Molecular dynamics simulations of Si etching in Cl- and Br-based plasmas: Cl{sup +} and Br{sup +} ion incidence in the presence of Cl and Br neutrals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakazaki, Nobuya, E-mail: nakazaki.nobuya.58x@st.kyoto-u.ac.jp; Takao, Yoshinori; Eriguchi, Koji

Classical molecular dynamics (MD) simulations have been performed for Cl{sup +} and Br{sup +} ions incident on Si(100) surfaces with Cl and Br neutrals, respectively, to gain a better understanding of the ion-enhanced surface reaction kinetics during Si etching in Cl- and Br-based plasmas. The ions were incident normally on surfaces with translational energies in the range E{sub i} = 20–500 eV, and low-energy neutrals of E{sub n} = 0.01 eV were also incident normally thereon with the neutral-to-ion flux ratio in the range Γ{sub n}{sup 0}/Γ{sub i}{sup 0} = 0–100, where an improved Stillinger--Weber potential form was employed for the interatomic potential concerned. The etch yieldsmore » and thresholds presently simulated were in agreement with the experimental results previously reported for Si etching in Cl{sub 2} and Br{sub 2} plasmas as well as in Cl{sup +}, Cl{sub 2}{sup +}, and Br{sup +} beams, and the product stoichiometry simulated was consistent with that observed during Ar{sup +} beam incidence on Si in Cl{sub 2}. Moreover, the surface coverage of halogen atoms, halogenated layer thickness, surface stoichiometry, and depth profile of surface products simulated for Γ{sub n}{sup 0}/Γ{sub i}{sup 0} = 100 were in excellent agreement with the observations depending on E{sub i} reported for Si etching in Cl{sub 2} plasmas. The MD also indicated that the yield, coverage, and surface layer thickness are smaller in Si/Br than in Si/Cl system, while the percentage of higher halogenated species in product and surface stoichiometries is larger in Si/Br. The MD further indicated that in both systems, the translational energy distributions of products and halogen adsorbates desorbed from surfaces are approximated by two Maxwellians of temperature T{sub 1} ≈ 2500 K and T{sub 2} ≈ 7000–40 000 K. These energy distributions are discussed in terms of the desorption or evaporation from hot spots formed through chemically enhanced physical sputtering and physically enhanced chemical sputtering, which have so far been speculated to both occur in the ion-enhanced surface reaction kinetics of plasma etching.« less

Electronic Structure Approach to Tunable Electronic Properties of Hybrid Organic-Inorganic Perovskites

NASA Astrophysics Data System (ADS)

Liu, Garnett; Huhn, William; Mitzi, David B.; Kanai, Yosuke; Blum, Volker

We present a study of the electronic structure of layered hybrid organic-inorganic perovskite (HOIP) materials using all-electron density-functional theory. Varying the nature of the organic and inorganic layers should enable systematically fine-tuning the carrier properties of each component. Using the HSE06 hybrid density functional including spin-orbit coupling (SOC), we validate the principle of tuning subsystem-specific parts of the electron band structures and densities of states in CH3NH3PbX3 (X=Cl, Br, I) compared to a modified organic component in layered (C6H5C2H4NH3) 2PbX4 (X=Cl, Br, I) and C20H22S4N2PbX4 (X=Cl, Br, I). We show that tunable shifts of electronic levels indeed arise by varying Cl, Br, I as the inorganic components, and CH3NH3+ , C6H5C2H4NH3+ , C20H22S4N22 + as the organic components. SOC is found to play an important role in splitting the conduction bands of the HOIP compounds investigated here. The frontier orbitals of the halide shift, increasing the gap, when Cl is substituted for Br and I.

Analysis of I-Br-Cl in single fluid inclusions by LA-ICP-MS

NASA Astrophysics Data System (ADS)

Giehl, C.; Fusswinkel, T.; Beermann, O.; Garbe-Schönberg, D.; Scholten, L.; Wagner, T.

2017-12-01

Halogens are excellent tracers of hydrothermal fluid sources and in-situ LA-ICP-MS analysis of Cl and Br in single fluid inclusions has provided fundamentally new insight into hydrothermal fluid flow and ore formation. There is mounting evidence that enrichment and depletion of Br relative to Cl may be caused by a number of processes beyond seawater evaporation and halite dissolution which cannot be discriminated on the basis of Br/Cl ratios alone. Expanding the analytical capabilities of fluid inclusion LA-ICP-MS analysis to include iodine would allow to discern between selective and coupled enrichment processes of Cl, Br and I, even in geologically complex samples that are inaccessible to bulk extraction techniques. We present iodine concentration data determined by LA-ICP-MS analysis of synthetic fluid inclusions, using the Sca17 scapolite reference material for external standardization (Seo et al., 2011). Iodine concentrations in Sca17 were determined using the Durango apatite standard. Four starting solutions containing I (0.3, 1.5, 27, 78 µg/g), Br (941, 1403, 2868, 4275 µg/g), Na (30.7, 94.7 mg/g), and Cl (50, 137 mg/g) (analyzed by ICP-OES and ICP-MS at CAU Kiel) were prepared by dissolving reagent grade chemical powders in ultra-pure water. Spherical inclusions (up to 40 µm) were synthesized from the starting solutions in pre-cracked, HF-treated synthetic quartz crystals which were placed in gold capsules and equilibrated at 600°C, 100/200 MPa in cold seal pressure vessels. Fluid inclusion LA-ICP-MS analysis (University of Helsinki) yielded average I concentrations in excellent agreement with the starting solutions (27.3 µg/g ± 14 %RSD for the 27 µg/g solution and 77.6 µg/g ± 8.3 %RSD for the 78 µg/g solution). Average Br and I concentrations deviate less than 10 % from solution concentration values. For the low I concentration solutions, the synthetic inclusions were too small to detect I. Thus, given suitable standard materials and sufficient inclusion sizes, LA-ICP-MS fluid inclusion microanalysis can be used to determine accurate I-Br-Cl concentration data and track the sources of crustal fluids in a wide range of geological settings. Seo, J.H., Guillong, M., Aerts, M., Zajacz, Z., Heinrich, C.A., 2011. Microanalysis of S, Cl, and Br in fluid inclusions by LA-ICP-MS. Chemical Geology 284, 35-44.

Unveiling the Shape Evolution and Halide-Ion-Segregation in Blue-Emitting Formamidinium Lead Halide Perovskite Nanocrystals Using an Automated Microfluidic Platform.

PubMed

Lignos, Ioannis; Protesescu, Loredana; Emiroglu, Dilara Börte; Maceiczyk, Richard; Schneider, Simon; Kovalenko, Maksym V; deMello, Andrew J

2018-02-14

Hybrid organic-inorganic perovskites and in particular formamidinium lead halide (FAPbX 3 , X = Cl, Br, I) perovskite nanocrystals (NCs) have shown great promise for their implementation in optoelectronic devices. Specifically, the Br and I counterparts have shown unprecedented photoluminescence properties, including precise wavelength tuning (530-790 nm), narrow emission linewidths (<100 meV) and high photoluminescence quantum yields (70-90%). However, the controlled formation of blue emitting FAPb(Cl 1-x Br x ) 3 NCs lags behind their green and red counterparts and the mechanism of their formation remains unclear. Herein, we report the formation of FAPb(Cl 1-x Br x ) 3 NCs with stable emission between 440 and 520 nm in a fully automated droplet-based microfluidic reactor and subsequent reaction upscaling in conventional laboratory glassware. The thorough parametric screening allows for the elucidation of parametric zones (FA-to-Pb and Br-to-Cl molar ratios, temperature, and excess oleic acid) for the formation of nanoplatelets and/or NCs. In contrast to CsPb(Cl 1-x Br x ) 3 NCs, based on online parametric screening and offline structural characterization, we demonstrate that the controlled synthesis of Cl-rich perovskites (above 60 at% Cl) with stable emission remains a challenge due to fast segregation of halide ions.

What is the best bonding model of the (σ-H-BR) species bound to a transition metal? Bonding analysis in complexes [(H)2Cl(PMe3)2M(σ-H-BR)] (M = Fe, Ru, Os).

PubMed

Pandey, Krishna K

2012-03-21

Density Functional Theory calculations have been performed for the σ-hydroboryl complexes of iron, ruthenium and osmium [(H)(2)Cl(PMe(3))(2)M(σ-H-BR)] (M = Fe, Ru, Os; R = OMe, NMe(2), Ph) at the BP86/TZ2P/ZORA level of theory in order to understand the interactions between metal and HBR ligands. The calculated geometries of the complexes [(H)(2)Cl(PMe(3))(2)Ru(HBNMe(2))], [(H)(2)Cl(PMe(3))(2)Os(HBR)] (R = OMe, NMe(2)) are in excellent agreement with structurally characterized complexes [(H)(2)Cl(P(i)Pr(3))(2)Os(σ-H-BNMe(2))], [(H)(2)Cl(P(i)Pr(3))(2)Os{σ-H-BOCH(2)CH(2)OB(O(2)CH(2)CH(2))}] and [(H)(2)Cl(P(i)Pr(3))(2)Os(σ-H-BNMe(2))]. The longer calculated M-B bond distance in complex [(H)(2)Cl(PMe(3))(2)M(σ-H-BNMe(2))] are due to greater B-N π bonding and as a result, a weaker M-B π-back-bonding. The B-H2 bond distances reveal that (i) iron complexes contain bis(σ-borane) ligand, (ii) ruthenium complexes contain (σ-H-BR) ligands with a stretched B-H2 bond, and (iii) osmium complexes contain hydride (H2) and (σ-H-BR) ligands. The H-BR ligands in osmium complexes are a better trans-directing ligand than the Cl ligand. Values of interaction energy, electrostatic interaction, orbital interaction, and bond dissociation energy for interactions between ionic fragments are very large and may not be consistent with M-(σ-H-BR) bonding. The EDA as well as NBO and AIM analysis suggest that the best bonding model for the M-σ-H-BR interactions in the complexes [(H)(2)Cl(PMe(3))(2)M(σ-H-BR)] is the interaction between neutral fragments [(H)(2)Cl(PMe(3))(2)M] and [σ-H-BR]. This becomes evident from the calculated values for the orbital interactions. The electron configuration of the fragments which is shown for C in Fig. 1 experiences the smallest change upon the M-σ-H-BR bond formation. Since model C also requires the least amount of electronic excitation and geometry changes of all models given by the ΔE(prep) values, it is clearly the most appropriate choice of interacting fragments. The π-bonding contribution is 14-22% of the total orbital contribution.

Diversity of band gap and photoluminescence properties of lead halide perovskite: A halogen-dependent spectroscopic study

NASA Astrophysics Data System (ADS)

Yu, Wenlei; Jiang, Yunfeng; Zhu, Xiuwei; Luo, Chunhua; Jiang, Kai; Chen, Liangliang; Zhang, Juan

2018-05-01

The effects of halogen substitution on microstructure, optical absorption, and phonon modes for perovskite CH3NH3PbX3 (MAPbX3, X = I/Br/Cl) films grown on FTO substrates have been investigated. The X-ray diffraction analysis exhibited good crystallization, and the strong diffraction peak assigned to (1 0 0) c for X = Br/Cl shifted toward a higher angle compared to (1 1 0) t of MAPbI3. Band-gap tuning from 1.63 to 2.37 to 3.11 eV in the I-Br-Cl series can be found due to the halogen effects. These energy values closely match the positions of peak determined from photoluminescence experiments. The remarkable absorption dip and emission peak appear for the MAPbBr3, suggesting higher crystallinity under the same preparation conditions. The wavenumbers of main IR-vibrations slightly decrease with ionic radius of the halogen increasing (in the order of Cl-Br-I), which related to the increasing polarizability. These results provide important progress towards the understanding of the halide role in the realization of high performance MAPbX3-based solar cells.

On the oxidation of the three-dimensional aromatics [B(12)X(12)](2-) (X=F, Cl, Br, I).

PubMed

Boeré, René T; Derendorf, Janis; Jenne, Carsten; Kacprzak, Sylwia; Kessler, Mathias; Riebau, Rainer; Riedel, Sebastian; Roemmele, Tracey L; Rühle, Monika; Scherer, Harald; Vent-Schmidt, Thomas; Warneke, Jonas; Weber, Stefan

2014-04-07

The perhalogenated closo-dodecaborate dianions [B12 X12 ](2-) (X=H, F, Cl, Br, I) are three-dimensional counterparts to the two-dimensional aromatics C6 X6 (X=H, F, Cl, Br, I). Whereas oxidation of the parent compounds [B12 H12 ](2-) and benzene does not lead to isolable radicals, the perhalogenated analogues can be oxidized by chemical or electrochemical methods to give stable radicals. The chemical oxidation of the closo-dodecaborate dianions [B12 X12 ](2-) with the strong oxidizer AsF5 in liquid sulfur dioxide (lSO2 ) yielded the corresponding radical anions [B12 X12 ](⋅-) (X=F, Cl, Br). The presence of radical ions was proven by EPR and UV/Vis spectroscopy and supported by quantum chemical calculations. Use of an excess amount of the oxidizing agent allowed the synthesis of the neutral perhalogenated hypercloso-boranes B12 X12 (X=Cl, Br). These compounds were characterized by single-crystal X-ray diffraction of dark blue B12 Cl12 and [Na(SO2 )6 ][B12 Br12 ]⋅B12 Br12 . Sublimation of the crude reaction products that contained B12 X12 (X=Cl, Br) resulted in pure dark blue B12 Cl12 or decomposition to red B9 Br9 , respectively. The energetics of the oxidation processes in the gas phase were calculated by DFT methods at the PBE0/def2-TZVPP level of theory. They revealed the trend of increasing ionization potentials of the [B12 X12 ](2-) dianions by going from fluorine to bromine as halogen substituent. The oxidation of all [B12 X12 ](2-) dianions was also studied in the gas phase by mass spectrometry in an ion trap. The electrochemical oxidation of the closo-dodecaborate dianions [B12 X12 ](2-) (X=F, Cl, Br, I) by cyclic and Osteryoung square-wave voltammetry in liquid sulfur dioxide or acetonitrile showed very good agreement with quantum chemical calculations in the gas phase. For [B12 X12 ](2-) (X=F, Cl, Br) the first and second oxidation processes are detected. Whereas the first process is quasi-reversible (with oxidation potentials in the range between +1.68 and +2.29 V (lSO2 , versus ferrocene/ferrocenium (Fc(0/+) ))), the second process is irreversible (with oxidation potentials ranging from +2.63 to +2.71 V (lSO2 , versus Fc(0/+) )). [B12 I12 ](2-) showed a complex oxidation behavior in cyclic voltammetry experiments, presumably owing to decomposition of the cluster anion under release of iodide, which also explains the failure to isolate the respective radical by chemical oxidation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Heterometallic aggregates of copper(I) with metalloligand Sn(edt)2 (edt = ethane-1,2-dithiolate): syntheses and structures of [Sn(edt)2Cl(mu-I)(mu3-I)(CuPPh3)3], [Sn(edt)2(mu-Br)2(mu3-Br)2(CuPPh3)4], and [{Sn(edt)2}3(mu-OH)3Cu5(PPh3)8][PF6]2.

PubMed

Han, Yan-Gong; Xu, Chao; Duan, Taike; Wu, Fang-Hui; Zhang, Qian-Feng; Leung, Wa-Hung

2009-09-21

The treatment of a slurry of an equimolar mixture of [Sn(edt)(2)] (edt = ethane-1,2- dithiolate) and [Et(4)N]Cl.xH(2)O with CuI in the presence of PPh(3) gave a tetranuclear compound, [Sn(edt)(2)Cl(mu-I)(mu(3)-I)(CuPPh(3))(3)] (1), which consists of a rectangular-pyramidal [Sn(edt)(2)Cl](-) moiety ligated by three [Cu(PPh(3))](+) fragments via the sulfur atoms of the edt(2-) ligands. The treatment of a slurry of [Sn(edt)(2)] and excess [Et(4)N]Br with [Cu(MeCN)(4)][PF(6)] in the presence of PPh(3) afforded a pentanuclear compound, [Sn(edt)(2)(mu-Br)(2)(mu(3)-Br)(2)(CuPPh(3))(4)] (2), which comprises two [(CuPPh(3))(2)(mu-Br)](+) fragments symmetrically ligating an octahedral trans-[Sn(edt)(2)Br(2)](2-) moiety via the sulfur and bromide atoms. Reaction of [Sn(edt)(2)] with [Cu(MeCN)(4)][PF(6)] and PPh(3) in a mixed MeCN/CH(2)Cl(2) solution yielded a novel octanuclear compound, [{Sn(edt)(2)}(3)(mu-OH)(3)Cu(5)(PPh(3))(8)][PF(6)](2) (3), which may be described as a triangular [{Sn(edt)(2)}(3)(mu-OH)(3)](3-) core chelated by three [Cu(PPh(3))(2)](+) species and capped by two [Cu(PPh(3))](+) species. The luminescent properties of compounds 1, 2, and 3 were investigated in a CH(2)Cl(2) solution at room temperature. Upon excitation at lambda > 360 nm, these compounds are luminescent in CH(2)Cl(2) solution with emissions having maxima at 422, 515, and 494 nm, respectively.

Two-Dimensional Lead(II) Halide-Based Hybrid Perovskites Templated by Acene Alkylamines: Crystal Structures, Optical Properties, and Piezoelectricity.

PubMed

Du, Ke-Zhao; Tu, Qing; Zhang, Xu; Han, Qiwei; Liu, Jie; Zauscher, Stefan; Mitzi, David B

2017-08-07

A series of two-dimensional (2D) hybrid organic-inorganic perovskite (HOIP) crystals, based on acene alkylamine cations (i.e., phenylmethylammonium (PMA), 2-phenylethylammonium (PEA), 1-(2-naphthyl)methanammonium (NMA), and 2-(2-naphthyl)ethanammonium (NEA)) and lead(II) halide (i.e., PbX 4 2- , X = Cl, Br, and I) frameworks, and their corresponding thin films were fabricated and examined for structure-property relationship. Several new or redetermined crystal structures are reported, including those for (NEA) 2 PbI 4 , (NEA) 2 PbBr 4 , (NMA) 2 PbBr 4 , (PMA) 2 PbBr 4 , and (PEA) 2 PbI 4 . Non-centrosymmetric structures from among these 2D HOIPs were confirmed by piezoresponse force microscopy-especially noteworthy is the structure of (PMA) 2 PbBr 4 , which was previously reported as centrosymmetric. Examination of the impact of organic cation and inorganic layer choice on the exciton absorption/emission properties, among the set of compounds considered, reveals that perovskite layer distortion (i.e., Pb-I-Pb bond angle between adjacent PbI 6 octahedra) has a more global effect on the exciton properties than octahedral distortion (i.e., variation of I-Pb-I bond angles and discrepancy among Pb-I bond lengths within each PbI 6 octahedron). In addition to the characteristic sharp exciton emission for each perovskite, (PMA) 2 PbCl 4 , (PEA) 2 PbCl 4 , (NMA) 2 PbCl 4 , and (PMA) 2 PbBr 4 exhibit separate, broad "white" emission in the long wavelength range. Piezoelectric compounds identified from these 2D HOIPs may be considered for future piezoresponse-type energy or electronic applications.

New molten salt systems for high-temperature molten salt batteries: LiF-LiCl-LiBr-based quaternary systems

NASA Astrophysics Data System (ADS)

Fujiwara, Syozo; Inaba, Minoru; Tasaka, Akimasa

To develop novel multi-component molten salt systems more effectively, we developed a simulative technique using the CALPHAD (Calculation of Phase Diagram and Thermodynamics) method to estimate the ionic conductivity and the melting point. The validity of this new simulative technique was confirmed by comparing the simulated ionic conductivities and melting points of typical high-temperature molten salts, such as LiF-LiCl-LiBr, LiF-LiBr-KBr, LiCl-LiBr-KBr, and LiCl-LiBr-LiI, with those reported data in the literature or experimentally obtained. This simulative technique was used to develop new quaternary molten salt systems for use as electrolytes in high-temperature molten salt batteries (called thermal batteries). The targets of the ionic conductivity and the melting point were set at 2.0 S cm -1 and higher at 500 °C, and in the range of 350-430 °C, respectively, to replace the LiCl-KCl system (1.85 S cm -1 at 500 °C) within the conventional design of the heat generation system for thermal batteries. Using the simulative method, six kinds of novel quaternary systems, LiF-LiCl-LiBr-MX (M = Na and K; X = F, Cl, and Br), which contain neither environmentally instable anions such as iodides nor expensive cations such as Rb + and Cs +, were proposed. Experimental results showed that the LiF-LiCl-LiBr-0.10NaX (X = Cl and Br) and LiF-LiCl-LiBr-0.10KX (X = F, Cl, and Br) systems meet our targets of both the ionic conductivity and the melting point.

Linking precious metal enrichment and halogen cycling in mafic magmatic systems: insights from the Rum layered intrusion, NW Scotland

NASA Astrophysics Data System (ADS)

Kelly, A. P.; O'Driscoll, B.; Clay, P. L.; Burgess, R.

2017-12-01

Layered intrusions host the world's largest known concentrations of the platinum-group elements (PGE). Emphasis has been attached to the role of halogen-bearing fluids in concentrating the precious metals, but whether this occurs at the magmatic stage, or via subsequent metasomatism, is actively debated. One obstacle to progress has been the analytical difficulty of measuring low abundances of the halogens in the cumulate products of layered intrusions. To elucidate the importance of the halogens in facilitating PGE-mineralisation, as well as fingerprint halogen provenance and assess the importance of halogen cycling in mafic magma systems more generally, a suite of samples encompassing different stages of activity of the Palaeogene Rum layered intrusion was investigated. Halogen abundances were measured by neutron irradiation noble gas mass spectrometric analysis, permitting the detection of relatively low (ppm-ppb) abundances of Cl, Br and I in mg-sized samples. The samples include PGE-enriched chromite seams, various cumulates (e.g., peridotites), picrites (approximating the Rum parental magma), and pegmatites representing volatile-rich melts that circulated the intrusion at a late-stage in its solidification history. The new data reveal that PGE-bearing chromite seams contain relatively low Cl concentrations (2-3 ppm), with high molar ratios of Br/Cl and I/Cl (0.005 and 0.009, respectively). The picrites and cumulates have Br/Cl and I/Cl ratios close to sub-continental lithospheric mantle values of approximately 0.0013 and 0.00002, respectively, and thus likely reflect the Rum magma source region. A positive correlation between Cl and Br signifies comparable partitioning behaviour in all samples. However, I is more variable, displaying a positive correlation with Cl for more primitive samples (e.g. picrite and peridotite), and seemingly decoupling from Br and Cl in chromite seams and pegmatites. The relative enrichment of I over Cl in the chromite seams points to the local involvement of an organic-rich sedimentary assimilant and potentially represents an important trigger for PGE-mineralisation. Similarly high I/Cl signatures in some of the late-stage pegmatites suggest that fluids with this distinctive composition circulated the cooling Rum intrusion for a protracted period of time.

Spectrum of excess partial molar absorptivity. Part II: a near infrared spectroscopic study of aqueous Na-halides.

PubMed

Sebe, Fumie; Nishikawa, Keiko; Koga, Yoshikata

2012-04-07

Our earlier thermodynamic studies suggested that F(-) and Cl(-) form hydration shells with the hydration number 14 ± 2 and 2.3 ± 0.6, respectively, and leave the bulk H(2)O away from hydration shells unperturbed. Br(-) and I(-), on the other hand, form hydrogen bonds directly with the momentarily existing hydrogen bond network of H(2)O, and retard the degree of entropy-volume cross fluctuation inherent in liquid H(2)O. The effect of the latter is stronger for I(-) than Br(-). Here we seek additional information about this qualitative difference between Cl(-) and (Br(-) and I(-)) pair by near infrared (NIR) spectroscopy. We analyze the ν(2) + ν(3) band of H(2)O in the range 4600-5500 cm(-1) of aqueous solutions of NaCl, NaBr and NaI, by a new approach. From observed absorbance, we calculate excess molar absorptivity, ε(E), excess over the additive contributions of solute and solvent. ε(E) thus contains information about the effect of inter-molecular interactions in the ν(2) + ν(3) spectrum. The spectrum of ε(E) shows three bands; two negative ones at 5263 and 4873 cm(-1), and the positive band at 5123 cm(-1). We then define and calculate the excess partial molar absorptivity of each salt, ε(E)(salt). From the behaviour of ε(E)(salt) we suggest that the negative band at 5263 cm(-1) represents free H(2)O without much hydrogen bonding under the influence of local electric field of ions. Furthermore, from a sudden change in the x(salt) (mole fraction of salt) dependence of ε(E)(salt), we suggest that there is an ion-pairing in x(salt) > 0.032, 0.036, and 0.04 for NaCl, NaBr and NaI respectively. The positive band of ε(E) at 5123 cm(-1) is attributed to a modestly organized hydrogen bond network of H(2)O (or liquid-likeness), and the x(salt) dependence of ε indicated a qualitative difference in the effect of Cl(-) from those of Br(-) and I(-). Namely, the values of ε(E)(salt) stay constant for Cl(-) but those for Br(-) and I(-) decrease smoothly on increasing the salt mole fraction. The mole fraction dependence of ε(E)(salt) at the 4873 cm(-1) band, due to ice-likeness in H(2)O, shows a subtle difference between Cl(-) and (Br(-), I(-)) pair.

Halogen content in Lesser Antilles arc volcanic rocks : exploring subduction recycling

NASA Astrophysics Data System (ADS)

Thierry, Pauline; Villemant, Benoit; Caron, Benoit

2016-04-01

Halogens (F, Cl, Br and I) are strongly reactive volatile elements which can be used as tracers of igneous processes, through mantle melting, magma differentiation and degassing or crustal material recycling into mantle at subduction zones. Cl, Br and I are higly incompatible during partial melting or fractional cristallization and strongly depleted in melts by H2O degassing, which means that no Cl-Br-I fractionation is expected through magmatic differenciation [current thesis]. Thus, Cl/Br/I ratios in lavas reflect the halogen content of their mantle sources. Whereas these ratios seemed quite constant (e.g. Cl/Br =300 as seawater), recent works suggest significant variations in arc volcanism [1,2]. In this work we provide high-precision halogen measurements in volcanic rocks from the recent activity of the Lesser Antilles arc (Montserrat, Martinique, Guadeloupe, Dominique). Halogen contents of powdered samples were determined through extraction in solution by pyrohydrolysis and analysed by Ion Chromatography for F and Cl and high performance ICP-MS (Agilent 8800 Tripe Quad) for Cl, Br and I [3,4]. We show that lavas - and mantle sources - display significant vraiations in Cl/Br/I ratios along the Lesser Antilles arc. These variations are compared with Pb, Nd and Sr isotopes and fluid-mobile elements (Ba, U, Sr, Pb etc.) compositions which vary along the arc from a nothern ordinary arc compositions to a southern 'crustal-like' composition [5,6]. These characteristics are attributed to subducted sediments recycling into the mantle wedge, whose contribution vary along the arc from north to south [7,8]. The proportion of added sediments is also related to the distance to the trench as sediment melting and slab dehydration may occur depending on the slab depth [9]. Further Cl-Br-I in situ measurements by LA-ICP-MS in Lesser Antilles arc lavas melt inclusions will be performed, in order to provide better constraints on the deep halogen recycling cycle from crust to mantle. 1. Villemant, B., Mouatt, J. & Michel, A., 2008. Earth Planet. Sci. Lett. 269(1), 212-229. 2. Kutterolf, S. et al., 2015. Earth Planet. Sci. Lett. 429, 234-246. 3. Michel, A. & Villemant, B., 2003. Geostand. Geoanalytical Res. 27(2), 163-171. 4. Balcone-Boissard, H., Michel, A. & Villemant, B., 2009. Geostand. Geoanalytical Res. 33(4), 477-485. 5. White, W. M. & Dupré, B., 1986. J. Geophys. Res. 91(B6), 5927. 6. Labanieh, S. et al., 2010. Earth Planet. Sci. Lett. 298(1-2), 35-46. 7. Turner, S. et al., 1996. Earth Planet. Sci. Lett. 142(1-2), 191-207. 8. Carpentier, M., Chauvel, C. & Mattielli, N., 2008. Earth Planet. Sci. Lett. 272(1-2), 199-211. 9. Labanieh, S. et al., 2012. J. Petrol. 53(12), 2441-2464.

The use of functionalized zirconocenes as precursors to silica-supported zirconocene olefin polymerization catalysts

NASA Astrophysics Data System (ADS)

Cheng, Xu

2001-07-01

Me3Si substituents adjacent to Cp2MCl2 (M = Ti, Zr, Hf) are converted to BrMe2Si groups using BBr 3. The high reactivity of the Si-Br bonds toward nucleophiles such as water suggested that these substituents could react with hydroxylated silica surfaces, immobilizing the metallocenes. This dissertation concerns the syntheses of electrophile-functionalized zirconocene dihalide complexes and their use as precursors to silica-supported metallocene olefin polymerization catalysts. First we extended the metallocene "functionalization" chemistry to obtain substituents bearing more than one electrophilic bond. (Me3Sn) 2C5H4 combined with CpZrCl3 in toluene to afford (eta5-Me3Sn-C5H4)CpZrCl 2 (A). Reactions of A with electrophiles (E-X = Cl2B-Cl, I-Cl, and I-I) afforded (eta5-XMe 2Sn-C5H4)CpZrCl2 (and E-Me) cleanly. The reaction of A with BBr3 afforded either (eta5-BrMe2Sn-C5H4)CpZrBr2 (25 °C, 10 min) or (eta5-Br2MeSn-C5H 4)CpZrBr2 (25 °C, 15 h). Ph2MeSi-C5H 4Li combined with ZrCl4•2THF to afford (eta 5-Ph2MeSi-C5H4)2ZrCl 2 (B). The reaction of B with BCl3 led to incomplete cleavage of the Ph-Si bonds, however treatment of B with BBr3 afforded (eta5-Br2MeSi-C 5H4)2ZrBr2 (C) efficiently. X-ray crystal structures of (eta5-ClMe2Sn-C 5H4)CpZrCl2•1/2toluene, (eta 5-Br2MeSn-C5H4)CpZrBr2•THF, B, and C were obtained. Metallocene C reacts with water to afford an oligosiloxane-supported zirconocene dibromide. Spectroscopic characterization suggested a stereoregular structure in which the metallocene units have meso symmetry. The oligomeric substance showed high activity for homogeneous ethylene polymerization. Supported metallocene olefin polymerization catalysts were prepared by combining a functionalized metallocene precursor (Cp2ZrBr 2 bearing either BrMe2Si or Br2MeSi groups) and partially dehydroxylated silica. The activities of the immobilized zirconocene catalysts decreased and the stabilities increased with increasing number of tethers. The immobilized catalyst prepared from (eta5-Br 2MeSi-C5H4)2ZrBr2, which is assumed to form two "double-tethers" to silica, was significantly more active than the catalyst prepared from [eta5-1,3-(BrMe 2Si)2C5H3]2ZrBr2, which is assumed to form four "single-tethers" to silica. Catalyst leaching was observed in all the immobilized zirconocene catalysts. Finally we report model studies on the stability of the Si-O-Si bonds toward methylaluminoxane (MAO). The reaction of (eta5-BrMe 2Si-C5H4)CpZrBr2 with tBuMe 2SiOH results in the formation of Si-O-Si bonds; addition of NEt 3 results in further reaction to afford Si-O-Zr bonds. The reaction of Me3Si-O-SiMe3 with MAO showed that Si-O-Si bonds can be cleaved under the conditions of our polymerization reactions.

First-principles thermodynamics study of phase stability in inorganic halide perovskite solid solutions

NASA Astrophysics Data System (ADS)

Bechtel, Jonathon S.; Van der Ven, Anton

2018-04-01

Halide substitution gives rise to a tunable band gap as a function of composition in halide perovskite materials. However, photoinduced phase segregation, observed at room temperature in mixed halide A Pb (IxBr1-x) 3 systems, limits open circuit voltages and decreases photovoltaic device efficiencies. We investigate equilibrium phase stability of orthorhombic P n m a γ -phase CsM (XxY1-x) 3 perovskites where M is Pb or Sn, and X and Y are Br, Cl, or I. Finite-temperature phase diagrams are constructed using a cluster expansion effective Hamiltonian parameterized from first-principles density-functional-theory calculations. Solid solution phases for CsM (IxBr1-x) 3 and CsM (BrxCl1-x) 3 are predicted to be stable well below room temperature while CsM (IxCl1-x) 3 systems have miscibility gaps that extend above 400 K. The height of the miscibility gap correlates with the difference in volume between end members. Also layered ground states are found on the convex hull at x =2 /3 for CsSnBr2Cl ,CsPbI2Br , and CsPbBrCl2. The impact of these ground states on the finite temperature phase diagram is discussed in the context of the experimentally observed photoinduced phase segregation.

UV photolysis of 4-iodo-, 4-bromo-, and 4-chlorophenol: Competition between C-Y (Y = halogen) and O-H bond fission

NASA Astrophysics Data System (ADS)

Sage, Alan G.; Oliver, Thomas A. A.; King, Graeme A.; Murdock, Daniel; Harvey, Jeremy N.; Ashfold, Michael N. R.

2013-04-01

The wavelength dependences of C-Y and O-H bond fission following ultraviolet photoexcitation of 4-halophenols (4-YPhOH) have been investigated using a combination of velocity map imaging, H Rydberg atom photofragment translational spectroscopy, and high level spin-orbit resolved electronic structure calculations, revealing a systematic evolution in fragmentation behaviour across the series Y = I, Br, Cl (and F). All undergo O-H bond fission following excitation at wavelengths λ ≲ 240 nm, on repulsive ((n/π)σ*) potential energy surfaces (PESs), yielding fast H atoms with mean kinetic energies ˜11 000 cm-1. For Y = I and Br, this process occurs in competition with prompt C-I and C-Br bond cleavage on another (n/π)σ* PES, but no Cl/Cl* products unambiguously attributable to one photon induced C-Cl bond fission are observed from 4-ClPhOH. Differences in fragmentation behaviour at longer excitation wavelengths are more marked. Prompt C-I bond fission is observed following excitation of 4-IPhOH at all λ ≤ 330 nm; the wavelength dependent trends in I/I* product branching ratio, kinetic energy release, and recoil anisotropy suggest that (with regard to C-I bond fission) 4-IPhOH behaves like a mildly perturbed iodobenzene. Br atoms are observed when exciting 4-BrPhOH at long wavelengths also, but their velocity distributions suggest that dissociation occurs after internal conversion to the ground state. O-H bond fission, by tunnelling (as in phenol), is observed only in the cases of 4-FPhOH and, more weakly, 4-ClPhOH. These observed differences in behaviour can be understood given due recognition of (i) the differences in the vertical excitation energies of the C-Y centred (n/π)σ* potentials across the series Y = I < Br < Cl and the concomitant reduction in C-Y bond strength, cf. that of the rival O-H bond, and (ii) the much increased spin-orbit coupling in, particularly, 4-IPhOH. The present results provide (another) reminder of the risks inherent in extrapolating photochemical behaviour measured for one molecule at one wavelength to other (related) molecules and to other excitation energies.

Tests of halogen photochemistry using in situ measurements of ClO and BrO in the lower polar stratosphere

NASA Astrophysics Data System (ADS)

Avallone, Linnea M.; Toohey, Darin W.

2001-05-01

In situ observations of the halogen oxides ClO and BrO made from the NASA ER-2 during the Airborne Arctic Stratospheric Expedition (AASE) I and II missions are used to test current understanding of photochemical parameters. Measurements of ClO obtained during AASE I in the dark perturbed polar vortex are analyzed with respect to temperature to derive the equilibrium expression for the ClO/Cl2O2 system. Assuming photochemical steady state and complete activation of chlorine (ClO + 2Cl2O2 = Cly), observations of ClO made during AASE II are used to derive the photolysis rate of Cl2O2. The photolysis rate derived from atmospheric observations is compared to J values calculated with a photochemical model and various values for the absorption cross section of Cl2O2. The photolysis rate calculated with the cross section of Huder and DeMore [1995] is shown to be systematically too small, while those of Burkholder et al. [1990] and Cox and Hayman [1988] are too large to be consistent with atmospheric observations. Observations of BrO made during AASE II indicate that our understanding of the inorganic bromine budget in the polar regions is incomplete. A possible role for the adduct BrOOCl is investigated.

Characterization and identification of Na-Cl sources in ground water

USGS Publications Warehouse

Panno, S.V.; Hackley, Keith C.; Hwang, H.-H.; Greenberg, S.E.; Krapac, I.G.; Landsberger, S.; O'Kelly, D. J.

2006-01-01

Elevated concentrations of sodium (Na+) and chloride (Cl -) in surface and ground water are common in the United States and other countries, and can serve as indicators of, or may constitute, a water quality problem. We have characterized the most prevalent natural and anthropogenic sources of Na+ and Cl- in ground water, primarily in Illinois, and explored techniques that could be used to identify their source. We considered seven potential sources that included agricultural chemicals, septic effluent, animal waste, municipal landfill leachate, sea water, basin brines, and road deicers. The halides Cl-, bromide (Br-), and iodide (I-) were useful indicators of the sources of Na+-Cl- contamination. Iodide enrichment (relative to Cl-) was greatest in precipitation, followed by uncontaminated soil water and ground water, and landfill leachate. The mass ratios of the halides among themselves, with total nitrogen (N), and with Na+ provided diagnostic methods for graphically distinguishing among sources of Na+ and Cl- in contaminated water. Cl/Br ratios relative to Cl- revealed a clear, although overlapping, separation of sample groups. Samples of landfill leachate and ground water known to be contaminated by leachate were enriched in I- and Br-; this provided an excellent fingerprint for identifying leachate contamination. In addition, total N, when plotted against Cl/Br ratios, successfully separated water contaminated by road salt from water contaminated by other sources. Copyright ?? 2005 National Ground Water Association.

The subtle balance of weak supramolecular interactions: The hierarchy of halogen and hydrogen bonds in haloanilinium and halopyridinium salts.

PubMed

Raatikainen, Kari; Cametti, Massimo; Rissanen, Kari

2010-01-15

THE SERIES OF HALOANILINIUM AND HALOPYRIDINIUM SALTS: 4-IPhNH₃Cl (1), 4-IPhNH₃Br (5), 4-IPhNH₃H₂PO₄ (6), 4-ClPhNH₃H₂PO₄ (8), 3-IPyBnCl (9), 3-IPyHCl (10) and 3-IPyH-5NIPA (3-iodopyridinium 5-nitroisophthalate, 13), where hydrogen or/and halogen bonding represents the most relevant non-covalent interactions, has been prepared and characterized by single crystal X-ray diffraction. This series was further complemented by extracting some relevant crystal structures: 4-BrPhNH₃Cl (2, CCDC ref. code TAWRAL), 4-ClPhNH₃Cl (3, CURGOL), 4-FPhNH₃Cl (4, ANLCLA), 4-BrPhNH₃H₂PO₄, (7, UGISEI), 3-BrPyHCl, (11, CIHBAX) and 3-ClPyHCl, (12, VOQMUJ) from Cambridge Structural Database for sake of comparison. Based on the X-ray data it was possible to highlight the balance between non-covalent forces acting in these systems, where the relative strength of the halogen bonding C-X...A⁻ (X = I, Br or Cl) and the ratio between the halogen and hydrogen bonds [C-X...A⁻ : D-H...A⁻] varied across the series.

Post-synthetic halide conversion and selective halogen capture in hybrid perovskites† †Electronic supplementary information (ESI) available. CCDC 1048945–1048947. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5sc01135c

PubMed Central

Solis-Ibarra, D.; Smith, I. C.

2015-01-01

Reaction with halogen vapor allows us to post-synthetically exchange halides in both three- (3D) and two-dimensional (2D) organic–inorganic metal-halide perovskites. Films of 3D Pb–I perovskites cleanly convert to films of Pb–Br or Pb–Cl perovskites upon exposure to Br2 or Cl2 gas, respectively. This gas–solid reaction provides a simple method to produce the high-quality Pb–Br or Pb–Cl perovskite films required for optoelectronic applications. Reactivity with halogens can be extended to the organic layers in 2D metal-halide perovskites. Here, terminal alkene groups placed between the inorganic layers can capture Br2 gas through chemisorption to form dibromoalkanes. This reaction's selectivity for Br2 over I2 allows us to scrub Br2 to obtain high-purity I2 gas streams. We also observe unusual halogen transfer between the inorganic and organic layers within a single perovskite structure. Remarkably, the perovskite's crystallinity is retained during these massive structural rearrangements. PMID:29218171

Oxidation of methyl halides by the facultative methylotroph strain IMB-1

USGS Publications Warehouse

Schaefer, J.K.; Oremland, R.S.

1999-01-01

Washed cell suspensions of the facultative methylotroph strain IMB-1 grown on methyl bromide (MeBr) were able to consume methyl chloride (MeCl) and methyl iodide (MeI) as well as MeBr. Consumption of >100 ??M MeBr by cells grown on glucose, acetate, or monomethylamine required induction. Induction was inhibited by chloramphenicol. However, cells had a constitutive ability to consume low concentrations (<20 nM) of MeBr. Glucose-grown cells were able to readily oxidize [14C]formaldehyde to 14CO2 but had only a small capacity for oxidation of [14C]methanol. Preincubation of cells with MeBr did not affect either activity, but MeBr-induced cells had a greater capacity for [14C]MeBr oxidation than did cells without preincubation. Consumption of MeBr was inhibited by MeI, and MeCl consumption was inhibited by MeBr. No inhibition of MeBr consumption occurred with methyl fluoride, propyl iodide, dibromomethane, dichloromethane, or difluoromethane, and in addition cells did not oxidize any of these compounds. Cells displayed Michaelis-Menten kinetics for the various methyl halides, with apparent K(s) values of 190, 280, and 6,100 nM for MeBr, MeI, and MeCl, respectively. These results suggest the presence of a single oxidation enzyme system specific for methyl halides (other than methyl fluoride) which runs through formaldehyde to CO2. The ease of induction of methyl halide oxidation in strain IMB-1 should facilitate its mass culture for the purpose of reducing MeBr emissions to the atmosphere from fumigated soils.

Photoelectron spectroscopy of aqueous solutions: Streaming potentials of NaX (X = Cl, Br, and I) solutions and electron binding energies of liquid water and X{sup −}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kurahashi, Naoya; Horio, Takuya; Suzuki, Toshinori, E-mail: suzuki@kuchem.kyoto-u.ac.jp

2014-05-07

The streaming potentials of liquid beams of aqueous NaCl, NaBr, and NaI solutions are measured using soft X-ray, He(I), and laser multiphoton ionization photoelectron spectroscopy. Gaseous molecules are ionized in the vicinity of liquid beams and the photoelectron energy shifts are measured as a function of the distance between the ionization point and the liquid beam. The streaming potentials change their polarity with concentration of electrolytes, from which the singular points of concentration eliminating the streaming potentials are determined. The streaming currents measured in air also vanish at these concentrations. The electron binding energies of liquid water and I{sup −},more » Br{sup −}, and Cl{sup −} anions are revisited and determined more accurately than in previous studies.« less

Comprehensive theoretical studies on the low-lying electronic states of NiF, NiCl, NiBr, and NiI.

PubMed

Zou, Wenli; Liu, Wenjian

2006-04-21

The low-lying electronic states of the nickel monohalides, i.e., NiF, NiCl, NiBr, and NiI, are investigated by using multireference second-order perturbation theory with relativistic effects taken into account. For the energetically lowest 11 lambda-S states and 26 omega states there into, the potential energy curves and corresponding spectroscopic constants (vertical and adiabatic excitation energies, equilibrium bond lengths, vibrational frequencies, and rotational constants) are reported. The calculated results are grossly in very good agreement with those solid experimental data. In particular, the ground state of NiI is shown to be different from those of NiF, NiCl, and NiBr, being in line with the recent experimental observation. Detailed analyses are provided on those states that either have not been assigned or have been incorrectly assigned by previous experiments.

Electron affinity of perhalogenated benzenes: A theoretical DFT study

NASA Astrophysics Data System (ADS)

Volatron, François; Roche, Cécile

2007-10-01

The potential energy surfaces (PES) of unsubstituted and perhalogenated benzene anions ( CX6-, X = F, Cl, Br, and I) were explored by means of DFT-B3LYP calculations. In the F and Cl cases seven extrema were located and characterized. In the Br and I cases only one minimum and two extrema were found. In each case the minimum was recomputed at the CCSD(T) level. The electron affinities of C 6X 6 were calculated (ZPE included). The results obtained agree well with the experimental determinations when available. The values obtained in the X = Br and the X = I cases are expected to be valuable predictions.

Photoproduction of I2, Br2, and Cl2 on n-semiconducting powder

NASA Technical Reports Server (NTRS)

Reichman, B.; Byvik, C. E.

1981-01-01

The photosynthetic production of Br2 and Cl2 and the photocatalytic production of I2 from aqueous solutions of the respective halide ions in the presence of platinized semiconducting n-TiO2 powder are reported. Reactions were produced in 2-3 M oxygen-saturated aqueous solutions of KI, KBr or NaCl containing Pt-TiO2 powder which were irradiated by a high-pressure mercury lamp at a power of 400 mW/sq cm. Halogens are found to be produced in greater quantities when platinized TiO2 powders are used rather than pure TiO2, and rates of halogen production are observed to increase from Cl2 to Br2 to I2. The presence of the synthetic reactions producing Br2 and Cl2 with a net influx of energy indicates that an effective separation of the photoproduced electron-hole pair occurs in the semiconductor. Quantum efficiencies of the reaction, which increase with decreasing solution pH, are found to be as high as 30%, implying a solar-to-chemical energy conversion efficiency between 0.03% and 3% for the case of chlorine production. It is concluded that the photoproduction of halogens may be of practical value if product halogens are efficiently removed from the reaction cell.

Substitution and Redox Chemistry of [Bu(4)N](2)[Ta(6)Cl(12)(OSO(2)CF(3))(6)].

PubMed

Prokopuk, Nicholas; Kennedy, Vance O.; Stern, Charlotte L.; Shriver, Duward F.

1998-09-21

Two sequential electrochemical reductions occur for the cluster anion [Ta(6)Cl(12)(OSO(2)CF(3))(6)](2)(-) at 0.89 and 0.29 V vs Ag/AgCl, with the generation [Ta(6)Cl(12)(OSO(2)CF(3))(6)](3)(-) and [Ta(6)Cl(12)(OSO(2)CF(3))(6)](4)(-). Chemical reduction of [Ta(6)Cl(12)(OSO(2)CF(3))(6)](2)(-) by ferrocene produces [Ta(6)Cl(12)(OSO(2)CF(3))(6)](3)(-) with the concomitant shift of the nu(SO(2)) stretch from 1002 to 1018 cm(-)(1). Reaction of [Bu(4)N](2)[Ta(6)Cl(12)(OSO(2)CF(3))(6)] (1) with [Bu(4)N]X (X = Cl, Br, I, NCS) occurs by reduction and substitution, yielding [Bu(4)N](3)[Ta(6)Cl(12)X(6)], where the clusters with X = Br, I, and NCS are new. Spectroscopic (IR and UV-vis) evidence indicates that the reduced cluster core {Ta(6)Cl(12)}(2+) is produced in reaction mixtures of 1 with the halide and pseudohalide ions. Concomitant substitution of the triflate ligands of 1 by X(-) occurs and the rates for the overall reduction and substitution increase in the order X(-) = Cl(-) < Br(-) < NCS(-) < I(-) < CN(-). Reduction of 1 with ferrocene followed by addition of [Bu(4)N]O(2)CCH(3) produces the new cluster [Ta(6)Cl(12)(O(2)CCH(3))(6)](3)(-) isolated as the tetrabutylammonium salt. Cyclic voltammetry and UV-vis spectroscopy on the new clusters [Bu(4)N](3)[Ta(6)Cl(12)X(6)] (X = Br, I, NCS, and O(2)CCH(3)) are reported. Crystal data for [Bu(4)N](3)[Ta(6)Cl(12)(NCS)(6)].CH(2)Cl(2): monoclinic, space group, P2(1)/c (No. 14); a = 25.855(6) Å, b = 21.843(6) Å, c = 16.423(3) Å; beta = 100.03(2) degrees; V = 9133(3) Å(3); Z = 4.

