rejections equal to or worse than Banff 1B. All transplantations occurred between August 2001 and May 2003. All patients had received antibody preconditioning (RATG 5 mg/kg, n = 34; C 1H 60 mg, n = 4; C 1H 30 mg, n = 2) preoperatively and were treated with Tacrolimus monotherapy (target level 10 ng/ml) postoperatively and subsequent spaced weaning. Elevated creatinine levels at follow-up were evaluated by renal transplant biopsy. Rejection was treated with steroids, reversal of weaning, addition of sirolimus, and/or antibody treatment, depending on grade of rejection. The mean duration of follow-up was 453 +/- 163 days after C 1H administration. Twenty-nine patients received C 1H for SRR and 11 patients for Banff 1B or worse rejections; 26 patients received more than 1 dose of C 1H. Graft survival was 62.5% (25 patients); 6 of the 15 allografts (40%) that failed had presented with rejections because of noncompliance. Graft survival in compliant patients with SRR or rejections equal to or worse than Banff 1B was 73.5% (25 of 34). Fourteen patients (35%) had infectious complications, of whom 2 patients (5%) died. C 1H is an effective agent for SRR and Banff 1B or worse rejections, with 95% patient survival and 73.5% graft survival (in compliant patients). The number of doses of 30 mg C 1H should be restricted to two, as there is a high incidence of potentially fatal infectious complications. PMID:15848576

Basu, A; Ramkumar, M; Tan, H P; Khan, A; McCauley, J; Marcos, A; Fung, J J; Starzl, T E; Shapiro, R

2005-03-01

357

Carbon nanotube IR detectors (SV)  

SciTech Connect

Sandia National Laboratories (Sandia) and Lockheed Martin Corporation (LMC) collaborated to (1) evaluate the potential of carbon nanotubes as channels in infrared (IR) photodetectors; (2) assemble and characterize carbon nanotube electronic devices and measure the photocurrent generated when exposed to infrared light;(3) compare the performance of the carbon nanotube devices with that of traditional devices; and (4) develop and numerically implement models of electronic transport and opto-electronic behavior of carbon nanotube infrared detectors. This work established a new paradigm for photodetectors.

Leonard, F. L.

2012-03-01

358

Synthesis, physicochemical characterization, cytotoxicity, antimicrobial, anti-inflammatory and psychotropic activity of new N-[1,3-(benzo)thiazol-2-yl]-?-[3,4-dihydroisoquinolin-2(1H)-yl]alkanamides.  

PubMed

A series of new N-[(benzo)thiazol-2-yl]-2/3-[3,4-dihydroisoquinolin-2(1H)-yl]ethan/propanamide derivatives was synthesized and characterized by (1)H, (13)C NMR and IR spectroscopy and mass-spectrometry. A single crystal X-ray study of N-(1,3-benzothiazol-2-yl)-2-[3,4-dihydroisoquinolin-2(1H)-yl]ethanamide is reported to determine its conformational feature. The investigated compounds were found to be active in psychotropic in vivo, anti-inflammatory in vivo and cytotoxicity in vitro screening. They possess marked sedative action, reveal high anti-inflammatory activity, have selective cytotoxic effects and NO-induction ability concerning tumour cell lines. Some of the compounds synthesized demonstrate antimicrobial action. An attempt was made to correlate the biological results with their structural characteristics and physicochemical parameters. Some specific combinations of types of activities for the synthesized compounds have been revealed. PMID:24262377

Zablotskaya, Alla; Segal, Izolda; Geronikaki, Athina; Eremkina, Tatiana; Belyakov, Sergey; Petrova, Marina; Shestakova, Irina; Zvejniece, Liga; Nikolajeva, Vizma

2013-12-01

359

Synthesis, Spectral Analysis, In Vitro Microbiological Evaluation, and Molecular Docking Studies of Some Novel 1-(1-Aryl-1H-tetrazol-5-yl)-2-(piperidin-1-yl)ethanone Derivatives  

PubMed Central

A new series of novel heterocyclic compounds containing both tetrazoles and piperidine nuclei together, namely, 1-(1-aryl-1H-tetrazol-5-yl)-2-(piperidin-1-yl)ethanone (22–28), were synthesized by the treatment of the respective 2-chloro-1-(1-aryl-1H-tetrazol-5-yl)ethanone (15–21) with piperidine in acetonitrile for 6?h. A series of novel tetrazole substituted piperidine derivatives were synthesized and evaluated for their antimicrobial activity using serial dilution method. The structures of the synthesized compounds were characterized by IR, 1H NMR, 13C NMR, mass spectral data, and elemental analysis. Evaluation of antimicrobial activity shows that several compounds exhibit good activity when compared with the reference drug candidates and thus could be promising new lead molecules.

Elavarasan, Thangasamy; Bhakiaraj, Durairaj Peter; Gopalakrishnan, Mannathusamy

2014-01-01

360

Synthesis, Spectral Analysis, In Vitro Microbiological Evaluation, and Molecular Docking Studies of Some Novel 1-(1-Aryl-1H-tetrazol-5-yl)-2-(piperidin-1-yl)ethanone Derivatives.  

PubMed

A new series of novel heterocyclic compounds containing both tetrazoles and piperidine nuclei together, namely, 1-(1-aryl-1H-tetrazol-5-yl)-2-(piperidin-1-yl)ethanone (22-28), were synthesized by the treatment of the respective 2-chloro-1-(1-aryl-1H-tetrazol-5-yl)ethanone (15-21) with piperidine in acetonitrile for 6?h. A series of novel tetrazole substituted piperidine derivatives were synthesized and evaluated for their antimicrobial activity using serial dilution method. The structures of the synthesized compounds were characterized by IR, (1)H NMR, (13)C NMR, mass spectral data, and elemental analysis. Evaluation of antimicrobial activity shows that several compounds exhibit good activity when compared with the reference drug candidates and thus could be promising new lead molecules. PMID:24944827

Elavarasan, Thangasamy; Bhakiaraj, Durairaj Peter; Gopalakrishnan, Mannathusamy

2014-01-01

361

2Alkyl4(1 H )-Quinolone Signalling in Pseudomonas aeruginosa  

Microsoft Academic Search

\\u000a In addition to the las and rhl qorum sensing (QS) systems, Pseudomonas aeruginosa utilises a non-acyl homoserine lactone (AHL)-based systems which relies on the production of 2-alkyl-4(1H)-quinolone (AQ) molecules. Although this organism produces a large range of AQ derivatives, the two main AQ signal molecules\\u000a described are 2-heptyl-3-hydroxy-4(1H)-quinolone (PQS), and its immediate precursor, 2-heptyl-3-hydroxy-4(1H)-quinolone (HHQ). AQ biosynthesis and signalling in

Matthew P. Fletcher; Stephan Heeb; Siri Ram Chhabra; Stephen P. Diggle; Paul Williams; Miguel Cámara

362

Further assignment of resonances in 1H NMR spectra of cerebrospinal fluid (CSF).  

PubMed

A number of previously unidentified 1H NMR signals detected in CSF spectra of patients with various neurological and metabolic diseases are assigned to metabolites, drugs and drug excipients. Two-dimensional 1H NMR spectroscopy (COSY and J-resolved) is employed to resolve resonances which are hidden by superimposed peaks in one-dimensional spectra. Assignments obtained by making use of 2-D techniques, and of a 1-D 1H NMR data base created for ca. 150 authentic compounds, enable us to clarify the nature of complex signal patterns found in crowded spectral regions of CSF such as the aliphatic methyl region at ca. 1.0 ppm. PMID:9559677

Lutz, N W; Maillet, S; Nicoli, F; Viout, P; Cozzone, P J

1998-03-27

363

Intermolecular Interactions between Eosin Y and Caffeine Using 1H-NMR Spectroscopy  

PubMed Central

DETECHIP has been used in testing analytes including caffeine, cocaine, and tetrahydrocannabinol (THC) from marijuana, as well as date rape and club drugs such as flunitrazepam, gamma-hydroxybutyric acid (GHB), and methamphetamine. This study investigates the intermolecular interaction between DETECHIP sensor eosin Y (DC1) and the analyte (caffeine) that is responsible for the fluorescence and color changes observed in the actual array. Using 1H-NMR, 1H-COSY, and 1H-DOSY NMR methods, a proton exchange from C-8 of caffeine to eosin Y is proposed.

Okuom, Macduff O.; Wilson, Mark V.; Jackson, Abby; Holmes, Andrea E.