A spectrophotometric study of aqueous Au(III) halide-hydroxide complexes at 25-80 °C

NASA Astrophysics Data System (ADS)

Usher, Al; McPhail, D. C.; Brugger, Joël

2009-06-01

The mobility and transport of gold in low-temperature waters and brines is affected by the aqueous speciation of gold, which is sensitive in particular to pH, oxidation and halide concentrations. In this study, we use UV-Vis spectrophotometry to identify and measure the thermodynamic properties of Au(III) aqueous complexes with chloride, bromide and hydroxide. Au(III) forms stable square planar complexes with hydroxide and halide ligands. Based on systematic changes in the absorption spectra of solutions in three binary systems NaCl-NaBr, NaCl-NaOH and NaBr-NaOH at 25 °C, we derived log dissociation constants for the following mixed and end-member halide and hydroxide complexes: [AuCl 3Br] -, [AuCl 2Br 2] -, [AuBr 3Cl] - and [AuBr 4] -; [AuCl 3(OH)] -, [AuCl 2(OH) 2] -, [AuCl(OH) 3] - and [Au(OH) 4] -; and [AuBr 3(OH)] -, [AuBr 2(OH) 2] - and [AuBr(OH) 3] -. These are the first reported results for the mixed chloride-bromide complexes. Increasing temperature to 80 °C resulted in an increase in the stability of the mixed chloride-bromide complexes, relative to the end-member chloride and bromide complexes. For the [AuCl (4-n)(OH) n] - series of complexes ( n = 0-4), there is an excellent agreement between our spectrophotometric results and previous electrochemical results of Chateau et al. [Chateau et al. (1966)]. In other experiments, the iodide ion (I -) was found to be unstable in the presence of Au(III), oxidizing rapidly to I 2(g) and causing Au to precipitate. Predicted Au(III) speciation indicates that Au(III) chloride-bromide complexes can be important in transporting gold in brines with high bromide-chloride ratios (e.g., >0.05), under oxidizing (atmospheric), acidic (pH < 5) conditions. Native gold solubility under atmospheric oxygen conditions is predicted to increase with decreasing pH in acidic conditions, increasing pH in alkaline conditions, increasing chloride, especially at acid pH, and increasing bromide for bromide/chloride ratios greater than 0.05. The results of our study increase the understanding of gold aqueous geochemistry, with the potential to lead to new methods for mineral exploration, hydrometallurgy and medicine.

Molecular simulations and density functional theory calculations of bromine in clathrate hydrate phases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dureckova, Hana, E-mail: houci059@uottawa.ca; Woo, Tom K., E-mail: tom.woo@uottawa.ca; Alavi, Saman, E-mail: saman.alavi@nrc-cnrc.gc.ca

Bromine forms a tetragonal clathrate hydrate structure (TS-I) very rarely observed in clathrate hydrates of other guest substances. The detailed structure, energetics, and dynamics of Br{sub 2} and Cl{sub 2} in TS-I and cubic structure I (CS-I) clathrate hydrates are studied in this work using molecular dynamics and quantum chemical calculations. X-ray diffraction studies show that the halogen-water–oxygen distances in the cages of these structures are shorter than the sum of the van der Waals radii of halogen and oxygen atoms. This suggests that the stabilizing effects of halogen bonding or other non-covalent interactions (NCIs) may contribute to the formationmore » of the unique tetragonal bromine hydrate structure. We performed molecular dynamics simulations of Br{sub 2} and Cl{sub 2} clathrate hydrates using our previously developed five-site charge models for the dihalogen molecules [Dureckova et al. Can. J. Chem. 93, 864 (2015)] which reproduce the computed electrostatic potentials of the dihalogens and account for the electropositive σ-hole of the halogen bond donor (the dihalogen). Analysis of the radial distribution functions, enthalpies of encapsulation, velocity and orientation autocorrelation functions, and polar angle distributions are carried out for Br{sub 2} and Cl{sub 2} guests in various cages to contrast the properties of these guests in the TS-I and CS-I phases. Quantum chemical partial geometry optimizations of Br{sub 2} and Cl{sub 2} guests in the hydrate cages using the M06-2X functional give short halogen-water distances compatible with values observed in X-ray diffraction experiments. NCI plots of guest-cage structures are generated to qualitatively show the relative strength of the non-bonding interactions between dihalogens and water molecules. The differences between behaviors of Br{sub 2} and Cl{sub 2} guests in the hydrate cages may explain why bromine forms the unique TS-I phase.« less

The synthesis of PNP-supported low-spin nitro manganese(I) carbonyl complexes

DOE PAGES

Tondreau, Aaron M.; Boncella, James M.

2016-09-01

In this study, the coordination chemistry of Mn(CO) 5Br was investigated with a series of PNP-pincer ligands. The ligands iPrPONOP ( iPrPONOP = 2,6-bis(diisopropylphosphinito)pyridine) and iPrPN HP ( iPrPN HP = HN{CH 2CH 2(PiPr 2)} 2) gave the desired organometallic manganese complexes ( iPrPONOP)Mn(CO) 2Br and ( iPrPN HP)Mn(CO) 2Br, respectively, upon chelation to Mn(CO) 5Br. The reactivity of iPrPNNNP ( iPrPNNNP = N,N'-bis(diisopropylphosphino)-2,6-diaminopyridine) with Mn(CO) 5Br yielded a pair of products, [( iPrPNNNP)Mn(CO) 3][Br] and ( iPrPNNNCO)Mn(CO) 3. The formation of the asymmetric chelate arises from a formal loss of iPr 2PBr and C–N bond formation from a carbonylmore » ligand and NH, yielding a Mn(I) amide core. The nitration reactions of ( iPrPONOP)Mn(CO) 2Br and ( iPrPN HP)Mn(CO) 2Br were carried out using silver nitrite, yielding the nitro compounds ( iPrPONOP)Mn(CO) 2(NO 2) and ( iPrPN HP)Mn(CO) 2(NO 2), respectively. The analogous iron complex ( iPrPONOP)Fe(CO)Cl 2 was nitrated under the same conditions to yield the salt pair [( iPrPONOP)Fe(CO) 2][FeCl 3NO]. This reactivity underlines the difference between iso-valent iron and manganese centers. The manganese complexes ( iPrPONOP)Mn(CO) 2(NO 2) and ( iPrPN HP)Mn(CO) 2(NO 2) were ineffective as oxygen atom transfer reagents for a variety of substrates.« less

Expanding the Chemistry of Actinide Metallocene Bromides. Synthesis, Properties and Molecular Structures of the Tetravalent and Trivalent Uranium Bromide Complexes: (C 5Me 4R) 2UBr 2, (C 5Me 4R) 2U(O-2,6- iPr 2C 6H 3)(Br), and [K(THF)][(C 5Me 4R) 2UBr 2] (R = Me, Et)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lichtscheidl, Alejandro Gaston; Pagano, Justin K.; Scott, Brian Lindley

The organometallic uranium species (C 5Me 4R) 2UBr 2 (R = Me, Et) were obtained by treating their chloride analogues (C 5Me 4R) 2UCl 2 (R = Me, Et) with Me 3SiBr. Treatment of (C 5Me 4R) 2UCl 2 and (C 5Me 4R) 2UBr 2 (R = Me, Et) with K(O-2,6- iPr 2C 6H 3) afforded the halide aryloxide mixed-ligand complexes (C 5Me 4R) 2U(O-2,6- iPr 2C 6H 3)(X) (R = Me, Et; X = Cl, Br). Complexes (C 5Me 4R) 2U(O-2,6- iPr 2C 6H 3)(Br) (R = Me, Et) can also be synthesized by treating (C 5Me 4R) 2U(O-2,6-more » iPr 2C 6H 3)(Cl) (R = Me, Et) with Me 3SiBr, respectively. Reduction of (C 5Me 4R) 2UCl 2 and (C 5Me 4R) 2UBr 2 (R = Me, Et) with KC 8 led to isolation of uranium(III) “ate” species [K(THF)][(C 5Me 5) 2UX 2] (X = Cl, Br) and [K(THF) 0.5][(C 5Me 4Et) 2UX 2] (X = Cl, Br), which can be converted to the neutral complexes (C 5Me 4R) 2U[N(SiMe 3) 2] (R = Me, Et). Analyses by nuclear magnetic resonance spectroscopy, X-ray crystallography, and elemental analysis are also presented.« less

Expanding the Chemistry of Actinide Metallocene Bromides. Synthesis, Properties and Molecular Structures of the Tetravalent and Trivalent Uranium Bromide Complexes: (C 5Me 4R) 2UBr 2, (C 5Me 4R) 2U(O-2,6- iPr 2C 6H 3)(Br), and [K(THF)][(C 5Me 4R) 2UBr 2] (R = Me, Et)

DOE PAGES

Lichtscheidl, Alejandro Gaston; Pagano, Justin K.; Scott, Brian Lindley; ...

2016-01-06

The organometallic uranium species (C 5Me 4R) 2UBr 2 (R = Me, Et) were obtained by treating their chloride analogues (C 5Me 4R) 2UCl 2 (R = Me, Et) with Me 3SiBr. Treatment of (C 5Me 4R) 2UCl 2 and (C 5Me 4R) 2UBr 2 (R = Me, Et) with K(O-2,6- iPr 2C 6H 3) afforded the halide aryloxide mixed-ligand complexes (C 5Me 4R) 2U(O-2,6- iPr 2C 6H 3)(X) (R = Me, Et; X = Cl, Br). Complexes (C 5Me 4R) 2U(O-2,6- iPr 2C 6H 3)(Br) (R = Me, Et) can also be synthesized by treating (C 5Me 4R) 2U(O-2,6-more » iPr 2C 6H 3)(Cl) (R = Me, Et) with Me 3SiBr, respectively. Reduction of (C 5Me 4R) 2UCl 2 and (C 5Me 4R) 2UBr 2 (R = Me, Et) with KC 8 led to isolation of uranium(III) “ate” species [K(THF)][(C 5Me 5) 2UX 2] (X = Cl, Br) and [K(THF) 0.5][(C 5Me 4Et) 2UX 2] (X = Cl, Br), which can be converted to the neutral complexes (C 5Me 4R) 2U[N(SiMe 3) 2] (R = Me, Et). Analyses by nuclear magnetic resonance spectroscopy, X-ray crystallography, and elemental analysis are also presented.« less

Elastic collisions of low-energy electrons with SiY4 (Y = Cl, Br, I) molecules

NASA Astrophysics Data System (ADS)

Bettega, M. H. F.

2011-11-01

We employed the Schwinger multichannel method to compute elastic integral, differential, and momentum transfer cross sections for low-energy electron collisions with SiY4 (Y = Cl, Br, I) molecules. The calculations were carried out in the static-exchange and static-exchange plus polarization approximations for energies up to 10 eV. The elastic integral cross section for SiCl4 and SiBr4, computed in the static-exchange plus polarization approximation, shows two shape resonances belonging to the T2 and E symmetries of the Td group, and for SiI4 shows one shape resonance belonging to the E symmetry of the Td group. The present results agree well in shape with experimental total cross sections. The positions of the resonances observed in the calculated integral cross sections are also in agreement with the experimental positions. We have found the presence of a virtual state for SiCl4 and a Ramsauer-Townsend minimum for SiI4 at 0.5 eV. The present results show that the proper inclusion of polarization effects is crucial in order to correctly describe the resonance spectra of these molecules and also to identify a Ramsauer-Townsend minimum for SiI4 and a virtual state for SiCl4.

Kinetics of the Reactions of O((sup 3)P) and Cl((sup 2)P) with HBr and Br2

NASA Technical Reports Server (NTRS)

Nicovich, J. M.; Wine, P. H.

1997-01-01

A laser flash photolysis-resonance fluorescence technique has been employed to study the kinetics of reactions (1)-(4) as a function of temperature. (1) O((sup 3)P) + Br2 yields BrO + Br((sup 2)P(sub 3/2)) at 255-350 K; (2) Cl((sup 2)P) + Br2 yields BrCl + Br((sup 2)P(sub 3/2)) at 298-401 K; (3) O((sup 3)P) + HBr yields OH + Br((sup 2)P(sub J)) at 250-402 K; (4) Cl((sup 2)P) + HBr yields HCl + Br((sup 2)P(sub J)) at 257-404 K. In all cases, the concentration of the excess reagent, i.e, HBr or Br2, was measured in situ in the slow flow system by UV-visible photometry. Heterogeneous dark reactions between XBr (X equals H or Br) and the photolytic precursors for Cl((sup 2)P) and O((sup 3)P) (Cl2 and O3, respectively) were avoided by injecting minimal amounts of precursor into the reaction mixture immediately upstream from the reaction zone. The following Arrhenius expressions summarize our results (errors are 2 sigma and represent precision only, units are cu cm/(molecule.s): k(sub 1) = (1.76 +/- 0.80) x 10(exp -11 exp[(40 +/- 100)/T]; k(sub 2) = (2.40 +/- 1.25) x 12(exp -10) exp[-(144 +/- 176)/T]; k(sub 3) = (5.11 +/- 2.82) x 10(exp -12) exp[-(1450 +/- 160)/T]; k(sub 4) = (2.25 +/- 0.56) x 10(exp -11) exp[-(400 +/- 80)/T]. The consistency (or lack thereof) of our results with those reported in previous kinetics and dynamics studies of reactions (1)-(4) is discussed.

Four new chalcohalides, NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br and CsBa{sub 2}SnS{sub 4}Cl: Syntheses, crystal structures and optical properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Chao; Feng, Kai; Tu, Heng

Four new chalcohalides, namely NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br, and CsBa{sub 2}SnS{sub 4}Cl, have been synthesized by the conventional high temperature solid-state reactions. They crystallize in three different space groups: space group I4/mcm for NaBa{sub 2}SnS{sub 4}Cl and KBa{sub 2}SnS{sub 4}Cl, Pnma for KBa{sub 2}SnS{sub 4}Br, and P2{sub 1}/c for CsBa{sub 2}SnS{sub 4}Cl. In all four compounds, the X{sup −} halide anions are only connected to six alkali metal or Ba cations, and the Sn atoms are only tetrahedrally enjoined to four S atoms. However, the M–X–Ba pseudo layers and the SnS{sub 4} tetrahedra are arrangedmore » in different ways in the three structural types, which demonstrates the interesting effect of ionic radii on the crystal structures. UV–vis–NIR spectroscopy measurements indicate that NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br, and CsBa{sub 2}SnS{sub 4}Cl have band gaps of 2.28, 2.30, 1.95, and 2.06 eV, respectively. - Graphical abstract: A new series of chalcohalides, NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br and CsBa{sub 2}SnS{sub 4}Cl have been obtained. They present three different space groups: NaBa{sub 2}SnS{sub 4}Cl and KBa{sub 2}SnS{sub 4}Cl in space group I4/mcm, KBa{sub 2}SnS{sub 4}Br in Pnma and CsBa{sub 2}SnS{sub 4}Cl in space group P2{sub 1}/c. UV–vis–NIR spectroscopy measurements indicate that NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br and CsBa{sub 2}SnS{sub 4}Cl have band gaps of 2.28, 2.30 1.95, and 2.06 eV, respectively. - Highlights: • Four new chalcohalides, NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br and CsBa{sub 2}SnS{sub 4}Cl were obtained. • They adopt three different structures owing to different ionic radii and elemental electronegativity. • NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br and CsBa{sub 2}SnS{sub 4}Cl have band gaps of 2.28, 2.30 1.95, and 2.06 eV, respectively.« less

Evidence for Interfacial Halogen Bonding.

PubMed

Swords, Wesley B; Simon, Sarah J C; Parlane, Fraser G L; Dean, Rebecca K; Kellett, Cameron W; Hu, Ke; Meyer, Gerald J; Berlinguette, Curtis P

2016-05-10

A homologous series of donor-π-acceptor dyes was synthesized, differing only in the identity of the halogen substituents about the triphenylamine (TPA; donor) portion of each molecule. Each Dye-X (X=F, Cl, Br, and I) was immobilized on a TiO2 surface to investigate how the halogen substituents affect the reaction between the light-induced charge-separated state, TiO2 (e(-) )/Dye-X(+) , with iodide in solution. Transient absorption spectroscopy showed progressively faster reactivity towards nucleophilic iodide with more polarizable halogen substituents: Dye-F < Dye-Cl < Dye-Br < Dye-I. Given that all other structural and electronic properties for the series are held at parity, with the exception of an increasingly larger electropositive σ-hole on the heavier halogens, the differences in dye regeneration kinetics for Dye-Cl, Dye-Br, and Dye-I are ascribed to the extent of halogen bonding with the nucleophilic solution species. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gold(I) and Gold(III) Complexes of Cyclic (Alkyl)(amino)carbenes

PubMed Central

2016-01-01

The chemistry of Au(I) complexes with two types of cyclic (alkyl)(amino)carbene (CAAC) ligands has been explored, using the sterically less demanding dimethyl derivative Me2CAAC and the 2-adamantyl ligand AdCAAC. The conversion of (AdCAAC)AuCl into (AdCAAC)AuOH by treatment with KOH is significantly accelerated by the addition of tBuOH. (AdCAAC)AuOH is a convenient starting material for the high-yield syntheses of (AdCAAC)AuX complexes by acid/base and C–H activation reactions (X = OAryl, CF3CO2, N(Tf)2, C2Ph, C6F5, C6HF4, C6H2F3, CH2C(O)C6H4OMe, CH(Ph)C(O)Ph, CH2SO2Ph), while the cationic complexes [(AdCAAC)AuL]+ (L = CO, CNtBu) and (AdCAAC)AuCN were obtained by chloride substitution from (AdCAAC)AuCl. The reactivity toward variously substituted fluoroarenes suggests that (AdCAAC)AuOH is able to react with C–H bonds with pKa values lower than about 31.5. This, together with the spectroscopic data, confirm the somewhat stronger electron-donor properties of CAAC ligands in comparison to imidazolylidene-type N-heterocyclic carbenes (NHCs). In spite of this, the oxidation of Me2CAAC and AdCAAC gold compounds is much less facile. Oxidations proceed with C–Au cleavage by halogens unless light is strictly excluded. The oxidation of (AdCAAC)AuCl with PhICl2 in the dark gives near-quantitative yields of (AdCAAC)AuCl3, while [Au(Me2CAAC)2]Cl leads to trans-[AuCl2(Me2CAAC)2]Cl. In contrast to the chemistry of imidazolylidene-type gold NHC complexes, oxidation products containing Au–Br or Au–I bonds could not be obtained; whereas the reaction with CsBr3 cleaves the Au–C bond to give mixtures of [AdCAAC-Br]+[AuBr2]− and [(AdCAAC-Br)]+ [AuBr4]−, the oxidation of (AdCAAC)AuI with I2 leads to the adduct (AdCAAC)AuI·I2. Irrespective of the steric demands of the CAAC ligands, their gold complexes proved more resistant to oxidation and more prone to halogen cleavage of the Au–C bonds than gold(I) complexes of imidazole-based NHC ligands. PMID:26146436

Chalcogen- and halogen-bonds involving SX2 (X = F, Cl, and Br) with formaldehyde.

PubMed

Mo, Lixin; Zeng, Yanli; Li, Xiaoyan; Zhang, Xueying; Meng, Lingpeng

2016-07-01

The capacity of SX2 (X = F, Cl, and Br) to engage in different kinds of noncovalent bonds was investigated by ab initio calculations. SCl2 (SBr2) has two σ-holes upon extension of Cl (Br)-S bonds, and two σ-holes upon extension of S-Cl (Br) bonds. SF2 contains only two σ-holes upon extension of the F-S bond. Consequently, SCl2 and SBr2 form chalcogen and halogen bonds with the electron donor H2CO while SF2 forms only a chalcogen bond, i.e., no F···O halogen bond was found in the SF2:H2CO complex. The S···O chalcogen bond between SF2 and H2CO is the strongest, while the strongest halogen bond is Br···O between SBr2 and H2CO. The nature of these two types of noncovalent interaction was probed by a variety of methods, including molecular electrostatic potentials, QTAIM, energy decomposition, and electron density shift maps. Termolecular complexes X2S···H2CO···SX'2 (X = F, Cl, Br, and X' = Cl, Br) were constructed to study the interplay between chalcogen bonds and halogen bonds. All these complexes contained S···O and Cl (Br)···O bonds, with longer intermolecular distances, smaller values of electron density, and more positive three-body interaction energies, indicating negative cooperativity between the chalcogen bond and the halogen bond. In addition, for all complexes studied, interactions involving chalcogen bonds were more favorable than those involving halogen bonds. Graphical Abstract Molecular electrostatic potential and contour map of the Laplacian of the electron density in Cl2S···H2CO···SCl2 complex.

Exceptional enhancement of Raman scattering on silver chlorobromide nanocube photonic crystals: chemical and photonic contributions

DOE PAGES

Li, Zheng; Gosztola, David J.; Sun, Cheng-Jun; ...

2015-02-02

Photonic crystals made from self-assembly of mono-dispersed AgCl xBr 1-x nanocubes, which are not plasmonically active, have been discovered to exceptionally enhance Raman scattering of molecules chemically adsorbed on their surfaces. Comprehensive control measurements and X-ray absorption near-edge structure spectroscopy indicate that the Raman enhancement on the AgCl xBr 1-x nanocube photonic crystals is primarily ascribed to the chemical enhancement mechanism associated with the chemical interactions between adsorbing molecules and the AgCl xBr 1-x surfaces. In addition, the ordering of the AgCl xBr 1-x nanocubes in the photonic crystals can selectively reflect Raman scattering back to the detector at themore » bandgap position of the photonic crystals to provide additional enhancement, i.e., photonic mode enhancement. The thiophenol molecules adsorbed on the AgCl 0.44Br 0.56 nanocube photonic crystals exhibit astonishingly strong Raman signals that are on the same order of magnitude as those recorded from the thiophenol molecules adsorbed on the assembled Ag nanocubes.« less

Synthesis, Crystal and Electronic Structures, and Optical Properties of (CH 3NH 3) 2CdX 4 (X = Cl, Br, I)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roccanova, Rachel; Ming, Wenmei; Whiteside, Vincent R.

Here, we report the synthesis, crystal and electronic structures, as well as optical properties of the hybrid organic–inorganic compounds MA 2CdX 4 (MA = CH 3NH 3; X = Cl, Br, I). MA 2CdI 4 is a new compound, whereas, for MA 2CdCl 4 and MA 2CdBr 4, structural investigations have already been conducted but electronic structures and optical properties are reported here for the first time. Single crystals were grown through slow evaporation of MA 2CdX 4 solutions with optimized conditions yielding mm-sized colorless (X = Cl, Br) and pale yellow (X = I) crystals. Single crystal and variablemore » temperature powder X-ray diffraction measurements suggest that MA 2CdCl 4 forms a 2D layered perovskite structure and has two structural transitions at 283 and 173 K. In contrast, MA 2CdBr 4 and MA 2CdI 4 adopt 0D K 2SO 4-derived crystal structures based on isolated CdX 4 tetrahedra and show no phase transitions down to 20 K. The contrasting crystal structures and chemical compositions in the MA 2CdX 4 family impact their air stabilities, investigated for the first time in this work; MA 2CdCl 4 is air-stable, whereas MA 2CdBr 4 and MA 2CdI 4 partially decompose when left in air. Optical absorption measurements suggest that MA 2CdX 4 have large optical band gaps above 3.9 eV. Room temperature photoluminescence spectra of MA 2CdX 4 yield broad peaks in the 375–955 nm range with full width at half-maximum values up to 208 nm. These PL peaks are tentatively assigned to self-trapped excitons in MA 2CdX 4 following the crystal and electronic structure considerations. The bands around the Fermi level have small dispersions, which is indicative of high charge localization with significant exciton binding energies in MA 2CdX 4. On the basis of our combined experimental and computational results, MA 2CdX 4 and related compounds may be of interest for white-light-emitting phosphors and scintillator applications.« less

Synthesis, Crystal and Electronic Structures, and Optical Properties of (CH 3NH 3) 2CdX 4 (X = Cl, Br, I)

DOE PAGES

Roccanova, Rachel; Ming, Wenmei; Whiteside, Vincent R.; ...

2017-11-02

Here, we report the synthesis, crystal and electronic structures, as well as optical properties of the hybrid organic–inorganic compounds MA 2CdX 4 (MA = CH 3NH 3; X = Cl, Br, I). MA 2CdI 4 is a new compound, whereas, for MA 2CdCl 4 and MA 2CdBr 4, structural investigations have already been conducted but electronic structures and optical properties are reported here for the first time. Single crystals were grown through slow evaporation of MA 2CdX 4 solutions with optimized conditions yielding mm-sized colorless (X = Cl, Br) and pale yellow (X = I) crystals. Single crystal and variablemore » temperature powder X-ray diffraction measurements suggest that MA 2CdCl 4 forms a 2D layered perovskite structure and has two structural transitions at 283 and 173 K. In contrast, MA 2CdBr 4 and MA 2CdI 4 adopt 0D K 2SO 4-derived crystal structures based on isolated CdX 4 tetrahedra and show no phase transitions down to 20 K. The contrasting crystal structures and chemical compositions in the MA 2CdX 4 family impact their air stabilities, investigated for the first time in this work; MA 2CdCl 4 is air-stable, whereas MA 2CdBr 4 and MA 2CdI 4 partially decompose when left in air. Optical absorption measurements suggest that MA 2CdX 4 have large optical band gaps above 3.9 eV. Room temperature photoluminescence spectra of MA 2CdX 4 yield broad peaks in the 375–955 nm range with full width at half-maximum values up to 208 nm. These PL peaks are tentatively assigned to self-trapped excitons in MA 2CdX 4 following the crystal and electronic structure considerations. The bands around the Fermi level have small dispersions, which is indicative of high charge localization with significant exciton binding energies in MA 2CdX 4. On the basis of our combined experimental and computational results, MA 2CdX 4 and related compounds may be of interest for white-light-emitting phosphors and scintillator applications.« less

Theoretical study on the molecular structure and vibrational properties, NBO and HOMO-LUMO analysis of the POX3 (X = F, Cl, Br, I) series of molecules

NASA Astrophysics Data System (ADS)

Galván, Jorge E.; Gil, Diego M.; Lanús, Hernán E.; Altabef, Aida Ben

2015-02-01

The fourth member of the series of compounds of the type POX3 with X = I was synthesized and characterized by infrared spectroscopy. The geometrical parameters and vibrational properties of POX3 (X = F, Cl, Br, I) molecules were investigated theoretically by means DFT and ab initio methods. Available geometrical and vibrational data were used together with theoretical calculations in order to obtain a set of scaled force constants. The observed trends in geometrical parameters are analyzed and compared with those obtained in a previous work for the VOX3 (X = F, Cl, Br, I) series of compounds. NBO analysis was performed in order to know the hyper-conjugative interactions that favor one structure over another. The molecular properties such as ionization potential, electron affinity, electronegativity, chemical potential, chemical hardness, softness and global electrophilicity index have been deduced from HOMO-LUMO analysis.

Guest-tuned spin crossover in flexible supramolecular assemblies templated by a halide (Cl -, Br - or I - )

DOE Office of Scientific and Technical Information (OSTI.GOV)

Darawsheh, M. D.; Barrios, L. A.; Roubeau, O.

Ligand 1,3-bis(3-(pyridin-2-yl)-1H-pyrazol-5-yl)benzene, L, forms mononuclear spin crossover complexes [FeL 3] 2+ with pendant arms that cause them to dimerize through numerous intermolecular interactions forming supramolecular (X@[FeL 3] 2) 3+ cations. Finally, hey have the flexibility to encapsulate Cl -, Br - or I -, which allow tuning the magnetic properties, in the solid state and in solution.

Guest-tuned spin crossover in flexible supramolecular assemblies templated by a halide (Cl -, Br - or I - )

DOE PAGES

Darawsheh, M. D.; Barrios, L. A.; Roubeau, O.; ...

2016-12-05

Ligand 1,3-bis(3-(pyridin-2-yl)-1H-pyrazol-5-yl)benzene, L, forms mononuclear spin crossover complexes [FeL 3] 2+ with pendant arms that cause them to dimerize through numerous intermolecular interactions forming supramolecular (X@[FeL 3] 2) 3+ cations. Finally, hey have the flexibility to encapsulate Cl -, Br - or I -, which allow tuning the magnetic properties, in the solid state and in solution.

Molecular structures and thermodynamic properties of 12 gaseous cesium-containing species of nuclear safety interest: Cs 2, CsH, CsO, Cs 2O, CsX, and Cs 2X 2 (X = OH, Cl, Br, and I)

NASA Astrophysics Data System (ADS)

Badawi, Michael; Xerri, Bertrand; Canneaux, Sébastien; Cantrel, Laurent; Louis, Florent

2012-01-01

Ab initio electronic structure calculations at the coupled cluster level with a correction for the triples extrapolated to the complete basis set limit have been made for the estimation of the thermochemical properties of Cs 2, CsH, CsO, Cs 2O, CsX, and Cs 2X 2 (X = OH, Cl, Br, and I). The standard enthalpies of formation and standard molar entropies at 298 K, and the temperature dependence of the heat capacities at constant pressure were evaluated. The calculated thermochemical properties are in good agreement with their literature counterparts. For Cs 2, CsH, CsOH, Cs 2(OH) 2, CsCl, Cs 2Cl 2, CsBr, CsI, and Cs 2I 2, the calculated ΔfH298K∘ values are within chemical accuracy of the most recent experimental values. Based on the excellent agreement observed between our calculated ΔfH298K∘ values and their literature counterparts, the standard enthalpies of formation at 298 K are estimated to be the following: ΔfH298K∘ (CsO) = 17.0 kJ mol -1 and ΔfH298K∘ (Cs 2Br 2) = -575.4 kJ mol -1.

All-Solid-State Mechanochemical Synthesis and Post-Synthetic Transformation of Inorganic Perovskite-type Halides.

PubMed

Pal, Provas; Saha, Sujoy; Banik, Ananya; Sarkar, Arka; Biswas, Kanishka

2018-02-06

All-inorganic and hybrid perovskite type halides are generally synthesized by solution-based methods, with the help of long chain organic capping ligands, complex organometallic precursors, and high boiling organic solvents. Herein, a room temperature, solvent-free, general, and scalable all-solid-state mechanochemical synthesis is demonstrated for different inorganic perovskite type halides, with versatile structural connectivity in three (3D), two (2D), and zero (0D) dimensions. 3D CsPbBr 3 , 2D CsPb 2 Br 5 , 0D Cs 4 PbBr 6 , 3D CsPbCl 3 , 2D CsPb 2 Cl 5 , 0D Cs 4 PbCl 6 , 3D CsPbI 3 , and 3D RbPbI 3 have all been synthesized by this method. The all-solid-state synthesis is materialized through an inorganic retrosynthetic approach, which directs the decision on the solid-state precursors (e.g., CsX and PbX 2 (X=Cl/Br/I) with desired stoichiometric ratios. Moreover, post-synthetic structural transformations from 3D to 2D and 0D perovskite halides were performed by the same mechanochemical synthetic approach at room temperature. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pitting corrosion of titanium. The relationship between pitting potential and competitive anion adsorption at the oxide film/electrolyte interface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Basame, S.B.; White, H.S.

2000-04-01

The potential-dependent breakdown of the native oxide film ({approximately}20 {angstrom} thick) on titanium has been investigated in aqueous Br{sup {minus}} solutions and in solutions that contain a mixture of Br{sup {minus}} and anions that inhibit oxide breakdown (i.e., Cl{sup {minus}}, I{sup {minus}}, SO{sub 4}{sup 2{minus}}, Fe(CN){sub 6}{sup 4{minus}}, and Fe(CN){sub 6}{sup 3{minus}}). The oxide film is unstable in neutral pH solutions containing only Br{sup {minus}}, resulting in the formation of stable corrosion pits at relatively low potentials ({approximately}1.4 V vs. Ag/AgCl). The pitting potential, E{sub p}, is strongly dependent upon the concentration of Br{sup {minus}}, and can be modeled usingmore » a Langmuir isotherm to describe the adsorption of Br{sup {minus}} at the oxide film/electrolyte interface. Addition of a second anion inhibits oxide film breakdown, as indicated by a large positive shift in E{sub p} and a decrease in the number of stable corrosion pits. The dependence of E{sub p} on the relative concentrations of Br{sup {minus}} and the inhibitor anion is consistent with competitive adsorption of the anions. Equilibrium adsorption coefficients for I{sup {minus}}, Br{sup {minus}}, and Cl{sup {minus}} are estimated from the dependence of E{sub p} on anion concentration. The results are used to establish a physical basis for the anomalously low pitting potential for titanium in aqueous Br{sup {minus}} solutions.« less

Double-inversion mechanisms of the X⁻ + CH₃Y [X,Y = F, Cl, Br, I] SN2 reactions.

PubMed

Szabó, István; Czakó, Gábor

2015-03-26

The double-inversion and front-side attack transition states as well as the proton-abstraction channels of the X(-) + CH3Y [X,Y = F, Cl, Br, I] reactions are characterized by the explicitly correlated CCSD(T)-F12b/aug-cc-pVTZ(-PP) level of theory using small-core relativistic effective core potentials and the corresponding aug-cc-pVTZ-PP bases for Br and I. In the X = F case the double-inversion classical(adiabatic) barrier heights are 28.7(25.6), 15.8(13.4), 13.2(11.0), and 8.6(6.6) kcal mol(-1) for Y = F, Cl, Br, and I, respectively, whereas the barrier heights are in the 40-90 kcal mol(-1) range for the other 12 reactions. The abstraction channels are always above the double-inversion saddle points. For X = F, the front-side attack classical(adiabatic) barrier heights, 45.8(44.8), 31.0(30.3), 24.7(24.2), and 19.5(19.3) kcal mol(-1) for Y = F, Cl, Br, and I, respectively, are higher than the corresponding double-inversion ones, whereas for the other systems the front-side attack saddle points are in the 35-70 kcal mol(-1) range. The double-inversion transition states have XH···CH2Y(-) structures with Cs point-group symmetry, and the front-side attack saddle points have either Cs (X = F or X = Y) or C1 symmetry with XCY angles in the 78-88° range. On the basis of the previous reaction dynamics simulations and the minimum energy path computations along the inversion coordinate of selected XH···CH2Y(-) systems, we suggest that the double inversion may be a general mechanism for SN2 reactions.

Mutual neutralization of He{sup +} with the anions Cl{sup −}, Br{sup −}, I{sup −}, and SF{sub 6}{sup −}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wiens, Justin P.; Shuman, Nicholas S.; Miller, Thomas M.

2016-05-28

Mutual neutralization (MN) rate coefficients k{sub MN} for He{sup +} with the anions Cl{sup −}, Br{sup −}, I{sup −}, and SF{sub 6}{sup −} are reported from 300 to 500 K. The measured rate coefficients may contain a contribution from transfer ionization, i.e., double ionization of the anion. The large rate coefficient for He{sup +} + SF{sub 6}{sup −} (2.4 × 10{sup −7} cm{sup 3} s{sup −1} at 300 K) is consistent with earlier polyatomic MN results found to have a reduced mass dependence of μ{sup −1/2}. Neutralization of He{sup +} by the atomic halides follows the trend observed earlier for Ne{sup +},more » Ar{sup +}, Kr{sup +}, and Xe{sup +} neutralized by atomic halides, k{sub MN} (Cl{sup −}) < k{sub MN} (Br{sup −}) < k{sub MN} (I{sup −}). Only an upper limit could be measured for the neutralization of He{sup +} by Cl{sup −}. Predictions of the rate coefficients from a previously proposed simple model of atomic–atomic MN results are consistent with the present He{sup +}–halide rate coefficients. The temperature dependences are modestly negative for Br{sup −} and I{sup −}, while that for SF{sub 6}{sup −} is small or negligible.« less

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

PubMed

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

2012-10-01

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

Synthesis, Structure, and Optical Properties of Antiperovskite-Derived Ba2MQ3X (M = As, Sb; Q = S, Se; X = Cl, Br, I) Chalcohalides.

PubMed

Wang, Ruiqi; Zhang, Xian; He, Jianqiao; Bu, Kejun; Zheng, Chong; Lin, Jianhua; Huang, Fuqiang

2018-02-05

Six isostructural antiperovskite-derived chalcohalides, Ba 2 MQ 3 X (M = As, Sb; Q = S, Se; X = Cl, Br, I), crystallizing in the space group Pnma, have been synthesized by solid-state reactions. The crystal structure features a 3D framework with the [XBa 5 ] 9+ disordered square pyramids as building blocks and [MQ 3 ] 3- units filling the interspace. [XBa 5 ] 9+ disordered square pyramids are edge-sharing along [010], derived from the fusing of the two pyramids in octahedral [XBa 6 ] 11+ . Surprisingly, Ba 2 AsS 3 X (X = Cl, Br, I) show almost the same optical band gap of 2.80 eV, and Ba 2 AsSe 3 X (X = Br, I) also have a similar band gap of 2.28 eV. The optical band gap of Ba 2 SbS 3 I is 2.64 eV. First-principles calculations reveal that the optical absorption is attributed to the transitions between Q np at the valence band maximum (VBM) and M np-Q np at the conduction band minimum (CBM). These compounds also possess interesting photoluminescence properties with splitting emission peaks on excitation at 200 nm.

Hydration of the Atlantis Massif: Halogen, Noble Gas and In-Situ δ18O Constraints

NASA Astrophysics Data System (ADS)

Williams, M. J.; Kendrick, M. A.; Rubatto, D.

2017-12-01

A combination of halogen (Cl, Br, I), noble gases (He, Ne, Ar, Kr and Xe) and in situ oxygen isotope analysis have been utilized to investigate the fluid-mobile element record of hydration and alteration processes at the Atlantis Massif (30°N on the Mid-Atlantic Ridge). The sample suite investigated includes serpentinite, talc-amphibole ± chlorite schist and hydrated gabbro recovered by seafloor drilling undertaken at sites on a transect across the Atlantis Massif during IODP Expedition 357. Serpentine mesh and veins analysed in-situ by SHRIMP SI exhibit δ18O from 6‰ down to ≈0‰, suggesting serpentinization temperatures of 150 to >280°C and water/rock ratios >5. Differences of 1.5-2.5‰ are observed between adjacent generations of serpentine, but the δ18O range is similar at each investigated drilling site. Halogen and noble gas abundances in serpentinites, talc-amphibole schist and hydrated gabbro have been measured by noble gas mass spectrometry of both irradiated and non-irradiated samples. Serpentinites contain low abundances of halogens and noble gases (e.g. 70-430 ppm Cl, 4.7-12.2 x 10-14 mol/g 36Ar) relative to other seafloor serpentinites. The samples have systematically different Br/Cl and I/Cl ratios related to their mineralogy. Serpentinites retain mantle-like Br/Cl with a wide variation in I/Cl that stretches toward seawater values. Talc-amphibole schists exhibit depletion of Br and I relative to Cl with increasing Cl abundances, suggesting tremolite exerts strong control on halogen abundance ratios. Serpentinites show no evidence of interaction with halogen-rich sedimentary pore fluids. Iodine abundances are variable across serpentinites, and are decoupled from Br and Cl; iodine enrichment (up to 530 ppb) is observed within relatively oxidised and clay-bearing samples. Serpentinized harzburgites exhibit distinct depletion of Kr and Xe relative to atmospheric 36Ar in seawater. Oxygen isotope compositions and low abundances of both halogens and noble gases are consistent with high water/rock ratios. Successive generations of serpentine have δ18O trends suggesting exposure to higher W/R ratios during exhumation and deformation of the massif. Low noble gas abundances of may also be influenced by thermal loss related to impregnation and intrusion of the Massif by gabbros and dolerites.

UV photolysis of 4-iodo-, 4-bromo-, and 4-chlorophenol: competition between C-Y (Y = halogen) and O-H bond fission.

PubMed

Sage, Alan G; Oliver, Thomas A A; King, Graeme A; Murdock, Daniel; Harvey, Jeremy N; Ashfold, Michael N R

2013-04-28

The wavelength dependences of C-Y and O-H bond fission following ultraviolet photoexcitation of 4-halophenols (4-YPhOH) have been investigated using a combination of velocity map imaging, H Rydberg atom photofragment translational spectroscopy, and high level spin-orbit resolved electronic structure calculations, revealing a systematic evolution in fragmentation behaviour across the series Y = I, Br, Cl (and F). All undergo O-H bond fission following excitation at wavelengths λ ≲ 240 nm, on repulsive ((n∕π)σ∗) potential energy surfaces (PESs), yielding fast H atoms with mean kinetic energies ∼11,000 cm(-1). For Y = I and Br, this process occurs in competition with prompt C-I and C-Br bond cleavage on another (n∕π)σ∗ PES, but no Cl∕Cl∗ products unambiguously attributable to one photon induced C-Cl bond fission are observed from 4-ClPhOH. Differences in fragmentation behaviour at longer excitation wavelengths are more marked. Prompt C-I bond fission is observed following excitation of 4-IPhOH at all λ ≤ 330 nm; the wavelength dependent trends in I∕I∗ product branching ratio, kinetic energy release, and recoil anisotropy suggest that (with regard to C-I bond fission) 4-IPhOH behaves like a mildly perturbed iodobenzene. Br atoms are observed when exciting 4-BrPhOH at long wavelengths also, but their velocity distributions suggest that dissociation occurs after internal conversion to the ground state. O-H bond fission, by tunnelling (as in phenol), is observed only in the cases of 4-FPhOH and, more weakly, 4-ClPhOH. These observed differences in behaviour can be understood given due recognition of (i) the differences in the vertical excitation energies of the C-Y centred (n∕π)σ∗ potentials across the series Y = I < Br < Cl and the concomitant reduction in C-Y bond strength, cf. that of the rival O-H bond, and (ii) the much increased spin-orbit coupling in, particularly, 4-IPhOH. The present results provide (another) reminder of the risks inherent in extrapolating photochemical behaviour measured for one molecule at one wavelength to other (related) molecules and to other excitation energies.

Tripodal polyphosphine ligands as inductors of chelate ring-opening processes in mononuclear palladium(II) and platinum(II) compounds. The X-ray crystal structure of two derivatives containing dangling phosphorus.

PubMed

Fernández-Anca, Damián; García-Seijo, M Inés; García-Fernández, M Esther

2010-03-07

The reaction of NP(3) (tris[2-(diphenylphosphino)ethyl]amine and PP(3) (tris[2-(diphenylphosphino)ethyl]phosphine) with the five-coordinate complexes [PdCl(NP(3))]Cl (1) and [MX(PP(3))]X [M = Pd: X = Cl(2), Br(3), I(4); M = Pt: X = Cl(5), Br(6), I(7)], respectively, followed by (31)P{(1)H}NMR when X = Cl, led to the formation of unprecedented four-coordinate halides in a 1 : 2 metal to ligand ratio, [M(AP(3))(2)]X(2) [A = N, M = Pd: X = Cl(8); A = P, M = Pd: X = Cl(9), Br(10), I(11); A = P, M = Pt: X = Cl(12), Br(13), I (14)], containing reactive dangling phosphorus. Given the non characterised precursors [M(ONO(2))(PP(3))](NO(3))], the interaction between the heteronuclear species [MAg(NO(3))(3)(PP(3))] [M = Pd(15), Pt(16)] and PP(3) was explored. It was found that the addition of 1 equivalent of phosphine afforded [MAg(NO(3))(PP(3))(2)](NO(3))(2) [M = Pd(15*), Pt(16*)] containing Ag(I) bound to two dangling phosphorus while the reaction with 2 equivalents led to the complexes [M(PP(3))(2)](NO(3))(2) [M = Pd (17), Pt (18)] in coexistence with [Ag(2)(mu-PP(3))(2)](NO(3))(2). The fate of Ag(I) on the reaction of the mixed metal compounds with excess PP(3) consisted of preventing dissociation, observed in solution for halides, and acting as an assistant for crystallization. Colourless single crystals of 18 and 10, studied by X-ray diffraction, were afforded by reaction of 16 with 4 equivalents of PP(3) and from solutions of 10 in chloroform coexisting with red crystals of 3, respectively. The structures revealed the presence of dications [M(PP(3))(2)](2+) that show two five-membered chelate rings to M(II) in a square-planar arrangement and four uncoordinated phosphine arms with the counter anions being symmetrically placed at 4.431 (Br(-)) and 13.823 (NO(3)(-)) A from M(II) above and below its coordination, MP(4), plane. Complexes 9 and 12 were shown to undergo an interesting reactivity in solution versus group 11 monocations. The reactions consisted of conversions of the two five-membered chelate rings to M into three (structure I) or two (structure II) fused five-membered chelate rings, formation of species where Pt(II) retained its square-planar environment with the two dangling phosphine arms of each PP(3) bound to Cu(I) or Ag(I) (structure III) and complexes bearing distorted square-planar (P(2)MCl(2)) and presumably tetrahedral (AuP(4)+ P(2)AuCl(2)) arrangements (structure IV). The processes with Ag(I) salts also gave mixtures of I+III (chloride and nitrate) or II+III (nitrate).

The binding of platinum hexahalides (Cl, Br and I) to hen egg-white lysozyme and the chemical transformation of the PtI{sub 6} octahedral complex to a PtI{sub 3} moiety bound to His15

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanley, Simon W. M.; Starkey, Laurina-Victoria; Lamplough, Lucinda

The platinum hexahalides have an octahedral arrangement of six halogen atoms bound to a Pt centre, thus having an octahedral shape that could prove to be useful in interpreting poor electron-density maps. In a detailed characterization, PtI{sub 6} chemically transformed to a square-planar PtI{sub 3} complex bound to the N{sup δ} atom of His15 of HEWL was also observed, which was not observed for PtBr{sub 6} or PtCl{sub 6}. This study examines the binding and chemical stability of the platinum hexahalides K{sub 2}PtCl{sub 6}, K{sub 2}PtBr{sub 6} and K{sub 2}PtI{sub 6} when soaked into pre-grown hen egg-white lysozyme (HEWL) crystalsmore » as the protein host. Direct comparison of the iodo complex with the chloro and bromo complexes shows that the iodo complex is partly chemically transformed to a square-planar PtI{sub 3} complex bound to the N{sup δ} atom of His15, a chemical behaviour that is not exhibited by the chloro or bromo complexes. Each complex does, however, bind to HEWL in its octahedral form either at one site (PtI{sub 6}) or at two sites (PtBr{sub 6} and PtCl{sub 6}). As heavy-atom derivatives of a protein, the octahedral shape of the hexahalides could be helpful in cases of difficult-to-interpret electron-density maps as they would be recognisable ‘objects’.« less

Synthesis and nonstoichiometry of the zirconium trihalides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daake, R.L.; Corbett, J.D.

1978-05-01

The synthesis of ZrX/sub 3/ (X = Cl, Br, I) by reaction of the corresponding tetrahalides with ZrCl, ZrBr, or ZrI/sub 1.8/ in sealed tantalum tubing gives high-purity, single-phase products, thereby avoiding problems of the relatively low reactivity of and contamination by zirconium powder reductant used previously. Phase limits for the three trihalides established by isopiestic equilibration with the adjoining phases are 2.94 (2) less than or equal to Cl:Zr less than or equal to 3.03 (2) (440/sup 0/C), 2.87 (2) less than or equal to Br:Zr less than or equal to 3.23 (2) (435/sup 0/C), and 2.83 (5) (775/supmore » 0/C) less than or equal to I:Zr less than or equal to 3.43 (5) (475/sup 0/C). The hexagonal lattice constants for the bromide phase (Guinier techniques) decrease linearly with increasing bromide content across the entire range without the development of any additional lines. The variation of the c dimension for ZrI/sub 3/ (and HfI/sub 3/) on oxidation is in the opposite direction, and in this case extra lines from a presumed superlattice structure developed toward the upper limit. The structural implications of these results are considered. The reported structure for ..cap alpha..-ZrCl/sub 3/, an unusual BiI/sub 3/-type variant, was based on a misassigned ZrCl powder pattern and therefore appears to be in error. 25 references.« less

Behaviour of I/Br/Cl-THMs and their projected toxicities under simulated cooking conditions: Effects of heating, table salt and residual chlorine.

PubMed

Yan, Mingquan; Li, Mingyang; Han, Xuze

2016-08-15

This study examined the effects of heating, residual chlorine and concentration of table salt on the generation of iodine-, bromine- and chlorine-containing trihalomethanes (THMs) under simulated cooking conditions. In the case of addition of either KI- or KIO3-fortified salt, total I-THM concentrations increased with increasing iodine concentration, while total Cl/Br-THM concentrations decreased. CHCl2I, CHBrClI, CHBrI2, CHBr2I and CHI3 were formed in the presence of KI salt, while only CHCl2I was formed in the presence of KIO3 salt. CHCl2I was unstable under cooking conditions, and >90% of this DBP was removed during heating, which in some cases increased the concentrations of the other I-THMs. The calculated cytotoxicity increased with addition of KI- or KIO3-fortified salt due to the generation of I-THMs, whose impact on the cytotoxicity at room temperature was equal to or five times higher, respectively, than the cytotoxicity of the simultaneously formed Cl/Br-THMs for the cases of salts. Heating decreased the cytotoxicity, except for the case of addition of KI salt, in which the calculated cytotoxicity of I-THMs increased above 150% as the temperature was increased up to 100°C. The reported results may have important implications for epidemiologic exposure assessments and, ultimately, for public health protection. Copyright © 2016 Elsevier B.V. All rights reserved.