2014-01-01

364

Comparison of 1H-19F two-dimensional NMR scalar coupling correlation pulse sequences.  

PubMed

The effectiveness of hetero-COSY, HETCOR, HMQC, and HSQC two-dimensional NMR pulse sequences for detection of (19)F-(1)H correlations by scalar coupling was evaluated on monofluorinated and polyfluorinated test compounds. All four of these sequences were effective in observing (1)H-(19)F correlations, using either (19) F or (1)H as the observe nucleus. All four sequences were amenable, to some degree, to adjustment to observe larger or smaller couplings preferentially. A 1/2J echo filter was effectively applied to remove artifacts from (2)JFF strong coupling. The HETCOR experiments afforded the best overall combination of sensitivity, resolution and selectivity for JHF. PMID:24535754

Marchione, Alexander A; Dooley, Rebecca J; Conklin, Breanna

2014-04-01

365

Nucleophilic Substitution of Oxazino-/Oxazolino-/Benzoxazin- [3,2-b]indazoles: An Effective Route to 1 H-Indazolones  

PubMed Central

A variety of nucleophiles – thiolates, alkoxides, amines, iodide, and cyanide – react with oxazino-, oxazolino-, and benzoxazin[3,2-b]indazoles under microwave conditions to yield a diverse set of 2-substituted 1 H-indazolones. The synthetic utility of these indazoles is further demonstrated by ANRORC (Addition of the Nucleophile, Ring Opening, and Ring Closure) reactions to yield isomeric pyrazoloindazolones by a process wherein iodide acts first as a nucleophile and subsequently as a leaving group.

Donald, Michael B.; Conrad, Wayne E.; Oakdale, James S.; Butler, Jeffrey D.; Haddadin, Makhluf J.; Kurth, Mark J.

2011-01-01

366

REGIOSELECTIVE SYNTHESIS OF EITHER 1H- OR 2H-1,2,3- TRIAZOLES VIA MICHAEL ADDITION TO ?,ss-UNSATURATED KETONES  

PubMed Central

The Michael reaction of NH-1,2,3-triazole (1) with ?,?-unsaturated ketones was studied. 1H-1,2,3-triazolyl-ketones were selectively generated when 1 was combined neat with a variety of enones. The use of aprotic solvents with catalytic base gave the corresponding 2H-regioisomers. Together, these two protocols provide direct access to either the N1- or N2-substituted 1,3-triazolyl ketone regioisomers.

Kwok, Sen Wai; Hein, Jason E.; Fokin, Valery V.; Sharpless, K. Barry

2009-01-01

367

Cross sections and Rosenbluth separations in 1H(e, e'K+)Lambda up to Q2=2.35 GeV2  

Microsoft Academic Search

The kaon electroproduction reaction 1H(e,e'K+)Lambda was studied as a function of the virtual-photon four-momentum, Q2, total energy, W, and momentum transfer, t, for different values of the virtual- photon polarization parameter. Data were taken at electron beam energies ranging from 3.40 to 5.75 GeV. The center of mass cross section was determined for 21 kinematics corresponding to Q2 of 1.90

M. Coman; P. Markowitz; K. A. Aniol; K. Baker; W. U. Boeglin; H. Breuer; P. Bydzovsky; A. Camsonne; J. Cha; C. Chang; N. Chant; J.-P. Chen; E. A. Chudakov; E. Cisbani; L. Cole; F. Cusanno; C. W. de Jager; R. De Leo; A. P. Deur; S. Dieterich; F. Dohrmann; D. Dutta; R. Ent; O. Filoti; K. Fissum; S. Frullani; F. Garibaldi; O. Gayou; F. Gilman; J. Gomez; P. Gueye; J. O. Hansen; D. W. Higinbotham; W. Hinton; T. Horn; B. Hu; G. M. Huber; M. Iodice; C. Jackson; X. Jiang; M. Jones; K. Kanda; C. Keppel; P. King; F. Klein; K. Kozlov; K. Kramer; L. Kramer; L. Lagamba; J. J. LeRose; N. Liyanage; D. J. Margaziotis; S. Marrone; K. McCormick; R. W. Michaels; J. Mitchell; T. Miyoshi; S. Nanda; M. Palomba; V. Pattichio; C. F. Perdrisat; E. Piasetzky; V. A. Punjabi; B. Raue; J. Reinhold; B. Reitz; R. E. Roche; P. Roos; A. Saha; A. J. Sarty; Y. SATO; S. Sirca; M. Sotona; L. Tang; H. Ueno; P. E. Ulmer; G. M. Urciuoli; A. Uzzle; A. Vacheret; K. Wang; K. Wijesooriya; B. Wojtsekhowski; S. Wood; I. Yaron; X. Zheng; L. Zhu

2010-01-01

368

Synthesis, Polymerization, and Copolymerization of Polyorganosiloxanes Containing Methacrylate Groups. II. Investigation of Polymerization and Copolymerization by Means of IR Spectra.  

National Technical Information Service (NTIS)

By comparing the ratios of the optical densities of absorption bands in the IR spectra of methacrylate polysiloxanes, the percentages of double bonds involved in polymerization and copolymerization reactions were determined. It is shown that with increase...

I. A. Alekseeva G. A. Semerneva L. A. Samarina M. A. Bulatov S. S. Spasskii

1964-01-01

369

N-Alkylation of amines with alcohols catalyzed by a Cp*Ir complex  

Microsoft Academic Search

A new effective catalytic system consisting of [Cp*IrCl2]2\\/K2CO3 (Cp*=pentamethylcyclopentadienyl) for the N-alkylation of primary amines with alcohols has been developed. As an example, the reaction of aniline with benzyl alcohol in the presence of [Cp*IrCl2]2 (5.0 mol%Ir) and K2CO3 (5.0 mol%) in toluene at 110°C for 17 h gave benzylaniline in an isolated yield of 88%.

Ken-ichi Fujita; Zhenzi Li; Naohiro Ozeki; Ryohei Yamaguchi

2003-01-01

370

Infrared spectroelectrochemistry of bacteriochlorophylls and bacteriopheophytins: Implications for the binding of the pigments in the reaction center from photosynthetic bacteria  

PubMed Central

The IR spectra of the bacteriochlorophyll a and b cations and the bacteriopheophytin a and b anions were obtained by using an IR and optically transparent electrochemical cell. Prominent effects of radical formation on the vibrational spectra were found for bands assigned to the ester, keto, and acetyl C=O groups and for vibrations from macrocycle bonds. The (radical-minus-neutral) difference spectra are compared to the light-induced difference spectra of the primary donor photooxidation and the intermediary acceptor photoreduction in the reaction center of photosynthetic bacteria. Light-induced absorbance changes from bacteriochlorophyll a-containing reaction centers bear striking similarities to the electrochemically induced absorbance changes observed upon formation of bacteriochlorophyll a+in vitro. Comparison of the radical formation in vitro in a hydrogen-bonding or a nonhydrogen-bonding solvent suggests an ester C=O group hydrogen bonded in the neutral state but free in the cation state. For the keto C=O group, the same comparison indicates one free carbonyl group. The (anion-minus-neutral) difference spectra of bacteriopheophytin a and b exhibit a single band in the ester C=O frequency range. In contrast, two bands are observed in the difference spectra of the intermediary acceptor reduction in the reaction center of Rhodopseudomonas viridis. The higher frequency band exhibits a sensitivity to 1H-2H exchange, which suggests a contribution from a protonated carboxyl group of an amino acid side chain.

Mantele, W. G.; Wollenweber, A. M.; Nabedryk, E.; Breton, J.

1988-01-01

371

On the Synthesis of Pyrazino[2,3-b]phenazine and 1H-Imidazo[4,5-b]phenazine Derivatives  

Microsoft Academic Search

Summary.  ?Several pyrazino[2,3-b]phenazine derivatives were prepared by the reaction of 2,3-diaminophenazine with different 1,2-diketones. Nucleophilic substitution\\u000a of 2,3-dibromomethyl-pyrazino[2,3-b]phenazine with propanol, morpholine, and potassium thiocyanate gave 2,3-bis-(propoxymethyl)-pyrazino[2,3-b]phenazine, 2,3-bis-(4-morpholinylmethyl)-pyrazino[2,3-b]phenazine, and 2,3-bis-(cyanosulfanylmethyl)-pyrazino[2,3-b]phenazine. 2-Aryl-1H-imidazo[4,5-b]phenazine derivatives were synthesized by a one-pot reaction of 2,3-diaminophenazine with different aromatic aldehydes or\\u000a acids. Reaction of 2,3-diaminophenazine with acetic anhydride and formic acid afforded 1H-imidazo[4,5-b]phenazine and 2-methyl-1H-imidazo[4,5-b]phenazine. Chemical and spectroscopic

Atef M. Amer; Adel A. El-Bahnasawi; Mohamed R. H. Mahran; Mostafa Lapib

1999-01-01

372

IR Detector Timing and Persistence  

NASA Astrophysics Data System (ADS)

The IR detector on WFC3 exhibits after images, known as persistence, following exposure to light that exceeds half saturation of individual pixels of the detector. The IR channel of WFC3 has no shutter and therefore light from bright objects reaches the detector between science exposures. For estimating persistence, the time that is important is the time between pixel resets. In intervals between science exposures, all pixels are discharged or reset every 2.91 s. For full-frame exposures, the time between resets is the science exposure time (EXPTIME) plus 5.82 s. Since fullframe exposures are usually much longer than 5.82 s, the difference between the time between resets and the science exposure time is usually not a significant problem for estimating persistence in full-frame exposures. However, the science exposure time for certain sub-array sequences can be considerably shorter than the time between resets, and in these cases, the persistence can be much greater than one expects if the time between resets is not correctly calculated. Here we discusses details of detector timing in order to allow a more accurate estimate of the effective persistence exposure time during an observation.

Long, Knox S.; Wheeler, Thomas; Bushouse, Howard

2011-04-01

373

The identification of vicinally substituted cyclohexane isomers in their mixtures by 1H and 13C NMR spectroscopy  

NASA Astrophysics Data System (ADS)

The radical addition reactions of organobromine compounds, XBr (X=CH 2COOMe, PhCH 2, CHBr 2 and CCl 3) with cyclohexene afforded mixtures of cis/ trans isomer pairs of 1-X-2-Br-cyclohexanes. In addition to benzyl benzoyloxy derivatives are formed also, when benzoyl peroxide is used as an initiator. Owing to the great difficulties in separating these cis/ trans isomer pairs, they are identified directly in their mixtures by NMR spectroscopy. In addition to one-dimensional (1D) 1H, proton decoupled 13C and DEPT-135, also two-dimensional (2D) 13C- 13C INADEQUATE as well as 1H- 13C HMQC experiments have been used in assigning the signals of each compound in their mixtures. The identification of each isomer was based on comparison of experimental 3JH,H coupling constants with theoretical ones based on the well-known Karplus type relationship. The more stable conformation for each isomer was estimated using the semiempirical AM1 molecular orbital method. The calculations support the isomer pair elucidations.

Laihia, Katri; Kolehmainen, Erkki; Nevalainen, Tapio; Kauppinen, Reijo; Vasilieva, Tamara T.; Terentiev, Alexander B.

2000-02-01

374

Finite-pulse radio frequency driven recoupling with phase cycling for 2D (1)H/(1)H correlation at ultrafast MAS frequencies.  

PubMed

The first-order recoupling sequence radio frequency driven dipolar recoupling (RFDR) is commonly used in single-quantum/single-quantum homonuclear correlation 2D experiments under magic angle spinning (MAS) to determine homonuclear proximities. From previously reported analysis of the use of XY-based super-cycling schemes to enhance the efficiency of the finite-pulse-RFDR (fp-RFDR) pulse sequence, XY8(1)4 phase cycling was found to provide the optimum performance for 2D correlation experiments on low-? nuclei. In this study, we analyze the efficiency of different phase cycling schemes for proton-based fp-RFDR experiments. We demonstrate the advantages of using a short phase cycle, XY4, and its super-cycle XY4(1)4 that only recouples the zero-quantum homonuclear dipolar coupling, for the fp-RFDR sequence in 2D (1)H/(1)H correlation experiments at ultrafast MAS frequencies. The dipolar recoupling efficiencies of XY4, XY4(1)4 and XY8(1)4 phase cycling schemes are compared based on results obtained from 2D (1)H/(1)H correlation experiments, utilizing the fp-RFDR pulse sequence, on powder samples of U-(13)C,(15)N-l-alanine, N-acetyl-(15)N-l-valyl-(15)N-l-leucine, and glycine. Experimental results and spin dynamics simulations show that XY4(1)4 performs the best when a high RF power is used for the 180° pulse, whereas XY4 renders the best performance when a low RF power is used. The effects of RF field inhomogeneity and chemical shift offsets are also examined. Overall, our results suggest that a combination of fp-RFDR-XY4(1)4 employed in the recycle delay with a large RF-field to decrease the recycle delay, and fp-RFDR-XY4 in the mixing period with a moderate RF-field, is a robust and efficient method for 2D single-quantum/single-quantum (1)H/(1)H correlation experiments at ultrafast MAS frequencies. PMID:24713171

Nishiyama, Yusuke; Zhang, Rongchun; Ramamoorthy, Ayyalusamy

2014-06-01

375

Finite-pulse radio frequency driven recoupling with phase cycling for 2D 1H/1H correlation at ultrafast MAS frequencies  

NASA Astrophysics Data System (ADS)

The first-order recoupling sequence radio frequency driven dipolar recoupling (RFDR) is commonly used in single-quantum/single-quantum homonuclear correlation 2D experiments under magic angle spinning (MAS) to determine homonuclear proximities. From previously reported analysis of the use of XY-based super-cycling schemes to enhance the efficiency of the finite-pulse-RFDR (fp-RFDR) pulse sequence, XY814 phase cycling was found to provide the optimum performance for 2D correlation experiments on low-? nuclei. In this study, we analyze the efficiency of different phase cycling schemes for proton-based fp-RFDR experiments. We demonstrate the advantages of using a short phase cycle, XY4, and its super-cycle XY414 that only recouples the zero-quantum homonuclear dipolar coupling, for the fp-RFDR sequence in 2D 1H/1H correlation experiments at ultrafast MAS frequencies. The dipolar recoupling efficiencies of XY4, XY414 and XY814 phase cycling schemes are compared based on results obtained from 2D 1H/1H correlation experiments, utilizing the fp-RFDR pulse sequence, on powder samples of U-13C,15N-L-alanine, N-acetyl-15N-L-valyl-15N-L-leucine, and glycine. Experimental results and spin dynamics simulations show that XY414 performs the best when a high RF power is used for the 180° pulse, whereas XY4 renders the best performance when a low RF power is used. The effects of RF field inhomogeneity and chemical shift offsets are also examined. Overall, our results suggest that a combination of fp-RFDR-XY414 employed in the recycle delay with a large RF-field to decrease the recycle delay, and fp-RFDR-XY4 in the mixing period with a moderate RF-field, is a robust and efficient method for 2D single-quantum/single-quantum 1H/1H correlation experiments at ultrafast MAS frequencies.

Nishiyama, Yusuke; Zhang, Rongchun; Ramamoorthy, Ayyalusamy

2014-06-01

376

1H NMR, a rapid method to monitor organic acids during cupuassu (Theobroma grandiflorum Spreng) processing.  

PubMed

The development of an analytical method using 1H nuclear magnetic resonance (1H NMR) spectrometry to monitor cupuassu (Theobroma grandiflorum Spreng) bean fermentation, drying, and roasting processes is reported. The analysis of organic acids and alcohols of crude water extracts of cupuassu ground kernels were monitored by HPLC and 1H NMR spectroscopy. The residual protein signals caused deleterious effects on acid and alcohol quantifications. Therefore, the analytical procedures were optimized by sample cleanup and water suppression pulse sequences in order to obtain compatible data using HPLC and 1H NMR. The quantification of lactic acid, acetic acid, and 2,3-butanediol by NMR is 5- to 10-fold faster than by HPLC, with the advantage of providing the identification of several chemical species in a single experiment. Application of these analytical conditions to some cupuassu samples revealed that this methodology can be applied to the quality profiles of fermentation and roasting processes. PMID:16756332

Figueiredo, Isis M; Pereira, Nadia R; Efraim, Priscilla; García, Nelson H P; Rodrigues, Nadia R; Marsaioli, Antônio; Marsaioli, Anita J

2006-06-14

377

Intervertebral disc changes after 1 h of running: a study on athletes.  