Reaction to Halogens and Interhalogens with 4-Halo-1,1,2-trifluorobut-1-enes: Rearrangement of 3-Membered Halonium to 5-Membered Trifluorotetramethylene Halonium Ion Intermediates and Comparison of Open-Chloronium Fluorosubstituted Ions to Flurocarbocations from Protons (Preprint)

DTIC Science & Technology

2008-02-28

were found to be open-ion (A or E), unsymmetrical (B or D), or symmetrical C depending on the halogen electrophile and on the position and number of...Rearranged products 4 (Structures A-E) 1 Z = Cl 2 Z = Br 3 Z = I XY = Cl2, Br2, BrCl ICl, IBr Scheme 1 Y on the fluorine atoms of 5 shield the carbon nucleus...and 3) WITH HALOGEN ELECTROPHILES IN METHYLENE CHLORIDE F F F Z XY CH2Cl2 CF2CFZ Y X CF2CFZ X Y CF2CFY X Z + + M aM Rearranged Run Alkene (Z

Structural, Electronic, and Optical Properties of BiOX1-xYx (X, Y = F, Cl, Br, and I) Solid Solutions from DFT Calculations.

PubMed

Zhao, Zong-Yan; Liu, Qing-Lu; Dai, Wen-Wu

2016-08-23

Six BiOX1-xYx (X, Y = F, Cl, Br, and I) solid solutions have been systematically investigated by density functional theory calculations. BiOCl1-xBrx, BiOBr1-xIx, and BiOCl1-xIx solid solutions have very small bowing parameters; as such, some of their properties increase almost linearly with increasing x. For BiOF1-xYx solid solutions, the bowing parameters are very large and it is extremely difficult to fit the related calculated data by a single equation. Consequently, BiOX1-xYx (X, Y = Cl, Br, and I) solid solutions are highly miscible, while BiOF1-xYx (Y = Cl, Br, and I) solid solutions are partially miscible. In other words, BiOF1-xYx solid solutions have miscibility gaps or high miscibility temperature, resulting in phase separation and F/Y inhomogeneity. Comparison and analysis of the calculated results and the related physical-chemical properties with different halogen compositions indicates that the parameters of BiOX1-xYx solid solutions are determined by the differences of the physical-chemical properties of the two halogen compositions. In this way, the large deviation of some BiOX1-xYx solid solutions from Vegard's law observed in experiments can be explained. Moreover, the composition ratio of BiOX1-xYx solid solutions can be measured or monitored using optical measurements.

Infrared Fiber Optics.

DTIC Science & Technology

1980-09-01

attention for IR fiber fabrication to date and gives their transmission ranges. At HRL, we have studied KCI, KBr, 8 TlBr , and KRS-5 (TlBrI); Honeywell...past three years to suc- cessfully fabricate KRS-5 and TlBr fibers. Polycrystalline fibers of these Tl-containing salts were prepared with losses as...crystalline materials such as KRS-5 (TIBrI), TlBr , AgCl, and KCI have been used for a variety of 10.6-pm, CO2 laser applications.1 - 4 The losses in the

Origin of halides (Cl- and Br-) and of their stable isotopes (d37Cl and d81Br) at the Tournemire URL (France) - Experimental and numerical approach

NASA Astrophysics Data System (ADS)

Bachir-Bey, Nassim; Matray, Jean-Michel

2014-05-01

This work is part of research conducted by the Institute of Radiological and Nuclear Safety (IRSN) on the geological disposal of High-Level and Intermediate-Level Long-Lived (HL-ILLL) radioactive waste in deep clayrocks. In France, the choice of the potential host rock for the geological storage is focused on the Callovian-Oxfordian (COx) of Meuse/Haute-Marne from its low permeability, capacity for self- sealing, high sorption and ability to radionuclide (RN) transport by diffusion. IRSN, which plays an expert role for ASN has its own underground research laboratory in a clayrock which has strong analogies to the COx. This is the Toarcian/Domerian clayrock located at Tournemire in southern Aveyron in France. The purpose of this study was to assess the transfer of RN in the Tournemire clayrock through the study of halides contents and of their stable isotopes (Cl-, Br-, Cl-/Br-, d37Cl, d81Br). The approach used was multiple and consisted for halides to: 1) Assess their stock in different fractions of the rock by applying several techniques including i) alkaline fusion for their total stock, ii) leaching to access their stock in porewater and to mineral phases sensitive to dissolution iii) cubic diffusion for their stock in porewater, 2) Get their diffusive transport parameters of a selection of samples from the upper Toarcian by cubic diffusion experiments modelled using the Hytec transport code developed by Mines ParisTech and 3) Model their transport after palaeohydrogeological known changes of the Tournemire massif. The experimental approach, conducted at the LAME lab, did not lead to an operational protocol for the alkaline fusion due to an incomplete rock dissolution. Leaching was used to characterize the concentrations of halides in the fractions of pore water and of minerals sensitive to dissolution. The results show levels of halides much higher than those of pore water with very low Cl/Br ratios likely resulting from the dissolution of mineral species. The cubic diffusion produced the pore diffusion coefficients for Cl and Br as well as their concentration in the porewater. Cubic diffusion also allowed to estimate a Cl to Br pore diffusion coefficient ratio, necessary to calculate the profiles of Cl/Br. These estimates have required the use of the transport code Hytec i) for dimensioning and implementing the experiment in a time frame compatible with the work period, ii) for analysing the sensitiveness of the model to the accessible porosity and to the diffusion coefficient which act respectively to the steady phase and transient phase of the experiments, and finally, iii ) for adjusting the pore diffusion coefficients of Cl and Br to an accessible porosity of 3-4%. The Hytec code was then used to check the consistency of the current profiles of chlorides, bromides, 35Cl , 37Cl , d37Cl, Cl/Br in 1D, a fake drilling assumed crossing the entire clayrock. The assumption is that halides have undergone a diffusive transport between seawater trapped during sedimentation and meteoric waters infiltrated at different times to domain boundaries. Four scenarios were tested according to the paleohydrogeological history of the massif. All tracers and scenarios are consistent with a unique marine source of halides more or less diluted by meteoric waters. The duration of the diffusive exchange initially suggested 85 ± 10 Ma (Bensenouci, 2010) is never contradicted despite uncertainties related to changes in boundary conditions. This body of evidence would suggest that molecular diffusion is the transport process which has affected and still affect the Tournemire clayrock, outside fault zones. The d37Cl results expected on the surrounding carbonated aquifers, leachates and fracture waters (including d81Br values) should help to refine the models and the results.

Permanent electric dipole moments of PtX (X = H, F, Cl, Br, and I) by the composite approach

NASA Astrophysics Data System (ADS)

Deng, Dan; Lian, Yongqin; Zou, Wenli

2017-11-01

Using the FPD composite approach of Peterson et. al. we calculate the permanent electric dipole moments of PtX (X = H, F, Cl, Br, and I) at the equilibrium geometries of their ground states. The dipole moment of PtF is estimated to be 3.421 Debye, being very close to the experimental value of 3.42(6) Debye. This research also suggests the ordering of dipole moments of PtX being proportional to the electronegativity of X.

Crystal-field analysis of U3+ ions in K2LaX5 (X=Cl, Br or I) single crystals

NASA Astrophysics Data System (ADS)

Karbowiak, M.; Edelstein, N.; Gajek, Z.; Drożdżyński, J.

1998-11-01

An analysis of low temperature absorption spectra of U3+ ions doped in K2LaX5 (X=Cl, Br or I) single crystals is reported. The energy levels of the U3+ ion in the single crystals were assigned and fitted to a semiempirical Hamiltonian representing the combined atomic and crystal-field interactions at the Cs symmetry site. An analysis of the nephelauxetic effect and crystal-field splittings in the series of compounds is also reported.

Determination of the total drug-related chlorine and bromine contents in human blood plasma using high performance liquid chromatography-tandem ICP-mass spectrometry (HPLC-ICP-MS/MS).

PubMed

Klencsár, Balázs; Bolea-Fernandez, Eduardo; Flórez, María R; Balcaen, Lieve; Cuyckens, Filip; Lynen, Frederic; Vanhaecke, Frank

2016-05-30

A fast, accurate and precise method for the separation and determination of the total contents of drug-related Cl and Br in human blood plasma, based on high performance liquid chromatography - inductively coupled plasma - tandem mass spectrometry (HPLC-ICP-MS/MS), has been developed. The novel approach was proved to be a suitable alternative to the presently used standard methodology (i.e. based on a radiolabelled version of the drug molecule and radiodetection), while eliminating the disadvantages of the latter. Interference-free determination of (35)Cl has been accomplished via ICP-MS/MS using H2 as reaction gas and monitoring the (35)ClH2(+) reaction product at mass-to-charge ratio of 37. Br could be measured "on mass" at a mass-to-charge of 79. HPLC was relied on for the separation of the drug-related entities from the substantial amount of inorganic Cl. The method developed was found to be sufficiently precise (repeatability <10% RSD) and accurate (recovery between 95 and 105%) and shows a linear dynamic range (R(2)>0.990) from the limit of quantification (0.05 and 0.01 mg/L for Cl and Br in blood plasma, respectively) to at least 5 and 1mg/L for Cl and Br, respectively. Quantification via either external or internal standard calibration provides reliable results for both elements. As a proof-of-concept, human blood plasma samples from a clinical study involving a newly developed Cl- and Br-containing active pharmaceutical ingredient were analysed and the total drug exposure was successfully described. Cross-validation was achieved by comparing the results obtained on Cl- and on Br-basis. Copyright © 2016 Elsevier B.V. All rights reserved.

Lasagna-type arrays with halide-nitromethane cluster filling. The first recognition of the Hal(-)···HCH2NO2 (Hal = Cl, Br, I) hydrogen bonding.

PubMed

Gushchin, Pavel V; Kuznetsov, Maxim L; Wang, Qian; Karasik, Andrey A; Haukka, Matti; Starova, Galina L; Kukushkin, Vadim Yu

2012-06-21

The previously predicted ability of the methyl group of nitromethane to form hydrogen bonding with halides is now confirmed experimentally based on X-ray data of novel nitromethane solvates followed by theoretical ab initio calculations at the MP2 level of theory. The cationic (1,3,5-triazapentadiene)Pt(II) complexes [Pt{HN=C(NC(5)H(10))N(Ph)C(NH(2))=NPh}(2)](Cl)(2), [1](Hal)(2) (Hal = Cl, Br, I), and [Pt{HN=C(NC(4)H(8)O)N(Ph)C(NH(2))=NPh}(2)](Cl)(2), [2](Cl)(2), were crystallized from MeNO(2)-containing systems providing nitromethane solvates studied by X-ray diffraction. In the crystal structure of [1][(Hal)(2)(MeNO(2))(2)] (Hal = Cl, Br, I) and [2][(Cl)(2)(MeNO(2))(2)], the solvated MeNO(2) molecules occupy vacant spaces between lasagna-type layers and connect to the Hal(-) ion through a weak hydrogen bridge via the H atom of the methyl thus forming, by means of the Hal(-)···HCH(2)NO(2) contact, the halide-nitromethane cluster "filling". The quantum-chemical calculations demonstrated that the short distance between the Hal(-) anion and the hydrogen atom of nitromethane in clusters [1][(Hal)(2)(MeNO(2))(2)] and [2][(Cl)(2)(MeNO(2))(2)] is not just a consequence of the packing effect but a result of the moderately strong hydrogen bonding.

Polymer-Nanoparticle Hybrid Photovoltaic Research for U.S. Air Force Applications

DTIC Science & Technology

2010-01-06

6 S S O S S O II xi xiviii xii (69%) (93%) (64%) (92%) 4S SBr Br S S OO OO II S S OO aReagents and Conditions: i.THF, n- BuLi , C6H13Br, -78oC, ii...CHCl3, FeCl3 (cat.), Br2, iii. THF, n- BuLi , B(OBu)3, -78oC, 2 M HCl, iv. Toluene, 1,3-propandiol, Reflux, v. (a) Ether, n- BuLi -78oC, (b) 3...thiophenecarboxaldehyde, vi. (a) n- BuLi (2eqiv.), -23oC, I2 (3eqiv.), (b) Na2SO3 and HI solun, vii. CH2Cl2, P.C.C, r.t, viii. Cu, DMF, Reflux, ix

TETRAHALOINDATE(III)-BASED IONIC LIQUIDS IN THE COUPLING REACTION OF CARBON DIOXIDE AND EPOXIDES TO GENERATE CYCLIC CARBONATES: H-BONDING AND MECHANISTIC STUDIES

EPA Science Inventory

The microwave reactions of InX₃ with [Q]Y produce a series of tetrahaloindate(III)-based ionic liquids (ILs) with a general formula of [Q][InX₃Y] (Q = imidazolium, phosphonium, ammonium, and pyridinium; X = Cl, Br, I; Y = Cl, Br). The reaction of CO₂

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prestwich, G.D.; Streinz, L.

A series of mono, di-, and trihalogenated acetate analogs of Z11-16:Ac were prepared and examined for electrophysiological activity in antennae of males of the diamondback moth, Plutella xylostella. In addition, two potential affinity labels, a diazoacetate (Dza) and a trifluoromethyl ketone (Tfp), were evaluated for EAG activity. The Z11-16:Ac showed the highest activity in EAG assays, followed by the fluorinated acetates, but other haloacetates were essentially inactive. The effects of these analogs on the hydrolysis of (/sup 3/H)Z11-16:Ac to (/sup 3/H)Z11-16:OH by antennal esterases was also examined. The three fluorinated acetates showed the greatest activity as inhibitors in competition assays,more » with rank order F/sub 2/Ac > F/sub 3/Ac > FAc > AC > Cl/sub 2/Ac > ClAc > Dza > Br/sub 2/Ac > BrAc > Tfp > I > Cl/sub 3/Ac > Br/sub 3/Ac > OH. The relative polarities of the haloacetates, as determined by TLC mobility, are in the order mono- > di- > trihalo, but F, Cl, Br, and I all confer similar polarities within a substitution group. Thus, the steric size appears to be the predominant parameter affecting the interactions of the haloacetate analogs with both receptor and catabolic proteins in P. xylostella males.« less

SYNTHESIS OF ZrI$sub 4$ AND HfI$sub 4$ BY HALOID EXCHANGE (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nisel'son, L.A.; Teslitskaya, M.V.; Shvedova, T.A.

1962-05-01

Syntheses of ZrI/sub 4/ and Hfl/sub 4/ by reactions of ZrCl/sub 4/ with SiI/sub 4/, Al/sub 2/I/sub 6/, HI, and Al/sub 2/Br and HfCl/sub 4/ with Al/sub 2 / I/sub 6/ are analyzed. The highest exchange yield was reached with /sub 4/ from ZrCl/sub 4/ and other admixtures was achieved by distillation. (R.V.J.)

Stability of bromine, iodine monochloride, copper (II) chloride, and nickel (II) chloride intercalated pitch-based graphite fibers

NASA Technical Reports Server (NTRS)

Gaier, James R.; Slabe, Melissa E.; Shaffer, Nanette

1987-01-01

Four different grades of pitch-based graphite fibers (Amoco P-55, P-75, P-100. and P-120) were intercalated with each of four different intercalates: bromine (Br2), iodine monochloride (ICl), copper (II) chloride (CuCl2), and nickel (II) chloride (NiCl2). The P-55 fibers did not react with Br2 or NiCl2, and the P-75 did not react with NiCl2. The stability of the electrical resistance of the intercalated fibers was monitored over long periods of time in ambient, high humidity (100 percent at 60 C), vacuum (10 to the -6 torr), and high temperature (up to 400 C) conditions. Fibers with lower graphitization form graphite intercalation compounds (GIC's) which are more stable than those with higher graphitization (i.e., P-55 (most stable) greater than P-75 greater than P-100 greater than P-120 (least stable). Br2 formed the most stable GIC's followed in order of decreasing stability by ICl, CuCl2, and NiCl2. While Br2 GIC's had the most stability, ICl had the advantages of forming GIC's with slightly greater reduction in resistance (by about 10%) than Br2, and the ability to intercalate P-55 fiber. Transition metal chlorides are susceptible to water vapor and high temperature. The stability of fibers in composites differs.

Liquid-liquid distribution of ion associates of tetrabromoindate(III) with quaternary ammonium counter ions.

PubMed

Yamamoto, K; Matsumoto, A

1997-11-01

The solvent extraction of an ion associate of tetrabromoindate(III) ion, InBr(-)(4), with quaternary ammonium cations (Q(+)) has been studied. The extraction constant (K(ex)) were determined for the ion associates of InBr(-)(4) with Q(+) between an aqueous phase and several organic phases (chloroform, chlorobenzene, benzene and toluene). A linear relationship was found between log K(ex) and the total number of carbon atoms in Q(+); from the slope of the lines, the contribution of a methylene group to log K(ex) was calculated to be 0.91 for the chloroform extraction system and 0.52 for the other extraction systems. The extractability with alkyltrimethylammonium cations was larger than that with symmetrical tetraalkylammonium cations and the mean difference in log K(ex) for two cations (one of each type) with the same number of carbon atoms was about 1.3. From the extraction constant obtained, the extractability of InBr(-)(4) among metal-halogeno complex anions was in the order TlBr(-)(4) > BiI(-)(4) > AuBr(-)(4) > AuCl(-)(4) > TlCl(-)(4) > InBr(-)(4) > CuCl(-)(2).

Volatile Element Geochemistry in the Lower Atmosphere of Venus

NASA Technical Reports Server (NTRS)

Schaefer, L.; Fegley, B., Jr.

2004-01-01

We computed equilibrium abundances of volatile element compounds as a function of altitude in Venus lower atmosphere. The elements included are generally found in volcanic gases and sublimates on Earth and may be emitted in volcanic gases on Venus or volatilized from its hot surface. We predict: 1) PbS, Bi2S3, or possibly a Pb-Bi sulfosalt are the radar bright heavy metal frost in the Venusian highlands; 2) It should be possible to determine Venus' age by Pb-Pb dating of PbS condensed in the Venusian highlands, which should be a representative sample of Venusian lead; 3) The gases HBr, PbCl2, PbBr2, As4O6, As4S4, Sb4O6, BiSe, InBr, InCl, Hg, TlCl, TlBr, SeS, Se2-7, HI, I, I2, ZnCl2, and S2O have abundances greater than 0.1 ppbv in our nominal model and may be spectroscopically observable; 4) Cu, Ag, Au, Zn, Cd, Ge, and Sn are approx. 100 % condensed at the 740 K (0 km) level on Venus.

Halogen bonds in some dihalogenated phenols: applications to crystal engineering.

PubMed

Mukherjee, Arijit; Desiraju, Gautam R

2014-01-01

3,4-Dichlorophenol (1) crystallizes in the tetragonal space group I41/a with a short axis of 3.7926 (9) Å. The structure is unique in that both type I and type II Cl⋯Cl interactions are present, these contact types being distinguished by the angle ranges of the respective C-Cl⋯Cl angles. The present study shows that these two types of contacts are utterly different. The crystal structures of 4-bromo-3-chlorophenol (2) and 3-bromo-4-chlorophenol (3) have been determined. The crystal structure of (2) is isomorphous to that of (1) with the Br atom in the 4-position participating in a type II interaction. However, the monoclinic P21/c packing of compound (3) is different; while the structure still has O-H⋯O hydrogen bonds, the tetramer O-H⋯O synthon seen in (1) and (2) is not seen. Rather than a type I Br⋯Br interaction which would have been mandated if (3) were isomorphous to (1) and (2), Br forms a Br⋯O contact wherein its electrophilic character is clearly evident. Crystal structures of the related compounds 4-chloro-3-iodophenol (4) and 3,5-dibromophenol (5) were also determined. A computational survey of the structural landscape was undertaken for (1), (2) and (3), using a crystal structure prediction protocol in space groups P21/c and I41/a with the COMPASS26 force field. While both tetragonal and monoclinic structures are energetically reasonable for all compounds, the fact that (3) takes the latter structure indicates that Br prefers type II over type I contacts. In order to differentiate further between type I and type II halogen contacts, which being chemically distinct are expected to have different distance fall-off properties, a variable-temperature crystallography study was performed on compounds (1), (2) and (4). Length variations with temperature are greater for type II contacts compared with type I. The type II Br⋯Br interaction in (2) is stronger than the corresponding type II Cl⋯Cl interaction in (1), leading to elastic bending of the former upon application of mechanical stress, which contrasts with the plastic deformation of (1). The observation of elastic deformation in (2) is noteworthy; in that it finds an explanation based on the strengths of the respective halogen bonds, it could also be taken as a good starting model for future property design. Cl/Br isostructurality is studied with the Cambridge Structural Database and it is indicated that this isostructurality is based on shape and size similarity of Cl and Br, rather than arising from any chemical resemblance.

Broad Wavelength Tunable Robust Lasing from Single-Crystal Nanowires of Cesium Lead Halide Perovskites (CsPbX3, X = Cl, Br, I).

PubMed

Fu, Yongping; Zhu, Haiming; Stoumpos, Constantinos C; Ding, Qi; Wang, Jue; Kanatzidis, Mercouri G; Zhu, Xiaoyang; Jin, Song

2016-08-23

Lead halide perovskite nanowires (NWs) are emerging as a class of inexpensive semiconductors with broad bandgap tunability for optoelectronics, such as tunable NW lasers. Despite exciting progress, the current organic-inorganic hybrid perovskite NW lasers suffer from limited tunable wavelength range and poor material stability. Herein, we report facile solution growth of single-crystal NWs of inorganic perovskite CsPbX3 (X = Br, Cl) and their alloys [CsPb(Br,Cl)3] and a low-temperature vapor-phase halide exchange method to convert CsPbBr3 NWs into perovskite phase CsPb(Br,I)3 alloys and metastable CsPbI3 with well-preserved perovskite crystal lattice and NW morphology. These single crystalline NWs with smooth end facets and subwavelength dimensions are ideal Fabry-Perot cavities for NW lasers. Optically pumped tunable lasing across the entire visible spectrum (420-710 nm) is demonstrated at room temperature from these NWs with low lasing thresholds and high-quality factors. Such highly efficient lasing similar to what can be achieved with organic-inorganic hybrid perovskites indicates that organic cation is not essential for light emission application from these lead halide perovskite materials. Furthermore, the CsPbBr3 NW lasers show stable lasing emission with no measurable degradation after at least 8 h or 7.2 × 10(9) laser shots under continuous illumination, which are substantially more robust than their organic-inorganic counterparts. The Cs-based perovskites offer a stable material platform for tunable NW lasers and other nanoscale optoelectronic devices.

Nanocrystals of Cesium Lead Halide Perovskites (CsPbX₃, X = Cl, Br, and I): Novel Optoelectronic Materials Showing Bright Emission with Wide Color Gamut.

PubMed

Protesescu, Loredana; Yakunin, Sergii; Bodnarchuk, Maryna I; Krieg, Franziska; Caputo, Riccarda; Hendon, Christopher H; Yang, Ruo Xi; Walsh, Aron; Kovalenko, Maksym V

2015-06-10

Metal halides perovskites, such as hybrid organic-inorganic CH3NH3PbI3, are newcomer optoelectronic materials that have attracted enormous attention as solution-deposited absorbing layers in solar cells with power conversion efficiencies reaching 20%. Herein we demonstrate a new avenue for halide perovskites by designing highly luminescent perovskite-based colloidal quantum dot materials. We have synthesized monodisperse colloidal nanocubes (4-15 nm edge lengths) of fully inorganic cesium lead halide perovskites (CsPbX3, X = Cl, Br, and I or mixed halide systems Cl/Br and Br/I) using inexpensive commercial precursors. Through compositional modulations and quantum size-effects, the bandgap energies and emission spectra are readily tunable over the entire visible spectral region of 410-700 nm. The photoluminescence of CsPbX3 nanocrystals is characterized by narrow emission line-widths of 12-42 nm, wide color gamut covering up to 140% of the NTSC color standard, high quantum yields of up to 90%, and radiative lifetimes in the range of 1-29 ns. The compelling combination of enhanced optical properties and chemical robustness makes CsPbX3 nanocrystals appealing for optoelectronic applications, particularly for blue and green spectral regions (410-530 nm), where typical metal chalcogenide-based quantum dots suffer from photodegradation.

Dithiolato- and halogenido-bridged nickel-iron complexes related to the active site of [NiFe]-H2ases: preparation, structures, and electrocatalytic H2 production.

PubMed

Song, Li-Cheng; Han, Xiao-Feng; Chen, Wei; Li, Jia-Peng; Wang, Xu-Yong

2017-08-14

A new series of the structural and functional models for the active site of [NiFe]-H 2 ases has been prepared by a simple and convenient synthetic route. Thus, treatment of diphosphines RN(PPh 2 ) 2 (1a, R = p-MeC 6 H 4 CH 2 ; 1b, R = EtO 2 CCH 2 ) with an equimolar NiCl 2 ·6H 2 O, NiBr 2 ·3H 2 O, and NiI 2 in refluxing CH 2 Cl 2 /MeOH or EtOH gave the mononuclear Ni complexes RN(PPh 2 ) 2 NiX 2 (2a, R = p-MeC 6 H 4 CH 2 , X = Cl; 2b, R = EtO 2 CCH 2 , X = Cl; 3a, R = p-MeC 6 H 4 CH 2 , X = Br; 3b, R = EtO 2 CCH 2 , X = Br; 4a, R = p-MeC 6 H 4 CH 2 , X = I; 4b, R = EtO 2 CCH 2 , X = I) in 67-97% yields. Further treatment of complexes 2a,b-4a,b with an equimolar mononuclear Fe complex (dppv)(CO) 2 Fe(pdt) and NaBF 4 resulted in formation of the targeted model complexes [RN(PPh 2 ) 2 Ni(μ-pdt)(μ-X)Fe(CO)(dppv)](BF 4 ) (5a, R = p-MeC 6 H 4 CH 2 , X = Cl; 5b, R = EtO 2 CCH 2 , X = Cl; 6a, R = p-MeC 6 H 4 CH 2 , X = Br; 6b, R = EtO 2 CCH 2 , X = Br; 7a, R = p-MeC 6 H 4 CH 2 , X = I; 7b, R = EtO 2 CCH 2 , X = I) in 60-96% yields. All the new complexes 3a,b-4a,b and 5a,b-7a,b have been characterized by elemental analysis and spectroscopy, and particularly for some of them (3a,b/4a,b and 5b/6b) by X-ray crystallography. More interestingly, the electrochemical and electrocatalytic properties of such halogenido-bridged model complexes are first studied systematically and particularly they have been found to be pre-catalysts for proton reduction to H 2 under CV conditions.

Studies of ClO and BrO reactions important in the polar stratosphere: Kinetics and mechanism of the ClO+BrO and ClO+ClO reactions

NASA Technical Reports Server (NTRS)

Friedl, Randall R.; Sander, Stanley P.

1988-01-01

The reactions, BrO + ClO yields Br + ClOO (1a) yields Br + OClO (1b) yields BrCl + O2 (1c) and ClO + ClO yields Cl + CiOO (2a) yields Cl + OClO (2b) yields Cl2 + O2 (2c) yields (ClO)2 (2d) have assumed new importance in explaining the unusual springtime depletion of ozone observed in the Antarctic stratosphere. The mechanisms of these reactions involve the formation of metastable intermediates which subsequently decompose through several energetically allowed products providing the motivation to study these reactions using both the discharge flow-mass spectrometric and flash photolysis - ultraviolet absorption techniques. These methods have also been used to explore aspects of the kinetics and spectroscopy of the ClO dimer.

Electronic structures and geometries of the XF{sub 3} (X = Cl, Br, I, At) fluorides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sergentu, Dumitru-Claudiu; CEISAM, UMR CNRS 6230, Université de Nantes, 2 Rue de la Houssinière, BP 92208, 44322 Nantes Cedex 3; Amaouch, Mohamed

The potential energy surfaces of the group 17 XF{sub 3} (X = Cl, Br, I, At) fluorides have been investigated for the first time with multiconfigurational wave function theory approaches. In agreement with experiment, bent T-shaped C{sub 2v} structures are computed for ClF{sub 3}, BrF{sub 3}, and IF{sub 3}, while we predict that an average D{sub 3h} structure would be experimentally observed for AtF{sub 3}. Electron correlation and scalar relativistic effects strongly reduce the energy difference between the D{sub 3h} geometry and the C{sub 2v} one, along the XF{sub 3} series, and in the X = At case, spin-orbit couplingmore » also slightly reduces this energy difference. AtF{sub 3} is a borderline system where the D{sub 3h} structure becomes a minimum, i.e., the pseudo-Jahn-Teller effect is inhibited since electron correlation and scalar-relativistic effects create small energy barriers leading to the global C{sub 2v} minima, although both types of effects interfere.« less

Continuous flow stable isotope methods for study of δ13C fractionation during halomethane production and degradation

USGS Publications Warehouse

Kalin, Robert M.; Hamilton, John T.G.; Harper, David B.; Miller, Laurence G.; Lamb, Clare; Kennedy, James T.; Downey, Angela; McCauley, Sean; Goldstein, Allen H.

2001-01-01

Gas chromatography/mass spectrometry/isotope ratio mass spectrometry (GC/MS/IRMS) methods for δ13C measurement of the halomethanes CH3Cl, CH3Br, CH3I and methanethiol (CH3SH) during studies of their biological production, biological degradation, and abiotic reactions are presented. Optimisation of gas chromatographic parameters allowed the identification and quantification of CO2, O2, CH3Cl, CH3Br, CH3I and CH3SH from a single sample, and also the concurrent measurement of δ13C for each of the halomethanes and methanethiol. Precision of δ13C measurements for halomethane standards decreased (±0.3, ±0.5 and ±1.3‰) with increasing mass (CH3Cl, CH3Br, CH3I, respectively). Given that carbon isotope effects during biological production, biological degradation and some chemical (abiotic) reactions can be as much as 100‰, stable isotope analysis offers a precise method to study the global sources and sinks of these halogenated compounds that are of considerable importance to our understanding of stratospheric ozone destruction. 

Synthesis and the crystal and molecular structures of (H{sub 3}L . Cl)[CoCl{sub 4}] and H{sub 2}L[CuBr{sub 4}] (L is 2,4,6-Tri(N,N-dimethylamino)methylphenol)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kovalchukova, O. V., E-mail: okovalchukova@mail.ru; Stash, A. I.; Strashnova, S. B.

2010-05-15

The complex compounds (H{sub 3}L . Cl)[CoCl{sub 4}] (I) and H{sub 2}L[CuBr{sub 4}] (II), where L is 2,4,6-tri(N,N-dimethylamino)methylphenol, were isolated in the crystalline state and studied by X-ray diffraction. The organic cations were found to be outer-sphere ligands. All three nitrogen atoms of the tertiary amino groups are protonated. In compound I, the H{sub 3}L{sup 3+} cation exists as the cis tautomer. In compound II, the H{sub 2}L{sup 2+} dication exists as the trans isomer. In the crystal structure, the dications are arranged in layers via hydrogen bonds.

'Pincer' dicarbene complexes of some early transition metals and uranium.

PubMed

Pugh, David; Wright, Joseph A; Freeman, Sandra; Danopoulos, Andreas A

2006-02-14

The complexes [(C-N-C)MX(n)(thf)(m)] with the 'pincer' 2,6-bis(imidazolylidene)pyridine, (C-N-C) = 2,6-bis(arylimidazol-2-ylidene)pyridine, aryl = 2,6-Pr(i)2C6H3, M = V, X = Cl, n = 2, m = 1 1a; M = Cr, X = Cl, n = 2, m = 0, 2a, X = Br, 2b; M = Mn, X = Br, n = 2, m = 0, 3; M = Nb, X = Cl, n = 3, m = 0, 4; and M = U, X = Cl, n = 4, m = 0, 5, were synthesised by (a) substitution of labile tmed (1a), thf (2a, 3, 5) or dme (4) by free (C-N-C) or by (b) reaction of the bisimidazolium salt (CH-N-CH)Br2 with {Cr[N(SiMe3)2]2(thf)2} followed by amine elimination (2b). Attempted alkylation of 1a, 2, 3a and 4 with Grignard or alkyl lithiums gave intractable mixtures, and in one case [reaction of 1a with (mesityl)MgBr] resulted in exchange of Cl by Br (1b). Oxidation of 1a or [(C-N-C)VCl3] with 4-methylmorpholine N-oxide afforded the trans-V(C-N-C)(=O)Cl2, 6, which by reaction with AgBF4 in MeCN gave trans-[V(C-N-C)(=O)(MeCN)2][BF4]2, 7. Reaction of 1a with p-tolyl azide gave trans-V(C-N-C)(=N-p-tolyl)Cl2 8. The complex trans-Ti(C-N-C)(=NBu(t))Cl2, 9, was prepared by substitution of the pyridine ligands in Ti(NBu(t))Cl2(py)3 by C-N-C.

Comprehensive ab initio calculation and simulation on the low-lying electronic states of TlX (X = F, Cl, Br, I, and At).

PubMed

Zou, Wenli; Liu, Wenjian

2009-03-01

The low-lying electronic states of TlX (X=F, Cl, Br, I, and At) are investigated using the configuration interaction based complete active space third-order perturbation theory [CASPT3(CI)] with spin-orbit coupling accounted for. The potential energy curves and the corresponding spectroscopic constants are reported. The results are grossly in good agreement with the available experimental data. The absorption spectra are simulated as well to reassign the experimental bands. The present results are also useful for guiding future experimental measurements.

Halogenides of dimethylglycine in comparison with respective salts of glycine, sarcosine and betaine

NASA Astrophysics Data System (ADS)

Petrosyan, A. M.; Ghazaryan, V. V.; Giester, G.; Fleck, M.; Tylczyński, Z.; Wiesner, M.

2018-04-01

We investigated salts formation in the DMG(dimethylglycine)sbnd HClsbnd H2O, DMGsbnd HBrsbnd H2O and DMGsbnd HIsbnd H2O systems. In addition to previously known dimethylglycinium chloride (DMGH)Cl, we obtained and characterized (structurally and spectroscopically) the following crystals: (DMGH)Br, (DMGH)I as well as the first salts of DMG with dimeric (DMG⋯DMGH) cation: (DMG⋯DMGH)Cl, (DMG⋯DMGH)Br, (DMG⋯DMGH)I. Obtained results are compared with results of known or newly obtained respective salts of glycine, sarcosine (monomethylglycine) and betaine (trimethylglycine).

New iodide-based molten salt systems for high temperature molten salt batteries

NASA Astrophysics Data System (ADS)

Fujiwara, Syozo; Kato, Fumio; Watanabe, Syouichiro; Inaba, Minoru; Tasaka, Akimasa

Novel multi-component molten salt systems containing iodides, LiF-LiBr-LiI, LiF-NaBr-LiI, and LiF-LiCl-LiBr-LiI, were investigated for use as electrolytes in high temperature molten salt batteries to improve the discharge rate-capability. The iodide-based molten salts showed higher ionic conductivity (∼3 S cm -1 at 500 °C) than conventional LiCl-KCl, and had low enough melting points (below 400 °C) that can be used in practical high temperature molten salt batteries. The iodide-based salts showed instability at temperatures higher than 280 °C in dried air. The decomposition mechanism of iodide-based molten salts was discussed, and it was found that elimination of oxygen from the environment is effective to stabilize the iodide-based molten salts at high temperatures.

Is the 'Bromine Explosion' generated from the reaction BrO HO2 alone?

NASA Astrophysics Data System (ADS)

Behnke, Wolfgang; Zetzsch, Cornelius

2010-05-01

We observed bromine explosions (a fast production of atomic Br and Cl under tropospheric conditions) in various smog chamber experiments in Teflon bags at room temperature at a relative humidity of about 80% in the presence of NaCl/NaBr-aerosol, simulated sunlight and ozone (200 - 400 ppb). Time profiles of ozone and hydrocarbons (HCs: n-butane, 2,2-dimethylbutane, tetramethylbutane and toluene, initially about 2 ppb each) were monitored to determine concentrations and source strengths of OH radicals, atomic Cl and Br and the corresponding time profiles of BrCl and Br2 as their photolytic precursors. The number and size of aerosols are measured as well as their chemical composition (Br-, Cl- and oxalic acid). Full records of raw data from the smog chamber runs are available at www.eurochamp.org for potential users. Chemical box model calculations deliver concentrations of various intermediates, such as aldehydes, HO2 and RO2 radicals and the inorganic halogen compounds ClO, BrO, HOCl and HOBr, where HOBr from O3 + Br- => BrO- + O2 in the aqueous/adsorbed phase induces the following gas-phase/ heterogeneous chain reaction Br + O3 => BrO + O2(1) BrO + HO2 => HOBr + O2(2a) HOBr + (Aerosol) => HOBrad(3) Surface-adsorbed HOBr reacts with Br- or Cl- to produce Br2 or BrCl, both of which are released and photolysed. Formation of Br2 should prevail up to Cl-/Br- -ratios of about 104 (Fickert, S., J.W. Adams, J.N. Crowley, J. Geophys. Res., D104, 23719-23727, 1999). A maximum of this ratio is reached about 30 minutes after the beginning and decreases during the next hours - probably by reaction of Br2 with oxalate and absorption of HBr, formed from the reaction of Br with aldehydes. Parallel to chain reaction (1)-(3) a chain reaction replacing Br by Cl seems possible but can not be realized, since the main sink of atomic Cl is its reaction with hydrocarbons - leading to chain termination - in contrast to atomic Br (ratio of rates: kCl[O3]/kCl[HC] ~ 0.1; kBr[O3]/kBr[toluene] ~ 100). Formation of aldehydes (R-CHO) interferes with the chain reaction (1) - (3) markedly, since kBr[O3] ≈kBr[R-CHO]. The chain reaction is limited by availability of ozone (degradation of HCs by atomic Cl stops completely with vanishing ozone), of HO2 (HCs are required to form HO2) and of aerosol. The central question is: will sufficient HO2 be formed from degradation of HCs to explain the magnitude of the formed Br2 and BrCl in our experiments? We found that the formation of HO2 should be by a factor of 2-4 larger to explain the formation of Br2 and BrCl. Which other sources for the formation of HOBr besides reaction (2a) are then available? The rate of CH3O2with BrO is 25% of that with HO2 (Enami, S.; Yamanaka, T.; Nakayama, T.; Hashimoto, S.; Kawasaki, M.; Shallcross, D.E.; Nakano, Y.; Ishiwata, T., J. Phys. Chem. A, 11, 3342 - 3348, 2007), suggesting that other RO2 radicals must contribute. In our model calculations we use this rate constant for all RO2 radicals to obtain reasonable agreement between the produced HOBr and the formed BrCl and Br2 necessary for our experimental degradation results. So reaction scheme (1) - (3) should be completed by: BrO + RO2 => HOBr + products (2b) The German Science Foundation (DFG) supported this research in unit 783 (HALOPROC).

The contribution of hydrothermally altered ocean crust to the mantle halogen and noble gas cycles

NASA Astrophysics Data System (ADS)

Chavrit, Déborah; Burgess, Ray; Sumino, Hirochika; Teagle, Damon A. H.; Droop, Giles; Shimizu, Aya; Ballentine, Chris J.

2016-06-01

Recent studies suggest that seawater-derived noble gases and halogens are recycled into the deep mantle by the subduction of oceanic crust. To understand the processes controlling the availability of halogens and noble gases for subduction, we determined the noble gas elemental and isotopic ratios and halogen (Cl, Br, I) concentrations in 28 igneous samples from the altered oceanic crust (AOC) from 5 ODP sites in the Eastern and Western Pacific Ocean. Crushing followed by heating experiments enabled determination of noble gases and halogens in fluid inclusions and mineral phases respectively. Except for He and Ar, Ne, Kr and Xe isotopic ratios were all air-like suggesting that primary MORB signatures have been completely overprinted by air and/or seawater interaction. In contrast, 3He/4He ratios obtained by crushing indicate that a mantle helium component is still preserved, and 40Ar/36Ar values are affected by radiogenic decay in the mineral phases. The 130Xe/36Ar and 84Kr/36Ar ratios are respectively up to 15 times and 5 times higher than those of seawater and the highest ratios are found in samples affected by low temperature alteration (shallower than 800-900 m sub-basement). We consider three possible processes: (i) adsorption onto the clays present in the samples; (ii) fluid inclusions with a marine pore fluid composition; and (iii) fractionation of seawater through phase separation caused by boiling. Ninety percent of the Cl, Br and I were released during the heating experiments, showing that halogens are dominantly held in mineral phases prior to subduction. I/Cl ratios vary by 4 orders of magnitude, from 3 × 10-6 to 2 × 10-2. The mean Br/Cl ratio is 30% lower than in MORB and seawater. I/Cl ratios lower than MORB values are attributed to Cl-rich amphibole formation caused by hydrothermal alteration at depths greater than 800-900 m sub-basement together with different extents of I loss during low and high temperature alteration. At shallower depths, I/Cl ratios higher than MORB values can be explained by the addition of organic-rich sediments or the presence of organic detritus, both known to efficiently sequester I. Concentrations of 36Ar of the pre-subducting materials are sufficient to account for the 36Ar and composition of the mantle in the context of existing subduction-flux models. We find the Cl subduction flux of the oceanic crust to be about three times higher than the previous estimates and that sufficient Cl and Br can potentially be delivered by subduction over the last 3 Ga to account for mantle source compositions.

Density functional theory study of homologous organometallic molecules of the [RhXL2]2 (X=Cl, Br, or I; L=CO, PH3, or PF3) type

NASA Astrophysics Data System (ADS)

Seuret, P.; Weber, J.; Wesolowski, T. A.

Density functional theory generalized gradient approximation calculations, which were tested in our previous detailed study of [RhCl(PF3)2]2 (Seuret et al., 2003, Phys. Chem. chem. Phys., 5, 268-274), were applied for a series of homologous organometallic compounds of the [RhXL2]2 (X = Cl, Br, or I; L = CO, PH3, or PF3) type. Various properties of the studied compounds were obtained. Optimized geometries of [RhCl(PH3)2]2 and [RhCl(CO)2]2 are in very good agreement with available experimental data. Geometries of other compounds as well as other properties (thermochemistry of selected fragmentation channels, barriers to structural changes, frontier orbitals) which are not available experimentally were predicted. All the considered compounds are not planar. Enforcing planarity of the central [RhX]2 moiety requires only a small energetic cost ranging from 2.2 to 3.9 kcal mol-1. The analysis of frontier orbitals indicates that the metals provide the most favourable site for the electrophilic attack in all considered compounds. The analysis of the shape of the lowest unoccupied molecular orbitals indicates that the halogens and ligands provide the most favourable site for the nucleophilic attack for [RhCl(CO)2]2 or [RhCl(PF3)2]. For [RhBr(PF3)2]2, [RhI(PF3)2]2 and [RhCl(PH3)2]2, the nucleophilic attack on the halogen is less probable. Except for [RhCl(CO)2]2, the least energetically expensive decomposition channel involves initial separation of ligands. For [RhCl(CO)2]2, its decomposition into the RhCl(CO)2 fragments was found to be the least energetically expensive fragmentation reaction which is probably one of the reasons for the known catalytic activity of this compound.

New molten salt systems for high temperature molten salt batteries: Ternary and quaternary molten salt systems based on LiF-LiCl, LiF-LiBr, and LiCl-LiBr

NASA Astrophysics Data System (ADS)

Fujiwara, Syozo; Inaba, Minoru; Tasaka, Akimasa

Using a new simulative technique developed by us, we systematically investigated new ternary or quaternary molten salt systems, which are based on LiF-LiCl, LiF-LiBr, and LiCl-LiBr binary systems, for use as electrolytes in thermal batteries, and evaluated their ionic conductivities and melting points experimentally. It was confirmed experimentally that LiF-LiBr-KF (melting point: 425 °C, ionic conductivity at 500 °C: 2.52 S cm -1), LiCl-LiBr-KF (405 °C, 2.56 S cm -1), LiCl-LiBr-NaF-KF (425 °C, 3.11 S cm -1), LiCl-LiBr-NaCl-KCl (420 °C, 2.73 S cm -1), and LiCl-LiBr-NaBr-KBr (420 °C, 2.76 S cm -1) meet our targets for both melting point (350-430 °C) and ionic conductivity (2.0 S cm -1 and higher at 500 °C). A single cell using the newly developed LiCl-LiBr-NaCl-KCl molten salt as an electrolyte was prepared, and the DC-IR of the cell decreased by 20% than that of a single cell using the conventional LiCl-KCl molten salt. It was therefore concluded that the use of new quaternary molten salt systems can improve the discharge rate-capability in practical battery applications because of their high ionic conductivities.

Haloacetate analogs of pheromones: Effects on catabolism and electrophysiology inPlutella xylostella.

PubMed

Prestwich, G D; Streinz, L

1988-03-01

A series of mono-, di-, and trihalogenated acetate analogs of Zl 1-16: Ac were prepared and examined for electrophysiological activity in antennae of males of the diamondback moth,Plutella xylostella. In addition, two potential affinity labels, a diazoacetate (Dza) and a trifluoromethyl ketone (Tfp), were evaluated for EAG activity. The Z11-16∶Ac showed the highest activity in EAG assays, followed by the fluorinated acetates, but other halo-acetates were essentially inactive. The polar diazoacetate and the trifluoromethyl ketone were also very weak EAG stimulants. The effects of these analogs on the hydrolysis of [(3)H]Z11-16∶Ac to [(3)H]Z11-16∶OH by antennal esterases was also examined. The three fluorinated acetates showed the greatest activity as inhibitors in competition assays, with rank order F2Ac > F(3)Ac > FAc > Ac > Cl2Ac > ClAc > Dza > Br2Ac > BrAc > Tfp > I > Cl3Ac > Br3Ac > OH. The relative polarities of the haloacetates, as determined by TLC mobility, are in the order mono- > di- > trihalo, but F, Cl, Br, and I all confer similar polarities within a substitution group. Thus, the steric size appears to be the predominant parameter affecting the interactions of the haloacetate analogs with both receptor and catabolic proteins inP. xylostella males.

Continued development of thallium bromide and related compounds for gamma-ray spectrometers

NASA Astrophysics Data System (ADS)

Kim, H.; Churilov, A.; Ciampi, G.; Cirignano, L.; Higgins, W.; Kim, S.; O'Dougherty, P.; Olschner, F.; Shah, Kanai

2011-02-01

Thallium bromide (TlBr) and related ternary compounds, TlBrI and TlBrCl, have been under development for room temperature gamma-ray spectroscopy due to high density, high Z and wide bandgap of the material. Low melting point and cubic crystal structure of selected compositions of these compounds facilitate crystal growth by melt techniques. Recent advances in material purification, crystal growth, and device processing have led to mobility-lifetime products of electrons in the mid 10 -3 cm 2/V range enabling working detectors of greater than 15 mm thickness to be fabricated. In this paper we report on our recent progress on TlBr detector development and first results from TlBr xCl 1- x devices. Pulse height spectra will be presented from TlBr arrays as thick as 18 mm. Depth corrected spectra will also be presented. For a 5 mm thick TlBr array, energy resolution of less than 1% (FWHM at 662 keV) was obtained after depth correction.

Periodicity, Electronic Structures, and Bonding of Gold Tetrahalides [AuX4](-) (X = F, CI, Br, I, At, Uus)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Wan-Lu; Li, Yong; Xu, Congqiao

2015-12-07

Systematic theoretical and experimental investigations have been performed to understand the periodicity and electronic structures of trivalent-gold halides using gold tetrahalides [AuX4]⁻ anions (X = F, Cl, Br, I, At, Uus). The [AuX4]⁻ (X = Cl, Br, I) anions were produced in gas phase and their negative-ion photoelectron spectra were obtained, which exhibited rich and well-resolved spectral peaks. We calculated the adiabatic as well as vertical electron detachment energies using density functional methods with scalar and spin-orbit coupling relativistic effects. The simulated photoelectron spectra based on these calculations are in good agreement with the experimental spectra. Our results show thatmore » the trivalent Au(III) oxidation state becomes progressively less stable while Au(I) is preferred when the halides become heavier along the Period Table. This trend reveals that the oxidation state of metals in complexes can be manipulated through ligand design« less

Theoretical descriptions of novel triplet germylenes M1-Ge-M2-M3 (M1 = H, Li, Na, K; M2 = Be, Mg, Ca; M3 = H, F, Cl, Br).

PubMed

Kassaee, Mohamad Zaman; Ashenagar, Samaneh

2018-02-06

In a quest to identify new ground-state triplet germylenes, the stabilities (singlet-triplet energy differences, ΔE S-T ) of 96 singlet (s) and triplet (t) M 1 -Ge-M 2 -M 3 species were compared and contrasted at the B3LYP/6-311++G**, QCISD(T)/6-311++G**, and CCSD(T)/6-311++G** levels of theory (M 1  = H, Li, Na, K; M 2  = Be, Mg, Ca; M 3  = H, F, Cl, Br). Interestingly, F-substituent triplet germylenes (M 3  = F) appear to be more stable and linear than the corresponding Cl- or Br-substituent triplet germylenes (M 3  = Cl or Br). Triplets with M 1  = K (i.e., the K-Ge-M 2 -M 3 series) seem to be more stable than the corresponding triplets with M 1  = H, Li, or Na. This can be attributed to the higher electropositivity of potassium. Triplet species with M 3  = Cl behave similarly to those with M 3  = Br. Conversely, triplets with M 3  = H show similar stabilities and linearities to those with M 3  = F. Singlet species of formulae K-Ge-Ca-Cl and K-Ge-Ca-Br form unexpected cyclic structures. Finally, the triplet germylenes M 1 -Ge-M 2 -M 3 become more stable as the electropositivities of the α-substituents (M 1 and M 2 ) and the electronegativity of the β-substituent (M 3 ) increase.