PubMed

The lumbar spines of 25 long-distance runners were examined using an upright magnetic resonance imaging scanner. All volunteer runners were scanned before and after running for 1 h. Scanning was performed with the runners seated upright (neutral), leaning forwards (flexion) and leaning backwards (extension). All measured discs showed a reduction in disc height after 1 h of running. A significant reduction in disc height was observed in all three body positions (neutral, flexion and extension) after 1 h of running. The results showed that, in flexion, extension and neutral positions, intervertebral discs undergo significant strain after 1 h of running. The lowest disc-height reduction was found at the L5 - S1 space in the neutral position; the same space had the highest percentage of disc degeneration. PMID:21672362

Dimitriadis, A T; Papagelopoulos, P J; Smith, F W; Mavrogenis, A F; Pope, M H; Karantanas, A H; Hadjipavlou, A G; Katonis, P G

2011-01-01

378

Synthesis of new 1,5-diaryl-3-(arylamino)-1H-pyrrol-2(5H)-ones under catalyst-free and solvent-free conditions.  

PubMed

Several new 1,5-diaryl-3-(arylamino)-1H-pyrrol-2(5H)-ones were synthesized via the three-component condensation reaction of aldehydes, aromatic amines, and ethyl pyruvate under catalyst-free and solvent-free conditions. Also, 5-(4-hydroxyl-3-nitrophenyl)-1-(4-methoxy-phenyl)-3-(4-methoxyphenylamino)-1,5-dihydro-pyrrol-2-one was synthesized using oxime instead of aldehyde. The eco-friendly, simple procedure, green procedure, catalyst-free and solvent-free conditions, short reaction times, and high yields of the products are the advantages of this method. PMID:24357192

Niknam, Khodabakhsh; Mojikhalifeh, Sanaz

2014-02-01

379

A Protic Ionic Liquid Catalyzes CO2 Conversion at Atmospheric Pressure and Room Temperature: Synthesis of Quinazoline-2,4(1H,3H)-diones.  

PubMed

The chemical fixation of CO2 under mild reaction conditions is of significance from a sustainable chemistry viewpoint. Herein a CO2 -reactive protic ionic liquid (PIL), [HDBU(+) ][TFE(-) ], was designed by neutralization of the superbase 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) with a weak proton donor trifluoroethanol (TFE). As a bifunctional catalyst for simultaneously activating CO2 and the substrate, this PIL displayed excellent performance in catalyzing the reactions of CO2 with 2-aminobenzonitriles at atmospheric pressure and room temperature, thus producing a series of quinazoline-2,4(1H,3H)-diones in excellent yields. PMID:24788820

Zhao, Yanfei; Yu, Bo; Yang, Zhenzhen; Zhang, Hongye; Hao, Leiduan; Gao, Xiang; Liu, Zhimin

2014-06-01

380

Complexes of IrIII-Octaethylporphyrin with Peptides as Probes for Sensing Cellular O2  

PubMed Central

IrIII–porphyrins are a relatively new group of phosphorescent dyes that have potential for oxygen sensing and labeling of biomolecules. The requirement of two axial ligands for the IrIII ion permits simple linkage of biomolecules by a one-step ligand-exchange reaction, for example, using precursor carbonyl chloride complexes and peptides containing histidine residue(s). Using this approach, we produced three complexes of IrIII–octaethylporphyrin with cell-penetrating (Ir1 and Ir2) and tumor-targeting (Ir3) peptides and studied their photophysical properties. All of the complexes were stable and possessed bright, long-decay (unquenched lifetimes exceeding 45 ?s) phosphorescence at around 650 nm, with moderate sensitivity to oxygen. The Ir1 and Ir2 complexes showed positive staining of a number of mammalian cell types, thus demonstrating localization similar to endoplasmic reticulum and ATP- and temperature-independent intracellular accumulation (direct translocation mechanism). Their low photo- and cytotoxicity allows intracellular oxygen to be probed.

Koren, Klaus; Dmitriev, Ruslan I; Borisov, Sergey M; Papkovsky, Dmitri B; Klimant, Ingo

2012-01-01

381

Synthesis and properties of photochromic biindenylidenedione derivatives containing thiophene groups, and new insights into the reaction of 2,2?-biindanylidene-1,1?,3,3?-tetraone with Grignard reagent  

NASA Astrophysics Data System (ADS)

Three indenone derivatives ( 1: 2-[3'-hydroxy-3'-(2-thienyl)indanone-2'-yl]-3-(2-thienyl)indenone; 2: trans- anti-3,3'-(2-thienyl)-3,3'-dihydroxy-[2,2'-bi-1H-indene]-1,1'-dione and 3: trans- syn-3,3'-(2-thienyl)-3,3'-dihydroxy-[2,2'-bi-1H-indene]-1,1'-dione) were obtained in a one-pot reaction of 2,2'-biindanylidene-1,1',3,3'-tetraone with 2-thienylmagnesium bromide. Their structures were characterized by means of IR, 1H NMR, MS, elemental analysis, and X-ray crystallography. The photochromic and photo-induced radical behaviors of these compounds were investigated by means of solid UV-vis spectroscopy and electron spin resonance (ESR) spectroscopy. The results show that compounds 2 and 3 exhibit photochromism in the solid state, whereas compound 1 does not. The relationship between the crystal structures and photochemical properties is also discussed. Based on the formation and product distribution of compounds 1, 2, and 3, a plausible pathway is suggested for the reaction of 2,2'-biindanylidene-1,1',3,3'-tetraone with 2-thienylmagnesium bromide. The findings obtained in this study also provide new insights into the addition-oxidation mechanism for the reaction of 2,2'-biindanylidene-1,1',3,3'-tetraone with Grignard reagent.

Liu, Juyan; Han, Jie; Song, Zhiyi; Wei, Yongheng; Pang, Meili; Meng, Jiben

2008-11-01

382

1 H, 13 C and 15 N chemical shift referencing in biomolecular NMR  

Microsoft Academic Search

A considerable degree of variability exists in the way that 1H, 13C and 15N chemical shifts are reported and referenced for biomolecules. In this article we explore some of the reasons for this situation and propose guidelines for future chemical shift referencing and for conversion from many common 1H, 13C and 15N chemical shift standards, now used in biomolecular NMR,

David S. Wishart; Colin G. Bigam; Jian Yao; Frits Abildgaard; H. Jane Dyson; Eric Oldfield; John L. Markley; Brian D. Sykes

1995-01-01

383

Molality as a unit of measure for expressing 1H MRS brain metabolite concentrations in vivo  

Microsoft Academic Search

Absolute concentrations of cerebral metabolite in in vivo1H magnetic resonance spectroscopy studies (1H-MRS) are widely reported in molar units as moles per liter of tissue, or in molal units as moles per kilogram of tissue. Such measurements require external referencing or assumptions as to local water content. To reduce the scan time, avoid assumptions that may be invalid under specific

Jack Knight-Scott; Andreana P. Haley; Sarah R. Rossmiller; Elana Farace; Vu M. Mai; John M. Christopher; Carol A. Manning; Virginia I. Simnad; Helmy M. Siragy

2003-01-01

384

Evidence for long-term neurotoxicity associated with methamphetamine abuse A 1H MRS study  

Microsoft Academic Search

Article abstract—Objective: To determine whether proton MRS (1H MRS) can detect long-term metabolite abnormalities in abstinent methamphetamine users. Background: Methamphetamine is toxic to dopaminergic and serotonergic neurons in rodents; however, little data are available on the toxic effects of methamphetamine on the human brain. Methods: 1H MRS was performed in 26 abstinent methamphetamine abusers with a history of methamphetamine dependence

Thomas Ernst; Linda Chang; Maria Leonido-Yee; Oliver Speck

385

Structural determination of epsilon-lactams by 1H and 13C NMR.  