GTE_TRACEP_P3B Parameters 1

Atmospheric Science Data Center

2013-02-19

... Methyl bromide (CH3Br) Bromopropane (C3H7 Br) Methyl Chloride (CH3Cl) Ethyl Chloride (C2H5Cl) Vinyl chloride (C2H3Cl) ... Trichloroethylene (C2HCl3) Tetrachloroethylene (C2Cl4) Methylene bromide (CH2Br2) Chlorodibromomethane (CHClBr2) Bromoform ...

GTE_TRACEP_DC8 Parameters 4

Atmospheric Science Data Center

2013-02-18

... Methyl bromide (CH3Br) Bromopropane (C3H7Br) Methyl Chloride(CH3Cl) Ethyl Chloride (C2H5Cl) Vinyl chloride (C2H3Cl) ... Trichloroethylene (C2HCl3) Tetrachloroethylene (C2Cl4) Methylene bromide (CH2Br2) Chlorodibromomethane(CHClBr2) Bromoform ...

Martian fluid and Martian weathering signatures identified in Nakhla, NWA 998 and MIL 03346 by halogen and noble gas analysis

NASA Astrophysics Data System (ADS)

Cartwright, J. A.; Gilmour, J. D.; Burgess, R.

2013-03-01

We report argon (Ar) noble gas, Ar-Ar ages and halogen abundances (Cl, Br, I) of Martian nakhlites Nakhla, NWA 998 and MIL 03346 to determine the presence of Martian hydrous fluids and weathering products. Neutron-irradiated samples were either crushed and step-heated (Nakhla only), or simply step-heated using a laser or furnace, and analysed for noble gases using an extension of the 40Ar-39Ar technique to determine halogen abundances. The data obtained provide the first isotopic evidence for a trapped fluid that is Cl-rich, has a strong correlation with 40ArXS (40ArXS = 40Armeasured - 40Arradiogenic) and displays 40ArXS/36Ar of ˜1000 - consistent with the Martian atmosphere. This component was released predominantly in the low temperature and crush experiments, which may suggest a fluid inclusion host. For the halogens, we observe similar Br/Cl and I/Cl ratios between the nakhlites and terrestrial reservoirs, which is surprising given the absence of crustal recycling, organic matter and frequent fluid activity on Mars. In particular, Br/Cl ratios in our Nakhla samples (especially olivine) are consistent with previously analysed Martian weathering products, and both low temperature and crush analyses show a similar trend to the evaporation of seawater. This may indicate that surface brines play an important role on Mars and on halogen assemblages within Martian meteorites and rocks. Elevated I/Cl ratios in the low temperature NWA 998 and MIL 03346 releases may relate to in situ terrestrial contamination, though we are unable to distinguish between low temperature terrestrial or Martian components. Whilst estimates of the amount of water present based on the 36Ar concentrations are too high to be explained by a fluid component alone, they are consistent with a mixed-phase inclusion (gas and fluid) or with shock-implanted Martian atmospheric argon. The observed fluid is dilute (low salinity, but high Br/Cl and I/Cl ratios), contains a Martian atmospheric component, and may represent a mixture of a shallow fluid with one derived from fluid circulation within the nakhlite cumulate pile - with heat for fluid circulation supplied by either the igneous intrusion or by an impact event.

NMR shielding and spin–rotation constants of {sup 175}LuX (X = {sup 19}F, {sup 35}Cl, {sup 79}Br, {sup 127}I) molecules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Demissie, Taye B.

2015-12-31

This presentation demonstrates the relativistic effects on the spin-rotation constants, absolute nuclear magnetic resonance (NMR) shielding constants and shielding spans of {sup 175}LuX (X = {sup 19}F, {sup 35}Cl, {sup 79}Br, {sup 127}I) molecules. The results are obtained from calculations performed using density functional theory (non-relativistic and four-component relativistic) and coupled-cluster calculations. The spin-rotation constants are compared with available experimental values. In most of the molecules studied, relativistic effects make an order of magnitude difference on the NMR absolute shielding constants.

Biocompatible Ferromagnetic Cr-Trihalide Monolayers

NASA Astrophysics Data System (ADS)

Sun, Qiang

Cr with an electronic configuration of 3d54s1 possesses the largest atomic magnetic moment (6µB) of all elements in the 3d transition metal series. Furthermore, the trivalent chromium (Cr3+) is biocompatible and is widely found in food and supplements. Here using first principles calculations combined with Monte Carlo simulations based on Ising model, we systematically study a class of 2D ferromagnetic monolayers CrX3 (X = Cl, Br, I). The feasibility of exfoliation from their layered bulk phase is confirmed by the small cleavage energy and high in-plane stiffness. Spin-polarized calculations, combined with self consistently determined Hubbard U that accounts for strong correlation energy, demonstrate that CrX3 (X =Cl, Br, I) monolayers are ferromagnetic and Cr is trivalent and carries a magnetic moment of 3µB, the resulting Cr3+ ions are biocompatible. The corresponding Curie temperatures for CrCl3 CrBr3 CrI3 are are found to 66, 86, and 107 K, respectively, which can be increased to 323, 314, 293 K by hole doping. The biocompatibility and ferromagnetism render these Cr-containing trichalcogenide monolayers unique for applications.

Laser microprobe analyses of Cl, Br, I, and K in fluid inclusions: Implications for sources of salinity in some ancient hydrothermal fluids

USGS Publications Warehouse

Böhlke, J.K.; Irwin, J.J.

1992-01-01

The relative concentrations of Cl, Br, I, and K in fluid inclusions in hydrothermal minerals were measured by laser microprobe noble gas mass spectrometry on irradiated samples containing 10−10 to 10−8 L of fluid. Distinctive halogen signatures indicate contrasting sources of fluid salinity in fluid inclusions from representative “magmatic” (St. Austell), “metamorphic” (Alleghany), and “geothermal” (Creede, Salton Sea) aqueous systems. Br/Cl mol ratios are lowest at Salton Sea (0.27–0.33 × 10−3), where high salinities are largely due to halite dissolution; intermediate at St. Austell (0.85 × 10−3), possibly representative of magmatic volatiles; and highest (near that of seawater) at Creede (1.5–2.1 × 10−3) and Alleghany (1.2–2.4 × 10−3), where dissolved halogens probably were leached from volcanic and (or) nonevaporitic sedimentary rocks. IC1">IC1 mol ratios are lowest (near that of seawater) at Creede (1–14 × 10−6), possibly because organisms scavenged I during low temperature recharge; intermediate at Salton Sea (24–26 × 10−6) and St. Austell (81× 10−6); and highest at Alleghany (320–940 × 10−6), probably because the fluids interacted with organic-rich sediments at high temperatures before being trapped. KCl">KCl mol ratios indicate disequilibrium with respect to hypothetical feldspathic alkali-Al-silicate mineral buffers at fluid inclusion trapping temperatures at Creede, and large contributions of (Na, K)-bicarbonate to total fluid ionic strength at Alleghany. Significant variations in Cl/Br/I/K ratios among different fluid inclusion types are correlated with previously documented mineralization stages at Creede, and with the apparent oxidation state of dissolved carbon at Alleghany. The new data indicate that Cl/ Br/I ratios in hydrothermal fluid inclusions vary by several orders of magnitude, as they do in modern surface and ground waters. This study demonstrates that halogen signatures of fluid inclusions determined by microanalysis yield important information about sources of fluid salinity and provide excellent definition of fluid reservoirs and tracers of flow and interaction in ancient hydrothermal systems.

THE RECIPROCAL SYSTEM FORMED BY THE CHLORIDES AND THE BROMIDES OF LITHIUM AND THALLIUM (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bergman, A.G.; Arabadzhan, A.S.

1963-06-01

The phase diagrams of 2 series of continuous solid solutions, the Li, K:: Cl,Br and the Li,Tl:: Cl,Br were investigated, as part of a study of the relation between thermal effect of equilibrium reactions and the structure of the melts. In the second system, the heat of the exchange reaction LiCl + TlBr in equilibrium LiBr + TlCl amounts to 8.19 kcal/mole, being larger than that of the corresponding reaction in the Li,K:: Cl,Br system; this affects the crystallization surface in the system. A Pt crucible and Pt, Au, Pd/Pt-Rh thermocouple were used in the thermal studies. It was foundmore » that the liquidus surface consists of 2 fields of continuous series of solid solutions. The joint crystallization curve has a maximum at 392 deg C at the stable portion of the LiCl-TlBr system. There is crest in the liquidus surface corresponding to the stable diagonal LiCl--TlBr; this is visible more markedly in the Li(Cl,Br) field. (TTT)« less

Trivalent Rare-Earth-Metal Bis(trimethylsilyl)amide Halide Complexes by Targeted Oxidations.

PubMed

Bienfait, André M; Wolf, Benjamin M; Törnroos, Karl W; Anwander, Reiner

2018-05-07

In contrast to previously applied salt metathesis protocols the targeted rare-earth-metal compounds Ln[N(SiMe 3 ) 2 ] 2 (halogenido) were accessed by oxidation of Ln(II) silylamide precursors. Treatment of Sm[N(SiMe 3 ) 3 ] 2 (thf) 2 with 0.5 equiv of C 2 Cl 6 or 0.25 equiv of TeBr 4 in thf and crystallization thereof gave [Sm{N(SiMe 3 ) 2 } 2 (μ-X)(thf)] 2 (X = Cl, Br). A similar reaction/crystallization procedure performed with 0.5 equiv of 1,2-diiodoethane gave monomeric Sm[N(SiMe 3 ) 2 ] 2 I(thf) 2 . Switching to Yb[N(SiMe 3 ) 2 ] 2 (thf) 2 , the aforementioned oxidants generated monomeric five-coordinate complexes Yb[N(SiMe 3 ) 2 ] 2 X(thf) 2 (X = Cl, Br, I). The reaction of Eu[N(SiMe 3 ) 2 ] 2 (thf) 2 with 0.5 equiv of C 2 Cl 6 in thf yielded the separated ion pair [Eu{N(SiMe 3 ) 2 } 3 Cl][(thf) 5 Eu(μ-Cl) 2 Eu(thf) 5 ]. Performing the chlorination in n-hexane led to oxidation followed by rapid disproportionation into EuCl 3 (thf) x and Eu[N(SiMe 3 ) 2 ] 3 . The bromination reaction did not afford crystalline material, while the iodination gave crystals of divalent EuI 2 (thf) 5 . Use of trityl chloride (Ph 3 CCl) as the oxidant in thf accomplished the Eu(III) species [Eu{N(SiMe 3 ) 2 } 2 (μ-Cl)(thf)] 2 . In situ oxidation of putative [Tm{N(SiMe 3 ) 2 } 2 (thf) x ] using 0.5 equiv of C 2 Cl 6 in thf followed by crystallization from n-hexane led to the formation of a mixture of [Tm{N(SiMe 3 ) 2 } 2 (μ-Cl)(thf)] 2 and Tm[N(SiMe 3 ) 2 ] 3 . Switching the oxidant to 0.5 equiv of 1,2-diiodoethane and crystallizing from thf repeatedly afforded the bis-halogenated complex Tm[N(SiMe 3 ) 2 ]I 2 (thf) 3 .

Energetics of halogen impurities in thorium dioxide

NASA Astrophysics Data System (ADS)

Kuganathan, Navaratnarajah; Ghosh, Partha S.; Arya, Ashok K.; Dey, Gautam K.; Grimes, Robin W.

2017-11-01

Defect energies for halogen impurity atoms (Cl, Br and I) in thoria are calculated using the generalized gradient approximation and projector augmented plane wave potentials under the framework of density functional theory. The energy to place a halogen atom at a pre-existing lattice site is the incorporation energy. Seven sites are considered: octahedral interstitial, O vacancy, Th vacancy, Th-O di-vacancy cluster (DV) and the three O-Th-O tri-vacancy cluster (NTV) configurations. For point defects and vacancy clusters, neutral and all possible defect charge states up to full formal charge are considered. The most favourable incorporation site for Cl is the singly charged positive oxygen vacancy while for Br and I it is the NTV1 cluster. By considering the energy to form the defect sites, solution energies are generated. These show that in both ThO2-x and ThO2 the most favourable solution equilibrium site for halides is the single positively charged oxygen vacancy (although in ThO2, I demonstrates the same solubility in the NTV1 and DV clusters). Solution energies are much lower in ThO2-x than in ThO2 indicating that stoichiometry is a significant factor in determining solubility. In ThO2, all three halogens are highly insoluble and in ThO2-x Br and I remain insoluble. Although ½Cl2 is soluble in ThO2-x alternative phases such as ZrCl4 exist which are of lower energy.

Continued development of room temperature semiconductor nuclear detectors

NASA Astrophysics Data System (ADS)

Kim, Hadong; Cirignano, Leonard; Churilov, Alexei; Ciampi, Guido; Kargar, Alireza; Higgins, William; O'Dougherty, Patrick; Kim, Suyoung; Squillante, Michael R.; Shah, Kanai

2010-08-01

Thallium bromide (TlBr) and related ternary compounds, TlBrI and TlBrCl, have been under development for room temperature gamma ray spectroscopy due to several promising properties. Due to recent advances in material processing, electron mobility-lifetime product of TlBr is close to Cd(Zn)Te's value which allowed us to fabricate large working detectors. We were also able to fabricate and obtain spectroscopic results from TlBr Capacitive Frisch Grid detector and orthogonal strip detectors. In this paper we report on our recent TlBr and related ternary detector results and preliminary results from Cinnabar (HgS) detectors.

Trinitromethyl Ethers and Other Derivatives as Superior Oxidizers

DTIC Science & Technology

2011-08-26

well as comparable or superior energy content, so that its performance will be at least equivalent to that of AP. Oxygen balance (relative to CO2) for...21]: 6 C(NO2)4 + M+Cl – → ClC(NO2)3 + M+NO2 – ClC(NO2)3 + LiBr → BrC(NO2)3 + ClC(NO2)2Br BrC(NO2)3 + LiCl → ClC(NO2)3 + LiBr ...hindrance parameter α > 8.87 would not be stable; where Ustrain is the strain energy or the potential energy of the molecule in the minimum position

Halide addition/abstraction in phosphido derivatives: isolation of the thallium and silver intermediates.

PubMed

Forniés, Juan; Fortuño, Consuelo; Ibáñez, Susana; Martín, Antonio

2008-07-07

Reaction of unsaturated (44e (-) skeleton) [PdPt 2(mu-PPh 2) 2(mu-P 2Ph 4)(R F) 4] 4 with Br (-) produces the saturated (48e (-) skeleton) complex [NBu 4][(R F) 2Pt(mu-PPh 2)(mu-Br)Pd(mu-PPh 2)(mu-P 2Ph 4)Pt(R F) 2] 5 without any M-M' bond. Attempts to eliminate Br (-) of 5 with Ag (+) in CH 2Cl 2 as a solvent gives a mixture of [(R F) 2Pt (III)(mu-PPh 2) 2Pt (III)(R F) 2] and some other unidentified products as a consequence of oxidation and partial fragmentation. However, when the reaction of 5 with Ag (+) is carried out in CH 3CN, no oxidation is observed but the elimination of Br (-) and the formation of [(R F) 2(CH 3CN)Pt(mu-PPh 2)Pd(mu-PPh 2)(mu-P 2Ph 4)Pt(R F) 2] 6 (46e (-) skeleton), a complex with a Pt-Pd bond, takes place. It is noteworthy that the reaction of 5 with TlPF 6 in CH 2Cl 2 does not precipitate TlBr but forms the adduct [(R F) 2PtTl(mu-PPh 2)(mu-Br)Pd(mu-PPh 2)(mu-P 2Ph 4)Pt(R F) 2] 7 with a Pt-Tl bond. Likewise, 5 reacts with [AgOClO 3(PPh 3)] in CH 2Cl 2 forming the adduct [AgPdPt 2(mu-Br)(mu-PPh 2) 2(mu-Ph 2P-PPh 2)(R F) 4(PPh 3)] 8, which contains a Pt-Ag bond. Both adducts are unstable in a CH 3CN solution, precipitating TlBr or AgBr and yielding the unsaturated 6. The treatment of [NBu 4] 2[(R F) 2Pt(mu-PPh 2) 2Pd(mu-PPh 2) 2Pt(R F) 2] in CH 3CN with I 2 (1:1 molar ratio) at 233 K yields a mixture of 4 and 6, which after recrystallization from CH 2Cl 2 is totally converted in 4. If the reaction with I 2 is carried out at room temperature, a mixture of the isomers [NBu 4][(R F) 2Pt(mu-PPh 2)(mu-I)Pd(mu-PPh 2)(mu-P 2Ph 4)Pt(R F) 2] 9 and [NBu 4][(R F)(PPh 2R F)Pt(mu-PPh 2)(mu-I)Pd(mu-PPh 2) 2Pt(R F) 2] 10 are obtained. The structures of the complexes have been established on the bases of NMR data, and the X-ray structures of 5- 8 have been studied. The relationship between the different complexes has been studied.

Nighttime OClO in the Winter Arctic Vortex

NASA Technical Reports Server (NTRS)

Canty, T.; Riviere, E. D.; Salawitch, R. J.; Berthet, G.; Renard, J. -B.; Pfeilsticker, K.; Dorf, M.; Butz, A.; Bosch, H.; Stimpfle, R. M.;

Recognition of a novel type X═N-Hal···Hal (X = C, S, P; Hal = F, Cl, Br, I) halogen bonding.

PubMed

Gushchin, Pavel V; Kuznetsov, Maxim L; Haukka, Matti; Kukushkin, Vadim Yu

2013-04-04

The chlorination of the eight-membered platinum(II) chelates [PtCl2{NH═C(NR2)N(Ph)C(═NH)N(Ph)C(NR2)═NH}] (R = Me (1); R2 = (CH2)5 (2)) with uncomplexed imino group with Cl2 gives complexes bearing the ═N-Cl moiety [PtCl4{NH═C(NR2)N(Ph)C(═NCl)N(Ph)C(NR2)═NH}] (R = Me (3); R2 = (CH2)5 (4)). X-ray study for 3 revealed a novel type intermolecular halogen bonding ═N-Cl···Cl(-), formed between the Cl atom of the chlorinated imine and the chloride bound to the platinum(IV) center. The processing relevant structural data retrieved from the Cambridge Structural Database (CSDB) shows that this type of halogen bonding is realized in 18 more molecular species having X═N-Hal moieties (X = C, P, S, V, W; Hal = Cl, Br, I), but this weak ═N-Hal···Hal(-) bonding was totally neglected in the previous works. The presence of the halogen bonding in 3 was confirmed by theoretical calculations at the density functional theory (DFT, M06-2X) level, and its nature was analyzed.

PbCl2-tuned inorganic cubic CsPbBr3(Cl) perovskite solar cells with enhanced electron lifetime, diffusion length and photovoltaic performance

NASA Astrophysics Data System (ADS)

Li, Bo; Zhang, Yanan; Zhang, Luyuan; Yin, Longwei

2017-08-01

Inorganic CsPbBr3 perovskite is arousing great interest following after organic-inorganic hybrid halide perovskites, and is found as a good candidate for photovoltaic devices for its prominent photoelectric property and stability. Herein, we for the first time report on PbCl2-tuned inorganic Cl-doped CsPbBr3(Cl) perovskite solar cells with adjustable crystal structure and Cl doping for enhanced carrier lifetime, extraction rate and photovoltaic performance. The effect of PbCl2 on the morphologies, structures, optical, and photovoltaic performance of CsPbBr3 perovskite solar cells is investigated systemically. Compared with orthorhombic CsPbBr3, cubic CsPbBr3 demonstrates a significant improvement for electron lifetime (from 6.7 ns to 12.3 ns) and diffusion length (from 69 nm to 197 nm), as well as the enhanced electron extraction rate from CsPbBr3 to TiO2. More importantly, Cl doping benefits the further enhancement of carrier lifetime (14.3 ns) and diffusion length (208 nm). The Cl doped cubic CsPbBr3(Cl) perovskite solar cell exhibits a Jsc of 8.47 mA cm-2 and a PCE of 6.21%, superior to that of pure orthorhombic CsPbBr3 (6.22 mA cm-2 and 3.78%). The improvement of photovoltaic performance can be attributed to enhanced carrier lifetime, diffusion length and extraction rates, as well as suppressed nonradiative recombination.

Characterization of constitutive and acid-induced outwardly rectifying chloride currents in immortalized mouse distal tubular cells.

PubMed

Valinsky, William C; Touyz, Rhian M; Shrier, Alvin

2017-08-01

Thiazides block Na + reabsorption while enhancing Ca 2+ reabsorption in the kidney. As previously demonstrated in immortalized mouse distal convoluted tubule (MDCT) cells, chlorothiazide application induced a robust plasma membrane hyperpolarization, which increased Ca 2+ uptake. This essential thiazide-induced hyperpolarization was prevented by the Cl - channel inhibitor 5-Nitro-2-(3-phenylpropylamino) benzoic acid (NPPB), implicating NPPB-sensitive Cl - channels, however the nature of these Cl - channels has been rarely described in the literature. Here we show that MDCT cells express a dominant, outwardly rectifying Cl - current at extracellular pH7.4. This constitutive Cl - current was more permeable to larger anions (Eisenman sequence I; I - >Br - ≥Cl - ) and was substantially inhibited by >100mM [Ca 2+ ] o , which distinguished it from ClC-K2/barttin. Moreover, the constitutive Cl - current was blocked by NPPB, along with other Cl - channel inhibitors (4,4'-diisothiocyanatostilbene-2,2'-disulfonate, DIDS; flufenamic acid, FFA). Subjecting the MDCT cells to an acidic extracellular solution (pH<5.5) induced a substantially larger outwardly rectifying NPPB-sensitive Cl - current. This acid-induced Cl - current was also anion permeable (I - >Br - >Cl - ), but was distinguished from the constitutive Cl - current by its rectification characteristics, ion sensitivities, and response to FFA. In addition, we have identified similar outwardly rectifying and acid-sensitive currents in immortalized cells from the inner medullary collecting duct (mIMCD-3 cells). Expression of an acid-induced Cl - current would be particularly relevant in the acidic IMCD (pH<5.5). To our knowledge, the properties of these Cl - currents are unique and provide the mechanisms to account for the Cl - efflux previously speculated to be present in MDCT cells. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Pressure and temperature dependences of the ionic conductivities of the thallous halidesTlCl, TlBr, and TlI

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samara, G.A.

1981-01-15

Detailed studies of the pressure and temperature dependences of the ionic conductivities of TlCl and TlBr have allowed determination of the lattice volume relaxations and energies associated with the formation and motion of Schottky defects in these crystals. The volume relaxations deduced from the conductivity are found to be comparable in magnitude with values calculated from the strain energy model and a dynamical model. The association energy of Tl/sup +/ vacancies and divalent impurities was also determined for TlBr. A particularly important result is the finding that for these CsCl-type crystals the relaxation of the lattice associated with vacancy formationmore » is outward. Earlier studies on ionic crystals having the NaCl structure have yielded a similar result. This outward relaxation thus appears to be a general result for ionic crystals of both the NaCl and CsCl types (and possibly other ionic lattice types), in disagreement with earlier theoretical calculations which show that the relaxation should be inward for all models of ionic vacancies investigated. The conductivity of TlI was studied in both the (low temperature and pressure) orthorhombic phase as well as in the cubic CsCl-type phase. There is a large electronic contribution to the conductivity in the orthorhombic phase. An interesting result for all three materials is the observation in the cubic phase of a pressure-induced transition from ionic to electronic conduction. This is in qualitative agreement with what is known about the pressure dependences of the electronic structure of these materials.« less

Atomic contributions from spin-orbit coupling to 29Si NMR chemical shifts in metallasilatrane complexes.

PubMed

Autschbach, Jochen; Sutter, Kiplangat; Truflandier, Lionel A; Brendler, Erica; Wagler, Jörg

2012-10-01

New members of a novel class of metallasilatrane complexes [X-Si-(μ-mt)(4)-M-Y], with M=Ni, Pd, Pt, X=F, Cl, Y=Cl, Br, I, and mt=2-mercapto-1-methylimidazolide, have been synthesized and characterized structurally by X-ray diffraction and by (29)Si solid-state NMR. Spin-orbit (SO) effects on the (29)Si chemical shifts induced by the metal, by the sulfur atoms in the ligand, and by heavy halide ligands Y=Cl, Br, I were investigated with the help of relativistic density functional calculations. Operators used in the calculations were constructed such that SO coupling can selectively be switched off for certain atoms. The unexpectedly large SO effects on the (29)Si shielding in the Ni complex with X=Y=Cl reported recently originate directly from the Ni atom, not from other moderately heavy atoms in the complex. With respect to Pd, SO effects are amplified for Ni owing to its smaller ligand-field splitting, despite the smaller nuclear charge. In the X=Cl, Y=Cl, Br, I series of complexes the Y ligand strongly modulates the (29)Si shift by amplifying or suppressing the metal SO effects. The pronounced delocalization of the partially covalent M←Y bond plays an important role in modulating the (29)Si shielding. We also demonstrate an influence from the X ligand on the (29)Si SO shielding contributions originating at Y. The NMR spectra for [X-Si-(μ-mt)(4)-M-Y] must be interpreted mainly based on electronic and relativistic effects, rather than structural differences between the complexes. The results highlight the sometimes unintuitive role of SO coupling in NMR spectra of complexes containing heavy atoms. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Unique Features of the Photocatalytic Reduction of H2O and CO2 by New Catalysts Based on the Analogues of CdS, Cd4P2X3 (X = Cl, Br, I).

PubMed

Roy, Anand; Chhetri, Manjeet; Prasad, Suchitra; Waghmare, Umesh V; Rao, C N R

2018-01-24

Photochemical reduction of H 2 O and CO 2 has been investigated with a new family of catalysts of the formula Cd 4 P 2 X 3 (X= Cl, Br, I), obtained by the complete aliovalent substitution of the sulfide ions in CdS by P and X (Cl, Br, I). Unlike CdS, the Cd 4 P 2 X 3 compounds exhibit hydrogen evolution and CO 2 reduction from water even in the absence of a sacrificial agent or a cocatalyst. Use of Ni x P y as the cocatalyst, enhances hydrogen evolution, reaching 3870 (apparent quantum yield (AQY) = 4.11) and 9258 (AQY = 9.83) μmol h -1 g -1 , respectively, under artificial and natural (sunlight) irradiation, in the case of Cd 4 P 2 Br 3 /Ni x P y . Electrochemical and spectroscopic studies have been employed to understand the photocatalytic activity of this family of compounds. Unlike most of the semiconductor-based photocatalysts, Cd 4 P 2 X 3 catalysts reduce CO 2 to CO and CH 4 in the absence of sacrificial-agent or cocatalyst using water as the electron source. CO, CH 4 , and H 2 have been obtained with these catalysts under artificial as well as sun-light irradiation. First-principles, calculations have been carried out to understand the electronic structure and catalytic features of these new catalysts.

Synthesis and analysis of 2-[211At]-L-phenylalanine and 4-[211At]-L-phenylalanine and their uptake in human glioma cell cultures in-vitro.

PubMed

Meyer, Geerd J; Walte, Almut; Sriyapureddy, Siva R; Grote, Michaela; Krull, Doris; Korkmaz, Zekiye; Knapp, Wolfram H

2010-06-01

2-[211At]-L-phenylalanine and 4-[211At]-L-phenylalanine were prepared from the corresponding iodo and bromo derivatives using the Cu(+)-assisted nucleophilic exchange. 4-[211At]-L-phenylalanine was additionally prepared by destannylation of the BOC-derivatized 4-tributylstannyl-L-phenylalanine. Radiochemical yields of 2-[211At]-L-phenylalanine and 4-[211At]-L-phenylalanine by nucleophilic exchange were 52-74% and 65-85%. Radiochemical yield of 4-[211At]-L-phenylalanine by electrophilic destannylation was 35-50%. HPLC sequence analysis showed that 2-[211At]-L-phenylalanine followed the halogen sequence (F

Deciphering Halogen Competition in Organometallic Halide Perovskite Growth

DOE PAGES

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

2016-03-01

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

Deciphering Halogen Competition in Organometallic Halide Perovskite Growth

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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

Tracing halogen and B cycling in subduction zones based on obducted, subducted and forearc serpentinites of the Dominican Republic.

PubMed

Pagé, Lilianne; Hattori, Keiko

2017-12-19

Serpentinites are important reservoirs of fluid-mobile elements in subduction zones, contributing to volatiles in arc magmas and their transport into the Earth's mantle. This paper reports halogen (F, Cl, Br, I) and B abundances of serpentinites from the Dominican Republic, including obducted and subducted abyssal serpentinites and forearc mantle serpentinites. Abyssal serpentinite compositions indicate the incorporation of these elements from seawater and sediments during serpentinization on the seafloor and at slab bending. During their subduction and subsequent lizardite-antigorite transition, F and B are retained in serpentinites, whilst Cl, Br and I are expelled. Forearc mantle serpentinite compositions suggest their hydration by fluids released from subducting altered oceanic crust and abyssal serpentinites, with only minor sediment contribution. This finding is consistent with the minimal subduction of sediments in the Dominican Republic. Forearc mantle serpentinites have F/Cl and B/Cl ratios similar to arc magmas, suggesting the importance of serpentinite dehydration in the generation of arc magmatism in the mantle wedge.

Conformational Isomerism of trans-[Pt(NH2C6H11)2I2] and the Classical Wernerian Chemistry of [Pt(NH2C6H11)4]X2 (X = Cl, Br, I)1

PubMed Central

Johnstone, Timothy C.; Lippard, Stephen J.

2012-01-01

X-ray crystallographic analysis of the compound trans-[Pt(NH2C6H11)2I2] revealed the presence of two distinct conformers within one crystal lattice. This compound was studied by variable temperature NMR spectroscopy to investigate the dynamic interconversion between these isomers. The results of this investigation were interpreted using physical (CPK) and computational (molecular mechanics and density functional theory) models. The conversion of the salts [Pt(NH2C6H11)4]X2 into trans-[Pt(NH2C6H11)2X2] (X = Cl, Br, I) was also studied and is discussed here with an emphasis on parallels to the work of Alfred Werner. PMID:23554544

A novel reduction of diketones with i-RMgBr catalyzed by Cp2TiCl2 and deoxygenation of sulfoxides by Cp2TiCl2/Al system*

PubMed Central

Zhang, Yong-min; Lin, Mao-qin; Yu, Yong-ping

2004-01-01

α-diketones and β-diketones react with Grignard reagents in the presence of a catalytic amount of Cp2TiCl2 to yield α-ketols and corresponding ketones respectively. Sulfoxides can be deoxygenated by Cp2TiCl2/Al system. The possible mechanisms are also discussed. PMID:15362186

Picosecond pulse radiolysis of direct and indirect radiolytic effects in highly concentrated halide aqueous solutions.

PubMed

Balcerzyk, Anna; Schmidhammer, Uli; El Omar, Abdel Karim; Jeunesse, Pierre; Larbre, Jean-Philippe; Mostafavi, Mehran

2011-08-25

Recently we measured the amount of the single product, Br(3)(-), of steady-state radiolysis of highly concentrated Br(-) aqueous solutions, and we showed the effect of the direct ionization of Br(-) on the yield of Br(3)(-). Here, we report the first picosecond pulse-probe radiolysis measurements of ionization of highly concentrated Br(-) and Cl(-) aqueous solutions to describe the oxidation mechanism of the halide anions. The transient absorption spectra are reported from 350 to 750 nm on the picosecond range for halide solutions at different concentrations. In the highly concentrated halide solutions, we observed that, due to the presence of Na(+), the absorption band of the solvated electron is shifted to shorter wavelengths, but its decay, taking place during the spur reactions, is not affected within the first 4 ns. The kinetic measurements in the UV reveal the direct ionization of halide ions. The analysis of pulse-probe measurements show that after the electron pulse, the main reactions in solutions containing 1 M of Cl(-) and 2 M of Br(-) are the formation of ClOH(-•) and BrOH(-•), respectively. In contrast, in highly concentrated halide solutions, containing 5 M of Cl(-) and 6 M of Br(-), mainly Cl(2)(-•) and Br(2)(-•) are formed within the electron pulse without formation of ClOH(-•) and BrOH(-•). The results suggest that, not only Br(-) and Cl(-) are directly ionized into Br(•) and Cl(•) by the electron pulse, the halide atoms can also be rapidly generated through the reactions initiated by excitation and ionization of water, such as the prompt oxidation by the hole, H(2)O(+•), generated in the coordination sphere of the anion. © 2011 American Chemical Society

Two-photon absorption and upconversion luminescence of colloidal CsPbX3 quantum dots

NASA Astrophysics Data System (ADS)

Han, Qiuju; Wu, Wenzhi; Liu, Weilong; Yang, Qingxin; Yang, Yanqiang

2018-01-01

The nonlinear optical and the upconversion luminescence (UCL) properties of CsPbX3 (X = Br or its binary mixtures with Cl, I) quantum dots (QDs) are investigated by femtosecond open-aperture (OA) Z-scan and time-resolved luminescence techniques in nonresonant spectral region. The OA Z-scan results show that CsPbX3 QDs have strong reverse saturable absorption (RSA), which is ascribed to two-photon absorption. Partially changing halide composition from Cl to Br, to I, two-photon absorption cross sections become larger at the same laser excitation intensity. The composition-tunable nonlinear absorption should be attributed to the gradual decrease of the lowest direct band gaps with the halide substitute. Moreover, the strong UCL can be observed under near infrared femtosecond laser excitation. Halide composition-tunable UCL dynamics of CsPbX3 QDs is analyzed by use of two-exponential fitting with deconvolution. When CsPbX3 QDs have similar sizes (10-13 nm), with partially changing halide composition from Cl to Br, to I, the average UCL lifetime becomes longer due to the variation of Kane energy. Our findings suggest all-inorganic perovskite QDs can be used as excellent gain medium for high-performance frequency-upconversion lasers and provide reference to engineer such QDs toward practical optoelectronic applications.

Activation barriers for series of exothermic homologous reactions. V. Boron group diatomic species reactions

NASA Astrophysics Data System (ADS)

Blue, Alan S.; Belyung, David P.; Fontijn, Arthur

1997-09-01

Semiempirical configuration interaction (SECI) theory is used to predict activation barriers E, as defined by k(T)=ATn exp(-E/RT). Previously SECI has been applied to homologous series of oxidation reactions of s1, s2, and s2p1 metal atoms. Here it is extended to oxidation reactions of diatomic molecules containing one s2p1 atom. E values are calculated for the reactions of BH, BF, BCl, AlF, AlCl, AlBr, GaF, GaI, InCl, InBr, InI, TlF, TlCl, TlBr, and TlI with O2, CO2, SO2, or N2O. These values correlate with the sums of the ionization potentials and Σ-Π promotion energies of the former minus the electron affinities of the latter. In the earlier work n was chosen somewhat arbitrarily, which affected the absolute values of E. Here it is shown that examination of available experimental and theoretical results allows determination of the best values of n. Using this approach yields n=1.9 for the present series. For the seven reactions which have been studied experimentally, the average deviation of the SECI activation barrier prediction from experiment is 4.0 kJ mol-1. Energy barriers are calculated for another 52 reactions.

Graphene-like monolayer InSe–X: several promising half-metallic nanosheets in spintronics

NASA Astrophysics Data System (ADS)

Liu, Jun; Kang, Wei; Zhou, Ting-Yan; Ma, Chong-Geng

2018-04-01

Several half-metallic graphene-like nanosheets, namely halogen atom adsorbed InSe–X (X  =  F, Cl, Br and I) nanosheets, are predicted by first-principles calculations. Then, their structural, electric and magnetic properties are studied in detail. The calculated negative adsorption energies of these InSe–X nanosheets ensure that they attain stable adsorption structures, which suggests that they may be prepared experimentally. The pristine InSe monolayer is a typical semi-conductor, whereas it is interesting that the X ion (X  =  F, Cl, Br and I) adsorbed InSe–X nanosheets are electronically conductive. They can be promising and good candidates for applications of half-metallic 2D materials. The calculated magnetic moments of these nanosheets are close to 1.0 µ B. In the InSe–F nanosheet, there are sp2 hybridized orbitals due to the crystal field effect, and its electroconductibility, half-metallicity and magnetic moments originate from the In and Se ions, not the F ion. However, in InSe–X (X  =  Cl, Br and I) nanosheets, there are sp3 hybridized orbitals, and their electroconductibility, half-metallicity and magnetic moments originate mainly from X ions, together partially with the In and Se ions.

Crystal structures of palladium(II) ternary complexes of 5-x-2-aminobenzoic acid with 1,10-phenanthroline and their interaction with calf thymus DNA (where X=Cl, Br and I).

PubMed

Wang, Yue; Okabe, Nobuo; Odoko, Mamiko

2005-10-01

The crystal structures of a series of three palladium(II) ternary complexes of 5-halogeno-2-aminobenzoic acid (5-X-AB, where X=Cl, Br and I) with 1,10-phenanthroline [Pd(5-Cl-AB)(phen)] (1), [Pd(5-Br-AB)(phen)] (2) and [Pd(5-I-AB)(phen)] (3) have been determined, and their coordination geometries and the crystal architecture characterized. All of the complexes are an isostructure in which each Pd(II) atom has basically similar square planar coordination geometry. The substitute halogen group at 5-position of AB plays an important role in producing the coordination bonds of the carboxylate and amino groups in which the carboxylate O atom and the amino N atom act as the negative monodentate ligand atoms. The coordination bond distances of O-Pd increase in the order 1<2<3, while those of N-Pd decrease in the same order. The binding of the complexes to the calf thymus DNA has also been studied by the fluorescence method. Each of the complexes shows high binding propensity to DNA which can be reflected as the relative order 1<2<3.

Spin splitting in band structures of BiTeX (X=Cl, Br, I) monolayers

NASA Astrophysics Data System (ADS)

Hvazdouski, D. C.; Baranava, M. S.; Stempitsky, V. R.

2018-04-01

In systems with breaking of inversion symmetry a perpendicular electric field arises that interacts with the conduction electrons. It may give rise to electron state splitting even without influence of external magnetic field due to the spin-orbital interaction (SOI). Such a removal of the spin degeneracy is called the Rashba effect. Nanostructure with the Rashba effect can be part of a spin transistor. Spin degeneracy can be realized in a channel from a material of this type without additive of magnetic ions. Lack of additive increases the charge carrier mobility and reliability of the device. Ab initio simulations of BiTeX (X=Cl, Br, I) monolayers have been carried out using VASP wherein implemented DFT method. The study of this structures is of interest because such sort of structures can be used their as spin-orbitronics materials. The crystal parameters of BiTeCl, BiTeBr, BiTeI have been determined by the ionic relaxation and static calculations. It is necessary to note that splitting of energy bands occurs in case of SOI included. The values of the Rashba coefficient aR (in the range from 6.25 to 10.00 eV·Å) have high magnitudes for spintronics materials. Band structure of monolayers structures have ideal Rashba electron gas, i.e. there no other energy states near to Fermi level except Rashba states.

Remarkably Enhancing Green-Excitation Efficiency for Solar Energy Utilization: Red Phosphors Ba2ZnS3:Eu2+, X- Co-Doped Halide Ions (X = Cl, Br, I).

PubMed

Luo, Tingting; Du, Yun; Qiu, Zhongxian; Li, Yanmei; Wang, Xiaofang; Zhou, Wenli; Zhang, Jilin; Yu, Liping; Lian, Shixun

2017-05-15

Eu 2+ -activated Ba 2 ZnS 3 has been reported as a red phosphor with a broad emission band peaking at 650 nm under blue excitation for white-LED. In this study, Ba 2 ZnS 3 :Eu 2+ , X - (X = F, Cl, Br, I) phosphors doped with halide ions were prepared by traditional high-temperature solid-state reaction. Phase identification of powders was performed by X-ray powder diffraction analysis, confirming the existence of single-phase Ba 2 ZnS 3 crystals without dopant. The corresponding excitation spectra showed an additional broad band in the green region peaking at 550 nm when the phosphor was halogenated except by the smallest F - . It was proved that the green-excitation efficiency successively strengthened from Cl - , to Br - , to I - , which suggested larger halide ions made a greater contribution to the further splitting of the t 2g energy level of the doped Eu 2+ ions in the host Ba 2 ZnS 3 , and the optimized formula Ba 1.995 ZnS 2.82 :Eu 2+ 0.005 , I - 0.18 showed a potential application in solar spectral conversion for agricultural greenhouse and solar cell. Defect chemistry theory and crystal field theory provided insights into the key role of halide ions in enhancing green-excitation efficiency.

Revealing the Chemistry between Band Gap and Binding Energy for Lead-/Tin-Based Trihalide Perovskite Solar Cell Semiconductors.

PubMed

Varadwaj, Arpita; Varadwaj, Pradeep R; Yamashita, Koichi

2018-01-23

A relationship between reported experimental band gaps (solid) and DFT-calculated binding energies (gas) is established, for the first time, for each of the four ten-membered lead (or tin) trihalide perovskite solar cell semiconductor series examined in this study, including CH 3 NH 3 PbY 3 , CsPbY 3 , CH 3 NH 3 SnY 3 and CsSnY 3 (Y=I (3-x) Br x=1-3 , I (3-x) Cl x=1-3 , Br (3-x) Cl x=1-3 , and IBrCl). The relationship unequivocally provides a new dimension for the fundamental understanding of the optoelectronic features of solid-state solar cell thin films by using the 0 K gas-phase energetics of the corresponding molecular building blocks. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Reactivity of BrCl, Br₂, BrOCl, Br₂O, and HOBr toward dimethenamid in solutions of bromide + aqueous free chlorine.

PubMed

Sivey, John D; Arey, J Samuel; Tentscher, Peter R; Roberts, A Lynn

2013-02-05

HOBr, formed via oxidation of bromide by free available chlorine (FAC), is frequently assumed to be the sole species responsible for generating brominated disinfection byproducts (DBPs). Our studies reveal that BrCl, Br(2), BrOCl, and Br(2)O can also serve as brominating agents of the herbicide dimethenamid in solutions of bromide to which FAC was added. Conditions affecting bromine speciation (pH, total free bromine concentration ([HOBr](T)), [Cl(-)], and [FAC](o)) were systematically varied, and rates of dimethenamid bromination were measured. Reaction orders in [HOBr](T) ranged from 1.09 (±0.17) to 1.67 (±0.16), reaching a maximum near the pK(a) of HOBr. This complex dependence on [HOBr](T) implicates Br(2)O as an active brominating agent. That bromination rates increased with increasing [Cl(-)], [FAC](o) (at constant [HOBr](T)), and excess bromide (where [Br(-)](o)>[FAC](o)) implicate BrCl, BrOCl, and Br(2), respectively, as brominating agents. As equilibrium constants for the formation of Br(2)O and BrOCl (aq) have not been previously reported, we have calculated these values (and their gas-phase analogues) using benchmark-quality quantum chemical methods [CCSD(T) up to CCSDTQ calculations plus solvation effects]. The results allow us to compute bromine speciation and hence second-order rate constants. Intrinsic brominating reactivity increased in the order: HOBr ≪ Br(2)O < BrOCl ≈ Br(2) < BrCl. Our results indicate that species other than HOBr can influence bromination rates under conditions typical of drinking water and wastewater chlorination.

Studies on the in vivo sensitivity of spindle microtubules to calcium ions and evidence for a vesicular calcium-sequestering system

PubMed Central

1981-01-01

I microinjected calcium ions into echinoderm eggs during mitosis to determine the calcium sensitivity of microtubules (Mts) in vivo. Spindle birefringence (BR), a measure of the number of aligned Mts in the spindle, is locally, rapidly, and reversibly abolished by small volumes of microinjected CaCl2 (1 mM). Rapid return of BR is followed by anaphase, and subsequent divisions are normal. Similar doses of MgCl2, BaCl2, KCl, NaCl, pH buffers, distilled water, or vegetable oil have no effect on spindle BR, whereas large doses of such agents sometimes cause slow, uniform loss in BR over the course of a minute or more. Of the ions tested, only Sr++ causes effects comparable to Ca++. Ca-EGTA buffers, containing greater than micromolar free Ca++, abolishes BR in a manner similar to millimolar concentrations of injected CaCl2. Caffeine, a potent uncoupler of the Ca++-pump/ATPase of sarcoplasmic reticulum, causes a local, transient depression in spindle BR in the injected region. Finally, injection of potassium oxalate results in the formation of small, highly BR crystals, presumably CA- oxalate, in Triton-sensitive compartments in the cytoplasm. Taken together, these findings demonstrate that spindle Mts are sensitive to levels of free Ca++ in the physiological range, provide evidence for the existence of a strong cytoplasmic Ca++-sequestering system, and support the notion that Mt assembly and disassembly in local regions of the spindle may be orchestrated by local changes in the cytoplasmic free Ca++ concentration during mitosis. An appendix offers the design of a new chamber for immobilizing echinoderm eggs for injection, a new method for determining the volume of the injected solution, and a description of the microinjection technique, which was designed, but never fully described, by Hiramoto (Y. Hiramoto, Exp. Cell. Res., 1962, 27:416-426.). PMID:7194345

Determination of bromine, chlorine and iodine in environmental aqueous samples by epithermal neutron activation analysis and Compton suppression

USGS Publications Warehouse

Landsberger, S.; O'Kelly, D. J.; Braisted, J.; Panno, S.

2006-01-01

Halides, particularly Br- and Cl-, have been used as indicators of potential sources of Na+ and Cl- in surface water and groundwater with limited success. Contamination of groundwater and surface water by Na+ and Cl- is a common occurrence in growing urban areas and adversely affects municipal and private water supplies in Illinois and other states, as well as vegetation in environmentally sensitive areas. Neutron activation analysis (NAA) can be effectively used to determine these halogens, but often the elevated concentrations of sodium and chlorine in water samples can give rise to very high detection limits for bromine and iodine due to elevated backgrounds from the activation process. We present a detailed analytical scheme to determine Cl, Br and I in aqueous samples with widely varying Na and Cl concentrations using epithermal NAA in conjunction with Compton suppression. ?? 2006 Akade??miai Kiado??.

Effects of strong hydrogen bonds and weak intermolecular interactions on supramolecular assemblies of 4-fluorobenzylamine

NASA Astrophysics Data System (ADS)

Wang, Shi; Ding, Xue-Hua; Li, Yong-Hua; Huang, Wei

2015-07-01

A series of supramolecular salts have been obtained by the self-assembly of 4-fluorobenzylamine and halide ions or metal chloride with 18-crown-6 as the host in the hydrochloric acid medium, i.e. (C7H9FN)+ṡX- (X = Cl-, 1; Br-, 2), [(C7H9FN)2ṡ(18-crown-6)2]2+ṡ(MCl4)2- (M = Mn, 3; Co, 5; Zn, 7; Cd, 8), [(C7H9FN)ṡ(18-crown-6)]+ṡ(FeCl4)- (4) and [(C7H9FN)ṡ(18-crown-6)]+ṡ1/2(CuCl4)2- (6). Structural analyses indicate that 1-2 crystallize in the triclinic space group P-1, 4 in orthorhombic space group Pnma and 3, 5, 6-8 in the monoclinic space group P21/c or C2/c. In these compounds, extensive intermolecular interactions have been utilized for the self-assembly of diverse supramolecular architectures, ranging from strong N-H⋯X (X = O, Cl, Br) hydrogen bonds to weak C-H⋯Y (Y = F, Cl, π) interactions. N-H⋯Cl/Br hydrogen bonds offer the major driving force in the crystal packing of salts 1-2 while N-H⋯O hydrogen bonds are found in salts 3-8.

Effects of cations and anions as aggregating agents on SERS detection of cotinine (COT) and trans-3'-hydroxycotinine (3HC).

PubMed

Han, Sungyub; Hong, Seongmin; Li, Xiao

2013-11-15

The sensitivity of surface-enhanced Raman spectroscopy (SERS) highly depends on experimental factors including aggregating agents and pH. Using silver nanoparticles as the substrate, the effect of five cationic (K(+), Na(+), Mg(2+), Li(+), Ca(2+)) and three anionic (Cl(-), Br(-), I(-)) aggregating agents was examined on the SERS detection of tobacco-related biomarkers, namely cotinine (COT) and trans-3'-hydroxycotinine (3HC). The optimal concentrations of the aggregating agents with respect to highest SERS intensity varied widely (from 1.5 mM for MgCl2 to 150 mM for LiCl). Both cations and anions strongly influenced the SERS enhancement. When Cl(-) was used as the anion, Mg(2+) and Na(+) exhibited the highest SERS intensities for COT and 3HC, respectively. When Mg(2+) was used as the cation, Cl(-) and Br(-) generated the highest SERS enhancement for COT and 3HC, respectively. Clearly, SERS enhancement also depended on the target molecule. Among the 11 aggregating agent combinations tested, the highest SERS enhancement is obtained using 1.5 mM MgCl2 for COT at pH 7.0 and 50 mM NaBr for 3HC at pH 3.0. Copyright © 2013 Elsevier Inc. All rights reserved.