PubMed

The thermodynamic products (epsilon-lactams) of the degradation of ten different spirocyclic oxaziridines were analyzed by 1H and 13C NMR spectroscopy. The preferred conformations were determined by examining the homonuclear spin-spin coupling constant and the chemical shift effects of the N-substituent and the alkyl group of the aliphatic ring on 1H and 13C NMR spectra. PMID:19722187

Montalvo-González, Rubén; Ariza-Castolo, Armando

2009-12-01

386

1 H NMR and Multivariate Calibration for the Prediction of Biodiesel Concentration in Diesel Blends  

Microsoft Academic Search

In this work, the use of 1H-NMR spectroscopy and a statistical approach to the analysis of biodiesel concentrations in blends with conventional diesel\\u000a is described. For this, we performed 1H-NMR analyses using distinct mixtures of biodiesel from soybean and castor oil in mineral diesel, in concentrations ranging\\u000a from 0.5 to 30%, and then we applied partial least squares regression (PLS)

Marcos R. Monteiro; Alessandra R. P. Ambrozin; Luciano M. Lião; Elisangela F. Boffo; Edenir R. Pereira-Filho; Antonio Gilberto Ferreira

2009-01-01

387

Evaluation of biodiesel–diesel blends quality using 1H NMR and chemometrics  

Microsoft Academic Search

In this work, the use of 1H NMR spectroscopy and statistical approach to the evaluation of biodiesel–diesel blends quality is described. Forty-six mixtures of oil–diesel, biodiesel–diesel, and oil–biodiesel–diesel were analyzed by 1H NMR and such data were employed to design four predictive models. Thirty-six mixtures were used in the calibration set and the others in the validation. The PCR and

Marcos Roberto Monteiro; Alessandra Regina Pepe Ambrozin; Maiara da Silva Santos; Elisangela Fabiana Boffo; Edenir Rodrigues Pereira-Filho; Luciano Morais Lião; Antonio Gilberto Ferreira

2009-01-01

388

Reversal of Acute Cellular Rejection After Renal Transplantation With Campath-1H  

Microsoft Academic Search

Between September 2002 and February 2004, 40 kidney transplant (27 from deceased and 13 from living donors) recipients (25 male and 15 female, aged 50.3 ± 15.1 years) were treated with Campath 1H (C 1H; 30 mg\\/dose IV) for biopsy-proven steroid-resistant rejection (SRR) or rejections equal to or worse than Banff 1B. All transplantations occurred between August 2001 and May

A. Basu; M. Ramkumar; H. P. Tan; A. Khan; J. McCauley; A. Marcos; J. J. Fung; T. E. Starzl; R. Shapiro

2005-01-01

389

Determination of biodiesel blend levels in different diesel samples by 1H NMR  

Microsoft Academic Search

The use of 1H NMR to quantify different methyl biodiesels in diesel from different sources is described. Biodiesel samples from soybean and castor oils, which have different fatty acid compositions, and three diesel fuels, which have distinct chemical compositions, were used to prepare biodiesel blends (0.5–30%, v\\/v). These samples were analyzed by 1H NMR and some relationships of integrals were

M. R. Monteiro; A. R. P. Ambrozin; L. M. Lião; A. G. Ferreira

2009-01-01

390

5-Substituted-1 H-tetrazoles as carboxylic acid isosteres: medicinal chemistry and synthetic methods  

Microsoft Academic Search

5-Substituted-1H-tetrazoles (RCN4H) are often used as metabolism-resistant isosteric replacements for carboxylic acids (RCO2H) in SAR-driven medicinal chemistry analogue syntheses. This review provides a brief summary of the medicinal chemistry of tetrazolic acids and highlights some examples of tetrazole-containing drug substances in the current literature. A survey of representative literature procedures for the preparation of 5-substituted-1H-tetrazoles, focusing on preparations from aryl

R. Jason Herr

2002-01-01

391

Effect of an allophanic soil on humification reactions between catechol and glycine: Spectroscopic investigations of reaction products  

NASA Astrophysics Data System (ADS)

Adduction of amino acids to phenols is a possible humification reaction pathway [F.J. Stevenson, Humus Chemistry: Genesis, Composition, Reaction, second ed., Wiley, New York, 1994, pp. 188-211; M.C. Wang, P.M. Huang, Sci. Total Environ. 62 (1987) 435; M.C. Wang, P.M. Huang, Soil Sci. Soc. Am. J. 55 (1991) 1156; M.C. Wang, P.M. Huang, Geoderma 112 (2003) 31; M.C. Wang, P.M. Huang, Geoderma 124 (2005) 415]. To elucidate the reaction kinetics and products of abiotic humification, the effects of an allophanic soil on the adduction of amino acids to phenols were investigated using catechol (CT) and glycine (Gly) as a model phenol and amino acid, respectively. An aqueous solution containing CT and Gly (pH 7.0) in the presence of allophanic soil was incubated for 2 weeks, and the kinetics of the humification reactions were monitored by analysis of absorptivity at 600 nm ( E600). A mixture of CT and Gly in the absence of allophanic soil was used as a control. The E600 value increased markedly in the presence of allophanic soil. In addition, unreacted CT was detected in the control reaction mixture, but not in the allophane-containing reaction mixture. Under the sterilized conditions, absorbance at 600 nm for the control reaction mixture was significantly smaller than that for the allophanic soil-containing reaction mixture, which indicates there was no microbial participation during incubation. These results indicate that the allophanic soil effectively facilitated humification reactions between CT and Gly. The reaction mixtures were acidified and humic-like acid (HLA) was isolated as a precipitate. The elemental composition, acidic functional group contents, molecular weight, FT-IR, solid-state CP-MAS 13C NMR, and 1H NMR spectra of the purified HLAs were analyzed. The results of these analyses indicate that the nitrogen atom of Gly binds to the aromatic carbon of CT in the HLA products.

Fukushima, Masami; Miura, Akitaka; Sasaki, Masahide; Izumo, Kenji

2009-01-01

392

1-Ethyl-2-phenyl-3-[2-(tri-methyl-sil-yl)ethyn-yl]-1H-indole  

PubMed Central

The title compound, C21H23NSi, was synthesized by Sonogashira-type reaction of 1-ethyl-3-iodo-2-phenyl-1H-indole with tri­methyl­silyl­acetyl­ene. The indole ring system is nearly planar [maximum atomic deviation = 0.0244?(15)?Å] and is oriented at a dihedral angle of 51.48?(4)° with respect to the phenyl ring. The supramolecular aggregation is completed by weak C—H?? inter­actions of the methylene and phenyl groups with the benzene and pyrrole rings of the indole ring system. The methyl groups of the tri­methyl­silyl unit are equally disordered over two sets of sites.

Baglai, Iaroslav; Maraval, Valerie; Duhayon, Carine; Chauvin, Remi

2013-01-01

393

(1)H Nuclear Magnetic Resonance monitoring of the degradation of margarines of varied compositions when heated to high temperature.  

PubMed

In this study, (1)H Nuclear Magnetic Resonance was used to monitor the evolution of three margarines of varied compositions when submitted to heating at 180°C in an oven with aeration. Heating causes degradation of polyunsaturated acyl groups and this depends not only on their unsaturation degree, but also on the concentration of the different acyl groups. The evolution of monounsaturated groups varies depending on the disappearance rate of the groups with higher unsaturation degree. Heat treatment also causes hydrolysis reactions that lead to a reduction in 1-monoglycerides and an increase in 1,2-diglycerides, especially in the margarines with higher water content, as well as degradation of some vegetable sterols. Different types of aldehydes and epoxides were identified and quantified, above all in the margarine with the highest proportion of polyunsaturated groups, especially linoleic; some of these are toxic, such as 4-hydroxy- and 4,5-epoxy-2-alkenals. PMID:25038657

Ibargoitia, María L; Sopelana, P; Guillén, María D

2014-12-15

394

Heterohelicenes with embedded P-chiral 1H-phosphindole or dibenzophosphole units: diastereoselective photochemical synthesis and structural characterization.  

PubMed

The oxidative photocyclization reactions of olefins that contain 1H-phosphindole or dibenzophosphole substituents have been applied to the synthesis of P/N-bi-heterosubstituted dimeric helicenes, as well as of new [6]- and [8]phosphahelicenes. In these photocyclization processes, the configuration of the stereogenic phosphorus center dictates the sense of helical chirality. Thus, by starting from enantiomerically pure P-menthylphosphole-oxide units, this method affords enantiopure helical compounds. The helical phosphine oxides were characterized by X-ray diffraction. After reduction of the phosphine-oxides, the corresponding helical phosphines have been used as ligands in transition-metal complexes. The X-ray crystal structure of a gold chloride complex of a [6]helicene is reported. PMID:23766244

Yavari, Keihann; Retailleau, Pascal; Voituriez, Arnaud; Marinetti, Angela

2013-07-22

395

Endothelial necrosis at 1h post-burn predicts progression of tissue injury  

PubMed Central

Burn injury progression has not been well characterized at the cellular level. To define burn injury progression in terms of cell death, histopathologic spatiotemporal relationships of cellular necrosis and apoptosis were investigated in a validated porcine model of vertical burn injury progression. Cell necrosis was identified by High Mobility Group Box 1 protein and apoptosis by Caspase 3a staining of tissue samples taken 1h, 24h and 7 days post-burn. Level of endothelial cell necrosis at 1h was predictive of level of apoptosis at 24h (Pearson's r=0.87) and of level of tissue necrosis at 7 days (Pearson's r=0.87). Furthermore, endothelial cell necrosis was deeper than interstitial cell necrosis at 1h (p<0.001). Endothelial cell necrosis at 1h divided the zone of injury progression (Jackson's zone of stasis) into an upper subzone with necrotic endothelial cells and initially viable adnexal and interstitial cells at 1h that progressed to necrosis by 24h, and a lower zone with initially viable endothelial cells at 1h, but necrosis and apoptosis of all cell types by 24h. Importantly, this spatiotemporal series of events and rapid progression resembles myocardial infarction and stroke, and implicates mechanisms of these injuries, ischemia, ischemia reperfusion, and programmed cell death, in burn progression.