A 3D-analysis of cluster formation and dynamics of the X(-)-benzene (X = F, Cl, Br, I) ionic dimer solvated by Ar atoms.

PubMed

Albertí, Margarita; Huarte-Larrañaga, Fermín; Aguilar, Antonio; Lucas, José M; Pirani, Fernando

2011-05-14

The specific influence of X(-) ions (X = F,Cl, Br, I) in the solvation process of halide-benzene (X(-)-Bz) ionic heterodimers by Ar atoms is investigated by means of molecular dynamic (MD) simulations. The gradual evolution from cluster rearrangement to solvation dynamics is discussed by considering ensembles of n (n = 1-15 and n = 30) Ar atoms around the X(-)-Bz stable ionic dimers. The potential energy surfaces employed are based on an atom/ion-atom and atom/ion-bond decomposition, which has been developed previously by some of the authors. The outcome of the dynamics is analyzed by employing radial distribution functions (RDF) and tridimensional (3D) probability densities.

Fractionation of Cl/Br during fluid phase separation in magmatic-hydrothermal fluids

NASA Astrophysics Data System (ADS)

Seo, Jung Hun; Zajacz, Zoltán

2016-06-01

Brine and vapor inclusions were synthesized to study Cl/Br fractionation during magmatic-hydrothermal fluid phase separation at 900 °C and pressures of 90, 120, and 150 MPa in Li/Na/K halide salt-H2O systems. Laser ablation ICP-MS microanalysis of high-density brine inclusions show an elevated Cl/Br ratio compared to the coexisting low-density vapor inclusions. The degree of Cl/Br fractionation between vapor and brine is significantly dependent on the identity of the alkali metal in the system: stronger vapor partitioning of Br occurs in the Li halide-H2O system compared to the systems of K and Na halide-H2O. The effect of the identity of alkali-metals in the system is stronger compared to the effect of vapor-brine density contrast. We infer that competition between alkali-halide and alkali-OH complexes in high-temperature fluids might cause the Cl/Br fractionation, consistent with the observed molar imbalances of alkali metals compared to halides in the analyzed brine inclusions. Our experiments show that the identity of alkali metals controls the degrees of Cl/Br fractionation between the separating aqueous fluid phases at 900 °C, and suggest that a significant variability in the Cl/Br ratios of magmatic fluids can arise in Li-rich systems.

Behavior of Halogen Bonds of the Y-X⋅⋅⋅π Type (X, Y=F, Cl, Br, I) in the Benzene π System, Elucidated by Using a Quantum Theory of Atoms in Molecules Dual-Functional Analysis.

PubMed

Sugibayashi, Yuji; Hayashi, Satoko; Nakanishi, Waro

2016-08-18

The nature of halogen bonds of the Y-X-✶-π(C6 H6 ) type (X, Y=F, Cl, Br, and I) have been elucidated by using the quantum theory of atoms in molecules (QTAIM) dual-functional analysis (QTAIM-DFA), which we proposed recently. Asterisks (✶) emphasize the presence of bond-critical points (BCPs) in the interactions in question. Total electron energy densities, Hb (rc ), are plotted versus Hb (rc )-Vb (rc )/2 [=(ħ(2) /8m)∇(2) ρb (rc )] for the interactions in QTAIM-DFA, in which Vb (rc ) are potential energy densities at the BCPs. Data for perturbed structures around fully optimized structures were used for the plots, in addition to those of the fully optimized ones. The plots were analyzed by using the polar (R, θ) coordinate for the data of fully optimized structures with (θp , κp ) for those that contained the perturbed structures; θp corresponds to the tangent line of the plot and κp is the curvature. Whereas (R, θ) corresponds to the static nature, (θp , κp ) represents the dynamic nature of the interactions. All interactions in Y-X-✶-π(C6 H6 ) are classified by pure closed-shell interactions and characterized to have vdW nature, except for Y-I-✶-π(C6 H6 ) (Y=F, Cl, Br) and F-Br-✶-π(C6 H6 ), which have typical hydrogen-bond nature without covalency. I-I-✶-π(C6 H6 ) has a borderline nature between the two. Y-F-✶-π(C6 H6 ) (Y=Br, I) were optimized as bent forms, in which Y-✶-π interactions were detected. The Y-✶-π interactions in the bent forms are predicted to be substantially weaker than those in the linear F-Y-✶-π(C6 H6 ) forms. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Heterogeneity of Equilibrium Molten Globule State of Cytochrome c Induced by Weak Salt Denaturants under Physiological Condition

PubMed Central

Rahaman, Hamidur; Alam Khan, Md. Khurshid; Hassan, Md. Imtaiyaz; Islam, Asimul; Moosavi-Movahedi, Ali Akbar; Ahmad, Faizan

2015-01-01

While many proteins are recognized to undergo folding via intermediate(s), the heterogeneity of equilibrium folding intermediate(s) along the folding pathway is less understood. In our present study, FTIR spectroscopy, far- and near-UV circular dichroism (CD), ANS and tryptophan fluorescence, near IR absorbance spectroscopy and dynamic light scattering (DLS) were used to study the structural and thermodynamic characteristics of the native (N), denatured (D) and intermediate state (X) of goat cytochorme c (cyt-c) induced by weak salt denaturants (LiBr, LiCl and LiClO4) at pH 6.0 and 25°C. The LiBr-induced denaturation of cyt-c measured by Soret absorption (Δε 400) and CD ([θ]409), is a three-step process, N ↔ X ↔ D. It is observed that the X state obtained along the denaturation pathway of cyt-c possesses common structural and thermodynamic characteristics of the molten globule (MG) state. The MG state of cyt-c induced by LiBr is compared for its structural and thermodynamic parameters with those found in other solvent conditions such as LiCl, LiClO4 and acidic pH. Our observations suggest: (1) that the LiBr-induced MG state of cyt-c retains the native Met80-Fe(III) axial bond and Trp59-propionate interactions; (2) that LiBr-induced MG state of cyt-c is more compact retaining the hydrophobic interactions in comparison to the MG states induced by LiCl, LiClO4 and 0.5 M NaCl at pH 2.0; and (3) that there exists heterogeneity of equilibrium intermediates along the unfolding pathway of cyt-c as highly ordered (X1), classical (X2) and disordered (X3), i.e., D ↔ X3 ↔ X2 ↔ X1 ↔ N. PMID:25849212

Heterogeneity of equilibrium molten globule state of cytochrome c induced by weak salt denaturants under physiological condition.

PubMed

Rahaman, Hamidur; Alam Khan, Md Khurshid; Hassan, Md Imtaiyaz; Islam, Asimul; Moosavi-Movahedi, Ali Akbar; Ahmad, Faizan

2015-01-01

While many proteins are recognized to undergo folding via intermediate(s), the heterogeneity of equilibrium folding intermediate(s) along the folding pathway is less understood. In our present study, FTIR spectroscopy, far- and near-UV circular dichroism (CD), ANS and tryptophan fluorescence, near IR absorbance spectroscopy and dynamic light scattering (DLS) were used to study the structural and thermodynamic characteristics of the native (N), denatured (D) and intermediate state (X) of goat cytochorme c (cyt-c) induced by weak salt denaturants (LiBr, LiCl and LiClO4) at pH 6.0 and 25°C. The LiBr-induced denaturation of cyt-c measured by Soret absorption (Δε400) and CD ([θ]409), is a three-step process, N ↔ X ↔ D. It is observed that the X state obtained along the denaturation pathway of cyt-c possesses common structural and thermodynamic characteristics of the molten globule (MG) state. The MG state of cyt-c induced by LiBr is compared for its structural and thermodynamic parameters with those found in other solvent conditions such as LiCl, LiClO4 and acidic pH. Our observations suggest: (1) that the LiBr-induced MG state of cyt-c retains the native Met80-Fe(III) axial bond and Trp59-propionate interactions; (2) that LiBr-induced MG state of cyt-c is more compact retaining the hydrophobic interactions in comparison to the MG states induced by LiCl, LiClO4 and 0.5 M NaCl at pH 2.0; and (3) that there exists heterogeneity of equilibrium intermediates along the unfolding pathway of cyt-c as highly ordered (X1), classical (X2) and disordered (X3), i.e., D ↔ X3 ↔ X2 ↔ X1 ↔ N.

Room temperature synthesis of ultra-small, near-unity single-sized lead halide perovskite quantum dots with wide color emission tunability, high color purity and high brightness.

PubMed

Peng, Lucheng; Geng, Jing; Ai, Lisha; Zhang, Ying; Xie, Renguo; Yang, Wensheng

2016-08-19

Phosphor with extremely narrow emission line widths, high brightness, and wide color emission tunability in visible regions is required for display and lighting applications, yet none has been reported in the literature so far. In the present study, single-sized lead halide perovskite (APbX 3; A = CH3NH3 and Cs; X = Cl, Br, and I) nanocrystalline (NC) phosphors were achieved for the first time in a one-pot reaction at room temperature (25 °C). The size-dependent samples, which included four families of CsPbBr3 NCs and exhibited sharp excitonic absorption peaks and pure band gap emission, were directly obtained by simply varying the concentration of ligands. The continuity of the optical spectrum can be successively tuned over the entire UV-visible spectral region (360-610 nm) by preparing CsPbCl3, CsPbI3, and CsPb(Y/Br)3 (Y = Cl and I) NCs with the use of CsPbBr3 NCs as templates by anion exchange while maintaining the size of NCs and high quantum yields of up to 80%. Notably, an emission line width of 10-24 nm, which is completely consistent with that of their single particles, indicates the formation of single-sized NCs. The versatility of the synthetic strategy was validated by extending it to the synthesis of single-sized CH3NH3PbX 3 NCs by simply replacing the cesium precursor by the CH3NH3 X precursor.

Lagrangian photochemical modeling studies of the 1987 Antarctic spring vortex. I - Comparison with AAOE observations

NASA Technical Reports Server (NTRS)

Jones, R. L.; Austin, J.; Mckenna, D. S.; Anderson, J. G.; Fahey, D. W.; Farmer, C. B.; Vedder, J. F.

1989-01-01

Results from the Lagrangian photochemical model integrated along computed air parcel trajectories intersected by the ER-2 aircraft are presented and compared with AAOE observations. According to the model, the BrO observations made from the ER-2 within the dehydrated denitrified region are consistent with there being approximately 5 parts per trillion by volume of BrO(y) at 428 K in spring. Within the high ClO region, ozone destruction rates are expected to exceed 2 percent/d with approximately 80 percent due to the ClO dimer mechanism.

40 CFR Appendix A to Subpart A of... - Class I Controlled Substances

Code of Federal Regulations, 2010 CFR

2010-07-01

...) 1.0 C2 F3 Cl3-Trichlorotrifluoroethane (CFC-113) 0.8 C2 F4 Cl2-Dichlorotetrafluoroethane (CFC-114) 1... F4 Br2-Dibromotetrafluoroethane (Halon-2402) 6.0 All isomers of the above chemicals C. Group III: CF3...) 1.0 C3 F2 Cl6-(CFC-212) 1.0 C3 F3 Cl5-(CFC-213) 1.0 C3 F4 Cl4-(CFC-214) 1.0 C3 F5 Cl3-(CFC-215) 1.0...

Crystal structures, vibrational spectra and DFT calculations of five halogeno-derivatives of 7-azaindole (3Br7AI, 4Br7AI, 4Cl7AI, 3Br4Cl7AI and 5Br3Cl7AI): a comparative study

NASA Astrophysics Data System (ADS)

Morzyk-Ociepa, Barbara; Dysz, Karolina; Turowska-Tyrk, Ilona; Michalska, Danuta

2018-01-01

Structures and vibrational spectra of 3-bromo-7-azaindole (3Br7AI), 4-bromo-7-azaindole (4Br7AI), 4-chloro-7-azaindole (4Cl7AI), 5-bromo-3-chloro-7-azaindole (5Br3Cl7AI) and 3-bromo-4-chloro-7-azaindole (3Br4Cl7AI) have been investigated. For the first time a single crystal analysis is reported for the three compounds: 3Br7AI (P21/n space group; a = 12.6586(3), b = 3.98664(12), c = 14.1189(4)Å, β = 100.901(2)o, Z = 4); 4Br7AI (P21/n space group; a = 5.38136 (13), b = 9.2262 (2), c = 13.9806 (4)Å, β = 90.052 (2)o, Z = 4); and 5Br3Cl7AI (C2/c space group; a = 22.9444(10), b = 3.91953(12), c = 17.8500(6)Å, β = 102.621(4)o, Z = 8). In the crystal structure, a pair of molecules forms a centrosymmetric dimer connected by dual nearly linear Nsbnd H⋯N hydrogen bonds between the pyrrole and pyridine rings. In addition, the structures of 4Br7AI and 5Br3Cl7AI are stabilized by C2sbnd H2⋯Br hydrogen bonds. The IR and Raman spectra of all compounds and their N-deuterated derivatives were recorded in the solid state. The theoretical molecular structures and vibrational spectra of the centrosymmetric dimers of five investigated compounds were calculated using the B3LYP method with the 6-311G++(d,p) basis set. The optimized structural parameters and the calculated vibrational spectra reproduce well the experiment. Detailed vibrational assignments for all these compounds have been made on the basis of the calculated potential energy distributions (PEDs). The characteristic marker bands for the chloro- and bromo-derivativeds of 7-azaindoles are reported.

Proposed method of hydrogeochemical exploration for salt deposits using ClBr ratios, Eastern Province, Kingdom of Saudi Arabia

USGS Publications Warehouse

Smith, C.L.

1991-01-01

Despite the value of the salt (NaCl) and brine used by the chemical industry, geochemical prospecting techniques are not customarily employed in the search for these raw materials. In this study, Br geochemistry is used as the basis for a proposed hydrogeochemical prospecting technique that was designed to search for shallow halite beds in the Eastern Province of the Kingdom of Saudi Arabia. Near-surface brine samples were collected at Sabkhah Jayb Uwayyid, both directly above and distant from a buried salt bed. Brine samples collected both directly above and offset to the north-west of the salt bed had ClBr ratios > 8000. The regional background ClBr ratio of fresh nonmarime ground water is ???300. The large range in ClBr ratios and the association of high ClBr ratios with the buried salt body suggest that the ratio can be useful in hydrogeochemical prospecting for sibakh-associated, shallow salt bodies. ?? 1991.

Tetrahalide complexes of the [U(NR)2]2+ ion: synthesis, theory, and chlorine K-edge X-ray absorption spectroscopy.

PubMed

Spencer, Liam P; Yang, Ping; Minasian, Stefan G; Jilek, Robert E; Batista, Enrique R; Boland, Kevin S; Boncella, James M; Conradson, Steven D; Clark, David L; Hayton, Trevor W; Kozimor, Stosh A; Martin, Richard L; MacInnes, Molly M; Olson, Angela C; Scott, Brian L; Shuh, David K; Wilkerson, Marianne P

2013-02-13

Synthetic routes to salts containing uranium bis-imido tetrahalide anions [U(NR)(2)X(4)](2-) (X = Cl(-), Br(-)) and non-coordinating NEt(4)(+) and PPh(4)(+) countercations are reported. In general, these compounds can be prepared from U(NR)(2)I(2)(THF)(x) (x = 2 and R = (t)Bu, Ph; x = 3 and R = Me) upon addition of excess halide. In addition to providing stable coordination complexes with Cl(-), the [U(NMe)(2)](2+) cation also reacts with Br(-) to form stable [NEt(4)](2)[U(NMe)(2)Br(4)] complexes. These materials were used as a platform to compare electronic structure and bonding in [U(NR)(2)](2+) with [UO(2)](2+). Specifically, Cl K-edge X-ray absorption spectroscopy (XAS) and both ground-state and time-dependent hybrid density functional theory (DFT and TDDFT) were used to probe U-Cl bonding interactions in [PPh(4)](2)[U(N(t)Bu)(2)Cl(4)] and [PPh(4)](2)[UO(2)Cl(4)]. The DFT and XAS results show the total amount of Cl 3p character mixed with the U 5f orbitals was roughly 7-10% per U-Cl bond for both compounds, which shows that moving from oxo to imido has little effect on orbital mixing between the U 5f and equatorial Cl 3p orbitals. The results are presented in the context of recent Cl K-edge XAS and DFT studies on other hexavalent uranium chloride systems with fewer oxo or imido ligands.

Gas-particle phase partitioning and particle size distribution of chlorinated and brominated polycyclic aromatic hydrocarbons in haze.

PubMed

Jin, Rong; Zheng, Minghui; Yang, Hongbo; Yang, Lili; Wu, Xiaolin; Xu, Yang; Liu, Guorui

2017-12-01

Chlorinated and brominated polycyclic aromatic hydrocarbons (Cl/Br-PAHs) are emerging semi-volatile organic pollutants in haze-associated particulate matter (PM). Their gas-particle phase partitioning and distribution among PM fractions have not been clarified. Clarification would increase understanding of atmospheric behavior and health risks of Cl/Br-PAHs. In this study, samples of the gas phase and 4 PM phases (aerodynamic diameters (d ae ) > 10 μm, 2.5-10 μm, 1.0-2.5 μm, and <1.0 μm) were collected simultaneously during haze events in Beijing and analyzed. Normalized histogram distribution indicated that the Cl/Br-PAHs tended to adhere to fine particles. Over 80% of the Cl-PAHs and 70% of the Br-PAHs were associated with fine PM (d ae  < 2.5 μm). The gas-particle phase partitioning and PM distribution of Cl/Br-PAHs when heating of buildings was required, which was associated with haze events, were obviously different from those when heating was not required. The relationship between the logarithmic geometric mean diameters of the Cl/Br-PAH congeners and reciprocal of the temperature (1/T) suggested that low air temperatures during the heating period could lead to high proportions of Cl/Br-PAHs in the fine particles. Increased coal burning during the heating period also contributed to high Cl/Br-PAH loads in the fine particles. Copyright © 2017 Elsevier Ltd. All rights reserved.

Facile Reductive Silylation of UO22+ to Uranium(IV) Chloride.

PubMed

Kiernicki, John J; Zeller, Matthias; Bart, Suzanne C

2017-01-19

General reductive silylation of the UO 2 2+ cation occurs readily in a one-pot, two-step stoichiometric reaction at room temperature to form uranium(IV) siloxides. Addition of two equivalents of an alkylating reagent to UO 2 X 2 (L) 2 (X=Cl, Br, I, OTf; L=triphenylphosphine oxide, 2,2'-bipyridyl) followed by two equivalents of a silyl (pseudo)halide, R 3 Si-X (R=aryl, alkyl, H; X=Cl, Br, I, OTf, SPh), cleanly affords (R 3 SiO) 2 UX 2 (L) 2 in high yields. Support is included for the key step in the process, reduction of U VI to U V . This procedure is applicable to a wide range of commercially available uranyl salts, silyl halides, and alkylating reagents. Under this protocol, one equivalent of SiCl 4 or two equivalents of Me 2 SiCl 2 results in direct conversion of the uranyl to uranium(IV) tetrachloride. Full spectroscopic and structural characterization of the siloxide products is reported. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Occurrence, profiles, and toxic equivalents of chlorinated and brominated polycyclic aromatic hydrocarbons in E-waste open burning soils.

PubMed

Nishimura, Chiya; Horii, Yuichi; Tanaka, Shuhei; Asante, Kwadwo Ansong; Ballesteros, Florencio; Viet, Pham Hung; Itai, Takaaki; Takigami, Hidetaka; Tanabe, Shinsuke; Fujimori, Takashi

2017-06-01

We conducted this study to assess the occurrence, profiles, and toxicity of chlorinated polycyclic aromatic hydrocarbons (Cl-PAHs) and brominated polycyclic aromatic hydrocarbons (Br-PAHs) in e-waste open burning soils (EOBS). In this study, concentrations of 15 PAHs, 26 Cl-PAHs and 14 Br-PAHs were analyzed in EOBS samples. We found that e-waste open burning is an important emission source of Cl-PAHs and Br-PAHs as well as PAHs. Concentrations of total Cl-PAHs and Br-PAHs in e-waste open burning soil samples ranged from 21 to 2800 ng/g and from 5.8 to 520 ng/g, respectively. Compared with previous studies, the mean of total Cl-PAH concentrations of the EOBS samples in this study was higher than that of electronic shredder waste, that of bottom ash, and comparable to fly ash from waste incinerators in Korea and Japan. The mean of total Br-PAH concentrations of the EOBS samples was generally three to four orders of magnitude higher than those in incinerator bottom ash and comparable to incinerator fly ash, although the number of Br-PAH congeners measured differed among studies. We also found that the Cl-PAH and Br-PAH profiles were similar among all e-waste open burning soil samples but differed from those in waste incinerator fly ash. The profiles and principal component analysis results suggested a unique mechanism of Cl-PAH and Br-PAH formation in EOBS. In addition, the Cl-PAHs and Br-PAHs showed high toxicities equivalent to PCDD/Fs measured in same EOBS samples when calculated based on their relative potencies to benzo[a]pyrene. Along with chlorinated and brominated dioxins and PAHs, Cl-PAHs and Br-PAHs are important environmental pollutants to investigate in EOBS. Copyright © 2016 Elsevier Ltd. All rights reserved.

Chiral halogenated Schiff base compounds: green synthesis, anticancer activity and DNA-binding study

NASA Astrophysics Data System (ADS)

Ariyaeifar, Mahnaz; Amiri Rudbari, Hadi; Sahihi, Mehdi; Kazemi, Zahra; Kajani, Abolghasem Abbasi; Zali-Boeini, Hassan; Kordestani, Nazanin; Bruno, Giuseppe; Gharaghani, Sajjad

2018-06-01

Eight enantiomerically pure halogenated Schiff base compounds were synthesized by reaction of halogenated salicylaldehydes with 3-Amino-1,2-propanediol (R or S) in water as green solvent at ambient temperature. All compounds were characterized by elemental analyses, NMR (1H and 13C), circular dichroism (CD) and FT-IR spectroscopy. FS-DNA binding studies of these compounds carried out by fluorescence quenching and UV-vis spectroscopy. The obtained results revealed that the ligands bind to DNA as: (Rsbnd ClBr) > (Rsbnd Cl2) > (Rsbnd Br2) > (Rsbnd I2) and (Ssbnd ClBr) > (Ssbnd Cl2) > (Ssbnd Br2) > (Ssbnd I2), indicating the effect of halogen on binding constant. In addition, DNA-binding constant of the Ssbnd and R-enantiomers are different from each other. The ligands can form halogen bonds with DNA that were confirmed by molecular docking. This method was also measured the bond distances and bond angles. The study of obtained data can have concluded that binding affinity of the ligands to DNA depends on strength of halogen bonds. The potential anticancer activity of ligands were also evaluated on MCF-7 and HeLa cancer cell lines by using MTT assay. The results showed that the anticancer activity and FS-DNA interaction is significantly dependent on the stereoisomers of Schiff base compounds as R-enantiomers displayed significantly higher activity than S-enantiomers. The molecular docking was also used to illustrate the specific DNA-binding of synthesized compounds and groove binding mode of DNA interaction was proposed for them. In addition, molecular docking results indicated that there are three types of bonds (Hsbnd and X-bond and hX-bond) between synthesized compounds and base pairs of DNA.

Geochemistry of halogens in the Milk River aquifer, Alberta, Canada

USGS Publications Warehouse

Fabryka-Martin, J.; Whittemore, Donald O.; Davis, S.N.; Kubik, P.W.; Sharma, Prakash

1991-01-01

Analytical data are presented for Cl, Br and I on a regional scale for the Milk River aquifer. The three halides show strikingly similar spatial distributions and are highly correlated. Concentrations are low in the freshwater portions of the aquifer but increase by as much as two orders of magnitude along the margins. However, halide ratios reach nearly constant values moving down-gradient, suggesting the dominance of a common subsurface source for these ions. Ratios of Cl/I and Cl/Br are less than those of seawater and fit an origin derived from the diagenesis of organic matter in the sediments. Halide ratios rule out leakage and/or diffusion from the underlying Colorado Group as a major influence on the chemistry; the favored hypothesis is altered connate seawater diffusing from low-permeability units within the Milk River Formation as the primary source of salts. This hypothesis of an internal source has important implications for solute sources in other aquifers affected by saline waters because it does not require the importation of a distant fluid. The 129I/I ratio has a meteoric value in groundwater collected near the recharge area, but ratios for downflow waters are only 8-70% of this value. Due to the 16 Ma half-life of 129I, these data indicate that most of the increase in dissolved I cannot derive from concentration of a meteoric source by ion filtration, but must have a subsurface origin. Concentrations of 129I produced in situ by spontaneous fission of 238U attain measurable levels only in the oldest waters sampled (ages ??? 105 a), in which it may account for nearly 90% of the total dissolved 129I concentration. Water ages based upon 36Cl/Cl data range up to 2 Ma if uncorrected for any dilution by subsurface sources of dead Cl. If one assumes that the subsurface contributions of Cl contribute at least 90% of total Cl in the distal portion, then the 36Cl-based ages are reduced to ??? 1 Ma, somewhat greater than those estimated by hydrodynamic modeling. ?? 1991.

Local unitary transformation method for large-scale two-component relativistic calculations: case for a one-electron Dirac Hamiltonian.

PubMed

Seino, Junji; Nakai, Hiromi

2012-06-28

An accurate and efficient scheme for two-component relativistic calculations at the spin-free infinite-order Douglas-Kroll-Hess (IODKH) level is presented. The present scheme, termed local unitary transformation (LUT), is based on the locality of the relativistic effect. Numerical assessments of the LUT scheme were performed in diatomic molecules such as HX and X(2) (X = F, Cl, Br, I, and At) and hydrogen halide clusters, (HX)(n) (X = F, Cl, Br, and I). Total energies obtained by the LUT method agree well with conventional IODKH results. The computational costs of the LUT method are drastically lower than those of conventional methods since in the former there is linear-scaling with respect to the system size and a small prefactor.

Halogens in normal- and enriched-basalts from Central Indian Ridge (18-20°S): Testing the E-MORB subduction origin hypothesis

NASA Astrophysics Data System (ADS)

Ruzie, L.; Burgess, R.; Hilton, D. R.; Ballentine, C. J.

2012-12-01

Basalts emitted along oceanic ridges have often been subdivided into two categories: the Normal-MORB and the Enriched-MORB, anomalously enriched in highly incompatible elements. Donnelly et al. (2004) proposed that the formation of enriched sources is related to two stages of melting. The first one occurs in subduction zones where the mantle wedge is enriched by the addition of low-degree melts of subducted slab. The second stage of melting occurs beneath ocean ridges. Because of their incompatibility, relatively high concentrations and distinct elemental compositions in surface reservoirs, the heavy halogens (Cl, Br, I) are good tracers to detect the slab contribution in E-MORB sources. However, the halogen systematics in mantle reservoirs remains poorly constrained mainly because of their very low abundance in materials of interest. An innovative halogen analytical technique, developed at the University of Manchester, involving neutron irradiation of samples to convert halogens to noble gases provides detection limits unmatched by any other technique studies [Johnson et al. 2000]. For the first time Cl, Br and I can now be determined in appropriate samples. We focus on the content of halogens in the glassy margins of basalts erupted along the CIR from 18-20°S and the off-axis Gasitao Ridge. Our set of samples contains both N- and E-MORB and is fully described in terms of major and trace elements, as well as 3He/4He ratios and water concentrations [Murton et al., 2005; Nauret et al., 2006; Füri et al., 2011; Barry et al., in prep.]. The halogen concentration range is between 10 and 140 ppm for Cl, 30 and 500 ppb for Br and 0.8 and 10 ppb for I. The higher concentrations are found in E-MORB samples from the northern part of ridge axis. Comparing our data with previous halogen studies, our sample suites fall within the range of N-MORB from East Pacific Ridge (EPR) and Mid-Atlantic Ridge (MAR) [Jambon et al. 1995; Deruelle et al. 1992] and in the lower range of E-MORB from Macquarie Island [Kendrick et al., 2012]. The concentrations are not related to superficial processes. The on-axis samples display a relatively restricted range (6.9-8.6wt%) of MgO contents, suggesting no control of the crystallisation processes. The basalts were erupted between 3900-2000 m bsl, so no appreciable degassing of halogens would be expected. The strong correlation, which exists between the halogens and other incompatible elements (e.g., Rb, La), also rules out seawater assimilation. Therefore, concentrations and elemental ratios can be directly linked to melting and source features. Estimates of halogens abundances in the depleted-mantle source are 4 ppm Cl, 14 ppb Br and 0.3 ppb I. These low abundances, which are in agreement with values derived for sub-continental mantle from coated diamonds [Burgess et al., 2002], suggest that, like noble gases, the upper mantle is degassed of its halogens. Critically, the halogen elemental ratios show no significant variations along the axial ridge and off-axis ridge or between N-MORB and E-MORB: Br/Cl=0.00147±0.00014, I/Cl=0.000021±0.000005; I/Br=0.0142±0.0036. These ratios are similar to E-MORB from Macquarie Island [Kendrick et al., 2012]. This observation is thus not consistent with subduction as a source of halogen enrichment in E-MORB.

Organic iodine in Antarctic sea ice: A comparison between winter in the Weddell Sea and summer in the Amundsen Sea

NASA Astrophysics Data System (ADS)

Granfors, Anna; Ahnoff, Martin; Mills, Matthew M.; Abrahamsson, Katarina

2014-12-01

Recent studies have recognized sea ice as a source of reactive iodine to the Antarctic boundary layer. Volatile iodinated compounds (iodocarbons) are released from sea ice, and they have been suggested to contribute to the formation of iodine oxide (IO), which takes part in tropospheric ozone destruction in the polar spring. We measured iodocarbons (CH3I, CH2ClI, CH2BrI, and CH2I2) in sea ice, snow, brine, and air during two expeditions to Antarctica, OSO 10/11 to the Amundsen Sea during austral summer and ANT XXIX/6 to the Weddell Sea in austral winter. These are the first reported measurements of iodocarbons from the Antarctic winter. Iodocarbons were enriched in sea ice in relation to seawater in both summer and winter. During summer, the positive relationship to chlorophyll a biomass indicated a biological origin. We suggest that CH3I is formed biotically in sea ice during both summer and winter. For CH2ClI, CH2BrI, and CH2I2, an additional abiotic source at the snow/ice interface in winter is suggested. Elevated air concentrations of CH3I and CH2ClI during winter indicate that they are enriched in lower troposphere and may take part in the formation of IO at polar sunrise.

Structural analysis of pyridine-imino boronic esters involving secondary interactions on solid state

NASA Astrophysics Data System (ADS)

Sánchez-Portillo, Paola; Arenaza-Corona, Antonino; Hernández-Ahuactzi, Irán F.; Barba, Victor

2017-04-01

Twelve boronic esters (1a-1l) synthesized from 4-halo- substituted arylboronic acids (halo = F, Cl, Br, I and CF3) with 2-amino-2- alkyl (H, Me) -1,3-propanediol in presence of (3- or 4)-pyridine carboxaldehyde are described. A solvent mixture toluene/methanol 1:4 ratio was used. All compounds include both donor/acceptor functional groups, which are the necessary elements to self-assembly of the molecular species. Several secondary interactions as I⋯N, Br⋯Br, Br⋯B, F⋯B, Csbnd H⋯N, Csbnd H⋯O, Br⋯π and Csbnd H⋯π support the 1D and 2D polymeric frameworks in solid state. The coordination of the nitrogen atom from the pyridine moiety with the boron atom was not observed in either solution or solid state.

Ultrafast photochemistry of polyatomic molecules containing labile halogen atoms in solution

NASA Astrophysics Data System (ADS)

Mereshchenko, Andrey S.

Because breaking and making of chemical bonds lies at the heart of chemistry, this thesis focuses on dynamic studies of labile molecules in solutions using ultrafast transient absorption spectroscopy. Specifically, my interest is two-fold: (i) novel reaction intermediates of polyhalogenated carbon, boron and phosphorus compounds; (ii) photophysics and photochemistry of labile copper(II) halide complexes. Excitation of CH2Br2, CHBr3, BBr 3, and PBr3 into n(Br)sigma*(X-Br) states, where X=C, B, or P, leads to direct photoisomerization with formation of isomers having Br-Br bonds as well as rupture of one of X-Br bonds with the formation of a Br atom and a polyatomic radical fragment, which subsequently recombine to form similar isomer products. Nonpolar solvation stabilizes the isomers, consistent with intrinsic reaction coordinate calculations of the isomer ground state potential energy surfaces at the density functional level of theory, and consequently, the involvement of these highly energetic species on chemically-relevant time scales needs to be taken into account. Monochlorocomplexes in methanol solutions promoted to the ligand-to-metal charge transfer (LMCT) excited state predominantly undergo internal conversion via back electron transfer, giving rise to vibrationally hot ground-state parent complexes. Copper-chloride homolitical bond dissociation yielding the solvated copper(I) and Cl- atom/solvent CT complexes constitutes a minor pathway. Insights into ligand substitution mechanisms were acquired by monitoring the recovery of monochloro complexes at the expense of two unexcited dichloro- and unsubstituted forms of Cu(II) complexes also present in the solution. Detailed description of ultrafast excited-state dynamics of CuCl 42- complexes in acetonitrile upon excitation into all possible Ligand Field (LF) excited states and two most intense LMCT transitions is reported. The LF states were found to be nonreactive with lifetimes remarkably longer than those for copper(II) complexes studied so far, in particular, copper blue proteins. The highest 2A1 and lowest 2E LF states relax directly to the ground electronic state whereas the intermediate 2B1 LF state relaxes stepwise through the 2E state. The LMCT excited states are short-lived undergoing either ionic dissociation (CuCl3- + Cl-) or cascading relaxation through the manifold of vibrationally hot LF states to the ground state.

Isolation of 1,4-Li(2)-C(6)H(4) and its reaction with [(Ph(3)P)AuCl].

PubMed

Flower, Kevin R; McGown, A T; Miles, Philip J; Pritchard, Robin G; Warren, John E

2010-04-14

The difficulty in generating 1,4-Li2-C6H4 utilising the lithium halogen exchange reaction on 1,4-Br2-C6H4, 1,4-I2-C6H4 and 1-Br-4-I-C6H4 is revisited and only on treatment of 1,4-I2-C6H4 with 2 molar equivalents of n-BuLi can 1,4-Li2-C6H4 1 be isolated in excellent yield. Treatment of 1 with two equivalents of [ClAu(PPh3)] gives [1,4-(Ph3PAu)2-C6H4] 2a in excellent yield. Subsequent treatment of 2a with 2.5 molar equivalents of PPh2Me, PPhMe2 or PMe3 affords the PPh3 substituted compounds [1,4-(LAu)2-C6H4] (L = PPh2Me 2b, PPhMe2 2c, PMe3 2d) in essentially quantitative yields. On treatment of 1,4-Br2-C6H4 or 1-Br-4-I-C6H4 with 2 molar equivalents of n-BuLi only mono-lithiation takes place to give 1-Br-4-Li-C6H4 3 as shown through the isolation of essentially 1:1 molar equivalents of Ph2PC6H4-4-Br and Ph2PBu on treatment with 2 molar equivalents of ClPPh2. Treatment of 3, prepared by lithium/iodine exchange on 1-Br-4-I-C6H4, with [ClAu(PPh3)] affords [(Ph3P)Au(C6H4-4-Br)] 4 as expected and in addition [(Ph3P)Au(n-Bu)(C6H4-4-Br)2] 5, indicating the straightforward chloride/aryl exchange at gold may proceed in competition with oxidative addition of the n-BuI, generated in the initial lithium/iodine exchange reaction, to some aurate complex Li[Au(C6H4-4-Br)2] 6 formed in situ followed by reductive elimination of Br-C6H4-4-n-Bu in a manner that mimics lithium diorganocuprate chemistry. All of the gold-containing compounds have been spectroscopically characterised by 1H and 31P-{1H} NMR and in addition compounds 2a-d and 5 by single crystal X-ray diffraction studies. The solid state structures observed for 2a-d are dictated by non-conventional hydrogen bonding and the packing requirements of the phosphine ligands. For 2a and 2b there is no close Au...Au approach, however for 2c and 2d the reduction in the number of phenyl rings allows the formation of Au...Au contacts. For 2c and 2d the extended structures appear to be helical chains with Au...Au contact parameters of 3.855(5) A and C-Au-Au-C 104.1(3)degrees for 2c and 3.139(4) A and C-Au-Au-C -92.0(2)degrees for 2d. The Au...Au approach in 2c is longer than is normally accepted for an AuAu contact and is dictated by ligand directed non-conventional hydrogen bonding to the aurated benzene ring and the pi-stacking requirements of the phosphine ligand. By comparison of the structures 2a-2d with other structures in the database it is evident that the aurophilic interaction is a poor supramolecular synthon in the presence of non-conventional hydrogen bond donors. Searches of the CCDC database suggest that the observed parameters for the Au...Au contact in 2c sit close to the cut-off point for observing this type of contact. In addition to aurophilic contacts and non-conventional hydrogen bonds there are a number of halogenated solvent C-Cl...Au contacts observed in the structures of 2a and 2d. The nature of these contacts have implications for the accepted van der Waals radius of gold which should be extended to 2 A.

Theoretical study of mixed LiLnX4 (Ln = La, Dy; X = F, Cl, Br, I) rare earth/alkali halide complexes.

PubMed

Groen, C P; Oskam, A; Kovács, A

2000-12-25

The structure, bonding and vibrational properties of the mixed LiLnX4 (Ln = La, Dy; X = F, Cl, Br, I) rare earth/alkali halide complexes were studied using various quantum chemical methods (HF, MP2 and the Becke3-Lee-Yang-Parr exchange-correlation density functional) in conjunction with polarized triple-zeta valence basis sets and quasi-relativistic effective core potentials for the heavy atoms. Our comparative study indicated the superiority of MP2 theory while the HF and B3-LYP methods as well as less sophisticated basis sets failed for the correct energetic relations. In particular, f polarization functions on Li and X proved to be important for the Li...X interaction in the complexes. From the three characteristic structures of such complexes, possessing 1-(C3v), 2-(C2v), or 3-fold coordination (C3v) between the alkali metal and the bridging halide atoms, the bi- and tridentate forms are located considerably lower on the potential energy surface then the monodentate isomer. Therefore only the bi- and tridentate isomers have chemical relevance. The monodentate isomer is only a high-lying local minimum in the case of X = F. For X = Cl, Br, and I this structure is found to be a second-order saddle point. The bidentate structure was found to be the global minimum for the systems with X = F, Cl, and Br. However, the relative stability with respect to the tridentate structure is very small (1-5 kJ/mol) for the heavier halide derivatives and the relative order is reversed in the case of the iodides. The energy difference between the three structures and the dissociation energy decrease in the row F to I. The ionic bonding in the complexes was characterized by natural charges and a topological analysis of the electron density distribution according to Bader's theorem. Variation of the geometrical and bonding characteristics between the lanthanum and dysprosium complexes reflects the effect of "lanthanide contraction". The calculated vibrational data indicate that infrared spectroscopy may be an effective tool for experimental investigation and characterization of LiLnX4 molecules.

Ab Initio Characterization of Triatomic Bromine Molecules of Potential Interest in Stratospheric Chemistry

NASA Technical Reports Server (NTRS)

Lee, Timothy J.

1995-01-01

The equilibrium structures, harmonic vibrational frequencies, quadratic force fields, dipole moments, and IR intensities of several triatomic bromine compounds of known or potential importance in stratospheric ozone depletion chemistry have been determined using the CCSD(T) electron correlation method in conjunction with a basis set of triple zeta double polarized (TZ2P) quality. Specifically, the molecules included in the present study are HOBr, HBrO, FOBr, FBrO, BrNO, BrON, Br2O, BrBrO, BrCN, BrNC, ClOBr, ClBrO, and BrClO. Very accurate isomeric energy differences have also been determined at the CCSD(T) level with atomic natural orbital basis sets that include through g-type functions. In most cases, the isomer with a normal neutral Lewis dot structure is the lowest energy form, with the single exception that FBrO is predicted to be 11.1 kcal/mol (0 K) lower in energy than FOBr. In all cases, however, the hypervalent isomer is more stable relative to the isomer with a normal Lewis dot structure as compared to the chlorine analogs. Consistent with this observation, the energy of the last three molecules given above increases in the order ClOBr less than ClBrO less than BrClO. The CCSD(T)/TZ2P geometries and vibrational frequencies are in good agreement with the available experimental data. Heats of formation are determined for all species using a combination of theoretical isomeric, homodesmic, and isodesmic reaction energies. The accuracy of these quantities is ultimately dependent on the reliability of the experimental heat of formation of HOBr.

Ab Initio Characterization of Triatomic Bromine Molecules of Potential Interest in Stratospheric Chemistry

NASA Technical Reports Server (NTRS)

Lee. Timothy J.

1995-01-01

The equilibrium structures, harmonic vibrational frequencies, quadratic force fields, dipole moments, and IR intensities of several triatomic bromine compounds of known or potential importance in stratospheric ozone depletion chemistry have been determined using the CCSD(T) electron correlation method in conjunction with a basis set of triple zeta double polarized (TZ2P) quality. Specifically, the molecules included in the present study are HOBr, HBrO, FOBr, FBrO, BrNO, BrON, Br2O, BrBrO, BrCN, BrNC, ClOBr, ClBrO, and BrClO. Very accurate isomeric energy differences have also been determined at the CCSD(T) level with atomic natural orbital basis sets that include through g-type functions. In most cases, the isomer with a normal neutral Lewis dot structure is the lowest energy form, with the single exception that FBRO is predicted to be 11.1 kcal/mol (0 K) lower in energy than FOBr. In all cases, however, the hypervalent isomer is more stable relative to the isomer with a normal Lewis dot structure as compared to the chlorine analogs. Consistent with this observation, the energy of the last three molecules given above increases in the order ClOBr less than ClBrO less than BrClO. The CCSD(T)/TZ2P geometries and vibrational frequencies are in good agreement with the available experimental data. Heats of formation are determined for all species using a combination of theoretical isomeric, homodesmic, and isodesmic reaction energies. The accuracy of these quantities is ultimately dependent on the reliability of the experimental heat of formation of HOBr.

Catalog of infrared and cryo-optical properties for selected materials

NASA Technical Reports Server (NTRS)

Heaney, James B.; Alley, Phillip W.; Bradley, Scott E.

1991-01-01

This report will describe the status of an effort to catalog the refractive index, absorption, reflectance and transmittance of selected IR transmitting materials over the wavelength range from 1 to 1000 microns, and at temperatures from 300 to about 2 K. Data are presented for LiF, CaF2, BaF2, KBr, and TlBr, as well as for KRS-5 (TlBr-I) and KRS-6 (TlBr-Cl). A cryooptical measurements facility at NASA-Goddard, which has been used to generate some of the cataloged data, is also described.

Specific anion binding to sulfobetaine micelles and kinetics of nucleophilic reactions.

PubMed

Marte, Luisa; Beber, Rosane C; Farrukh, M Akhyar; Micke, Gustavo A; Costa, Ana C O; Gillitt, Nicholas D; Bunton, Clifford A; Di Profio, Pietro; Savelli, Gianfranco; Nome, Faruk

2007-08-23

With fully micellar bound substrates reactions of OH- with benzoic anhydride, Bz(2)O, and of Br- with methyl naphthalene-2-sulfonate, MeONs, in micellized sulfobetaines are strongly inhibited by NaClO4 which displaces the nucleophilic anions from the micellar pseudophases. Micellar incorporations of ClO4- and Br- are estimated with an ion-selective electrode and by electrophoresis, and partitioning of Br- between water and micelles is related to changes in NMR spectral (79)Br- line widths. Extents of inhibition by ClO4- of these nucleophilic reactions in the micellar pseudophase are related to quantitative displacement of the reactive anions from the micelles by ClO4-. The kinetic data are correlated with physical evidence on the strong interactions between sulfobetaines and ClO4-, which turn sulfobetaine micelles anionic and effectively provoke displacement of OH- and Br-.

73Ge, 119Sn and 207Pb: general cooperative effects of single atom ligands on the NMR signals observed in tetrahedral [MXnY4-n] (M = Ge, Sn, Pb; 1 ≤ n ≤ 4; X, Y = Cl, Br, I) coordination compounds of heavier XIV group elements.

PubMed

Benedetti, M; De Castro, F; Fanizzi, F P

2017-02-28

An inverse linear relationship between 73 Ge, 119 Sn and 207 Pb NMR chemical shifts and the overall sum of ionic radii of coordinated halido ligands has been discovered in tetrahedral [MX n Y 4-n ] (M = Ge, Sn, Pb; 1 ≤ n ≤ 4; X, Y = Cl, Br, I) coordination compounds. This finding is consistent with a previously reported correlation found in octahedral, pentacoordinate and square planar platinum complexes. The effect of the coordinated halido ligands acting on the metal as shielding conducting rings is therefore confirmed also by 73 Ge, 119 Sn and 207 Pb NMR spectroscopy.

Spectroscopy and heats of formation of CXI (X = Br, Cl, F) iodocarbenes: quantum chemical characterisation of the ?, ? and ? states

NASA Astrophysics Data System (ADS)

Bacskay, George B.

2015-07-01

The equilibrium energies of the iodocarbenes CXI (X = Br, Cl, F) in their ?, ? and ? states and their atomisation and dissociation energies in the complete basis limit were determined by extrapolating valence correlated (R/U)CCSD(T) and Davidson corrected multi-reference configuration interaction (MRCI) energies calculated with the aug-cc-pVxZ (x = T,Q,5) basis sets and the ECP28MDF pseudopotential of iodine plus corrections for core and core-valence correlation, scalar relativity, spin-orbit coupling and zero-point energies. Spin-orbit energies were computed in a large basis of configurations chosen so as to accurately describe dissociation to the 3P and 2P states of C and of the halogens X and I, respectively. The computed singlet-triplet splittings are 13.6, 14.4 and 27.3 kcal mol-1 for X = Br, Cl and F, respectively. The enthalpies of formation at 0 K are predicted to be 97.4, 82.6 and 38.1 kcal mol-1 with estimated errors of ±1.0 kcal mol-1. The ? excitation energies (T00) in CBrI and CClI are calculated to be 41.1 and 41.7 kcal mol-1, respectively. The Renner-Teller intersections in both molecules are predicted to be substantially higher than the dissociation barriers on the ? surfaces. By contrast, in CFI the ? state is found to be unbound with respect to dissociation.

In-situ Cl/Br measurements in scapolite and fluid inclusions by LA-ICP-MS: A powerful tool to constrain fluid sources

NASA Astrophysics Data System (ADS)

Hammerli, J.; Rusk, B.; Spandler, C.; Oliver, N. H. S.; Emsbo, P.

2012-04-01

Chlorine and bromine are highly conservative elements, and are therefore widely used to trace the origin of fluids in sedimentary and hydrothermal/magmatic systems (e.g. Hanor & McIntosh, 2007; Nahnybida et al., 2009). Halogens are important ligands for metal transport in hydrothermal solutions and thus their behavior in hydrothermal environments is crucial for comprehending ore-forming processes. Besides fluid inclusions, scapolite-group minerals hold great potential as a tracer of igneous, metamorphic, and hydrothermal processes, as no Cl/Br fractionation in scapolite has been observed and therefore halogen ratios in scapolite are thought to mirror the halogen ratios in coexisting melts and fluids (Pan & Dong, 2003). Hence, Cl/Br ratios in fluid inclusions and minerals can be utilized to trace the origin of fluids and fluid-rock interaction pathways. Due to their high ionization energies, bromine and chlorine are not routinely measured by LA-ICP-MS and suitable standards are rare. Little is known about the potential interferences and analytical limitations of in-situ chlorine and bromine analysis by LA-ICP-MS. Nevertheless, Seo et al. (2011) showed that quantification of Br and Cl in single synthetic and natural fluid inclusions is possible. In this study, we have analyzed several scapolite grains of known bromine and chlorine concentrations by LA-ICP-MS and assess the capabilities and limitations of this method. The results show that Cl/Br ratios measured by LA-ICP-MS closely reproduce known values determined by microprobe (Cl), the Noble Gas Method (Br) and INAA (Br) (Kendrick, 2011; Lieftink et al., 1993) using laser ablation spot sizes from 24-120 μm. The well-characterized scapolite grains cover bromine concentrations from 50-883 ppm and chlorine concentrations from 3 to 4 wt.%. In order to further assess the method, we analyzed Cl/Br ratios in natural fluid inclusions hosted in sphalerite that were previously characterized by crush and leach ion chromatography. This is the first time that bulk crush and leach Cl/Br analyses can be compared with Cl/Br ratios within individual fluid inclusions. Our LA-ICP-MS measurements are in good agreement with bulk crush and leach analyses. For instance, molar Cl/Br ratios of single fluid inclusions (183±33) in sphalerite form East Tennessee match those obtained by crush and leach (206±8) Additionally, scapolite in samples from dykes of the Burstall granite, associated banded skarns and metasediments from the Mary Kathleen Fold Belt, Queensland, Australia are being studied. Scapolite is highly luminescent and therefore, cathodoluminescence images resolve chemical zoning in scapolite group minerals that, in combination with in-situ Cl/Br analyses, is a powerful tool to better understand fluid sources and fluid-rock interaction within various geological environments.