Hirth, Douglas; McClain, Steve A.; Singer, Adam J.; Clark, Richard A.F.

2013-01-01

396

3-Hydroxyquinolin-2(1H)-ones As Inhibitors of Influenza A Endonuclease  

PubMed Central

Several 3-hydroxyquinolin-2(1H)-ones derivatives were synthesized and evaluated as inhibitors of 2009 pandemic H1N1 influenza A endonuclease. All five of the monobrominated 3-hydroxyquinolin(1H)-2-ones derivatives were synthesized. Suzuki-coupling of p-fluorophenylboronic acid with each of these brominated derivatives provided the respective p-fluorophenyl 3-hydroxyquinolin(1H)-2-ones. In addition to 3-hydroxyquinolin-2(1H)-one, its 4-methyl, 4-phenyl, 4-methyl-7-(p-fluorophenyl), and 4-phenyl-7-(p-fluorophenyl) derivatives were also synthesized. Comparative studies on their relative activity revealed that both 6- and 7-(p-fluorophenyl)-3-hydroxyquinolin-2(1H)-one are among the more potent inhibitors of H1N1 influenza A endonuclease. An X-ray crystal structure of 7-(p-fluorophenyl)-3-hydroxyquinolin-2(1H)-one complexed to the influenza endonuclease revealed that this molecule chelates to two metal ions at the active site of the enzyme.

2013-01-01

397

Bioinspired, cysteamine-catalyzed co-silicification of (1H, 1H, 2H, 2HPerfluorooctyl) triethoxysilane and tetraethyl orthosilicate: formation of superhydrophobic surfaces.  

PubMed

Bioinspired silicification attracts a great deal of interest because of its physiologically relevant, mild conditions for hydrolysis and condensation of silica precursors, which makes the bioinspired approach superior to the conventional sol–gel process, particularly when dealing with biological entities. However, the morphological control of silica structures with incorporation of functional groups in the bioinspired silicilication has been unexplored. In this work, we co-silicificated (1H, 1H, 2H, 2H-perfluorooctyl)triethoxysilane and tetraethyl orthosilicate to investigate the morphological evolution of fluorinated silica structures in the cetyltrimethylammonium bromide-mediated, cysteamine-catalyzed silicification. The generated micrometer-long wormlike and spherical silica structures display superhydrophobicity after film formation. Interestingly, the measurement of dynamic water contact angles shows that the morphological difference leads to a different wetting state, either the self-cleaning or the pinning state of the superhydrophobic surface. PMID:24730056

Park, Ji Hun; Kim, Ji Yup; Cho, Woo Kyung; Choi, Insung S

2014-03-01

398

Measurements of the ^1H(^18F,p)^18F and ^1H(^18F,?)^15O Excitation Functions at the HRIBF  

NASA Astrophysics Data System (ADS)

Knowledge of the astrophysical ^18F(p,?)^15O rate is important for understanding gamma-ray emission from novae and heavy-element production in x-ray bursts. A state with Ex ~= 7.075 MeV in ^19Ne provides an s-wave resonance and, depending on its properties, could dominate the ^18F(p,?)^15O rate. By simultaneously measuring the ^1H(^18F,p)^18F and ^1H(^18F,?)^15O excitation functions with a radioactive ^18F beam at ORNL's Holifield Radioactive Ion Beam Facility, we have resolved discrepancies(Utku et al.), Phys. Rev. C57, 2731 (1998).^,(Coszach et al.), Phys. Lett. B353, 184 (1995).^,(Rehm et al.), Phys. Rev. C52, R460 (1995); 53, 1950 (1996). in the properties of this astrophysically-important state. Our results will be presented.

Bardayan, D. W.; Blackmon, J. C.; Smith, M. S.; Bradfield-Smith, W.; Lewis, R.; Parker, P. D.; Visser, D. W.; Brune, C. R.; Champagne, A. E.; Johnson, B. A.; Kozub, R. L.; Davinson, T.; Shotter, A. C.; Woods, P. J.; Lee, C. S.

2000-10-01

399

Magnesium Silicate Dissolution Investigated by 29Si MAS, 1H-29Si CP MAS, 25Mg QCPMG, and 1H-25Mg CP QCPMG NMR  

SciTech Connect

Olivine has been the subject of frequent investigation in the earth sciences because of its simple structure and rapid dissolution kinetics. Several studies have observed a preferential release of magnesium with respect to silica during weathering under acidic conditions, which has been correlated to the formation of a silicon rich leached layer. While leached layer formation has been inferred through the changing solution chemistry, a thorough spectroscopic investigation of olivine reacted under acidic conditions has not been conducted. In particular, the fate of magnesium in the system is not understood and spectroscopic interrogations through nuclear magnetic resonance can elucidate the changing magnesium coordination and bonding environment. In this study, we combine analysis of the changing solution chemistry with advanced spectroscopic techniques (29Si MAS, 1H-29Si CP MAS, 25Mg QCPMG, and 1H-25Mg 2 CP QCPMG NMR) to probe leached layer formation and possible secondary phase precipitation during the dissolution of forsterite at 150 oC.

Davis, Michael C.; Brouwer, William J.; Wesolowski, David J.; Anovitz, Lawrence M.; Lipton, Andrew S.; Mueller, Karl T.

2009-08-01

400

1-{[(2,3-Dihydro-1H-inden-2-yl)-oxy]meth-yl}quinazoline-2,4(1H,3H)-dione  

PubMed Central

In the title mol­ecule, C18H16N2O3, the five-membered ring has an envelope conformation, with the substituted C atom deviating by 0.342?(4)?Å from the mean plane P calculated for the remainder of the non-H atoms of the 2,3-dihydro-1H-indene fragment. The mean planes of quinazoline-2,4(1H,3H)-dione fragment and P form a dihedral angle of 59.08?(4)°. In the crystal, pairs of N—H?O hydrogen bonds link mol­ecules into inversion dimers, and weak C—H?O hydrogen bonds and ?–? inter­actions between the benzene rings of the quinazoline ring systems [centroid–centroid distance = 3.538?(3)?Å] further consolidate the packing.

El-Brollosy, Nasser R.; Dege, Necmi; Demirtas, Gunes; Attia, Mohamed I.; El-Emam, Ali A.; Buyukgungor, Orhan

2012-01-01

401

Effect of IR laser on myoblasts: a proteomic study.  

PubMed

Laser therapy is used in physical medicine and rehabilitation to accelerate muscle recovery and in sports medicine to prevent damages produced by metabolic disturbances and inflammatory reactions after heavy exercise. The aim of this research was to get insight into possible benefits deriving from the application of an advanced IR laser system to counteract deficits of muscle energy metabolism and stimulate the recovery of hypotrophic tissue. We studied the effect of IR laser treatment on proliferation, differentiation, cytoskeleton organization and global protein expression in C2C12 myoblasts. We found that laser treatment induced a decrease in the cell proliferation rate without affecting cell viability, while leading to cytoskeletal rearrangement and expression of the early differentiation marker MyoD. The differential proteome analysis revealed the up-regulation and/or modulation of many proteins known to be involved in cell cycle regulation, cytoskeleton organization and differentiation. PMID:23364335

Monici, Monica; Cialdai, Francesca; Ranaldi, Francesco; Paoli, Paolo; Boscaro, Francesca; Moneti, Gloriano; Caselli, Anna

2013-06-01

402

Chemical models for the contracting W3 IRS4  

NASA Astrophysics Data System (ADS)

We have studied the chemical evolution in the central core of a contracting cloud representing W3 IRS4. We modified the equation of temperature to satisfy the physical conditions of W3 IRS4. The chemical rate equations and the hydrodynamics are integrated simultaneously. The contraction is followed from a very low density of n = 10 cm -3 to high core density of n = 10 6 cm -3. The chemical evolution is studied for various chemical conditions, including both the effects of varying cosmic ray ionization rate and the effect of ion-dipole molecule collisions. The main results by using the more extensive chemical network with the most updating reaction rates show that the calculated fractional abundances are in agreement with observation at intermediate and enhanced cosmic ray ionization rate at high depletion of elemental atoms.