In situ quantification of Br and Cl in minerals and fluid inclusions by LA-ICP-MS: a powerful tool to identify fluid sources

USGS Publications Warehouse

Hammerli, Johannes; Rusk, Brian; Spandler, Carl; Emsbo, Poul; Oliver, Nicholas H.S.

2013-01-01

Bromine and chlorine are important halogens for fluid source identification in the Earth's crust, but until recently we lacked routine analytical techniques to determine the concentration of these elements in situ on a micrometer scale in minerals and fluid inclusions. In this study, we evaluate the potential of in situ Cl and Br measurements by LA-ICP-MS through analysis of a range of scapolite grains with known Cl and Br concentrations. We assess the effects of varying spot sizes, variable plasma energy and resolve the contribution of polyatomic interferences on Br measurements. Using well-characterised natural scapolite standards, we show that LA-ICP-MS analysis allows measurement of Br and Cl concentrations in scapolite, and fluid inclusions as small as 16 μm in diameter and potentially in sodalite and a variety of other minerals, such as apatite, biotite, and amphibole. As a demonstration of the accuracy and potential of Cl and Br analyses by LA-ICP-MS, we analysed natural fluid inclusions hosted in sphalerite and compared them to crush and leach ion chromatography Cl/Br analyses. Limit of detection for Br is ~8 μg g−1, whereas relatively high Cl concentrations (> 500 μg g−1) are required for quantification by LA-ICP-MS. In general, our LA-ICP-MS fluid inclusion results agree well with ion chromatography (IC) data. Additionally, combined cathodoluminescence and LA-ICP-MS analyses on natural scapolites within a well-studied regional metamorphic suite in South Australia demonstrate that Cl and Br can be quantified with a ~25 μm resolution in natural minerals. This technique can be applied to resolve a range of hydrothermal geology problems, including determining the origins of ore forming brines and ore deposition processes, mapping metamorphic and hydrothermal fluid provinces and pathways, and constraining the effects of fluid–rock reactions and fluid mixing.

THE SCATTERING OF K AND Cs BY SEVERAL COMPOUNDS.

DTIC Science & Technology

The nonreactive scattering of K from C10H16, (CH3)3CBr, SiCl4 , Cl2, Br2, I2, ICl, (CN)2C=C(CN)2, and Cs from HBr has been studied in experiments with... SiCl4 , and Cs + HBr and also from the supernumerary rainbows for K + C10H16 and (CH3)3CBr. An optical model analysis on K+(CH3)3CBr and Cs + HBr

Eu(2+)-Activated Alkaline-Earth Halophosphates, M5(PO4)3X:Eu(2+) (M = Ca, Sr, Ba; X = F, Cl, Br) for NUV-LEDs: Site-Selective Crystal Field Effect.

PubMed

Kim, Donghyeon; Kim, Sung-Chul; Bae, Jong-Seong; Kim, Sungyun; Kim, Seung-Joo; Park, Jung-Chul

2016-09-06

Eu(2+)-activated M5(PO4)3X (M = Ca, Sr, Ba; X = F, Cl, Br) compounds providing different alkaline-earth metal and halide ions were successfully synthesized and characterized. The emission peak maxima of the M5(PO4)3Cl:Eu(2+) (M = Ca, Sr, Ba) compounds were blue-shifted from Ca to Ba (454 nm for Ca, 444 nm for Sr, and 434 nm for Ba), and those of the Sr5(PO4)3X:Eu(2+) (X = F, Cl, Br) compounds were red-shifted along the series of halides, F → Cl → Br (437 nm for F, 444 nm for Cl, and 448 nm for Br). The site selectivity and occupancy of the activator ions (Eu(2+)) in the M5(PO4)3X:Eu(2+) (M = Ca, Sr, Ba; X = F, Cl, Br) crystal lattices were estimated based on theoretical calculation of the 5d → 4f transition energies of Eu(2+) using LCAO. In combination with the photoluminescence measurements and theoretical calculation, it was elucidated that the Eu(2+) ions preferably enter the fully oxygen-coordinated sites in the M5(PO4)3X:Eu(2+) (M = Ca, Sr, Ba; X = F, Cl, Br) compounds. This trend can be well explained by "Pauling's rules". These compounds may provide a platform for modeling a new phosphor and application in the solid-state lighting field.

Investigating Planetary Volatile Accretion Mechanisms Using the Halogens

NASA Astrophysics Data System (ADS)

Ballentine, C. J.; Clay, P. L.; Burgess, R.; Busemann, H.; Ruzié, L.; Joachim, B.; Day, J. M.

2014-12-01

Depletion of the volatile elements in the Earth relative to the CI chondrites is roughly correlated with volatility, or decreasing condensation temperature. For the heavy halogen group elements (Cl, Br and I), volatility alone does not account for their apparent depletion, which early data has suggested is far greater than predicted [1-2]. Such depletion has been used to argue for the preferential loss of halogens by, amongst other processes, impact-driven erosive loss from Earth's surface [2]. Little consensus exists as to why the halogens should exhibit such preferential behavior during accretionary processes. Early efforts to constrain halogen abundance and understand their behavior in both Earth and planetary materials [3-6] have been hampered by their typically low abundance (ppb level) in most geologic materials. We present the results of halogen analysis of 23 chondrite samples, selected to represent diverse groups and petrologic type. Halogen abundances were measured by neutron irradiation noble gas mass spectrometry (NI-NGMS). Significant concentration heterogeneity is observed within some samples. However, a single Br/Cl and I/Cl ratio of 1.9 ± 0.2 (x 10-3) and 335 ± 10 (x 10-6) can be defined for carbonaceous chondrites with a good correlation between Br and Cl (R2 = 0.97) and between I and Cl (R2 = 0.84). Ratios of I/Cl overlap with terrestrial estimates of Bulk Silicate Earth and Mid Ocean Ridge Basalts. Similarly, good correlations are derived for enstatite (E) chondrites and a sulfide- and halogen- rich subset of E-chondrites. Chlorine abundances of CI (Orgueil) in this study are lower by factor of ~ 3 than the value of ~ 700 ppm Cl (compilation in [1]). Our results are similar to early discarded low values for Ivuna and Orgueil from [5,6] and agree more closely with values for CM chondrites. Halogens may not be as depleted in Earth as previously suggested, or a high degree of heterogeneity in the abundance of these volatile elements in carbonaceous chondrites should be considered when we assess Earth's halogen abundance relative to CI. [1] Lodders (2003) Astr J 591:1220-47. [2] Sharp et al. (2013) EPSL 369/70: 71-7. [3] Dreibus et al. (1979) Phys Chem Earth 11:33-8. [4] Goles et al. (1967) GCA 31: 1771-7. [5] Reed and Allen (1966) GCA 30: 779-800. [6] Greenland & Lovering (1965) GCA 29: 821-58.

Computational Discovery of Two Lead Free Halide Double Perovskites with Band Gaps in the Visible Range: Cs2BiAgCl6 and Cs2BiAgBr6

NASA Astrophysics Data System (ADS)

Filip, Marina; Volonakis, George; Haghighirad, Amir Abbas; Hillman, Samuel; Sakai, Nobuya; Wenger, Bernard; Snaith, Henry; Giustino, Feliciano

The perovskite solar cell is emerging as one of the most promising solution processable photovoltaic technologies, with an efficiency that now exceeds the performance of thin-film silicon devices. This performance is exclusively due to the optimum optoelectronic properties of the prototypical methylammonium lead-iodide perovskite (MAPI). However, the presence of lead in MAPI, and its problematic stability in ambient conditions poses concerns for its potential environmental impact. These concerns are motivating the search for novel non-toxic halide perovskites with similar optoelectronic properties to MAPI. In this work we will present the computational search for the homovalent and the heterovalent replacement of Pb in lead-halide perovskites. This search has lead to the computational discovery and experimental synthesis of two stable lead-free halide double perovskites based on Bi and Ag: Cs2BiAgCl6 and Cs2BiAgBr6. These new compounds are highly stable, they are semiconducting and absorb light in the visible range. In this talk we will present the electronic and optical properties of Cs2BiAgCl6 and Cs2BiAgBr6 calculated within DFT and GW and discuss the stability and formability of the entire Cs2BB'X6 family of semiconductors (B = Bi, Sb, B = Cu, Ag, Au, X = Cl, Br, I). This work was supported by the and the Leverhulme Trust (RL-2012-001).

Investigations of the Rg-BrCl (Rg = He, Ne, Ar, Kr, Xe) binary van der Waals complexes: ab initio intermolecular potential energy surfaces, vibrational states and predicted pure rotational transition frequencies

NASA Astrophysics Data System (ADS)

Li, Song; Zheng, Rui; Chen, Shan-Jun; Chen, Yan; Chen, Peng

2017-03-01

The intermolecular potential energy surfaces (PESs) of the ground electronic state for the Rg-BrCl (Rg = He, Ne, Ar, Kr, Xe) van der Waals complexes have been constructed by using the coupled-cluster method in combination with the augmented quadruple-zeta correlation-consistent basis sets supplemented with an additional set of bond functions. The features of the anisotropic PESs for these complexes are remarkably similar, which are characterized by three minima and two saddle points between them. The global minimum corresponds to a collinear Rg-Br-Cl configuration. Two local minima, correlate with an anti-linear Rg-Cl-Br geometry and a nearly T-shaped structure, can also be located on each PES. The quantum bound state calculations enable us to investigate intermolecular vibrational states and rotational energy levels of the complexes. The transition frequencies are predicted and are fitted to obtain their corresponding spectroscopic constants. In general, the periodic trends are observed for this complex family. Comparisons with available experimental data for the collinear isomer of Ar-BrCl demonstrate reliability of our theoretical predictions, and our results for the other two isomers of Ar-BrCl as well as for other members of the complex family are also anticipated to be trustable. Except for the collinear isomer of Ar-BrCl, the data presented in this paper would be beneficial to improve our knowledge for these experimentally unknown species.

Low dimensional CH3NH3PbBr3 cubes for persistent luminescence: Energy variation of electron excitation

NASA Astrophysics Data System (ADS)

Besral, N.; Paul, T.; Thakur, S.; Sarkar, S.; Sardar, K.; Chanda, K.; Das, A.; Chattopadhyay, K. K.

2018-04-01

The impact of varying electron beam voltage upon room temperature CL (cathodoluminescence) properties of crystalline organic-inorganic lead halide perovskite CH3NH3PbBr3 (Methylammonium lead tribromide) microcubes have been studied. CH3NH3PbBr3 microcubes were synthesized at room temperature by a very straight forward wet chemical route. After preliminary characterizations like XRD (X-ray diffraction), FESEM (Field emission scanning electron microscopy), UV-Vis spectroscopy, CL study at three different beam voltages i.e. 5 kV, 10 kV and 15 kV respectively was performed at room temperature. Prominent emission signals were obtained with emission peaks at 2.190 eV (FWHM 0.120 eV), 2.222 eV (FWHM 0.108 eV) and 2.242 eV (FWHM 0.095 eV) for electron beam voltages 5 kV, 10 kV and 15 kV respectively.

On chemical inhibition of shock wave ignition of hydrogen-oxygen mixtures

NASA Astrophysics Data System (ADS)

Drakon, A. V.; Eremin, A. V.; Mikheyeva, E. Yu

2018-01-01

In this work an influence of the wide range of various inhibitors, namely CCl4, CF3H, C2F4Br2, (CH3O)3P, CF3I and C3F7I on shock-induced ignition of hydrogen was experimentally investigated. Observed temperature dependencies of induction times indicates that CF3H and (CH3O)3P do not show noticeable inhibiting activity at given conditions, while the effectiveness of halogen-containing specie dramatically increases in a row Cl → Br → I. It is shown that the most effective inhibitors of ignition of hydrogen-oxygen mixtures are iodinated hydrocarbons CF3I and C3F7I.

Salt-induced inhibition of the precipitin reaction of concanavalin A with polysaccharides and glycoprotein.

PubMed

Salahuddin, A; Begum, R; Averill, B K

1984-06-15

The time course of the precipitin reactions of concanavalin A with glycogen, dextran and ovalbumin was investigated by a light-scattering method near 30 degrees C in 10 mM-Tris/HCl buffer, pH 7.4, containing neutral salts, i.e. NaCl, KCl, NaBr, KI and NaClO4. With 0.8 microM-lectin and 0.36 mg of glycogen/ml, the half-life, t 1/2, of the precipitin reaction was independent of salt concentration between 0.1 M and 1.5 M, and was the same (175s) in the presence of NaCl, KCl, NaBr and KI but was significantly (27%) higher in NaClO4. In contrast, the five salts caused significant to marked enhancement in t 1/2 for the reactions of concanavalin A with dextran and ovalbumin. Likewise, whereas the turbidity produced in 1 h as a result of lectin-glycogen precipitation remained unchanged, those measured for the binding of dextran and ovalbumin were decreased in the presence of three salts. The increase in t 1/2 and decrease in turbidity were found to be higher with NaClO4, followed by KI; NaBr produced moderate and NaCl (or KCl) small but generally significant inhibition of the precipitin reactions with dextran and ovalbumin. The results showed that the lectin-ligand precipitin reactions involve salt-sensitive polar interactions that are less pronounced with compactly folded ligands such as glycogen.

Dissociative Photoionization of 1-Halogenated Silacyclohexanes: Silicon Traps the Halogen.

PubMed

Bodi, Andras; Sigurdardottir, Katrin Lilja; Kvaran, Ágúst; Bjornsson, Ragnar; Arnason, Ingvar

2016-11-23

The threshold photoelectron spectra and threshold photoionization mass spectra of 1-halogenated-1-silacyclohexanes, for the halogens X = F, Cl, Br, and I, have been obtained using synchrotron vacuum ultraviolet radiation and photoelectron photoion coincidence spectroscopy. As confirmed by a similar ionization onset and density functional theory molecular orbitals, the ionization to the ground state is dominated by electron removal from the silacyclohexane ring for X = F, Cl, and Br, and from the halogen lone pair for X = I. The breakdown diagrams show that the dissociative photoionization mechanism is also different for X = I. Whereas the parent ions decay by ethylene loss for X = F to Br in the low-energy regime, the iodine atom is lost for X = I. The first step is followed by a sequential ethylene loss at higher internal energies in each of the compounds. It is argued that the tendency of silicon to lower bond angles stabilizes the complex cation in which C 2 H 4 is η 2 -coordinated to it, and which precedes ethylene loss. Together with the relatively strong silicon-halogen bonds and the increased inductive effect of the silacyclohexane ring in stabilizing the cation, this explains the main differences observed in the fragmentation of the halogenated silacyclohexane and halogenated cyclohexane ions. The breakdown diagrams have been modeled taking into account slow dissociations at threshold and the resulting kinetic shift. The 0 K appearance energies have been obtained to within 0.08 eV for the ethylene loss for X = F to Br (10.56, 10.51, and 10.51 eV, respectively), the iodine atom loss for X = I (10.11 eV), the sequential ethylene loss for X = F to I (12.29, 12.01, 11.94, and 11.86 eV, respectively), and the minor channels of H loss for X = F (10.56 eV) and propylene loss in X = Cl (also at 10.56 eV). The appearance energies for the major channels likely correspond to the dissociative photoionization reaction energy.

Coordination Chemistry of Diiodine and Implications for the Oxidation Capacity of the Synergistic Ag(+) /X2 (X=Cl, Br, I) System.

PubMed

Malinowski, Przemysław J; Himmel, Daniel; Krossing, Ingo

2016-08-01

The synergistic Ag(+) /X2 system (X=Cl, Br, I) is a very strong, but ill-defined oxidant-more powerful than X2 or Ag(+) alone. Intermediates for its action may include [Agm (X2 )n ](m+) complexes. Here, we report on an unexpectedly variable coordination chemistry of diiodine towards this direction: (A)Ag-I2 -Ag(A), [Ag2 (I2 )4 ](2+) (A(-) )2 and [Ag2 (I2 )6 ](2+) (A(-) )2 ⋅(I2 )x≈0.65 form by reaction of Ag(A) (A=Al(OR(F) )4 ; R(F) =C(CF3 )3 ) with diiodine (single crystal/powder XRD, Raman spectra and quantum-mechanical calculations). The molecular (A)Ag-I2 -Ag(A) is ideally set up to act as a 2 e(-) oxidant with stoichiometric formation of 2 AgI and 2 A(-) . Preliminary reactivity tests proved this (A)Ag-I2 -Ag(A) starting material to oxidize n-C5 H12 , C3 H8 , CH2 Cl2 , P4 or S8 at room temperature. A rough estimate of its electron affinity places it amongst very strong oxidizers like MF6 (M=4d metals). This suggests that (A)Ag-I2 -Ag(A) will serve as an easily in bulk accessible, well-defined, and very potent oxidant with multiple applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Degradation of methyl bromide and methyl chloride in soil microcosms: Use of stable C isotope fractionation and stable isotope probing to identify reactions and the responsible microorganisms

USGS Publications Warehouse

Miller, L.G.; Warner, K.L.; Baesman, S.M.; Oremland, R.S.; McDonald, I.R.; Radajewski, S.; Murrell, J.C.

2004-01-01

Bacteria in soil microcosm experiments oxidized elevated levels of methyl chloride (MeCl) and methyl bromide (MeBr), the former compound more rapidly than the latter. MeBr was also removed by chemical reactions while MeCl was not. Chemical degradation dominated the early removal of MeBr and accounted for more than half of its total loss. Fractionation of stable carbon isotopes during chemical degradation of MeBr resulted in a kinetic isotope effect (KIE) of 59 ?? 7???. Soil bacterial oxidation dominated the later removal of MeBr and MeCl and was characterized by different KIEs for each compound. The KIE for MeBr oxidation was 69 ?? 9??? and the KIE for MeCl oxidation was 49 ?? 3???. Stable isotope probing revealed that different populations of soil bacteria assimilated added 13C-labeled MeBr and MeCl. The identity of the active MeBr and MeCl degrading bacteria in soil was determined by analysis of 16S rRNA gene sequences amplified from 13C-DNA fractions, which identified a number of sequences from organisms not previously thought to be involved in methyl halide degradation. These included Burkholderia , the major clone type in the 13C-MeBr fraction, and Rhodobacter, Lysobacter and Nocardioides the major clone types in the 13C-MeCl fraction. None of the 16S rRNA gene sequences for methyl halide oxidizing bacteria currently in culture (including Aminobacter strain IMB-1 isolated from fumigated soil) were identified. Functional gene clone types closely related to Aminobacter spp. were identified in libraries containing the sequences for the cmuA gene, which codes for the enzyme known to catalyze the initial step in the oxidation of MeBr and MeCl. The cmuA gene was limited to members of the alpha-Proteobacteria whereas the greater diversity demonstrated by the 16S rRNA gene may indicate that other enzymes catalyze methyl halide oxidation in different groups of bacteria. Copyright ?? 2004 Elsevier Ltd.

Degradation of methyl bromide and methyl chloride in soil microcosms: Use of stable C isotope fractionation and stable isotope probing to identify reactions and the responsible microorganisms

NASA Astrophysics Data System (ADS)

Miller, Laurence G.; Warner, Karen L.; Baesman, Shaun M.; Oremland, Ronald S.; McDonald, Ian R.; Radajewski, Stefan; Murrell, J. Colin

2004-08-01

Bacteria in soil microcosm experiments oxidized elevated levels of methyl chloride (MeCl) and methyl bromide (MeBr), the former compound more rapidly than the latter. MeBr was also removed by chemical reactions while MeCl was not. Chemical degradation dominated the early removal of MeBr and accounted for more than half of its total loss. Fractionation of stable carbon isotopes during chemical degradation of MeBr resulted in a kinetic isotope effect (KIE) of 59 ± 7‰. Soil bacterial oxidation dominated the later removal of MeBr and MeCl and was characterized by different KIEs for each compound. The KIE for MeBr oxidation was 69 ± 9‰ and the KIE for MeCl oxidation was 49 ± 3‰. Stable isotope probing revealed that different populations of soil bacteria assimilated added 13C-labeled MeBr and MeCl. The identity of the active MeBr and MeCl degrading bacteria in soil was determined by analysis of 16S rRNA gene sequences amplified from 13C-DNA fractions, which identified a number of sequences from organisms not previously thought to be involved in methyl halide degradation. These included Burkholderia, the major clone type in the 13C-MeBr fraction, and Rhodobacter, Lysobacter and Nocardioides the major clone types in the 13C-MeCl fraction. None of the 16S rRNA gene sequences for methyl halide oxidizing bacteria currently in culture (including Aminobacter strain IMB-1 isolated from fumigated soil) were identified. Functional gene clone types closely related to Aminobacter spp. were identified in libraries containing the sequences for the cmuA gene, which codes for the enzyme known to catalyze the initial step in the oxidation of MeBr and MeCl. The cmuA gene was limited to members of the alpha-Proteobacteria whereas the greater diversity demonstrated by the 16S rRNA gene may indicate that other enzymes catalyze methyl halide oxidation in different groups of bacteria.

Modulated structure and molecular dissociation of solid chlorine at high pressures

NASA Astrophysics Data System (ADS)

Li, Peifang; Gao, Guoying; Ma, Yanming

2012-08-01

Among diatomic molecular halogen solids, high pressure structures of solid chlorine (Cl2) remain elusive and least studied. We here report first-principles structural search on solid Cl2 at high pressures through our developed particle-swarm optimization algorithm. We successfully reproduced the known molecular Cmca phase (phase I) at low pressure and found that it remains stable up to a high pressure 142 GPa. At 150 GPa, our structural searches identified several energetically competitive, structurally similar, and modulated structures. Analysis of the structural results and their similarity with those in solid Br2 and I2, it was suggested that solid Cl2 adopts an incommensurate modulated structure with a modulation wave close to 2/7 in a narrow pressure range 142-157 GPa. Eventually, our simulations at >157 GPa were able to predict the molecular dissociation of solid Cl2 into monatomic phases having body centered orthorhombic (bco) and face-centered cubic (fcc) structures, respectively. One unique monatomic structural feature of solid Cl2 is the absence of intermediate body centered tetragonal (bct) structure during the bco → fcc transition, which however has been observed or theoretically predicted in solid Br2 and I2. Electron-phonon coupling calculations revealed that solid Cl2 becomes superconductors within bco and fcc phases possessing a highest superconducting temperature of 13.03 K at 380 GPa. We further probed the molecular Cmca → incommensurate phase transition mechanism and found that the softening of the Ag vibrational (rotational) Raman mode in the Cmca phase might be the driving force to initiate the transition.

Spin-Orbit Effect on the Molecular Properties of TeXn (X = F, Cl, Br, and I; n = 1, 2, and 4): A Density Functional Theory and Ab Initio Study.

PubMed

Moon, Jiwon; Kim, Joonghan

2016-09-29

Density functional theory (DFT) and ab initio calculations, including spin-orbit coupling (SOC), were performed to investigate the spin-orbit (SO) effect on the molecular properties of tellurium halides, TeXn (X = F, Cl, Br, and I; n = 1, 2, and 4). SOC elongates the Te-X bond and slightly reduces the vibrational frequencies. Consideration of SOC leads to better agreement with experimental values. Møller-Plesset second-order perturbation theory (MP2) seriously underestimates the Te-X bond lengths. In contrast, B3LYP significantly overestimates them. SO-PBE0 and multireference configuration interactions with the Davidson correction (MRCI+Q), which include SOC via a state-interaction approach, give the Te-I bond length of TeI2 that matches the experimental value. On the basis of the calculated thermochemical energy and optimized molecular structure, TeI4 is unlikely to be stable. The use of PBE0 including SOC is strongly recommended for predicting the molecular properties of Te-containing compounds.

Cation Dynamics Governed Thermal Properties of Lead Halide Perovskite Nanowires.

PubMed

Wang, Yuxi; Lin, Renxing; Zhu, Pengchen; Zheng, Qinghui; Wang, Qianjin; Li, Deyu; Zhu, Jia

2018-05-09

Metal halide perovskite (MHP) nanowires such as hybrid organic-inorganic CH 3 NH 3 PbX 3 (X = Cl, Br, I) have drawn significant attention as promising building blocks for high-performance solar cells, light-emitting devices, and semiconductor lasers. However, the physics of thermal transport in MHP nanowires is still elusive even though it is highly relevant to the device thermal stability and optoelectronic performance. Through combined experimental measurements and theoretical analyses, here we disclose the underlying mechanisms governing thermal transport in three different kinds of lead halide perovskite nanowires (CH 3 NH 3 PbI 3 , CH 3 NH 3 PbBr 3 and CsPbBr 3 ). It is shown that the thermal conductivity of CH 3 NH 3 PbBr 3 nanowires is significantly suppressed as compared to that of CsPbBr 3 nanowires, which is attributed to the cation dynamic disorder. Furthermore, we observed different temperature-dependent thermal conductivities of hybrid perovskites CH 3 NH 3 PbBr 3 and CH 3 NH 3 PbI 3 , which can be attributed to accelerated cation dynamics in CH 3 NH 3 PbBr 3 at low temperature and the combined effects of lower phonon group velocity and higher Umklapp scattering rate in CH 3 NH 3 PbI 3 at high temperature. These data and understanding should shed light on the design of high-performance MHP based thermal and optoelectronic devices.

Experimental studies of transplutonium metals and compounds under pressure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peterson, J.R.; Haire, R.G.; Benedict, U.

1986-01-01

The structural behavior of the first four transplutonium metals and two Bk-Cf alloys as a function of pressure has been studied in diamond anvil cells via x-ray diffraction. The sequence of structures exhibited as pressure is increased is dhcp ..-->.. ccp ..-->.. orthorhombic. In addition a distorted ccp phase is observed in Am, Bk/sub 0.40/Cf/sub 0.60/, and Cf between the ccp and orthorhombic phases. Diamond anvil cells have also been used to contain AmI/sub 3/, CfBr/sub 3/, and CfCl/sub 3/ under pressure for investigation by absorption spectrophotometry. Both AmI/sub 3/ and CfBr/sub 3/ exhibit pressure-induced, irreversible phase transformations to themore » PuBr/sub 3/-type orthorhombic structure, a more dense form of these compounds. Thus the driving force for these transformations is more efficient crystal packing. Both hexagonal (to 22 GPa) and orthorhombic (to 35 GPa) CfCl/sub 3/ exhibit only reversible spectral changes with pressure. This probably reflects their nearly identical RTP unit cell volumes. In both cases the spectra obtained are consistent with a continuous alteration of the RTP structure with pressure; physical compression seems to make a given f-f transition easier. Additional data are being sought to elucidate more completely the behavior of CfCl/sub 3/ under pressure. 23 refs., 4 figs.« less

Salt in the Air during the Nitrogen, Aerosol Composition, and Halogens on a Tall Tower (NACHTT) Campaign

NASA Astrophysics Data System (ADS)

Pszenny, A.; Keene, W. C.; Sander, R.; Bearekman, R.; Deegan, B.; Maben, J. R.; Warrick-Wriston, C.; Young, A.

2011-12-01

Bulk and size-segregated aerosol samples were collected 22 m AGL at the Boulder Atmospheric Observatory (40°N, 105°W, 1563 m ASL) from 18 February to 13 March 2011. Total concentrations of Na, Mg, Al, Cl, V, Mn, Br and I in bulk samples were determined by neutron activation analysis. Ionic composition of all size-segregated and a subset of bulk samples was determined by ion chromatography of aqueous extracts. Mg, Al, V and Mn mass concentrations were highly correlated and present in ratios similar to those in Denver area surface soils. Na and Cl were less well correlated with these soil elements but, after correction for soil contributions, highly correlated with each other. Linear regression of non-soil Cl vs. non-soil Na yielded a slope of 1.69 ± 0.09 (95% C.I.; n = 173), a value between the mass ratios of sea salt (1.80) and halite (1.54). The median Na and Cl concentrations (6.8 and 6.6 nmol m-3 STP, respectively) were factors of 25 to 35 less than those typically measured in the marine boundary layer. Br and I were somewhat correlated and appeared to represent a third aerosol component. The average bulk Cl-:total Cl ratio was 0.99 ± 0.03 (n = 44) suggesting that essentially all aerosol chlorine was water-soluble. Na+ and Cl- mass distributions were bimodal with most of the masses (medians 75% and 78%, respectively, n = 45) in supermicrometer particles. Possible origins of the "salt" component will be discussed based on consideration of 5-day HYSPLIT back trajectories and other information on sampled air mass characteristics.

Halide anion effects on coordination polymerization of cadmium(II) halide with 1: 1 mixed ligands

NASA Astrophysics Data System (ADS)

Ryu, Minjoo; Lee, Young-A.; Jung, Ok-Sang

2018-05-01

Insight into self-assembly of CdX2 (X = Cl and Br) with a mixture of L1 and L2 (L1 = diallylbis(3-pyridyl)silane; L2 = diallylbis(4-pyridyl)silane) was carried out. The self-assembly of CdCl2 with the 1: 1 mixture of L1 and L2 produces only 2D [CdCl2(L1)(L2)] with heteroleptic ligands, whereas that of CdBr2 with the 1: 1 mixture of L1 and L2 gives rise to the statistical mixture of 2D sheet [CdBr2(L1)2]·2H2O, 1D loop-chain [CdBr2(L2)2]·2CH2Cl2, and the 2D [CdBr2(L1)(L2)] with heteroleptic ligands.

Brightly Luminescent and Color-Tunable Colloidal CH3NH3PbX3 (X = Br, I, Cl) Quantum Dots: Potential Alternatives for Display Technology.

PubMed

Zhang, Feng; Zhong, Haizheng; Chen, Cheng; Wu, Xian-gang; Hu, Xiangmin; Huang, Hailong; Han, Junbo; Zou, Bingsuo; Dong, Yuping

2015-04-28

Organometal halide perovskites are inexpensive materials with desirable characteristics of color-tunable and narrow-band emissions for lighting and display technology, but they suffer from low photoluminescence quantum yields at low excitation fluencies. Here we developed a ligand-assisted reprecipitation strategy to fabricate brightly luminescent and color-tunable colloidal CH3NH3PbX3 (X = Br, I, Cl) quantum dots with absolute quantum yield up to 70% at room temperature and low excitation fluencies. To illustrate the photoluminescence enhancements in these quantum dots, we conducted comprehensive composition and surface characterizations and determined the time- and temperature-dependent photoluminescence spectra. Comparisons between small-sized CH3NH3PbBr3 quantum dots (average diameter 3.3 nm) and corresponding micrometer-sized bulk particles (2-8 μm) suggest that the intense increased photoluminescence quantum yield originates from the increase of exciton binding energy due to size reduction as well as proper chemical passivations of the Br-rich surface. We further demonstrated wide-color gamut white-light-emitting diodes using green emissive CH3NH3PbBr3 quantum dots and red emissive K2SiF6:Mn(4+) as color converters, providing enhanced color quality for display technology. Moreover, colloidal CH3NH3PbX3 quantum dots are expected to exhibit interesting nanoscale excitonic properties and also have other potential applications in lasers, electroluminescence devices, and optical sensors.

Use of Less Reactive Materials and More Stable Gases to Reduce Corrosive Wear When Lubricating with Halogenated Gases

NASA Technical Reports Server (NTRS)

Buckley, Donald H.; Johnson, Robert L.

1960-01-01

The gases CF2Cl-CF2Cl, CF2Cl2, and CF2Br-CF2Br were used to lubricate metals, cermets, and ceramics in this study. One of the criteria for determining the effectiveness of a reactive-gas-lubricated systems is the stability of the halogen-containing gas molecule. The carbon-to-halogen bond in the ethane molecule has extremely good thermal stability superior to the methane analogs (CF2Cl2 and CF2Br2) used in earlier research. For this reason, the ethane compounds CF2Cl-CF2Cl and CF2Br-CF2Br were considered as high-temperature lubricants. Friction and wear studies were made with a hemisphere (3/16-in. rad.) rider sliding in a circumferential path on the flat surface of a rotating disk (21/2-in. diam. ). The specimens of metal alloys, cermets, and ceramics were run In an atmosphere of the various gases with a load of 1200 grams, sliding velocities from 75 to 8000 feet per minute, and temperatures from 75 to 1400 F. The gas CF2Cl-CF2Cl was found to be an effective lubricant for the cermet LT-LB (59.0 Cr, 19.0 Al2O3, 20.0 Mo, 2.0 Ti) and the ceramic Al2O3 sliding on Stellite Star J (cobalt-base alloy) at temperatures to 1400 F. The bromine-containing gas CF2Br-CF2Br was found to give friction and wear values that can be considered to be in a region of effective boundary lubrication for the cermet K175D (nickel-bonded metal carbide) sliding on the metal Hastelloy R-235 (nickel-base alloy) at temperatures to 1200 F.

A simple distillation method to extract bromine from natural water and salt samples for isotope analysis by multi-collector inductively coupled plasma mass spectrometry.

PubMed

Eggenkamp, H G M; Louvat, P

2018-04-30

In natural samples bromine is present in trace amounts, and measurement of stable Br isotopes necessitates its separation from the matrix. Most methods described previously need large samples or samples with high Br/Cl ratios. The use of metals as reagents, proposed in previous Br distillation methods, must be avoided for multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) analyses, because of risk of cross-contamination, since the instrument is also used to measure stable isotopes of metals. Dedicated to water and evaporite samples with low Br/Cl ratios, the proposed method is a simple distillation that separates bromide from chloride for isotopic analyses by MC-ICP-MS. It is based on the difference in oxidation potential between chloride and bromide in the presence of nitric acid. The sample is mixed with dilute (1:5) nitric acid in a distillation flask and heated over a candle flame for 10 min. The distillate (bromine) is trapped in an ammonia solution and reduced to bromide. Chloride is only distilled to a very small extent. The obtained solution can be measured directly by MC-ICP-MS for stable Br isotopes. The method was tested for a variety of volumes, ammonia concentrations, pH values and distillation times and compared with the classic ion-exchange chromatography method. The method more efficiently separates Br from Cl, so that samples with lower Br/Cl ratios can be analysed, with Br isotope data in agreement with those obtained by previous methods. Unlike other Br extraction methods based on oxidation, the distillation method presented here does not use any metallic ion for redox reactions that could contaminate the mass spectrometer. It is efficient in separating Br from samples with low Br/Cl ratios. The method ensures reproducible recovery yields and a long-term reproducibility of ±0.11‰ (1 standard deviation). The distillation method was successfully applied to samples with low Br/Cl ratios and low Br amounts (down to 20 μg). Copyright © 2018 John Wiley & Sons, Ltd.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Charkin, Dmitri O.; Black, Cameron; Downie, Lewis J.

Two new rare-earth – alkali – tellurium oxide halides were synthesized by a salt flux technique and characterized by single-crystal X-ray diffraction. The structures of the new compounds Cs{sub 7}Sm{sub 11}[TeO{sub 3}]{sub 12}Cl{sub 16} (I) and Rb{sub 7}Nd{sub 11}[TeO{sub 3}]{sub 12}Br{sub 16} (II) (both tetragonal, space group I4/mcm) correspond to the sequence of [MLn{sub 11}(TeO{sub 3}){sub 12}] and [M{sub 6}X{sub 16}] layers and bear very strong similarities to those of known selenite analogs. We discuss the trends in similarities and differences in compositions and structural details between the Se and Te compounds; more members of the family are predicted. -more » Graphical abstract: Two new rare-earth – alkali – tellurium oxide halides were predicted and synthesized. - Highlights: • Two new rare-earth – alkali – tellurium oxide halides were synthesized. • They adopt slab structure of rare earth-tellurium-oxygen and CsCl-like slabs. • The Br-based CsCl-like slabs have been observed first in this layered family.« less

Energetic Diagrams and Structural Properties of Monohaloacetylenes HC≡CX (X = F, Cl, Br).

PubMed

Khiri, D; Hochlaf, M; Chambaud, G

2016-08-04

Highly correlated electronic wave functions within the Multi Reference Configuration Interaction (MRCI) approach are used to study the stability and the formation processes of the monohaloacetylenes HCCX and monohalovinylidenes C2HX (X = F, Cl, Br) in their electronic ground state. These tetra-atomics can be formed through the reaction of triatomic fragments C2F, C2Cl, and C2Br with a hydrogen atom or of C2H with halogen atoms via barrierless reactions, whereas the reactions between the diatomics [C2 + HX] need to overcome barriers of 1.70, 0.89, and 0.58 eV for X = F, Cl, and Br. It is found that the linear HCCX isomers, in singlet symmetry, are more stable than the singlet C2HX iso-forms by 1.995, 2.083, and 1.958 eV for X = F, Cl, and Br. The very small isomerization barriers from iso to linear forms are calculated 0.067, 0.044, and 0.100 eV for F, Cl, and Br systems. The dissociation energies of the HCCX systems (without ZPE corrections), resulting from the breaking of the CX bond, are calculated to be 5.647, 4.691, and 4.129 eV for X = F, Cl, Br, respectively. At the equilibrium geometry of the X(1)Σ(+) state of HCCX, the vertical excitation energies in singlet and triplet symmetries are all larger than the respective dissociation energies. Stable excited states are found only as (3)A', (3)A″, and (1)A″ monohalovinylidene structures.

Investigations of the Rg-BrCl (Rg=He, Ne, Ar, Kr, Xe) binary van der Waals complexes: ab initio intermolecular potential energy surfaces, vibrational states and predicted pure rotational transition frequencies.

PubMed

Li, Song; Zheng, Rui; Chen, Shan-Jun; Chen, Yan; Chen, Peng

2017-03-05

The intermolecular potential energy surfaces (PESs) of the ground electronic state for the Rg-BrCl (Rg=He, Ne, Ar, Kr, Xe) van der Waals complexes have been constructed by using the coupled-cluster method in combination with the augmented quadruple-zeta correlation-consistent basis sets supplemented with an additional set of bond functions. The features of the anisotropic PESs for these complexes are remarkably similar, which are characterized by three minima and two saddle points between them. The global minimum corresponds to a collinear Rg-Br-Cl configuration. Two local minima, correlate with an anti-linear Rg-Cl-Br geometry and a nearly T-shaped structure, can also be located on each PES. The quantum bound state calculations enable us to investigate intermolecular vibrational states and rotational energy levels of the complexes. The transition frequencies are predicted and are fitted to obtain their corresponding spectroscopic constants. In general, the periodic trends are observed for this complex family. Comparisons with available experimental data for the collinear isomer of Ar-BrCl demonstrate reliability of our theoretical predictions, and our results for the other two isomers of Ar-BrCl as well as for other members of the complex family are also anticipated to be trustable. Except for the collinear isomer of Ar-BrCl, the data presented in this paper would be beneficial to improve our knowledge for these experimentally unknown species. Copyright © 2016 Elsevier B.V. All rights reserved.

Theoretical investigations of the optical spectra and g-shift in CsVX 3 ( X=Cl, Br, I)

NASA Astrophysics Data System (ADS)

Lei, Y.; He, W. S.; Zu, X. T.; Zhao, M. G.

2007-04-01

The paper presents a molecular orbital calculation of the optical spectra and g shift in CsVX 3 ( X=Cl, Br, I), in which the contribution due to the electrostatic parameter A0, the Trees correction, the spin-orbit coupling of the central transition metal ion and the ligand are included. In the present calculations, instead of the 10 parameters in the previous works, there are three fitting parameters because the appropriate double- ζ function of V is used. The calculated optical spectra and g shift agree well with the available experimental data. This indicates again that the double- ζ wave functions are the appropriate approximation in the calculation of the electronic structure properties. The results show that the contribution due to the 3s of the ligand and the conjunct action between the center metal ion and the ligand cannot been neglected.

X2Y2 isomers: tuning structure and relative stability through electronegativity differences (X = H, Li, Na, F, Cl, Br, I; Y = O, S, Se, Te).

PubMed

El-Hamdi, Majid; Poater, Jordi; Bickelhaupt, F Matthias; Solà, Miquel

2013-03-04

We have studied the XYYX and X2YY isomers of the X2Y2 species (X = H, Li, Na, F, Cl, Br, I; Y = O, S, Se, Te) using density functional theory at the ZORA-BP86/QZ4P level. Our computations show that, over the entire range of our model systems, the XYYX isomers are more stable than the X2YY forms except for X = F and Y = S and Te, for which the F2SS and F2TeTe isomers are slightly more stable. Our results also point out that the Y-Y bond length can be tuned quite generally through the X-Y electronegativity difference. The mechanism behind this electronic tuning is the population or depopulation of the π* in the YY fragment.

Closed-cage (fullerene-like) structures of NiBr{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bar-Sadan, M.; Popovitz-Biro, R.; Prior, Yehiam

It is well accepted by now that nanoparticles of inorganic layered compounds form closed-cage structures (IF). In particular closed-cage nanoparticles of metal dihalides, like NiCl{sub 2}, CdCl{sub 2} and CdI{sub 2} were shown to produce such structures in the past. In the present report IF-NiBr{sub 2} polyhedra and quasi-spherical structures were obtained by the evaporation/recrystallization technique as well as by laser ablation. When the nanoclusters were formed in humid atmosphere, nickel perbromate hydrate [Ni(BrO{sub 4}){sub 2}(H{sub 2}O){sub 6}] polyhedra and short tubules were produced, as a result of a reaction with water. Nanooctahedra of NiBr{sub 2} were found occasionally inmore » the irradiated soot. The reoccurrence of this structure in the IF family suggests that it is a generic one. Consistent with previous observations, this study showed that formation of the IF materials stabilized the material under the electron-beam irradiation. The growth mechanism of these nanostructures is briefly discussed.« less

Variation of Ionic Conductivity with Annealing Temperature in Argyrodite Solid Electrolytes

NASA Astrophysics Data System (ADS)

Rao, R. Prasada; Chen, Maohua; Adams, Stefan

2013-07-01

In situ neutron diffraction studies of argyrodite-type Li6PS5X (X = Cl, Br, I) were conducted for mechanically milled sample to reveal the formation and growth of crystalline phases. These studies indicated the formation of crystals in all the compounds started from as low as 80°C. The Rietveld refinements of the resulting crystalline phases at 150°C indicate the formation of the argyrodite structure. Structure refinements using high-intensity neutron diffraction provide insight into the influence of disorder on the fast ionic conductivity. Besides the disorder in the lithium distribution, it is the disorder in the S2-/Cl- or S2-/Br- distribution that we find to promote ion mobility. Among the samples studied Li6PS5Br, annealed at 250°C, exhibited the highest ionic conductivity, 1.05 × 10-3 S/cm at room temperature. An all solid state battery with Li4Ti5O12/Li6PS5Br/Li exhibited 57 mAh/g first discharge capacity at 75°C with 91% coulombic efficiency after 60 cycles.

In situ observations of midlatitude stratospheric ClO and BrO

NASA Technical Reports Server (NTRS)

Brune, William H.; Anderson, James C.

1986-01-01

A balloon-borne experiment to measure midlatitude stratospheric BrO and ClO concentrations by NO chemical conversion/atomic resonance fluorescence was flown from Palestine, Texas, on May 20 1986. In this first study of BrO, no signal attributable to BrO was detected, and upper limits (2 sigma uncertainty) between 35 and 24 km altitude give BrO mixing ratios less than 15 pptv. Current models predict mixing ratios that are 1.7 times larger. Measurements of ClO were obtained at less than 0.2-km altitude resolution from 41 to 22 km. The smoothly varying altitude profile lies within the range of two-dimensional model calculations.

Mercury(II) complexes of unsymmetric phosphorus ylides: Synthesis, spectroscopic and antibacterial activity studies

NASA Astrophysics Data System (ADS)

Sabounchei, Seyyed Javad; Panahimehr, Mohammad; Hosseinzadeh, Marjan; Karamian, Roya; Asadbegy, Mostafa; Masumi, Azadeh

2014-03-01

The reaction of Ph2PCH2PPh2 (dppm) with 2-bromo-3-nitroacetophenone and 2,2‧,4‧-trichloroacetophenone in chloroform produce the new phosphonium salts [Ph2PCH2PPh2CH2C(O)C6H4NO2]Br (1) and [Ph2PCH2PPh2CH2C(O)C6H3Cl2]Cl (2). Further, by reaction of the monophosphonium salts of dppm with the strong base triethylaminethe corresponding bidentate phosphorus ylides, Ph2PCH2PPh2C(H)C(O)C6H4NO2 (3) and Ph2PCH2PPh2C(H)C(O)C6H3Cl2 (4) were obtained. The reaction of these ligands with mercury(II) halides in dry methanol led to the formation of the mononuclear complexes {HgX2[(Ph2PCH2PPh2C(H)C(O)C6H4NO2)]} [X = Cl (5), Br (6), I (7)] and {HgX2[(Ph2PCH2PPh2C(H)C(O)C6H3Cl2)]} [X = Cl (8), Br (9), I (10)]. Characterization of the obtained compounds was performed by elemental analysis, IR, 1H, 31P and 13C NMR. The structure of compound 1 being unequivocally determined by single crystal X-ray diffraction techniques. The mass spectrum of compound 6 (as an instance) also demonstrates the synthesize of these compounds. In all complexes the title ylides are coordinated through the ylidic carbon and the phosphine atom. These compounds form five membered ring under complexation. The antibacterial effects of DMSO solutions of the ligands and their metal complexes were evaluated by the disc diffusion method against six Gram positive and negative bacteria. All compounds represent antibacterial activity against these bacteria with high levels of inhibitory potency exhibited against the Gram positive species.

Syntheses, crystal structures, and properties of six new lanthanide(III) transition metal tellurium(IV) oxyhalides with three types of structures.

PubMed

Shen, Yue-Ling; Mao, Jiang-Gao

2005-07-25

Solid-state reactions of lanthanide(III) oxide (and lanthanide(III) oxyhalide), transition metal halide (and transition metal oxide), and TeO(2) at high temperature lead to six new lanthanide transition metal tellurium(IV) oxyhalides with three different types of structures, namely, DyCuTe(2)O(6)Cl, ErCuTe(2)O(6)Cl, ErCuTe(2)O(6)Br, Sm(2)Mn(Te(5)O(13))Cl(2), Dy(2)Cu(Te(5)O(13))Br(2), and Nd(4)Cu(TeO(3))(5)Cl(3). Compounds DyCuTe(2)O(6)Cl, ErCuTe(2)O(6)Cl, and ErCuTe(2)O(6)Br are isostructural. The lanthanide(III) ion is eight-coordinated by eight oxygen atoms, and the copper(II) ion is five-coordinated by four oxygens and a halide anion in a distorted square pyramidal geometry. The interconnection of Ln(III) and Cu(II) ions by bridging tellurite anions results in a three-dimensional (3D) network with tunnels along the a-axis; the halide anion and the lone-pair electrons of the tellurium(IV) ions are oriented toward the cavities of the tunnels. Compounds Sm(2)Mn(Te(5)O(13))Cl(2) and Dy(2)Cu(Te(5)O(13))Br(2) are isostructural. The lanthanide(III) ions are eight-coordinated by eight oxygens, and the divalent transition metal ion is octahedrally coordinated by six oxygens. Two types of polymeric tellurium(IV) oxide anions are formed: Te(3)O(8)(4)(-) and Te(4)O(10)(4)(-). The interconnection of the lanthanide(III) and divalent transition metal ions by the above two types of polymeric tellurium(IV) oxide anions leads to a 3D network with long, narrow-shaped tunnels along the b-axis. The halide anions remain isolated and are located at the above tunnels. Nd(4)Cu(TeO(3))(5)Cl(3) features a different structure. All five of the Nd(III) ions are eight-coordinated (NdO(8) for Nd(1), Nd(2), Nd(4), and Nd(5) and NdO(7)Cl for Nd(3)), and the copper(I) ion is tetrahedrally coordinated by four chloride anions. The interconnection of Nd(III) ions by bridging tellurite anions resulted in a 3D network with large tunnels along the b-axis. The CuCl(4) tetrahedra are interconnected into a 1D two-unit repeating (zweier) chain via corner-sharing. These 1D copper(I) chloride chains are inserted into the tunnels of the neodymium(III) tellurite via Nd-Cl-Cu bridges. Luminescent studies show that ErCuTe(2)O(6)Cl and Nd(4)Cu(TeO(3))(5)Cl(3) exhibit strong luminescence in the near-IR region. Magnetic measurements indicate the antiferromagnetic interactions between magnetic centers in these compounds.

Semiconducting perovskites (2-XC6H4C2H4NH3)2SnI4 (X = F, Cl, Br): steric interaction between the organic and inorganic layers.