Amin, Magdy Y.

2000-12-01

403

Properties of the transition metal dichalcogenides: The case of IrS sub 2 and IrSe sub 2  

SciTech Connect

The syntheses and structure determination of IrSe{sub 2} and IrS{sub 2} were undertaken. Pure phases were obtained and powder data were measured on an X-ray diffractometer. Rietveld refinement was successfully carried out for both structures (IrSe{sub 2}, 269 observations R (weighted profile) 0.062; IrS{sub 2}, 205 observations R (weighted profile) 0.074). The Pnam space group (No. 62) was found to yield the best results, eliminating Pna2{sub 1} as the other possible space group considered in a previous study of IrSe{sub 2}. Chalcogen pairs are found in both structures and these may correspond, in a first approach, to the charge balance Ir{sup 3+}X{sup 2{minus}}(X{sub 2}){sup 2{minus}}{sub 1/2}. However, long bond lengths were found in the chalcogen pairs (S-S 2.299(11) {angstrom}, Se-Se 2.555(4) {angstrom}) along with an unexpectedly small effective cationic radius of 0.50 {angstrom} for Ir{sup 3+}. These features of IrS{sub 2} and IrSe{sub 2} are discussed.

Jobic, S.; Deniard, P.; Brec, R.; Rouxel, J. (Institut de Physique et Chimie des Materiaux, Nantes (France)); Drew, M.G.B. (The University, Reading (England)); David, W.I.F. (Rutherford Appleton Laboratory, Didcot (England))

1990-12-01

404

IR Thermography NDE of ISS Radiator Panels  

NASA Technical Reports Server (NTRS)

The presentation covers an active and a passive infrared (IR) thermography for detection of delaminations in the radiator panels used for the International Space Station (ISS) program. The passive radiator IR data was taken by a NASA astronaut in an extravehicular activity (EVA) using a modified FLIR EVA hand-held camera. The IR data could be successfully analyzed to detect gross facesheet disbonds. The technique used the internal hot fluid tube as the heat source in analyzing the IR data. Some non-flight ISS radiators were inspected using an active technique of IR flash thermography to detect disbond of face sheet with honeycomb core, and debonds in facesheet overlap areas. The surface temperature and radiated heat emission from flight radiators is stable during acquisition of the IR video data. This data was analyzed to detect locations of unexpected surface temperature gradients. The flash thermography data was analyzed using derivative analysis and contrast evolutions. Results of the inspection are provided.

Koshti, Ajay; Winfree, William; Morton, Richard; Wilson, Walter; Reynolds, Gary

2010-01-01

405

Protein-Cofactor Interactions in Bacterial Reaction Centers from Rhodobacter sphaeroides R-26: II. Geometry of the Hydrogen Bonds to the Primary Quinone \\documentclass[10pt]{article} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{pmc} \\pagestyle{empty} \\oddsidemargin -1.0in \\begin{document} \\begin{equation*}{\\mathrm{Q}}_{{\\mathrm{A}}}^{{\\cdot}\\hspace{.167em}-}\\end{equation*}\\end{document} by 1H and 2H ENDOR Spectroscopy  

PubMed Central

The geometry of the hydrogen bonds to the two carbonyl oxygens of the semiquinone \\documentclass[10pt]{article} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{pmc} \\pagestyle{empty} \\oddsidemargin -1.0in \\begin{document} \\begin{equation*}{\\mathrm{Q}}_{{\\mathrm{A}}}^{{\\cdot}\\hspace{.167em}-}\\end{equation*}\\end{document} in the reaction center (RC) from the photosynthetic purple bacterium Rhodobacter sphaeroides R-26 were determined by fitting a spin Hamiltonian to the data derived from 1H and 2H ENDOR spectroscopies at 35 GHz and 80 K. The experiments were performed on RCs in which the native Fe2+ (high spin) was replaced by diamagnetic Zn2+ to prevent spectral line broadening of the \\documentclass[10pt]{article} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{pmc} \\pagestyle{empty} \\oddsidemargin -1.0in \\begin{document} \\begin{equation*}{\\mathrm{Q}}_{{\\mathrm{A}}}^{{\\cdot}\\hspace{.167em}-}\\end{equation*}\\end{document} due to magnetic coupling with the iron. The principal components of the hyperfine coupling and nuclear quadrupolar coupling tensors of the hydrogen-bonded protons (deuterons) and their principal directions with respect to the quinone axes were obtained by spectral simulations of ENDOR spectra at different magnetic fields on frozen solutions of deuterated \\documentclass[10pt]{article} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{pmc} \\pagestyle{empty} \\oddsidemargin -1.0in \\begin{document} \\begin{equation*}{\\mathrm{Q}}_{{\\mathrm{A}}}^{{\\cdot}\\hspace{.167em}-}\\end{equation*}\\end{document} in H2O buffer and protonated \\documentclass[10pt]{article} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{pmc} \\pagestyle{empty} \\oddsidemargin -1.0in \\begin{document} \\begin{equation*}{\\mathrm{Q}}_{{\\mathrm{A}}}^{{\\cdot}\\hspace{.167em}-}\\end{equation*}\\end{document} in D2O buffer. Hydrogen-bond lengths were obtained from the nuclear quadrupolar couplings. The two hydrogen bonds were found to be nonequivalent, having different directions and different bond lengths. The H-bond lengths rO?H are 1.73 ± 0.03 Å and 1.60 ± 0.04 Å, from the carbonyl oxygens O1 and O4 to the NH group of Ala M260 and the imidazole nitrogen N? of His M219, respectively. The asymmetric hydrogen bonds of \\documentclass[10pt]{article} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{pmc} \\pagestyle{empty} \\oddsidemargin -1.0in \\begin{document} \\begin{equation*}{\\mathrm{Q}}_{{\\mathrm{A}}}^{{\\cdot}\\hspace{.167em}-}\\end{equation*}\\end{document} affect the spin density distribution in the quinone radical and its electronic structure. It is proposed that the H-bonds play an important role in defining the physical properties of the primary quinone, which affect the electron transfer processes in the RC.

Flores, M.; Isaacson, R.; Abresch, E.; Calvo, R.; Lubitz, W.; Feher, G.

2007-01-01

406

Triruthenium clusters derived from the reactions of [Ru 3(CO) 12] with benzothiazole, pyrimidine-2-thione and benzimidazole-2-thione; X-ray structures of [Ru 3(?-H)(?-2,3-? 2NSC 7H 4)(CO) 10] and [Ru 3(?-H)(? 3-? 2SN 2C 4H 3)(CO) 9  

Microsoft Academic Search

The reaction of [Ru3(CO)12] with benzothiazole (C7H5NS) in THF at 68°C yields [Ru3(?-H)(?-2,3-?2-NSC7H4)(CO)10] 3 and [Ru3(?-H)(?3-1,2,3-?3-NSC7H4)(CO)9] 4. An X-ray diffraction analysis of 3 shows that the benzothiazolide ligand is coordinated through the imino-nitrogen and C-2 carbon atoms. The organic ligand in 4 is coordinated through the sulfur, the imino nitrogen and the C-2 carbon atoms as suggested by IR, 1H-NMR

Rahima Dilshad; Khandakar M. Hanif; Michael B. Hursthouse; Shariff E. Kabir; K. M. Abdul Malik; Edward Rosenberg

1999-01-01

407

Higgs phenomenology in Type-I 2HDM with U(1) H Higgs gauge symmetry  

NASA Astrophysics Data System (ADS)

It is well known that generic two-Higgs-doublet models (2HDMs) suffer from potentially large Higgs-mediated flavor-changing neutral current (FCNC) problem, unless additional symmetries are imposed on the Higgs fields thereby respecting the Natural Flavor Conservation Criterion (NFC) by Glashow and Weinberg. A common way to respect the NFC is to impose Z 2 symmetry which is softly broken by a dim-2 operator. Another new way is to introduce local U(1) H Higgs flavor symmetry that distinguishes one Higgs doublet from the other. In this paper, we consider the Higgs phenomenology in Type-I 2HDMs with the U(1) H symmetry with the simplest U(1) H assignments that the SM fermions are all neutral under U(1) H , and we make detailed comparison with the ordinary Type-I 2HDM. After imposing various constraints such as vacuum stability and perturbativity as well as the electroweak precision observables and collider search bounds on charged Higgs boson, we find that the allowed Higgs signal strengths in our model are much broader than those in the ordinary Type-I 2HDM, because of newly introduced U(1) H -charged singlet scalar and U(1) H gauge boson. Still the ATLAS data on gg ? h ? ?? cannot be accommodated. Our model could be distinguished from the ordinary 2HDM with the Z 2 symmetry in a certain parameter region and some channels. If the couplings of the new boson turn out to be close to those in the SM, it would be essential to search for extra U(1) H gauge boson and/or one more neutral scalar boson to distinguish two models.

Ko, P.; Omura, Yuji; Yu, Chaehyun

2014-01-01

408

14N quadrupole resonance and 1H T1 dispersion in the explosive RDX.  

PubMed

The explosive hexahydro-1,3,5-trinitro-s-triazine (CH2-N-NO2)3, commonly known as RDX, has been studied by 14N NQR and 1H NMR. NQR frequencies and relaxation times for the three ?+ and ?- lines of the ring 14N nuclei have been measured over the temperature range 230-330 K. The 1H NMR T1 dispersion has been measured for magnetic fields corresponding to the 1H NMR frequency range of 0-5.4 M Hz. The results have been interpreted as due to hindered rotation of the NO2 group about the N-NO2 bond with an activation energy close to 92 kJ mol(-1). Three dips in the 1H NMR dispersion near 120, 390 and 510 kHz are assigned to the ?0, ?- and ?+ transitions of the 14NO2 group. The temperature dependence of the inverse line-width parameters T2? of the three ?+ and ?- ring nitrogen transitions between 230 and 320 K can be explained by a distribution in the torsional oscillational amplitudes of the NO2 group about the N-NO2 bond at crystal defects whose values are consistent with the latter being mainly edge dislocations or impurities in the samples studied. Above 310 K, the 14N line widths are dominated by the rapid decrease in the spin-spin relaxation time T2 due to hindered rotation of the NO2 group. A consequence of this is that above this temperature, the 1H T1 values at the quadrupole dips are dominated by the spin mixing time between the 1H Zeeman levels and the combined 1H and 14N spin-spin levels. PMID:21978662

Smith, John A S; Blanz, Martin; Rayner, Timothy J; Rowe, Michael D; Bedford, Simon; Althoefer, Kaspar

2011-12-01

409

New supersymmetric quartet of nuclei: {sup 192,193}Os-{sup 193,194}Ir  

SciTech Connect

We present evidence for the existence of a new supersymmetric quartet of nuclei in the A{approx}190 mass region. The analysis is based on new experimental information on the odd-odd nucleus {sup 194}Ir from transfer and neutron capture reactions. The new data allow the identification of a new supersymmetric quartet, consisting of the {sup 192,193}Os and {sup 193,194}Ir nuclei. We make explicit predictions for {sup 193}Os, and suggest that its spectroscopic properties be measured in dedicated experiments. Finally, we study correlations between different transfer reactions.

Bijker, R.; Frank, A. [ICN-UNAM, AP 70-543, 04510 Mexico DF (Mexico); Barea, J. [Center for Theoretical Physics, Sloane Physics Laboratory, Yale University, P.O. Box 208210, New Haven, Connecticut 06520-8120 (United States); Graw, G.; Wirth, H.-F. [Sektion Physik, Ludwig-Maximilians-Universitaet Muenchen, D-85748 Garching (Germany); Hertenberger, R. [Fakultaet fuer Physik, Ludwig-Maximilians-Universitaet Muenchen, D-85748 Garching (Germany); Jolie, J. [Institut fuer Kernphysik, Universitaet zu Koeln, D-50937 Koeln (Germany)

2009-01-28

410

Drug Reactions  

MedlinePLUS

... adverse drug reaction. One medicine might cause an adverse reaction if it’s taken with another medicine. One way ... reaction. Are prescription medicines the only cause of adverse reactions? No. Even medicines that you don't need ...

411

1H NMR based metabolic profiling in the evaluation of Japanese green tea quality.  

PubMed

Classification of tea quality is now mainly performed according to the sensory results by professional tea tasters. However, this evaluation method is inconsistent in differentiating their qualities. A combination of a (1)H NMR technique and a multivariate analysis was introduced to the quality evaluation of green tea by means of a metabolomic technique. A broad range of metabolites were detected by (1)H NMR spectrometry. The principal component analysis (PCA) was used to reduce the complexity of the (1)H NMR spectra data set and provided the quality discrimination result. It offered an extensive clue for classification and quality assessment without any prepurification method. A set of green teas from a Japanese tea contest were analyzed by (1)H NMR to classify the quality with respect to that judged by tea tasters and to conceive a quality prediction model. Metabolic profiling and fingerprinting of (1)H NMR spectra of green teas with different quality were studied. PCA showed a separation between the high- and the low-quality green teas. The taste marker compounds contributing to the discrimination of tea quality were identified. Reliable prediction models were obtained by the partial least-squares projection to latent structure (PLS) analysis together with a preprocessing filter of both orthogonal signal correction (OSC) and a combination between OSC and wavelet transform algorithms. PMID:17944534

Tarachiwin, Lucksanaporn; Ute, Koichi; Kobayashi, Akio; Fukusaki, Eiichiro

2007-11-14

412

Quantitative Determination of Carthamin in Carthamus Red by 1H-NMR Spectroscopy.  

PubMed

Carthamus Red is a food colorant prepared from the petals of Carthamus tinctorius (Asteraceae) whose major pigment is carthamin. Since an authentic carthamin standard is difficult to obtain commercially for the preparation of calibration curves in HPLC assays, we applied (1)H-NMR spectroscopy to the quantitative determination of carthamin in commercial preparations of Carthamus Red. Carthamus Red was repeatedly extracted in methanol and the extract was dissolved in pyridine-d(5) containing hexamethyldisilane (HMD) prior to (1)H-NMR spectroscopic analysis. The carthamin contents were calculated from the ratios of singlet signal intensities at approximately ?: 9.3 derived from H-16 of carthamin to those of the HMD signal at ?: 0. The integral ratios exhibited good repeatability among NMR spectroscopic analyses. Both the intra-day and inter-day assay variations had coefficients of variation of <5%. Based on the coefficient of absorption, the carthamin contents of commercial preparations determined by (1)H-NMR spectroscopy correlated well with those determined by colorimetry, although the latter were always approximately 1.3-fold higher than the former, irrespective of the Carthamus Red preparations. In conclusion, the quantitative (1)H-NMR spectroscopy used in the present study is simple and rapid, requiring no carthamin standard for calibration. After HMD concentration has been corrected using certified reference materials, the carthamin contents determined by (1)H-NMR spectroscopy are System of Units (SI)-traceable. PMID:24436958

Yoshida, Takamitsu; Terasaka, Kazuyoshi; Kato, Setsuko; Bai, Fan; Sugimoto, Naoki; Akiyama, Hiroshi; Yamazaki, Takeshi; Mizukami, Hajime

2013-01-01

413

Urinary metabolic fingerprint of acute intermittent porphyria analyzed by (1)H NMR spectroscopy.  

PubMed

(1)H NMR is a nonbiased technique for the quantification of small molecules that could result in the identification and characterization of potential biomarkers with prognostic value and contribute to better understand pathophysiology of diseases. In this study, we used (1)H NMR spectroscopy to analyze the urinary metabolome of patients with acute intermittent porphyria (AIP), an inherited metabolic disorder of heme biosynthesis in which an accumulation of the heme precursors 5-aminolaevulinic acid (ALA) and porphobilinogen (PBG) promotes sudden neurovisceral attacks, which can be life-threatening. Our objectives were (1) to demonstrate the usefulness of (1)H NMR to identify and quantify ALA and PBG in urines from AIP patients and (2) to identify metabolites that would predict the response to AIP crisis treatment and reflect differential metabolic reprogramming. Our results indicate that (1)H NMR can help to diagnose AIP attacks based on the identification of ALA and PBG. We also show that glycin concentration increases in urines from patients with frequent recurrences at the end of the treatment, after a