PubMed

Xu, Zhengtao; Mitzi, David B; Dimitrakopoulos, Christos D; Maxcy, Karen R

2003-03-24

Two new semiconducting hybrid perovskites based on 2-substituted phenethylammonium cations, (2-XC(6)H(4)C(2)H(4)NH(3))(2)SnI(4) (X = Br, Cl), are characterized and compared with the previously reported X = F compound, with a focus on the steric interaction between the organic and inorganic components. The crystal structure of (2-ClC(6)H(4)C(2)H(4)NH(3))(2)SnI(4) is solved in a disordered subcell [C2/m, a = 33.781(7) A, b = 6.178(1) A, c = 6.190(1) A, beta = 90.42(3)(o), and Z = 2]. The structure is similar to the known (2-FC(6)H(4)C(2)H(4)NH(3))(2)SnI(4) structure with regard to both the conformation of the organic cations and the bonding features of the inorganic sheet. The (2-BrC(6)H(4)C(2)H(4)NH(3))(2)SnI(4) system adopts a fully ordered monoclinic cell [P2(1)/c, a = 18.540(2) A, b = 8.3443(7) A, c = 8.7795(7) A, beta = 93.039(1)(o), and Z = 2]. The organic cation adopts the anti conformation, instead of the gauche conformation observed in the X = F and Cl compounds, apparently because of the need to accommodate the additional volume of the bromo group. The steric effect of the bromo group also impacts the perovskite sheet, causing notable distortions, such as a compressed Sn-I-Sn bond angle (148.7(o), as compared with the average values of 153.3 and 154.8(o) for the fluoro and chloro compounds, respectively). The optical absorption features a substantial blue shift (lowest exciton peak: 557 nm, 2.23 eV) relative to the spectra of the fluoro and chloro compounds (588 and 586 nm, respectively). Also presented are transport properties for thin-film field-effect transistors (TFTs) based on spin-coated films of the two hybrid semiconductors.

Rejection of Bromide and Bromate Ions by a Ceramic Membrane.

PubMed

Moslemi, Mohammadreza; Davies, Simon H; Masten, Susan J

2012-12-01

Effects of pH and the addition of calcium chloride (CaCl(2)) on bromate (BrO(3) (-)) and bromide (Br(-)) rejection by a ceramic membrane were investigated. Rejection of both ions increased with pH. At pH 8, the rejection of BrO(3) (-) and Br(-) was 68% and 63%, respectively. Donnan exclusion appears to play an important role in determining rejection of BrO(3) (-) and Br(-). In the presence of CaCl(2), rejection of BrO(3) (-) and Br(-) ions was greatly reduced, confirming the importance of electrostatic interactions in determining rejection of BrO(3) (-) and Br(-). The effect of Ca(2+) is so pronounced that in most natural waters, rejection of both BrO(3) (-) and Br(-) by the membrane would be extremely small.

Direct evidence of a multicentre halogen bond: unexpected contraction of the P-XXX-P fragment in triphenylphosphine dihalides.

PubMed

Nikitin, Kirill; Müller-Bunz, Helge; Gilheany, Declan

2013-02-18

Triphenylhalophosphonium halides, Ph(3)PX(2), form crystals comprising bridged linear cations [Ph(3)P-X-X-X-PPh(3)](+) where the X(3) bridge is shortened from 6.56 Å in Cl-Cl-Cl to 6.37 Å in the Br-Br-Br system. It is proposed that this structure is stabilised by five-centre/six-electron (5c-6e) hypervalent interactions.

Investigating the Weak to Evaluate the Strong: An Experimental Determination of the Electron Binding Energy of Carborane Anions and the Gas phase Acidity of Carborane Acids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meyer, Matthew M; Wang, Xue B; Reed, Christopher A

2009-12-23

Five CHB 11X 6Y 5 - carborane anions from the series X = Br, Cl, I and Y = H, Cl, CH 3 were generated by electrospray ionization, and their reactivity with a series of Brønsted acids and electron transfer reagents were examined in the gas phase. The undecachlorocarborane acid, H(CHB 11Cl 11), was found to be far more acidic than the former record holder, (1-C 4F 9SO 2) 2NH (i.e., ΔH° acid = 241 ± 29 vs 291.1 ± 2.2 kcal mol -1) and bridges the gas-phase acidity and basicity scales for the first time. Its conjugate base, CHBmore » 11Cl 11 -, was found by photoelectron spectroscopy to have a remarkably large electron binding energy (6.35 ± 0.02 eV) but the value for the (1-C 4F 9SO 2) 2N - anion is even larger (6.5 ± 0.1 eV). Consequently, it is the weak H-(CHB 11Cl 11) BDE (70.0 kcal mol -1, G3(MP2)) compared to the strong BDE of (1-C 4F 9SO 2) 2N-H (127.4 ± 3.2 kcal mol -1) that accounts for the greater acidity of carborane acids.« less

Using Kalman Filter Chemical Data Assimilation to Study Ozone Catalytic Loss Cycles in January 1992

NASA Technical Reports Server (NTRS)

Lary, David J.

2002-01-01

This paper presents for the first time a global study of the ozone catalytic destruction cycles operating in the stratosphere using a stratospheric analyses for January 1992. The chemical analyses were produced using a Kalman filter data assimilation system. Because a major component of the variability of trace gases is due to the atmospheric motions the analyses have been cast in a flow-tracking coordinate system that moves with the large scale flow pattern. Particular attention is paid to the kinetic aspects of these cycles such as the rate limiting step and chain length. Although it is an important kinetic parameter, the chain length of the various cycles is seldom considered when the various catalytic cycles are discussed. This survey highlights that in the low stratosphere the cycles involving HO2 and halogens (notably bromine) are particularly important. In approximate order of effectiveness the most important ozone loss cycles in the polar lower stratosphere are the BrO/ClO, HO2/BrO, and OH/HO2 cycles. The ClO/ClO cycle clearly delineates the regions of chlorine activation. The chain length of the HO2/ClO, OH/HO2, Br/BrO, and ClO/NO2, clearly delineate the vortex edge region. The chain length of the BrO/NO2 and Cl/NO2 cycles highlight the regions of chemical processing outside the vortex where streamers of chemically processed air are stripped-off and transported away from the vortex. This is also true in the very low stratosphere for the Cl/ClO and BrO/ClO cycles.

Tunable White-Light Emission in Single-Cation-Templated Three-Layered 2D Perovskites (CH 3 CH 2 NH 3 ) 4 Pb 3 Br 10–x Cl x

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mao, Lingling; Wu, Yilei; Stoumpos, Constantinos C.

Two-dimensional (2D) hybrid halide perovskites come as a family (B) 2(A) n-1PbnX 3n+1 (B and A= cations; X= halide). These perovskites are promising semiconductors for solar cells and optoelectronic applications. Among the fascinating properties of these materials is white-light emission, which has been mostly observed in single-layered 2D lead bromide or chloride systems (n = 1), where the broad emission comes from the transient photoexcited states generated by self-trapped excitons (STEs) from structural distortion. Here we report a multilayered 2D perovskite (n = 3) exhibiting a tunable white-light emission. Ethylammonium (EA+) can stabilize the 2D perovskite structure in EA 4Pbmore » 3Br 10–xCl x (x = 0, 2, 4, 6, 8, 9.5, and 10) with EA + being both the A and B cations in this system. Because of the larger size of EA, these materials show a high distortion level in their inorganic structures, with EA4Pb3Cl10 having a much larger distortion than that of EA 4Pb 3Br 10, which results in broadband white-light emission of EA 4Pb 3Cl 10 in contrast to narrow blue emission of EA4Pb3Br10. The average lifetime of the series decreases gradually from the Cl end to the Br end, indicating that the larger distortion also prolongs the lifetime (more STE states). The band gap of EA 4Pb 3Br 10–xCl x ranges from 3.45 eV (x = 10) to 2.75 eV (x = 0), following Vegard’s law. First-principles density functional theory calculations (DFT) show that both EA 4Pb 3Cl 10 and EA 4Pb 3Br 10 are direct band gap semiconductors. The color rendering index (CRI) of the series improves from 66 (EA 4Pb 3Cl 10) to 83 (EA 4Pb 3Br 0.5Cl 9.5), displaying high tunability and versatility of the title compounds.« less

Surfactant-Modified Ultrafine Gold Nanoparticles with Magnetic Responsiveness for Reversible Convergence and Release of Biomacromolecules.

PubMed

Xu, Lu; Dong, Shuli; Hao, Jingcheng; Cui, Jiwei; Hoffmann, Heinz

2017-03-28

It is difficult to synthesize magnetic gold nanoparticles (AuNPs) with ultrafine sizes (<2 nm) based on a conventional method via coating AuNPs using magnetic particles, compounds, or ions. Here, magnetic cationic surfactants C 16 H 33 N + (CH 3 ) 3 [CeCl 3 Br] - (CTACe) and C 16 H 33 N + (CH 3 ) 3 [GdCl 3 Br] - (CTAGd) are prepared by a one-step coordination reaction, i.e., C 16 H 33 N + (CH 3 ) 3 Br - (CTABr) + CeCl 3 or GdCl 3 → CTACe or CTAGd. A simple strategy for fabricate ultrafine (<2 nm) magnetic gold nanoparticles (AuNPs) via surface modification with weak oxidizing paramagnetic cationic surfactants, CTACe or CTAGd, is developed. The resulting AuNPs can highly concentrate the charges of cationic surfactants on their surfaces, thereby presenting strong electrostatic interaction with negatively charged biomacromolecules, DNA, and proteins. As a consequence, they can converge DNA and proteins over 90% at a lower dosage than magnetic surfactants or existing magnetic AuNPs. The surface modification with these cationic surfactants endows AuNPs with strong magnetism, which allows them to magnetize and migrate the attached biomacromolecules with a much higher efficiency. The native conformation of DNA and proteins can be protected during the migration. Besides, the captured DNA and proteins could be released after adding sufficient inorganic salts such as at c NaBr = 50 mmol·L -1 . Our results could offer new guidance for a diverse range of systems including gene delivery, DNA transfection, and protein delivery and separation.

Synthesis and investigation of Pd(I) carbonyl complexes with heteroorganic ligands

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lamberov, A.A.; Polovnyak, V.K.; Akhmetov, N.S.

1987-09-10

Pd(I) carbonyl complexes are attracting attention because they have been shown to have catalytic properties in a series of organic syntheses. The stability and catalytic properties of these compounds are determined by the nature of the phosphine ligand and the bridge coordination of the carbonylgroup. Through the partial replacement of carbonyl and acido ligands by heteroorganic ligands in carbonyl halogenide and carbonyl acetate Pd(I) complexes, new stable Pd(I) complexes were obtained: (PdLX)/sub 2/CO, where L = PPh/sub 3/, X = OAc; L = AsPh/sub 3/, X = Cl, Br, OAc; L = SbPh/sub 3/, X = Cl Br, OAc; Lmore » = Ph/sub 2/PCH/sub 2/PPh/sub 2/, Ph/sub 2/AsCH/sub 2/AsPh/sub 2/, X = OAc. Atoms of the heteroorganic and acido ligands are equivalently coordinated to the palladium atoms. The carbonyl group in the complexes has bridge coordination to palladium atoms in the Pd(CO)Pd fragment; in complexes with bidentate heteroorganic ligands the covalent bond between palladium atoms is absent.« less

In-Plane Angular Effect of Magnetoresistance of Quasi-One-Dimensional Organic Metals, (DMET) 2AuBr 2 and (TMTSF) 2ClO 4

NASA Astrophysics Data System (ADS)

Yoshino, Harukazu; Saito, Kazuya; Nishikawa, Hiroyuki; Kikuchi, Koichi; Kobayashi, Keiji; Ikemoto, Isao

1997-08-01

Comparative study is presented for the in-plane angular effect of magnetoresistance of quasi-one-dimensional organic conductors, (DMET)2AuBr2 and (TMTSF)2ClO4. The magnetoresistance for the magnetic and electrical fields parallel and perpendicular to the most conducting plane, respectively, was measured at 4.2 K and up to 7.0 T. (DMET)2AuBr2 shows an anomalous hump in the field-orientation dependence of the magnetoresistance for the magnetic field nearly parallel to the most conducting axis and this is very similar to what previously reported for (DMET)2I3. Weak anomaly was detected for the magnetoresistance of (TMTSF)2ClO4 in the Relaxed state, while no anomaly was observed in the SDW phase in the Quenched state. By comparing the numerical angular derivatives of the magnetoresistance, it is shown that the anomaly in the in-plane angular effect continuously develops from zero magnetic field and is closely related to the quasi-one-dimensional Fermi surface. A simple method is proposed to estimate the anisotropy of the transfer integral from the width of the hump anomaly.

Low Pressure Vapor-assisted Solution Process for Tunable Band Gap Pinhole-free Methylammonium Lead Halide Perovskite Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sutter-Fella, Carolin M.; Li, Yanbo; Cefarin, Nicola

Organo-lead halide perovskites have recently attracted great interest for potential applications in thin-film photovoltaics and optoelectronics. Herein, we present a protocol for the fabrication of this material via the low-pressure vapor assisted solution process (LP-VASP) method, which yields ~19% power conversion efficiency in planar heterojunction perovskite solar cells. First, we report the synthesis of methylammonium iodide (CH 3NH 3I) and methylammonium bromide (CH 3NH 3Br) from methylamine and the corresponding halide acid (HI or HBr). Then, we describe the fabrication of pinhole-free, continuous methylammonium-lead halide perovskite (CH 3NH 3PbX 3 with X = I, Br, Cl and their mixture) filmsmore » with the LP-VASP. This process is based on two steps: i) spin-coating of a homogenous layer of lead halide precursor onto a substrate, and ii) conversion of this layer to CH 3NH 3PbI 3-xBr x by exposing the substrate to vapors of a mixture of CH 3NH 3I and CH 3NH 3Br at reduced pressure and 120 °C. Through slow diffusion of the methylammonium halide vapor into the lead halide precursor, we achieve slow and controlled growth of a continuous, pinhole-free perovskite film. The LP-VASP allows synthetic access to the full halide composition space in CH 3NH 3PbI 3-xBr x with 0 ≤ x ≤ 3. Depending on the composition of the vapor phase, the bandgap can be tuned between 1.6 eV ≤ E g ≤ 2.3 eV. In addition, by varying the composition of the halide precursor and of the vapor phase, we can also obtain CH 3NH 3PbI 3-xCl x. Films obtained from the LP-VASP are reproducible, phase pure as confirmed by X-ray diffraction measurements, and show high photoluminescence quantum yield. The process does not require the use of a glovebox.« less

Low Pressure Vapor-assisted Solution Process for Tunable Band Gap Pinhole-free Methylammonium Lead Halide Perovskite Films

DOE PAGES

Sutter-Fella, Carolin M.; Li, Yanbo; Cefarin, Nicola; ...

2017-09-08

Organo-lead halide perovskites have recently attracted great interest for potential applications in thin-film photovoltaics and optoelectronics. Herein, we present a protocol for the fabrication of this material via the low-pressure vapor assisted solution process (LP-VASP) method, which yields ~19% power conversion efficiency in planar heterojunction perovskite solar cells. First, we report the synthesis of methylammonium iodide (CH 3NH 3I) and methylammonium bromide (CH 3NH 3Br) from methylamine and the corresponding halide acid (HI or HBr). Then, we describe the fabrication of pinhole-free, continuous methylammonium-lead halide perovskite (CH 3NH 3PbX 3 with X = I, Br, Cl and their mixture) filmsmore » with the LP-VASP. This process is based on two steps: i) spin-coating of a homogenous layer of lead halide precursor onto a substrate, and ii) conversion of this layer to CH 3NH 3PbI 3-xBr x by exposing the substrate to vapors of a mixture of CH 3NH 3I and CH 3NH 3Br at reduced pressure and 120 °C. Through slow diffusion of the methylammonium halide vapor into the lead halide precursor, we achieve slow and controlled growth of a continuous, pinhole-free perovskite film. The LP-VASP allows synthetic access to the full halide composition space in CH 3NH 3PbI 3-xBr x with 0 ≤ x ≤ 3. Depending on the composition of the vapor phase, the bandgap can be tuned between 1.6 eV ≤ E g ≤ 2.3 eV. In addition, by varying the composition of the halide precursor and of the vapor phase, we can also obtain CH 3NH 3PbI 3-xCl x. Films obtained from the LP-VASP are reproducible, phase pure as confirmed by X-ray diffraction measurements, and show high photoluminescence quantum yield. The process does not require the use of a glovebox.« less

Negative ion electron impact studies of arsenic trihalides: AsF/sub 3/, AsCl/sub 3/, and AsBr/sub 3/

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pabst, R.E.; Bennett, S.L.; Margrave, J.L.

1976-08-15

Low energy eleAsF/sup 2/-tron impact of AsF/sub 3/, AsCl/sub 3/, and AsBr/sub 3/ gases gave many ions by dissociative resonance capture. Appearance potentials have been determined by deconvolution of the capture curves, and translational energies of the majority of the ions have been measured through the resonance processes. The X/sup -/ ions are formed along with electronically excited neutral AsX/sub 2/, and the results allow the electronic transition energies to be determined: 7.3, 4.3, and 2.6 eV for AsF/sub 2/, AsCl/sup 2/, and AsBr/sup 2/, respectively. From the processes giving AsX/sup -2/+X, the experimental data allow the heats of formationmore » of the negative ions ..delta..H/subf/(AsX/sup -2/) to be derived: -129.7, -65.3, and -72.5 kcal mole/sup -1/ for AsF/sup -2/, AsCl/sup -2/, and AsBr/sup -2/, respectively. The ions AsCl/sup -/ and AsBr/sup -/ appear to be formed along with electronically excited X/sub 2/ neutral: ..delta..H/subf/(AsCl/sup -/) =-2.2 kcal mole/sup -1/ and ..delta..H/subf/(AsBr/sup -/) =1.7 kcal mole/sup -1/ are derived. The ions X/sup -2/ appear to be formed with electronically excited AsX neutral, allowing the electronic transition energies to be derived: E*/sub el/(AsBr) >0.6 eV and E*/sub el/(AsCl) =2.5 eV. (AIP)« less

Impacts of inorganic anions and natural organic matter on thermally activated persulfate oxidation of BTEX in water.

PubMed

Ma, Jie; Yang, Yongqi; Jiang, Xianchenghao; Xie, Zhuoting; Li, Xiaoxuan; Chen, Changzhao; Chen, Hongkun

2018-01-01

The present study investigated the impacts of water matrix constituents (CO 3 2- , HCO 3 - , Cl - , Br - , PO 4 3- , HPO 4 2- , H 2 PO 4 - , NO 3 - , SO 4 2- and natural organic matters (NOM) on the oxidation of a mixture of benzene, toluene, ethylbenzene, and xylenes (BTEX) by thermally activated persulfate (PS). In the absence of matrix constituents, the BTEX oxidation rates decreased in the following order: xylenes > toluene ≈ ethylbenzene > benzene. HCO 3 - /CO 3 2- and NOM inhibited the BTEX oxidation and the inhibiting effects became more pronounced as the HCO 3 - /CO 3 2- /NOM concentration increased. SO 4 2- , NO 3 - , PO 4 3- and H 2 PO 4 - did not affect the BTEX oxidation while HPO 4 2- slightly inhibited the reaction. The impacts of Cl - and Br - were complex. Cl - inhibited the benzene oxidation while 100 mM and 500 mM of Cl - promoted the oxidation of m-xylene and p-xylene. Br - completely suppressed the benzene oxidation while 500 mM of Br - strongly promoted the oxidation of xylenes. Detailed explanations on the influence of each matrix constituent were discussed. In addition, various halogenated degradation byproducts were detected in the treatments containing Cl - and Br - . Overall, this study indicates that some matrix constituents such as NOM, HCO 3 - , CO 3 2- , H 2 PO 4 - , Cl - and Br - may reduce the BTEX removal efficiency of sulfate radical-based advanced oxidation process (SR-AOP) and the presence of Cl - and Br - may even lead to the formation of toxic halogenated byproducts. Copyright © 2017 Elsevier Ltd. All rights reserved.

Likelihood of atom-atom contacts in crystal structures of halogenated organic compounds.

PubMed

Jelsch, Christian; Soudani, Sarra; Ben Nasr, Cherif

2015-05-01

The likelihood of occurrence of intermolecular contacts in crystals of halogenated organic compounds has been analysed statistically using tools based on the Hirshfeld surface. Several families of small halogenated molecules (containing organic F, Cl, Br or I atoms) were analysed, based on chemical composition and aromatic or aliphatic character. The behaviour of crystal contacts was also probed for molecules containing O or N. So-called halogen bonding (a halogen making short interactions with O or N, or a π interaction with C) is generally disfavoured, except when H is scarce on the molecular surface. Similarly, halogen⋯halogen contacts are more rare than expected, except for molecules that are poor in H. In general, the H atom is found to be the preferred partner of organic halogen atoms in crystal structures. On the other hand, C⋯C interactions in parallel π-stacking have a high propensity to occur in halogenated aromatic molecules. The behaviour of the four different halogen species (F, Cl, Br, I) is compared in several chemical composition contexts. The analysis tool can be refined by distinguishing several types for a given chemical species, such as H atoms bound to O or C. Such distinction shows, for instance, that C-H⋯Cl and O-H⋯O are the preferred interactions in compounds containing both O and Cl.

Influence of halogenides on luminescence from silver molecular clusters in photothermorefractive glasses

NASA Astrophysics Data System (ADS)

Dubrovin, V. D.; Ignat'ev, A. I.; Nikonorov, N. V.; Sidorov, A. I.

2014-05-01

It is shown experimentally that a rise in the sodium halogenide (NaCl, NaBr) concentration in photothermorefractive glasses increases the intensity of luminescence from silver neutral molecular clusters. Substitution of NaBr for NaCl with their concentration being the same shifts the luminescence band toward longer waves and raises its intensity. These findings can be explained by the formation of molecular clusters of type Ag n -Hal (Hal = Cl, Br) in photothermorefractive glass.

Divergent electronic structures of isoelectronic metalloclusters: tungsten(II) halides and rhenium(III) chalcogenide halides.

PubMed

Gray, Thomas G

2009-03-02

Same but different: DFT calculations on hexanuclear tungsten(II) halide clusters [W(6)X(8)X'(6)](2-) (X, X'=Cl, Br, I) indicate a breakdown in the isoelectronic analogy between themselves and the isostructural rhenium(III) chalcogenide clusters [Re(6)S(8)X(6)](4-) (see figure).The hexanuclear tungsten(II) halide clusters and the sulfido-halide clusters of rhenium(III) are subsets of a broad system of 24-electron metal-metal bonded assemblies that share a common structure. Tungsten(II) halide clusters and rhenium(III) sulfide clusters luminesce from triplet excited states upon ultraviolet or visible excitation; emission from both cluster series has been extensively characterized elsewhere. Reported here are density-functional theory studies of the nine permutations of [W(6)X(8)X'(6)](2-) (X, X'=Cl, Br, I). Ground-state properties including geometries, harmonic vibrational frequencies, and orbital energy-level diagrams, have been calculated. Comparison is made to the sulfide clusters of rhenium(III), of which [Re(6)S(8)Cl(6)](4-) is representative. [W(6)X(8)X'(6)](2-) and [Re(6)S(8)Cl(6)](4-) possess disparate electronic structures owing to the greater covalency of the metal-sulfur bond and hence of the [Re(6)S(8)](2+) core. Low-lying virtual orbitals are raised in energy in [Re(6)S(8)Cl(6)](4-) with the result that the LUMO+7 (or LUMO+8 in some cases) of tungsten(II) halide clusters is the LUMO of [Re(6)S(8)Cl(6)](4-) species. An inversion of the HOMO and HOMO-1 between the two cluster series also occurs. Time-dependent density-functional calculations using asymptotically correct functionals do not recapture the experimentally observed periodic trend in [W(6)X(14)](2-) luminescence (E(em) increasing in the order [W(6)Cl(14)](2-) < [W(6)Br(14)](2-) < [W(6)I(14)](2-)), predicting instead that emission energies decrease with incorporation of the heavier halides. This circumstance is either a gross failure of the time-dependent formalism of DFT or it indicates extensive multistate emission in [W(6)X(8)X'(6)](2-) clusters. The inapplicability of isoelectronic analogies between clusters of Group 6 and Group 7 is emphasized.

Cd4As2Br3

PubMed Central

Kars, Mohammed; Roisnel, Thierry; Dorcet, Vincent; Rebbah, Allaoua; Otero-Diáz, L. Carlos

2014-01-01

Single crystals of Cd4As2Br3 (tetra­cadmium biarsenide tri­bromide) were grown by a chemical transport reaction. The structure is isotypic with the members of the cadmium and mercury pnictidohalides family with general formula M 4 A 2 X 3 (M = Cd, Hg; A = P, As, Sb; X = Cl, Br, I) and contains two independent As atoms on special positions with site symmetry -3 and two independent Cd atoms, of which one is on a special position with site symmetry -3. The Cd4As2Br3 structure consists of AsCd4 tetra­hedra sharing vertices with isolated As2Cd6 octa­hedra that contain As–As dumbbells in the centre of the octahedron. The Br atoms are located in the voids of this three-dimensional arrangement and bridge the different polyhedra through Cd⋯Br contacts. PMID:24764933

Biogeochemical cycles at the sulfate-methane transition zone (SMTZ) and geochemical characteristics of the pore fluids offshore southwestern Taiwan

NASA Astrophysics Data System (ADS)

Hu, Ching-Yi; Frank Yang, Tsanyao; Burr, George S.; Chuang, Pei-Chuan; Chen, Hsuan-Wen; Walia, Monika; Chen, Nai-Chen; Huang, Yu-Chun; Lin, Saulwood; Wang, Yunshuen; Chung, San-Hsiung; Huang, Chin-Da; Chen, Cheng-Hong

2017-11-01

In this study, we used pore water dissolved inorganic carbon (DIC), SO42-, Ca2+ and Mg2+ gradients at the sulfate-methane transition zone (SMTZ) to estimate biogeochemical fluxes for cored sediments collected offshore SW Taiwan. Net DIC flux changes (ΔDIC-Prod) were applied to determine the proportion of sulfate consumption by organic matter oxidation (heterotrophic sulfate reduction) and anaerobic oxidation of methane (AOM), and to determine reliable CH4 fluxes at the SMTZ. Our results show that SO42- profiles are mainly controlled by AOM rather than heterotrophic sulfate reduction. Refinement of CH4 flux estimates enhance our understanding of methane abundance from deep carbon reservoirs to the SMTZ. Concentrations of chloride (Cl-), bromide (Br-) and iodide (I-) dissolved in pore water were used to identify potential sources that control fluid compositions and the behavior of dissolved ions. Constant Cl- concentrations throughout ∼30 m sediment suggest no influence of gas hydrates for the compositions within the core. Bromide (Br-) and Iodine (I-) concentrations increase with sediment depth. The I-/Br- ratio appears to reflect organic matter degradation. SO42- concentrations decrease with sediment depth at a constant rate, and sediment depth profiles of Br- and I- concentrations suggests diffusion as the main transport mechanism. Therefore diffusive flux calculations are reasonable. Coring sites with high CH4 fluxes are more common in the accretionary wedge, amongst thrust faults and fractures, than in the passive continental margin offshore southwestern Taiwan. AOM reactions are a major sink for CH4 passing upward through the SMTZ and prevent high methane fluxes in the water column and to the atmosphere.

Understanding the insight into the mechanisms and dynamics of the Cl-initiated oxidation of (CH3)3CC(O)X and the subsequent reactions in the presence of NO and O2 (X = F, Cl, and Br).

PubMed

Bai, Feng-Yang; Lv, Shuang; Ma, Yuan; Liu, Chun-Yu; He, Chun-Fang; Pan, Xiu-Mei

2017-03-01

In this work, the density functional and high-level ab initio theories are adopted to investigate the mechanisms and kinetics of reaction of (CH 3 ) 3 CC(O)X (X = F, Cl, and Br) with atomic chlorine. Rate coefficients for the reactions of chlorine atom with (CH 3 ) 3 CC(O)F (k 1 ), (CH 3 ) 3 CC(O)Cl (k 2 ), and (CH 3 ) 3 CC(O)Br (k 3 ) are calculated using canonical variational transition state theory coupled with small curvature tunneling method over a wide range of temperatures from 250 to 1000 K. The dynamic calculations are performed by the variational transition state theory with the interpolated single-point energies method at the CCSD(T)/aug-cc-pVDZ//B3LYP/6-311++G(d,p) level of theory. Computed rate constant is in good line with the available experimental value. The rate constants for the title reactions are in this order: k 1

The selective activation of a C-F bond with an auxiliary strong Lewis acid: a method to change the activation preference of C-F and C-H bonds.

PubMed

Wang, Lin; Sun, Hongjian; Li, Xiaoyan; Fuhr, Olaf; Fenske, Dieter

2016-11-15

The selective activation of the C-F bonds in substituted (2,6-difluorophenyl)phenylimines (2,6-F 2 H 3 C 6 -(C[double bond, length as m-dash]NH)-n'-R-C 6 H 4 (n' = 2, R = H (1); n' = 2, R = Me (2); n' = 4, R = tBu (3))) by Fe(PMe 3 ) 4 with an auxiliary strong Lewis acid (LiBr, LiI, or ZnCl 2 ) was explored. As a result, iron(ii) halides ((H 5 C 6 -(C[double bond, length as m-dash]NH)-2-FH 3 C 6 )FeX(PMe 3 ) 3 (X = Br (8); Cl (9)) and (n-RH 4 C 6 -(C[double bond, length as m-dash]NH)-2'-FH 3 C 6 )FeX(PMe 3 ) 3 (n = 2, R = Me, X = Br (11); n = 4, R = tBu, X = I (12))) were obtained. Under similar reaction conditions, using LiBF 4 instead of LiBr or ZnCl 2 , the reaction of (2,6-difluorophenyl)phenylimine with Fe(PMe 3 ) 4 afforded an ionic complex [(2,6-F 2 H 3 C 6 -(C[double bond, length as m-dash]NH)-H 4 C 6 )Fe(PMe 3 ) 4 ](BF 4 ) (10) via the activation of a C-H bond. The method of C-F bond activation with an auxiliary strong Lewis acid is appropriate for monofluoroarylmethanimines. Without the Lewis acid, iron(ii) hydrides ((2-RH 4 C 6 -(C[double bond, length as m-dash]NH)-2'-FH 3 C 6 )FeH(PMe 3 ) 3 (R = H (13); Me (14))) were generated from the reactions of Fe(PMe 3 ) 4 with the monofluoroarylmethanimines (2-FH 4 C 6 -(C[double bond, length as m-dash]NH)-2'-RC 6 H 4 (R = H (4); Me (5))); however, in the presence of ZnCl 2 or LiBr, iron(ii) halides ((2-RH 4 C 6 -(C[double bond, length as m-dash]NH)-H 4 C 6 )FeX(PMe 3 ) 3 (R = H, X = Cl (15); R = Me, X = Br (16))) could be obtained through the activation of a C-F bond. Furthermore, a C-F bond activation with good regioselectivity in (pentafluorophenyl)arylmethanimines (F 5 C 6 -(C[double bond, length as m-dash]NH)-2,6-Y 2 C 6 H 3 (Y = F (6); H (7))) could be realized in the presence of ZnCl 2 to produce iron(ii) chlorides ((2,6-Y 2 H 3 C 6 -(C[double bond, length as m-dash]NH)-F 4 C 6 )FeCl(PMe 3 ) 3 (Y = F (17); H (18))). This series of iron(ii) halides could be used to catalyze the hydrosilylation reaction of aldehydes. Due to the stability of iron(ii) halides to high temperature, the reaction mixture was allowed to be heated to 100 °C and the reaction could finish within 0.5 h.

Reaction of atomic bromine with acetylene and loss rate of atmospheric acetylene due to reaction with OH, Cl, O, and Br

NASA Technical Reports Server (NTRS)

Payne, W. A.; Nava, D. F.; Brunning, J.; Stief, L. J.

1986-01-01

The first-order, diffusion, and bimolecular rate constants for the reaction Br + C2H2 yields C2H3Br are evaluated. The rate constants are measured at 210, 248, 298, and 393 K and at pressures between 15-100 torr Ar using flash photolysis combined with time-resolved detection of atomic bromine via Br resonance radiation. It is observed that the reaction is not affected by pressure or temperature and the bimolecular constant = (4.0 + or - 0.8) x 10 to the -15th cu cm/sec with an error of two standard deviations. The C2H2 + Br reaction rates are compared with reactions of C2H2 with Cl, OH, NH2, and H. The loss rates for atmospheric C2H2 for reactions with OH, Cl, O, and Br are calculated as a function of altitude.

Tunable White-Light Emission in Single-Cation-Templated Three-Layered 2D Perovskites (CH3CH2NH3)4Pb3Br10-xClx.

PubMed

Mao, Lingling; Wu, Yilei; Stoumpos, Constantinos C; Traore, Boubacar; Katan, Claudine; Even, Jacky; Wasielewski, Michael R; Kanatzidis, Mercouri G

2017-08-30

Two-dimensional (2D) hybrid halide perovskites come as a family (B) 2 (A) n-1 Pb n X 3n+1 (B and A= cations; X= halide). These perovskites are promising semiconductors for solar cells and optoelectronic applications. Among the fascinating properties of these materials is white-light emission, which has been mostly observed in single-layered 2D lead bromide or chloride systems (n = 1), where the broad emission comes from the transient photoexcited states generated by self-trapped excitons (STEs) from structural distortion. Here we report a multilayered 2D perovskite (n = 3) exhibiting a tunable white-light emission. Ethylammonium (EA + ) can stabilize the 2D perovskite structure in EA 4 Pb 3 Br 10-x Cl x (x = 0, 2, 4, 6, 8, 9.5, and 10) with EA + being both the A and B cations in this system. Because of the larger size of EA, these materials show a high distortion level in their inorganic structures, with EA 4 Pb 3 Cl 10 having a much larger distortion than that of EA 4 Pb 3 Br 10 , which results in broadband white-light emission of EA 4 Pb 3 Cl 10 in contrast to narrow blue emission of EA 4 Pb 3 Br 10 . The average lifetime of the series decreases gradually from the Cl end to the Br end, indicating that the larger distortion also prolongs the lifetime (more STE states). The band gap of EA 4 Pb 3 Br 10-x Cl x ranges from 3.45 eV (x = 10) to 2.75 eV (x = 0), following Vegard's law. First-principles density functional theory calculations (DFT) show that both EA 4 Pb 3 Cl 10 and EA 4 Pb 3 Br 10 are direct band gap semiconductors. The color rendering index (CRI) of the series improves from 66 (EA 4 Pb 3 Cl 10 ) to 83 (EA 4 Pb 3 Br 0.5 Cl 9.5 ), displaying high tunability and versatility of the title compounds.

Halogens in chondritic meteorites and terrestrial accretion

NASA Astrophysics Data System (ADS)

Clay, Patricia L.; Burgess, Ray; Busemann, Henner; Ruzié-Hamilton, Lorraine; Joachim, Bastian; Day, James M. D.; Ballentine, Christopher J.

2017-11-01

Volatile element delivery and retention played a fundamental part in Earth’s formation and subsequent chemical differentiation. The heavy halogens—chlorine (Cl), bromine (Br) and iodine (I)—are key tracers of accretionary processes owing to their high volatility and incompatibility, but have low abundances in most geological and planetary materials. However, noble gas proxy isotopes produced during neutron irradiation provide a high-sensitivity tool for the determination of heavy halogen abundances. Using such isotopes, here we show that Cl, Br and I abundances in carbonaceous, enstatite, Rumuruti and primitive ordinary chondrites are about 6 times, 9 times and 15-37 times lower, respectively, than previously reported and usually accepted estimates. This is independent of the oxidation state or petrological type of the chondrites. The ratios Br/Cl and I/Cl in all studied chondrites show a limited range, indistinguishable from bulk silicate Earth estimates. Our results demonstrate that the halogen depletion of bulk silicate Earth relative to primitive meteorites is consistent with the depletion of lithophile elements of similar volatility. These results for carbonaceous chondrites reveal that late accretion, constrained to a maximum of 0.5 ± 0.2 per cent of Earth’s silicate mass, cannot solely account for present-day terrestrial halogen inventories. It is estimated that 80-90 per cent of heavy halogens are concentrated in Earth’s surface reservoirs and have not undergone the extreme early loss observed in atmosphere-forming elements. Therefore, in addition to late-stage terrestrial accretion of halogens and mantle degassing, which has removed less than half of Earth’s dissolved mantle gases, the efficient extraction of halogen-rich fluids from the solid Earth during the earliest stages of terrestrial differentiation is also required to explain the presence of these heavy halogens at the surface. The hydropilic nature of halogens, whereby they track with water, supports this requirement, and is consistent with volatile-rich or water-rich late-stage terrestrial accretion.

A Confined Fabrication of Perovskite Quantum Dots in Oriented MOF Thin Film.

PubMed

Chen, Zheng; Gu, Zhi-Gang; Fu, Wen-Qiang; Wang, Fei; Zhang, Jian

2016-10-26

Organic-inorganic hybrid lead organohalide perovskites are inexpensive materials for high-efficiency photovoltaic solar cells, optical properties, and superior electrical conductivity. However, the fabrication of their quantum dots (QDs) with uniform ultrasmall particles is still a challenge. Here we use oriented microporous metal-organic framework (MOF) thin film prepared by liquid phase epitaxy approach as a template for CH 3 NH 3 PbI 2 X (X = Cl, Br, and I) perovskite QDs fabrication. By introducing the PbI 2 and CH 3 NH 3 X (MAX) precursors into MOF HKUST-1 (Cu 3 (BTC) 2 , BTC = 1,3,5-benzene tricarboxylate) thin film in a stepwise approach, the resulting perovskite MAPbI 2 X (X = Cl, Br, and I) QDs with uniform diameters of 1.5-2 nm match the pore size of HKUST-1. Furthermore, the photoluminescent properties and stability in the moist air of the perovskite QDs loaded HKUST-1 thin film were studied. This confined fabrication strategy demonstrates that the perovskite QDs loaded MOF thin film will be insensitive to air exposure and offers a novel means of confining the uniform size of the similar perovskite QDs according to the oriented porous MOF materials.

Larger spontaneous polarization ferroelectric inorganic-organic hybrids: [PbI3](infinity) chains directed organic cations aggregation to Kagomé-shaped tubular architecture.

PubMed

Zhao, Hai-Rong; Li, Dong-Ping; Ren, Xiao-Ming; Song, You; Jin, Wan-Qin

2010-01-13

Four isostructural inorganic-organic hybrid ferroelectric compounds, assembled from achiral 3-R-benzylidene-1-aminopyridiniums (R = NO(2), Br, Cl, or F for 1-4, respectively) and [PbI(3)](-) anions with the chiral Kagomé-shaped tubular aggregating architecture, show larger spontaneous polarizations.

Preparation, IR spectroscopy, and time-of-flight mass spectrometry of halogenated and methylated Si(111)

NASA Astrophysics Data System (ADS)

Salingue, Nils; Hess, Peter

2011-09-01

The preparation of chlorine-, bromine-, and iodine-terminated silicon surfaces (Si(111):Cl, Br, and I) using atomically flat Si(111)-(1×1):H is described. The halogenated surfaces were obtained by photochemically induced radical substitution reactions with the corresponding dihalogen in a Schlenk tube by conventional inert gas chemistry. The nucleophilic substitution of the Si-Cl functionality with the Grignard reagent (CH3MgCl) resulted in the unreconstructed methylated Si(111)-(1×1):CH3 surface. The halogenated and methylated silicon surfaces were characterized by Fourier transform infrared (FTIR) spectroscopy and laser-induced desorption of monolayers (LIDOM). Calibration of the desorption temperature via analysis of time-of-flight (TOF) distributions as a function of laser fluence allowed the determination of the originally emitted neutral fragments by TOF mass spectrometry using electron-impact ionization. The halogens were desorbed atomically and as SiX n (X = Cl, Br) clusters. The methyl groups mainly desorbed as methyl and ethyl fragments and a small amount of +SiCH3.

Transformation of methylparaben during water chlorination: Effects of bromide and dissolved organic matter on reaction kinetics and transformation pathways.

PubMed

Yoom, Hoonsik; Shin, Jaedon; Ra, Jiwoon; Son, Heejong; Ryu, Dongchoon; Kim, Changwon; Lee, Yunho

2018-09-01

The reaction kinetics, products, and pathways of methylparaben (MeP) during water chlorination with and without bromide (Br - ) were investigated to better understand the fate of parabens in chlorinated waters. During the chlorination of MeP-spiked waters without Br - , MeP was transformed into mono-Cl-MeP and di-Cl-MeP with apparent second-order rate constants (k app ) of 64M -1 s -1 and 243M -1 s -1 at pH7, respectively, while further chlorination of di-Cl-MeP was relatively slower (k app =1.3M -1 s -1 at pH7). With increasing Br - concentration, brominated MePs, such as mono-Br-MeP, Br-Cl-MeP, and di-Br-MeP, became major transformation products. The di-halogenated MePs (di-Cl-MeP, Br,Cl-MeP, and di-Br-MeP) showed relatively low reactivity to chlorine at pH7 (k app =1.3-4.6M -1 s -1 ) and bromine (k app =32-71M -1 s -1 ), which explains the observed high stability of di-halogenated MePs in chlorinated waters. With increasing pH from 7 to 8.5, the transformation of di-halogenated MePs was further slowed due to the decreasing reactivity of di-MePs to chlorine. The formation of the di-halogenated MePs and their further transformation become considerably faster at Br - concentrations higher than 0.5μM (40μg/L). Nonetheless, the accelerating effect of Br - diminishes in the presence of dissolved organic matter (DOM) extract (Suwannee River humic acid (SRHA)) due to a more rapid consumption of bromine by DOM than chlorine. The effect of Br - on the fate of MeP was less in the tested real water matrices, possibly due to a more rapid bromine consumption by the real water DOM compared to SRHA. A kinetic model was developed based on the determined species-specific second-order rate constants for chlorination/bromination of MeP and its chlorinated and brominated MePs and the transformation pathway information, which could reasonably simulate the transformation of MePs during the chlorination of water in the presence of Br - and selected DOM. Copyright © 2017 Elsevier B.V. All rights reserved.

Spectrophotometric estimation of bromide ion in excess chloride media.

PubMed

Adimurthy, S; Susarla, V R K S; Reddy, M P; Ramachandraiah, G

2005-10-31

The redox reaction between bromate and chloride ions in the presence and the absence of two or less equivalents of bromide ion ascertaining the formation of bromine chloride species of type BrCl and BrCl(2)(-) in subsequent reactions in 4% H(2)SO(4), has been studied by spectrophotometry. Calibration graphs for the bromide ion estimation in 0.1% KBrO(3)-4% H(2)SO(4) medium are determined separately in the presence of known amounts of NaCl. The effect of Cl(-) ion percentage on the determination of Br(-) ion is studied and reported herewith a suitable equation for a precise, reliable and quick spectrophotometric estimation.

Simultaneously promoting charge separation and photoabsorption of BiOX (X = Cl, Br) for efficient visible-light photocatalysis and photosensitization by compositing low-cost biochar

NASA Astrophysics Data System (ADS)

Li, Min; Huang, Hongwei; Yu, Shixin; Tian, Na; Dong, Fan; Du, Xin; Zhang, Yihe

2016-11-01

Exploration of novel and efficient composite photocatalysts is of great significance for advancing the practical application of photocatalysis. BiOX (X = Cl, Br) is a kind of promising photocatalysts, but the charge separation efficiency and photoabsorption need to be ameliorated. In this work, we first employ a low-cost and easily accessable carbon material biochar to modify BiOX (X = Cl, Br) and develop biochar/BiOX (X = Cl, Br) composite photocatalysts via a facile in-situ deposition method. The as-prepared composites are detailedly characterized by SEM, SEM-mapping, TEM, XRD and XPS, and DRS result demonstrates that the visible-light absorption of BiOX (X = Cl, Br) catalysts can be exceedingly enhanced by biochar. The biochar/BiOX (X = Cl, Br) composites are found to unfold remarkably enhanced visible-light-driven photocatalytic activity toward degradation of MO and photocurrent generation. The strengthened photocatalytic performance mainly stems from the profoundly improved charge separation and delivery efficiency, as evidenced by the electrochemical impedance spectra (EIS), photoluminescence (PL), and time-resolved PL decay spectra. Additionally, the biochar exerts importance in enhancing the two different types of photochemical reactions of BiOBr and BiOCl, in which the photocatalytic mechanisms are found to be photocatalysis and photosensitization process, respectively. The present work may open up a new avenue for framing economic and efficient photocatalytic materials and new composite materials for photoelectric application.

Variations in trace metal and halogen ratios in magmatic gases through an eruptive cycle of the Pu'u O'o vent, Kilauea, Hawaii: July-August 1985

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, T.L.; Zoller, W.H.; Crowe, B.M.

1990-08-10

Particle and gas samples were obtained before and after eruptive episode 35 in July and August 1985 at the fuming Pu'u O'o vent, Kilauea volcano, Hawaii. The sampling system employed consisted of a particle filter followed by four {sup 7}LiOH treated filters to collect acidic gases. The filters were analyzed using instrumental neutron activation analysis (INAA). The results indicate that Br/Cl and Re/Cl ratios do not fluctuate through an eruption cycle but the F/Cl, F/Br and metal/Cl ratios (In and Cd) do change through the cycle. An inverse relationship between F/Cl and metal/Cl was observed. The changes are probably duemore » to influxes of relatively undegassed magma during the repose period releasing fume with lower F/Cl, F/BR and higher metal/Cl ratios. As the magma in the Pu'u O'o conduit gradually degasses either before or several days after an eruptive episode, F/Cl and F/Br ratios increase and the metal/Cl ratios decrease. One sample collected on July 24, two days before eruptive episode 35, did not follow this general trend. This can be explained by a gas pulse from a deeper, less degassed portion of magma making its way to the top of the conduit.« less

"Variations in trace metal and halogen ratios in magmatic gases through an eruptive. Cycle of the Pu'u O'o Vent, Kilauea, Hawaii: July-August 1985""

NASA Astrophysics Data System (ADS)

Miller, Theresa L.; Zoller, William H.; Crowe, Bruce M.; Finnegan, David L.

1990-08-01

Particle and gas samples were obtained before and after eruptive episode 35 in July and August 1985 at the fuming Pu'u O'o vent, Kilauea volcano, Hawaii. The sampling system employed consisted of a particle filter followed by four 7LiOH treated filters to collect acidic gases. The filters were analyzed using instrumental neutron activation analysis (INAA). The results indicate that Br/Cl and Re/Cl ratios do not fluctuate through an eruption cycle but the F/Cl, F/Br and metal/Cl ratios (In and Cd) do change through the cycle. An inverse relationship between F/Cl and metal/Cl was observed. The changes are probably due to influxes of relatively undegassed magma during the repose period releasing fume with lower F/Cl, F/Br and higher metal/Cl ratios. As the magma in the Pu'u O'o conduit gradually degasses either before or several days after an eruptive episode, F/Cl and F/Br ratios increase and the metal/Cl ratios decrease. One sample collected on July 24, two days before eruptive episode 35, did not follow this general trend. This can be explained by a gas pulse from a deeper, less degassed portion of magma making its way to the top of the conduit.

The protonated 2-halogenated imidazolium cation as the noncovalent interaction donor: the σ-hole and π-hole interactions.

PubMed

Wang, Jingjing; Mo, Lixin; Li, Xiaoyan; Geng, Zongke; Zeng, Yanli

2016-12-01

The σ-hole and π-hole of the protonated 2-halogenated imidazolium cation (XC 3 H 4 N 2 + ; X = F, Cl, Br, I) were investigated and analyzed. The monomers of (CH 3 ) 3 SiY(Y=F, Cl, Br, I), considered as the Lewis base, were combined with the σ-hole and π-hole of XC 3 H 4 N 2 + to form the σ-hole and π-hole interactions in the bimolecular complexes (CH 3 ) 3 SiY · · · XC 3 H 4 N 2 + and (CH 3 ) 3 SiY · · · C 3 (X)H 4 N 2 + (X/Y=F, Cl, Br, I), respectively. For both the σ-hole and π-hole interactions, the equilibrium geometries of complexes show regular changes according to the sequence of heavy sequence of the noncovalent interaction acceptors and donors. The electrostatic energy is the main contribution in the formation of both kinds of interactions, it has linear relations with the V S,max values of σ-hole and the V' S,max values of π-hole. Both the σ-hole and π-hole interactions belong to the closed-shell and noncovalent interactions. The π-hole interactions are stronger than the σ-hole interactions. For the π-hole interactions, the contribution percents of the dispersion energies are somewhat greater than those of the σ-hole interactions, while it is contrary for the polarization energy. Graphical Abstract The protonated 2-halogenated imidazolium cation as the noncovalent interaction donor: the σ-hole and π-hole interactionsᅟ.

Novel germanetellones: XYGe=Te (X, Y = H, F, Cl, Br, I and CN) - structures and energetics. Comparison with the first synthetic successes.

PubMed

Jaufeerally, Naziah B; Abdallah, Hassan H; Ramasami, Ponnadurai; Schaefer, Henry F

2014-03-14

No stable germanetellone was described until Tbt(Dis)Ge=Te and Tbt(Tip)Ge=Te (Tbt = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl, Dis = bis(trimethylsilyl)methyl and Tip = 2,4,6-triisopropylphenyl) were reported in 1997. Following these initial experiments, there has arisen considerable interest in Ge[double bond, length as m-dash]Te systems. An obvious question is: why have the simple XYGe=Te (X, Y = H, F, Cl, Br, I and CN) molecules not yet been isolated? In view of the present situation, theoretical information may be of great help for further advances in germanetellone chemistry. A systematic investigation of the XYGe=Te molecules is carried out using the second order Møller-Plesset perturbation theory (MP2) and density functional theory (DFT). The structures and energetics, including ionization potentials (IPad and IPad(ZPVE)), four different forms of neutral-anion separations (EAad, EAad(ZPVE), VEA and VDE) and the singlet-triplet gaps, are reported. The electronegativity (χ) reactivity descriptor for the halogens (F, Cl, Br and I) and the natural charge separations of the Ge=Te moiety are used to assess the interrelated properties of germanetellone and its derivatives. The results are analyzed, discussed and compared with analogous studies of telluroformaldehyde, silanetellone and their derivatives. The thermodynamic viabilities of some of the novel germanetellones have also been evaluated in terms of the bond dissociation enthalpies of Tbt(Dis)Ge=Te and Tbt(Tip)Ge=Te. The simple mono-substituted germanetellones appear to be slightly more thermodynamically favored than Tbt(Dis)Ge=Te and Tbt(Tip)Ge=Te, since the bond dissociation enthalpies of these kinetically stabilized germanetellones are about 28 and 51 kcal mol(-1) lower, respectively.

Cl/Br ratios and chlorine isotope evidences for groundwater salinization and its impact on groundwater arsenic, fluoride and iodine enrichment in the Datong basin, China.

PubMed

Li, Junxia; Wang, Yanxin; Xie, Xianjun

2016-02-15

In order to identify the salinization processes and its impact on arsenic, fluoride and iodine enrichment in groundwater, hydrogeochemical and environmental isotope studies have been conducted on groundwater from the Datong basin, China. The total dissolved solid (TDS) concentrations in groundwater ranged from 451 to 8250 mg/L, and 41% of all samples were identified as moderately saline groundwater with TDS of 3000-10,000 mg/L. The results of groundwater Cl concentrations, Cl/Br molar ratio and Cl isotope composition suggest that three processes including water-rock interaction, surface saline soil flushing, and evapotranspiration result in the groundwater salinization in the study area. The relatively higher Cl/Br molar ratio in groundwater from multiple screening wells indicates the contribution of halite dissolution from saline soil flushed by vertical infiltration to the groundwater salinization. However, the results of groundwater Cl/Br molar ratio model indicate that the effect of saline soil flushing practice is limited to account for the observed salinity variation in groundwater. The plots of groundwater Cl vs. Cl/Br molar ratio, and Cl vs δ(37)Cl perform the dominant effects of evapotranspiration on groundwater salinization. Inverse geochemical modeling results show that evapotranspiration may cause approximately 66% loss of shallow groundwater to account for the observed hydrochemical pattern. Due to the redox condition fluctuation induced by irrigation activities and evapotranspiration, groundwater salinization processes have negative effects on groundwater arsenic enrichment. For groundwater iodine and fluoride enrichment, evapotranspiration partly accounts for their elevation in slightly saline water. However, too strong evapotranspiration would restrict groundwater fluoride concentration due to the limitation of fluorite solubility. Copyright © 2015. Published by Elsevier B.V.

The absorption, fluorescence and phosphorescence spectra of α and β-F, Cl, Br-naphthalenes in crystalline matrixes at 77 K

NASA Astrophysics Data System (ADS)

Iliescu, T.; Milea, I.; Abdolrahman, P. M.

1984-03-01

The paper studies the absorption, fluorescence and phosphorescence spectra of α and β-F, Cl, Br-naphtalenes (α, β-F, Cl,BrN) in different matrixes at 77 K and different concentrations. From these spectra one obtaines the vibrational frequences.

Using Perovskite Nanoparticles as Halide Reservoirs in Catalysis and as Spectrochemical Probes of Ions in Solution

DOE PAGES

Doane, Tennyson L.; Ryan, Kayla L.; Pathade, Laxmikant; ...

2016-05-05

The ability of cesium lead halide (CsPbX 3; X = Cl –, Br –, I –) perovskite nanoparticles (P-NPs) to participate in halide exchange reactions, to catalyze Finkelstein organohalide substitution reactions, and to colorimetrically monitor chemical reactions and detect anions in real time is described. With the use of tetraoctylammonium halide salts as a starting point, halide exchange with the P-NPs was performed to calibrate reactivity, stability, and extent of ion exchange. Also, the exchange of CsPbI 3 with Cl – or Br – causes a significant blue-shift in absorption and photoluminescence, whereas reacting I – with CsPbBr 3 causesmore » a red-shift of similar magnitudes. With the high local halide concentrations and the facile nature of halide exchange in mind, we then explored the ability of P-NPs to catalyze organohalide exchange in Finkelstein like reactions. Results indicate that the P-NPs serve as excellent halide reservoirs for substitution of organohalides in nonpolar media, leading to not only different organohalide products, but also a complementary color change over the course of the reaction, which can be used to monitor kinetics in a precise manner. Finally, the merits of using P-NP as spectrochemical probes for real time assaying is then expanded to other anions which can react with, or result in unique, classes of perovskites.« less

Three-Dimensional BiOI/BiOX (X = Cl or Br) Nanohybrids for Enhanced Visible-Light Photocatalytic Activity

PubMed Central

Liu, Yazi; Xu, Jian; Wang, Liqiong; Zhang, Huayang; Xu, Ping; Duan, Xiaoguang; Sun, Hongqi; Wang, Shaobin

2017-01-01

Three-dimensional flower-like BiOI/BiOX (X = Br or Cl) hybrids were synthesized via a facile one-pot solvothermal approach. With systematic characterizations by X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission electron microscopy (TEM), the Brunauer-Emmett-Teller (BET)specific surface area, X-ray photoelectron spectroscopy (XPS), and the UV-Vis diffuse reflectance spectra (DRS), the BiOI/BiOCl composites showed a fluffy and porous 3-D architecture with a large specific surface area (SSA) and high capability for light absorption. Among all the BiOX (X = Cl, Br, I) and BiOI/BiOX (X = Cl or Br) composites, BiOI/BiOCl stands out as the most efficient photocatalyst under both visible and UV light irradiations for methyl orange (MO) oxidation. The reaction rate of MO degradation on BiOI/BiOCl was 2.1 times higher than that on pure BiOI under visible light. Moreover, BiOI/BiOCl exhibited enhanced water oxidation efficiency for O2 evolution which was 1.5 times higher than BiOI. The enhancement of photocatalytic activity could be attributed to the formation of a heterojunction between BiOI and BiOCl, with a nanoporous structure, a larger SSA, and a stronger light absorbance capacity especially in the visible-light region. The in situ electron paramagnetic resonance (EPR) revealed that BiOI/BiOCl composites could effectively evolve superoxide radicals and hydroxyl radicals for photodegradation, and the superoxide radicals are the dominant reactive species. The superb photocatalytic activity of BiOI/BiOCl could be utilized for the degradation of various industrial dyes under natural sunlight irradiation which is of high significance for the remediation of industrial wastewater in the future. PMID:28336897

Phase diagram of pressure-induced superconductor β-(BDA-TTP)2MX4 (M=Fe, Ga and X=Cl, Br) with localized magnetic moments

NASA Astrophysics Data System (ADS)

Choi, E. S.; Graf, D.; Tokumoto, T.; Brooks, J. S.; Yamada, Jun-Ichi

2007-03-01

We have investigated transport and magnetization properties of β-(BDA-TTP)2MX4 (M=Fe, Ga and X=Cl, Br) as a function of pressure, temperature and magnetic field. The title material undergoes metal-insulator transitions above 100 K at ambient pressure. The insulating phase is suppressed with pressure and superconductivity eventually appears above Pc= 4.5 kbar (X=Cl) and 13 kbar (X=Br). The general temperature-pressure (TP) phase diagram is similar each other, while higher pressure is required for X=Br compounds to suppress the insulating state and induce the superconductivity. Pressure dependent DC magnetization studies on β-(BDA-TTP)2FeCl4 compound revealed that the AFM ordering persist well above Pc. In spite of similarity of phase diagram between M=Fe and M=Ga compounds, magnetoresistance results show distinct behaviors, which indicates the magnetic interaction with the conduction electrons are still effective. The comparison between X=Cl and X=Br compounds suggests the anion-size effect rather than the existence of localized magnetic moments plays more important role in determining the ground state.

Enhanced ozone loss by active inorganic bromine chemistry in the tropical troposphere

NASA Astrophysics Data System (ADS)

Le Breton, Michael; Bannan, Thomas J.; Shallcross, Dudley E.; Khan, M. Anwar; Evans, Mathew J.; Lee, James; Lidster, Richard; Andrews, Stephen; Carpenter, Lucy J.; Schmidt, Johan; Jacob, Daniel; Harris, Neil R. P.; Bauguitte, Stephane; Gallagher, Martin; Bacak, Asan; Leather, Kimberley E.; Percival, Carl J.

2017-04-01

Bromine chemistry, particularly in the tropics, has been suggested to play an important role in tropospheric ozone loss although a lack of measurements of active bromine species impedes a quantitative understanding of its impacts. Recent modelling and measurements of bromine monoxide (BrO) by Wang et al. (2015) have shown current models under predict BrO concentrations over the Pacific Ocean and allude to a missing source of BrO. Here, we present the first simultaneous aircraft measurements of atmospheric bromine monoxide, BrO (a radical that along with atomic Br catalytically destroys ozone) and the inorganic Br precursor compounds HOBr, BrCl and Br2 over the Western Pacific Ocean from 0.5 to 7 km. The presence of 0.17-1.64 pptv BrO and 3.6-8 pptv total inorganic Br from these four species throughout the troposphere causes 10-20% of total ozone loss, and confirms the importance of bromine chemistry in the tropical troposphere; contributing to a 6 ppb decrease in ozone levels due to halogen chemistry. Observations are compared with a global chemical transport model and find that the observed high levels of BrO, BrCl and HOBr can be reconciled by active multiphase oxidation of halide (Br- and Cl-) by HOBr and ozone in cloud droplets and aerosols. Measurements indicate that 99% of the instantaneous free Br in the troposphere up to 8 km originates from inorganic halogen photolysis rather than from photolysis of organobromine species.

Importance of halogen···halogen contacts for the structural and magnetic properties of CuX2(pyrazine-N,N′-dioxide)(H2O)2 (X = Cl and Br).

PubMed

Schlueter, John A; Park, Hyunsoo; Halder, Gregory J; Armand, William R; Dunmars, Cortney; Chapman, Karena W; Manson, Jamie L; Singleton, John; McDonald, Ross; Plonczak, Alex; Kang, Jinhee; Lee, Chaghoon; Whangbo, Myung-Hwan; Lancaster, Tom; Steele, Andrew J; Franke, Isabel; Wright, Jack D; Blundell, Stephen J; Pratt, Francis L; deGeorge, Joseph; Turnbull, Mark M; Landee, Christopher P

2012-02-20

The structural and magnetic properties of the newly crystallized CuX(2)(pyzO)(H(2)O)(2) (X = Cl, Br; pyzO = pyrazine-N,N'-dioxide) coordination polymers are reported. These isostructural compounds crystallize in the monoclinic space group C2/c with, at 150 K, a = 17.0515(7) Å, b = 5.5560(2) Å, c = 10.4254(5) Å, β = 115.400(2)°, and V = 892.21(7) Å(3) for X = Cl and a = 17.3457(8) Å, b = 5.6766(3) Å, c = 10.6979(5) Å, β = 115.593(2)°, and V = 950.01(8) Å(3) for X = Br. Their crystal structure is characterized by one-dimensional chains of Cu(2+) ions linked through bidentate pyzO ligands. These chains are joined together through OH···O hydrogen bonds between the water ligands and pyzO oxygen atoms and Cu-X···X-Cu contacts. Bulk magnetic susceptibility measurements at ambient pressure show a broad maximum at 7 (Cl) and 28 K (Br) that is indicative of short-range magnetic correlations. The dominant spin exchange is the Cu-X···X-Cu supersuperexchange because the magnetic orbital of the Cu(2+) ion is contained in the CuX(2)(H(2)O)(2) plane and the X···X contact distances are short. The magnetic data were fitted to a Heisenberg 1D uniform antiferromagnetic chain model with J(1D)/k(B) = -11.1(1) (Cl) and -45.9(1) K (Br). Magnetization saturates at fields of 16.1(3) (Cl) and 66.7(5) T (Br), from which J(1D) is determined to be -11.5(2) (Cl) and -46.4(5) K (Br). For the Br analog the pressure dependence of the magnetic susceptibility indicates a gradual increase in the magnitude of J(1D)/k(B) up to -51.2 K at 0.84 GPa, suggesting a shortening of the Br···Br contact distance under pressure. At higher pressure X-ray powder diffraction data indicates a structural phase transition at ∼3.5 GPa. Muon-spin relaxation measurements indicate that CuCl(2)(pyzO)(H(2)O)(2) is magnetically ordered with T(N) = 1.06(1) K, while the signature for long-range magnetic order in CuBr(2)(pyzO)(H(2)O)(2) was much less definitive down to 0.26 K. The results for the CuX(2)(pyzO)(H(2)O)(2) complexes are compared to the related CuX(2)(pyrazine) materials.

Crystal engineering of versatile Hg(II) halides complexes of N,N,N‧,N‧-tetraalkyl substituted 3,5 pyridinedicarboxamides

NASA Astrophysics Data System (ADS)

Rana, Love Karan; Sharma, Sanyog; Hundal, Geeta

2018-02-01

Two new ligands N,N,N‧,N‧-tetraisopropyl/butyl-3,5-pyridinedicarboxamide (L3-L4) and six of their Hg(II)X2 complexes (where X = Cl-, Br- and I-), have been synthesized and characterized using single crystal X-ray diffraction and spectroscopic techniques. Complexes of L3 (1-3) with HgCl2/Br2/I2, have dimeric structure, with the ligand behaving as a 2-C linker. Complexes 4-6 are 1D coordination polymers with either 3- or 2-C, L4 linker and bridging halides. A delicate balance of anion, solvent, denticity and conformation of the ligands on the ensuing molecular and crystal structures has been delineated. Various non-covalent interactions, extending the dimensionality of the complexes are calculated, analyzed and discussed. A significant role of semi-localized LP···π non-covalent interactions in stabilizing the basic dimeric unit in the complexes, has been discerned.

Tailoring Oxygen Sensitivity with Halide Substitution in Difluoroboron Dibenzoylmethane Polylactide Materials

PubMed Central

DeRosa, Christopher A.; Kerr, Caroline; Fan, Ziyi; Kolpaczynska, Milena; Mathew, Alexander S.; Evans, Ruffin E.; Zhang, Guoqing; Fraser, Cassandra L.

2015-01-01

The dual-emissive properties of solid-state difluoroboron β-diketonate-poly(lactic acid) (BF2bdkPLA) materials have been utilized for biological oxygen sensing. In this work, BF2dbm(X)PLA materials were synthesized, where X = H, F, Cl, Br, and I. The effects of changing the halide substituent and PLA polymer chain length on the optical properties in dilute CH2Cl2 solutions and solid-state polymer films were studied. These luminescent materials show fluorescence, phosphorescence, and lifetime tunability on the basis of molecular weight, as well as lifetime modulation via the halide substituent. Short BF2dbm(Br)PLA (6.0 kDa) and both short and long BF2dbm(I)PLA polymers (6.0 or 20.3 kDa) have fluorescence and intense phosphorescence ideal for ratiometric oxygen sensing. The lighter halide-dye polymers with hydrogen, fluorine, and chlorine substitution have longer phosphorescence lifetimes and can be utilized as ultrasensitive oxygen sensors. Photostability was also analyzed for the polymer films. PMID:26480236

Theoretical study on the identity ion pair SN2 reactions of LiX with CH3SX (X=Cl, Br, and I): structure, mechanism, and potential energy surface.

PubMed

Ren, Yi; Gai, Jing-Gang; Xiong, Yan; Lee, Kuo-Hsing; Chu, San-Yan

2007-07-26

Three archetypal ion pair nucleophilic substitution reactions at the methylsulfenyl sulfur atom LiX+CH3SX-->XSCH3+LiX (X=Cl, Br, and I) are investigated by the modified Gaussian-2 theory. Including lithium cation in the anionic models makes the ion pair reactions proceed along an SN2 mechanism, contrary to the addition-elimination pathway occurring in the corresponding anionic nucleophilic substitution reactions X-+CH3SX-->XSCH3+X-. Two reaction pathways for the ion pair SN2 reactions at sulfur, inversion and retention, are proposed. Results indicate the inversion pathway is favorable for all the halogens. Comparison of the transition structures and energetics for the ion pair SN2 at sulfur with the potential competition ion pair SN2 reactions at carbon LiX+CH3SX-->XCH3+LiXS shows that the SN2 reactions at carbon are not favorable from the viewpoints of kinetics and thermodynamics.

Excimer Laser Research.

DTIC Science & Technology

1975-08-01

and sample cylinder were repeatedly allowed to outgas at room temperature (under vacuum but valved off) and then cooled with liquid N_ snd pumped...i i I i | I I I I i I i i i | I I i i i i i l i | I l I I I 320 330 340 350 360 E7470 WAVELENGTH (nm) 2 2 Fig. 9 Densitometer Trace of XeF...2, Xs are within 10%. eFor Arl, Nel, NeBr, NeCl, and the helium halides the inert-gas ionization potential is so large that the Coulomb curve does

Chloride and bromide sources in water: Quantitative model use and uncertainty

NASA Astrophysics Data System (ADS)

Horner, Kyle N.; Short, Michael A.; McPhail, D. C.

2017-06-01

Dissolved chloride is a commonly used geochemical tracer in hydrological studies. Assumptions underlying many chloride-based tracer methods do not hold where processes such as halide-bearing mineral dissolution, fluid mixing, or diffusion modify dissolved Cl- concentrations. Failure to identify, quantify, or correct such processes can introduce significant uncertainty to chloride-based tracer calculations. Mass balance or isotopic techniques offer a means to address this uncertainty, however, concurrent evaporation or transpiration can complicate corrections. In this study Cl/Br ratios are used to derive equations that can be used to correct a solution's total dissolved Cl- and Br- concentration for inputs from mineral dissolution and/or binary mixing. We demonstrate the equations' applicability to waters modified by evapotranspiration. The equations can be used to quickly determine the maximum proportion of dissolved Cl- and Br- from each end-member, providing no halide-bearing minerals have precipitated and the Cl/Br ratio of each end member is known. This allows rapid evaluation of halite dissolution or binary mixing contributions to total dissolved Cl- and Br-. Equation sensitivity to heterogeneity and analytical uncertainty is demonstrated through bench-top experiments simulating halite dissolution and variable degrees of evapotranspiration, as commonly occur in arid environments. The predictions agree with the experimental results to within 6% and typically much less, with the sensitivity of the predicted results varying as a function of end-member compositions and analytical uncertainty. Finally, we present a case-study illustrating how the equations presented here can be used to quantify Cl- and Br- sources and sinks in surface water and groundwater and how the equations can be applied to constrain uncertainty in chloride-based tracer calculations.

Greatly enhanced flux pinning properties of fluorine-free metal-organic decomposition YBCO films by co-addition of halogens (Cl, Br) and metals (Zr, Sn, Hf)

NASA Astrophysics Data System (ADS)

Motoki, Takanori; Ikeda, Shuhei; Nakamura, Shin-ichi; Honda, Genki; Nagaishi, Tatsuoki; Doi, Toshiya; Shimoyama, Jun-ichi

2018-04-01

Additive-free YBCO films, as well as those with halogen (X) added, metal (M) added and (X, M) co-added, have been prepared by the fluorine-free metal-organic decomposition method on SrTiO3(100) single crystalline substrates, where X = Cl, Br and M = Zr, Sn, Hf. It was revealed that the addition of both Cl and Br to the starting solution resulted in the generation of oxyhalide, Ba2Cu3O4 X 2, in the YBCO films, and that the oxyhalide was found to promote the bi-axial orientation of the YBCO crystals. By adding a decent amount of Cl or Br, highly textured YBCO films with high J c were reproducibly obtained, even when an impurity metal, M, was co-added, while the addition of M without X did not greatly improve J c owing to the poor bi-axial orientation of the YBCO crystals. Our results suggest that the addition of Br more effectively enhances J c than the addition of Cl. The pinning force density at 40 K in 4.8 T reached ˜55 GN m-3 with the co-addition of (Br, M). This value is much larger than that of the pure YBCO film, reaching ˜17 GN m-3.

Matrix isolation infrared spectra of hydrogen halide and halogen complexes with nitrosyl halides

NASA Technical Reports Server (NTRS)

Allamandola, Louis J.; Lucas, Donald; Pimentel, George C.

1982-01-01

Matrix isolation infrared spectra of nitrosyl halide (XNO) complexes with HX and X2 (X = Cl, Br) are presented. The relative frequency shifts of the HX mode are modest (ClNO H-Cl, delta-nu/nu = -0.045; BrNO H-Br, delta-nu/nu = -0.026), indicating weak hydrogen bonds 1-3 kcal/mol. These shifts are accompanied by significant shifts to higher frequencies in the XN-O stretching mode (CIN-O HCl, delta-nu/nu = +0.016; BrN-O HBr, delta-nu/nu = +0.011). Similar shifts were observed for the XN-O X2 complexes (ClN-O Cl2, delta-nu/nu = +0.009; BrN-O-Br2, delta-nu/nu = +0.013). In all four complexes, the X-NO stretching mode relative shift is opposite in sign and about 1.6 times that of the NO stretching mode. These four complexes are considered to be similar in structure and charge distribution. The XN-O frequency shift suggests that complex formation is accompanied by charge withdrawal from the NO bond ranging from about .04 to .07 electron charges. The HX and X2 molecules act as electron acceptors, drawing electrons out of the antibonding orbital of NO and strengthening the XN-O bond. The implications of the pattern of vibrational shifts concerning the structure of the complexes are discussed.

Nonequilibrium Effects in Ion and Electron Transport

DTIC Science & Technology

1990-11-01

GaAs, Si oxide, Si nitride , metals) CF4, CxFy, SF6, SF 4, NF3, CClxFy, Cl2, CC14, BC13, HC1, PC 3, SiCl4, H2, 02, CF3H, Br2, CBrxFy, Rare gases, plus...numerous stable and intermediate product species Deposition Gases (For Si, Si oxides, Ti oxides, Si,B nitride , metals) SiH4, 5i2H6, TEOS, 02, N20, C02...I. C. Walker, and K. J. Mathieson, 1988, J. Phys. D 21, 1271. Davies, D. K., August 1982, "Measurements of swarm parameters in chlorine -bearing

Facile formation of Ag{sub 2}WO{sub 4}/AgX (X = Cl, Br, I) hybrid nanorods with enhanced visible-light-driven photoelectrochemical properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Jingjing; Yu, Caiyun; Zheng, Changcheng

2015-01-15

Highlights: • Ag{sub 2}WO{sub 4}/AgX hybrid nanorods were prepared by a facile in-situ anion exchange reaction. • Ag{sub 2}WO{sub 4} nanorods and different X{sup −} ions were reacted in water at room temperature. • The hybrids possess significantly enhanced photoelectrochemical properties. • Ag{sub 2}WO{sub 4}/AgBr hybrids exhibit the highest photocatalytic activity among three samples. • The active species tests were also investigated to confirm photocatalytic mechanism. - Abstract: In this work, we demonstrated a general strategy for the preparation of a series of uniform Ag{sub 2}WO{sub 4}/AgX (X = Cl, Br, I) hybrid nanorods by a facile in-situ anion exchangemore » reaction occurring at room temperature between pregrown Ag{sub 2}WO{sub 4} nanorods and different X{sup −} ions in water. Compared with Ag{sub 2}WO{sub 4} nanorods, further investigation has revealed that the as-prepared hybrid nanorods possess significantly enhanced photocurrent response and photocatalytic activity in degrading methyl orange (MO) under visible-light irradiation. In particular, the Ag{sub 2}WO{sub 4}/AgBr hybrid nanorods exhibit the highest photocatalytic activity among the three kinds of samples. The active species tests indicate that superoxide anion radicals and photogenerated holes are responsible for the enhanced photocatalytic performance.« less

Long-chain alkylimidazolium ionic liquids, a new class of cationic surfactants coated on ODS columns for anion-exchange chromatography.

PubMed

Qiu, Hongdeng; Zhang, Qinghua; Chen, Limei; Liu, Xia; Jiang, Shengxiang

2008-08-01

Separations of common inorganic anions were carried out on ODS columns coated with two long-chain alkylimidazolium ionic liquids ([C(12)MIm]Br and [C(14)MIm]Br) as new cationic surfactants for ion chromatography. With phthalate buffer solution as the mobile phases and non-suppressed conductivity detection, high column efficiencies and excellent selectivity were obtained in the separation of inorganic anions. Chromatographic parameters are calculated and the results show that the coated column possesses significant potential for the analysis of some inorganic anions such as CH(3)COO(-), IO(3)(-), Cl(-), BrO(3)(-), NO(2)(-), Br(-), NO(3)(-), SO(4)(2-), I(-), BF(4)(-), and SCN(-). The effect of eluent pH values on the separation of anions has been studied on the column coated with [C(12)MIm]Br. The stability of the coated columns was also examined.

Cultural adaptation and the Clavien-Dindo surgical complications classification translated to Brazilian Portuguese.

PubMed

Moreira, Luis Fernando; Pessôa, Marcelo Castro Marçal; Mattana, Diego Sachet; Schmitz, Fernando Fernandes; Volkweis, Bernardo Silveira; Antoniazzi, Jorge Luiz; Ribeiro, Liacyr

2016-01-01

to generate a translated and validated version of the Clavien-Dindo Classification of Surgical Complications (CDC) to Brazilian Portuguese (CDC-BR). the process of translation and adaptation followed the guideline of Beaton et al., 2000. We divided 76 participating surgeons, in different levels of experience, from the Department Surgery of the Hospital de Clínicas de Porto Alegre, into two groups: Group I applied the original version (CDC, n=36);r Group II used the modified version (CDC-BR, n=40). Each group classified 15 clinical cases of surgical complications. We compared performance between the groups (Mann-Whitney test) relating to the level of experience of the surgeon (Kruskal-Wallis test), considering p value <0.05 as significant. the performance of the Group II (CDC-BR) was higher, with 85% accuracy, compared with 79% of Group I (CDC), p-value =0.012. The performance of the groups as for surgeons experience displayed p=0.171 for Group I, p=0.528 for Group II, and p=0.135 for overall performance. we produced a translated and validated version of the CDC for Brazilian Portuguese. The instrument will be a useful tool in the production of evidence on surgical outcomes. gerar uma versão traduzida e validada da Classificação de Complicações Cirúrgicas de Clavien-Dindo (CCD) para o Português-Brasileiro (CCD-BR). o processo de tradução e adaptação seguiu a diretriz de Beaton et al., de 2000. Formaram-se dois grupos, Grupo I, que utilizou a versão original (CCD, n=36) testado em relação ao Grupo II, com a versão modificada (CCD-BR, n=40), com um total de 76 cirurgiões participantes em níveis de experiência distintos do Departamento de Cirurgia do Hospital de Clínicas de Porto Alegre. Quinze casos clínicos de complicações cirúrgicas foram classificados em cada grupo. Comparou-se o desempenho entre grupos (teste de Mann-Whitney) relacionando ao nível de experiência dos cirurgiões (teste de Kruskal-Wallis). Valor de p<0,05 como significativo. o desempenho do Grupo II (CCD-BR) foi superior, com 85% de acertos, contra 79% do Grupo I (CCD), p-valor=0,012 do teste de Mann-Whitney. O desempenho dos grupos em relação à experiência dos cirurgiões foi p-valor=0,171 para o Grupo I, p-valor=0,528 para o Grupo II, e p-valor=0,135 para o desempenho geral, teste de Kruskal-Wallis. foi produzida uma versão traduzida e validada da CCD para o Português-Brasileiro. O instrumento produzido será ferramenta útil na produção de evidências sobre os resultados cirúrgicos.

The chlorine abundance of Earth: Implications for a habitable planet

NASA Astrophysics Data System (ADS)

Sharp, Z. D.; Draper, D. S.

2013-05-01

The Cl, Br and I contents of Earth are depleted by a factor of 10 relative to predicted values from chondritic and solar abundances. Possible explanations for the apparent discrepancy include (1) unrecognized sequestration of Cl in the core, (2) a much higher nebular volatility than normally presumed or (3) a preferential loss of the heavy halogens during planetary accretion. We tested the first assumption by conducting high pressure-temperature equilibration experiments between silicate and metal. At 15 GPa and 1900 °C, the DCl(metal-silicate) value for Cl is less than 0.007, indicating that the core is not a significant reservoir for Cl. The concentration of Cl in all chondritic classes follows a depletion trend very similar to that of Na and Mn, arguing against a low condensation temperature for Cl. Instead, we propose that the depletion of the heavy halogens is due to their unique hydrophilic behavior. Almost half of Earth's Cl and Br inventory resides in the ocean and evaporites, demonstrating the unique affinity for aqueous solutions for these elements. During planetary accretion, there would have been a strong sequestration of halogens into the crustal reservoir. 'Collisional erosion' during planetary accretion provides a mechanism that would uniquely strip the heavy halogens out of an accreting Earth. Had such loss not occurred, the salinity of the oceans would be 10× the present value, and complex life would probably never have evolved.

Thermodynamic Study of Solid-Liquid Equilibrium in NaCl-NaBr-H2O System at 288.15 K

NASA Astrophysics Data System (ADS)

Li, Dan; Meng, Ling-zong; Deng, Tian-long; Guo, Ya-fei; Fu, Qing-Tao

2018-06-01

The solubility data, composition of the solid solution and refractive indices of the NaCl-NaBr-H2O system at 288.15 K were studied with the isothermal equilibrium dissolution method. The solubility diagram and refractive index diagram of this system were plotted at 288.15 K. The solubility diagram consists of two crystallization zones for solid solution Na(Cl,Br) · 2H2O and Na(Cl,Br), one invariant points cosaturated with two solid solution and two univariant solubility isothermal curves. On the basis of Pitzer and Harvie-Weare (HW) chemical models, the composition equations and solubility equilibrium constant equations of the solid solutions at 288.15 K were acquired using the solubility data, the composition of solid solutions, and binary Pitzer parameters. The solubilities calculated using the new method combining the equations are in good agreement with the experimental data.

Computational design of bio-inspired carnosine-based HOBr antioxidants

NASA Astrophysics Data System (ADS)

Sarrami, Farzaneh; Yu, Li-Juan; Karton, Amir

2017-10-01

During a respiratory burst the enzyme myeloperoxidase generates significant amounts of hypohalous acids (HOX, X = Cl and Br) in order to inflict oxidative damage upon invading pathogens. However, excessive production of these potent oxidants is associated with numerous inflammatory diseases. It has been suggested that the endogenous antioxidant carnosine is an effective HOCl scavenger. Recent computational and experimental studies suggested that an intramolecular Cl+ transfer from the imidazole ring to the terminal amine might play an important role in the antioxidant activity of carnosine. Based on high-level ab initio calculations, we propose a similar reaction mechanism for the intramolecular Br+ transfer in carnosine. These results suggest that carnosine may be an effective HOBr scavenger. On the basis of the proposed reaction mechanism, we proceed to design systems that share similar structural features to carnosine but with enhanced HOX scavenging capabilities for X = Cl and Br. We find that (i) elongating the β-alanyl-glycyl side chain by one carbon reduces the reaction barriers by up to 44%, and (ii) substituting the imidazole ring with strong electron-donating groups reduces the reaction barriers by similar amounts. We also show that the above structural and electronic effects are largely additive. In an antioxidant candidate that involves both of these effects the reaction barriers are reduced by 71%.

A comparative study via Monte Carlo simulation of new inorganic scintillator Cs2HfCl6 for applications in nuclear medicine, security and defense, and astrophysics

NASA Astrophysics Data System (ADS)

Chen, Henry; Raby, Paul

2016-09-01

Cs2HfCl6 (CHC) is one of the most promising recently discovered new inorganic single crystal scintillator that has high light output, non-hygroscopic, no self-activity, having energy resolution significantly better than NaI(Tl), even approaching that of LaBr3 yet can also potentially be at a much lower cost than LaBr3. This study attempts to use Monte Carlo simulation to examine the great potential offered by this new scintillator. CHC's detector performance is compared via simulation with that of 4 typical existing scintillators of the same size and same PMT readout. Two halide-scintillators: NaI(Tl) and LaBr3 and two oxide-scintillators: GSO and LSO were used in this simulation to compare their 122 keV and 511 keV gamma responses with that of CHC with both spectroscopy application and imaging applications in mind. Initial simulation results are very promising and consistent with reported experimental measurements. Beside detector energy resolution, image-quality measurement parameters commonly used to characterize imaging detectors as in nuclear medicine such as Light Response Function (LRF) which goes in parallel with spatial resolution and simulated position spectra will also be presented and discussed.

Synthesis of Cesium Lead Halide Perovskite Nanocrystals in a Droplet-Based Microfluidic Platform: Fast Parametric Space Mapping.

PubMed

Lignos, Ioannis; Stavrakis, Stavros; Nedelcu, Georgian; Protesescu, Loredana; deMello, Andrew J; Kovalenko, Maksym V

2016-03-09

Prior to this work, fully inorganic nanocrystals of cesium lead halide perovskite (CsPbX3, X = Br, I, Cl and Cl/Br and Br/I mixed halide systems), exhibiting bright and tunable photoluminescence, have been synthesized using conventional batch (flask-based) reactions. Unfortunately, our understanding of the parameters governing the formation of these nanocrystals is still very limited due to extremely fast reaction kinetics and multiple variables involved in ion-metathesis-based synthesis of such multinary halide systems. Herein, we report the use of a droplet-based microfluidic platform for the synthesis of CsPbX3 nanocrystals. The combination of online photoluminescence and absorption measurements and the fast mixing of reagents within such a platform allows the rigorous and rapid mapping of the reaction parameters, including molar ratios of Cs, Pb, and halide precursors, reaction temperatures, and reaction times. This translates into enormous savings in reagent usage and screening times when compared to analogous batch synthetic approaches. The early-stage insight into the mechanism of nucleation of metal halide nanocrystals suggests similarities with multinary metal chalcogenide systems, albeit with much faster reaction kinetics in the case of halides. Furthermore, we show that microfluidics-optimized synthesis parameters are also directly transferrable to the conventional flask-based reaction.

Coordination trends in alkali metal crown ether uranyl halide complexes: the series [A(crown)]2[UO(2)X(4)] where A=Li, Na, K and X=Cl, Br.

PubMed

Danis, J A; Lin, M R; Scott, B L; Eichhorn, B W; Runde, W H

2001-07-02

UO(2)(C(2)H(3)O(2))(2).2H(2)O reacts with AX or A(C(2)H(3)O(2) or ClO(4)) (where A = Li, Na, K; X = Cl, Br) and crown ethers in HCl or HBr aqueous solutions to give the sandwich-type compounds [K(18-crown-6)](2)[UO(2)Cl(4)] (1), [K(18-crown-6)](2)[UO(2)Br(4)] (2), [Na(15-crown-5)](2)[UO(2)Cl(4)] (3), [Na(15-crown-5)](2)[UO(2)Br(4)] (4), [Li(12-crown-4)](2)[UO(2)Cl(4)] (5), and [Li(12-crown-4)](2)[UO(2)Br(4)] (6). The compounds have been characterized by single-crystal X-ray diffraction, powder diffraction, elemental analysis, IR, and Raman spectroscopy. The [UO(2)X(4)](2-) ions coordinate to two [A(crown)](+) cations through the four halides only (2), through two halides only (3), through the two uranyl oxygens and two halides (3, 4), or through the two uranyl oxygen atoms only (5, 6). Raman spectra reveal nu(U-O) values that correlate with expected trends. The structural trends are discussed within the context of classical principles of hard-soft acid-base theory.

Synthesis, structural and optical characterization of APbX{sub 3} (A=methylammonium, dimethylammonium, trimethylammonium; X=I, Br, Cl) hybrid organic-inorganic materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mancini, Alessandro; Quadrelli, Paolo; Amoroso, Giuseppe

2016-08-15

In this paper we report the synthesis, the crystal structure and the optical response of APbX{sub 3} (A=MA, DMA, and TMA; X=I, Br) hybrid organic-inorganic materials including some new phases. We observe that as the cation group increases in size, the optical absorption edge shifts to higher energies with energy steps which are systematic and independent on the anion. A linear correlation between the optical bad gap and the tolerance factor has been shown for the series of samples investigated. - Graphical abstract: The crystal structure and the optical response of the two series of hybrid organic-inorganic materials APbX{sub 3}more » (A=MA, DMA, and TMA; X=I, Br), which include some new phases, are reported. A dependence of crystal structure and band-gap with tolerance factor is shown. Display Omitted - Highlights: • DMAPbI{sub 3}, TMAPbI{sub 3} and TMAPbBr{sub 3} are reported as new hybrid organic-inorganic compounds. • Crystal structure and optical properties as a function of the number of methyl groups are provided. • Correlation between structure and optical properties are given as a function of tolerance factor.« less

Fundamental studies of gas phase ionic reactions by ion mobility spectrometry

NASA Technical Reports Server (NTRS)

Giles, K.; Knighton, W. B.; Sahlstrom, K. E.; Grimsrud, E. P.

1995-01-01

Ion mobility spectrometry (IMS) provides a promising approach to the study of gas phase ionic reactions in buffer gases at unusually high pressures. This point is illustrated here by studies of the Sn2 nucleophilic displacement reaction, Cl(-) + CH3Br yields Br + CH3Br, using IMS at atmospheric pressure. The equilibrium clustering reaction, Cl(-)(CHCI3)(n - 1) + CHCI3 yields Cl(-)(CHCI3)(n), where n = 1 and 2, and the effect of clustering on the Sn2 reaction with CH3Br have also been characterized by this IMS-based kinetic method. Present problems and anticipated improvements in the application of ion mobility spectrometry to studies of other gas phase ionic processes are discussed.

IONIC LIQUID-CATALYZED ALKYLATION OF ISOBUTANE WITH 2-BUTENE

EPA Science Inventory

A detailed study of the alkylation of isobutane with 2-butene in ionic liquid media has been conducted using 1-alkyl-3-methylimidazolium halides?aluminum chloride encompassing various alkyl groups (butyl-, hexyl-, and octyl-) and halides (Cl, Br, and I) on its cations and anions,...

P3N-PIPO, a Frameshift Product from the P3 Gene, Pleiotropically Determines the Virulence of Clover Yellow Vein Virus in both Resistant and Susceptible Peas

PubMed Central

Suzuki, Haruka; Miyashita, Yuri; Choi, Sun Hee; Hisa, Yusuke; Rihei, Shunsuke; Shimada, Ryoko; Jeon, Eun Jin; Abe, Junya; Uyeda, Ichiro

2016-01-01

ABSTRACT Peas carrying the cyv1 recessive resistance gene are resistant to clover yellow vein virus (ClYVV) isolates No.30 (Cl-No.30) and 90-1 (Cl-90-1) but can be infected by a derivative of Cl-90-1 (Cl-90-1 Br2). The main determinant for the breaking of cyv1 resistance by Cl-90-1 Br2 is P3N-PIPO produced from the P3 gene via transcriptional slippage, and the higher level of P3N-PIPO produced by Cl-90-1 Br2 than by Cl-No.30 contributes to the breaking of resistance. Here we show that P3N-PIPO is also a major virulence determinant in susceptible peas that possess another resistance gene, Cyn1, which does not inhibit systemic infection with ClYVV but causes hypersensitive reaction-like lethal systemic cell death. We previously assumed that the susceptible pea cultivar PI 226564 has a weak allele of Cyn1. Cl-No.30 did not induce cell death, but Cl-90-1 Br2 killed the plants. Our results suggest that P3N-PIPO is recognized by Cyn1 and induces cell death. Unexpectedly, heterologously strongly expressed P3N-PIPO of Cl-No.30 appears to be recognized by Cyn1 in PI 226564. The level of P3N-PIPO accumulation from the P3 gene of Cl-No.30 was significantly lower than that of Cl-90-1 Br2 in a Nicotiana benthamiana transient assay. Therefore, Cyn1-mediated cell death also appears to be determined by the level of P3N-PIPO. The more efficiently a ClYVV isolate broke cyv1 resistance, the more it induced cell death systemically (resulting in a loss of the environment for virus accumulation) in susceptible peas carrying Cyn1, suggesting that antagonistic pleiotropy of P3N-PIPO controls the resistance breaking of ClYVV. IMPORTANCE Control of plant viral disease has relied on the use of resistant cultivars; however, emerging mutant viruses have broken many types of resistance. Recently, we revealed that Cl-90-1 Br2 breaks the recessive resistance conferred by cyv1, mainly by accumulating a higher level of P3N-PIPO than that of the nonbreaking isolate Cl-No.30. Here we show that a susceptible pea line recognized the increased amount of P3N-PIPO produced by Cl-90-1 Br2 and activated the salicylic acid-mediated defense pathway, inducing lethal systemic cell death. We found a gradation of virulence among ClYVV isolates in a cyv1-carrying pea line and two susceptible pea lines. This study suggests a trade-off between breaking of recessive resistance (cyv1) and host viability; the latter is presumably regulated by the dominant Cyn1 gene, which may impose evolutionary constraints upon P3N-PIPO for overcoming resistance. We propose a working model of the host strategy to sustain the durability of resistance and control fast-evolving viruses. PMID:27279605

Ionic liquids and solids with paramagnetic anions.

PubMed

Krieger, Brenna M; Lee, Heather Y; Emge, Thomas J; Wishart, James F; Castner, Edward W

2010-08-21

Four paramagnetic ionic compounds have been prepared and their magnetic, structural and thermal properties have been investigated. The four compounds are methylbutylpyrrolidinium tetrachloroferrate(III) ([Pyrr(14)](+)/[FeCl(4)](-)), methyltributylammonium tetrachloroferrate(III) ([N(1444)](+)/[FeCl(4)](-)), butylmethylimidazolium tetrachloroferrate(III) ([bmim](+)/[FeCl(4)](-)) and tetrabutylammonium bromotrichloroferrate(III) ([N(4444)](+)/[FeBrCl(3)](-)). Temperature-dependent studies of their magnetic behaviors show that all four compounds are paramagnetic at ambient temperatures. Glass transitions are observed for only two of the four compounds, [Pyrr(14)](+)/[FeCl(4)](-) and [bmim](+)/[FeCl(4)](-). Crystal structures for [Pyrr(14)](+)/[FeCl(4)](-) and [N(1444)](+)/[FeCl(4)](-) are compared with the previously reported [N(4444)](+)/[FeBrCl(3)](-).

Predicting the thermodynamic stability of double-perovskite halides from density functional theory

DOE PAGES

Han, Dan; Zhang, Tao; Huang, Menglin; ...

2018-05-24

Recently, a series of double-perovskite halide compounds such as Cs 2AgBiCl 6 and Cs 2AgBiBr 6 have attracted intensive interest as promising alternatives to the solar absorber material CH 3NH 3PbI 3 because they are Pb-free and may exhibit enhanced stability. The thermodynamic stability of a number of double-perovskite halides has been predicted based on density functional theory (DFT) calculations of compound formation energies. In this paper, we found that the stability prediction can be dependent on the approximations used for the exchange-correlation functionals, e.g., the DFT calculations using the widely used Perdew, Burke, Ernzerhof (PBE) functional predict that Csmore » 2AgBiBr 6 is thermodynamically unstable against phase-separation into the competing phases such as AgBr, Cs 2AgBr 3, Cs 3Bi 2Br 9, etc., obviously inconsistent with the good stability observed experimentally. The incorrect prediction by the PBE calculation results from its failure to predict the correct ground-state structures of AgBr, AgCl, and CsCl. By contrast, the DFT calculations based on local density approximation, optB86b-vdW, and optB88-vdW functionals predict the ground-state structures of these binary halides correctly. Furthermore, the optB88-vdW functional is found to give the most accurate description of the lattice constants of the double-perovskite halides and their competing phases. Given these two aspects, we suggest that the optB88-vdW functional should be used for predicting thermodynamic stability in the future high-throughput computational material design or the construction of the Materials Genome database for new double-perovskite halides. As a result, using different exchange-correlation functionals has little influence on the dispersion of the conduction and the valence bands near the electronic bandgap; however, the calculated bandgap can be affected indirectly by the optimized lattice constant, which varies for different functionals.« less

Predicting the thermodynamic stability of double-perovskite halides from density functional theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Dan; Zhang, Tao; Huang, Menglin

Recently, a series of double-perovskite halide compounds such as Cs 2AgBiCl 6 and Cs 2AgBiBr 6 have attracted intensive interest as promising alternatives to the solar absorber material CH 3NH 3PbI 3 because they are Pb-free and may exhibit enhanced stability. The thermodynamic stability of a number of double-perovskite halides has been predicted based on density functional theory (DFT) calculations of compound formation energies. In this paper, we found that the stability prediction can be dependent on the approximations used for the exchange-correlation functionals, e.g., the DFT calculations using the widely used Perdew, Burke, Ernzerhof (PBE) functional predict that Csmore » 2AgBiBr 6 is thermodynamically unstable against phase-separation into the competing phases such as AgBr, Cs 2AgBr 3, Cs 3Bi 2Br 9, etc., obviously inconsistent with the good stability observed experimentally. The incorrect prediction by the PBE calculation results from its failure to predict the correct ground-state structures of AgBr, AgCl, and CsCl. By contrast, the DFT calculations based on local density approximation, optB86b-vdW, and optB88-vdW functionals predict the ground-state structures of these binary halides correctly. Furthermore, the optB88-vdW functional is found to give the most accurate description of the lattice constants of the double-perovskite halides and their competing phases. Given these two aspects, we suggest that the optB88-vdW functional should be used for predicting thermodynamic stability in the future high-throughput computational material design or the construction of the Materials Genome database for new double-perovskite halides. As a result, using different exchange-correlation functionals has little influence on the dispersion of the conduction and the valence bands near the electronic bandgap; however, the calculated bandgap can be affected indirectly by the optimized lattice constant, which varies for different functionals.« less

Syntheses and structure characterization of ten acid-base hybrid crystals based on imidazole derivatives and mineral acids

NASA Astrophysics Data System (ADS)

Hu, Kaikai; Deng, Bowen; Jin, Shouwen; Ding, Aihua; Jin, Shide; Zhu, Jin; Zhang, Huan; Wang, Daqi

2018-04-01

Cocrystallization of the imidazole derivatives with a series of mineral acids gave a total of ten hybrid salts with the compositions: [(H2bzm)(Cl)2·3H2O] (1), [(H2bzm)(ClO4)2] (2), [(H2bze)(Cl)2·2H2O] (3), [(H2bze)(Br)2·2H2O] (4), [(H2bzp)(Cl)2·4H2O] (5), [(H2bzp)(Br)2·4H2O] (6), (2-(imidazol-1-yl)-1-phenylethanone): (phosphoric acid) [(Himpeta)+(H2PO4)-] (7), [(H2impd)(Br)2] (8), [(H2impd)(ClO4)2] (9), and [(Hbzml)(Cl)] (10). The ten salts have been characterised by X-ray diffraction analysis, IR, and elemental analysis, and the melting points of all the salts were also reported. And their structural and supramolecular aspects are fully analyzed. The result reveals that among the ten investigated crystals the ring N atoms of the imidazole are protonated when the acids are deprotonated, and the crystal packing is interpreted in terms of the strong charge-assisted classical H-bonds between the NH+ and deprotonated acidic groups. Further analysis of the crystal packing of the salts indicated that a different set of additional CHsbnd O, CH2sbnd O, CHsbnd Cl, CH2sbnd Cl, CHsbnd N, CHsbnd Br, CH2sbnd Br, Osbnd O, O-π, Br-π, CH-π, and π-π associations contribute to the stabilization and expansion of the total high-dimensional frameworks. For the coexistence of the various weak nonbonding interactions these structures adopted homo or hetero supramolecular synthons or both. Some classical supramolecular synthons, such as R21(7), R22(7), R22(8), and R42(8), usually observed in the organic solids, were again shown to be involved in constructing some of these H-bonding networks.

Dielectric Study of the Phase Transitions in [P(CH3)4]2CuY4 (Y = Cl, Br)

NASA Astrophysics Data System (ADS)

Gesi, Kazuo

2002-05-01

Phase transitions in [P(CH3)4]2CuY4 (Y = Cl, Br) have been studied by dielectric measurements. In [P(CH3)4]2CuCl4, a slight break and a discontinuous jump on the dielectric constant vs. temperature curve are seen at the normal-incommensurate and the incommensurate-commensurate phase transitions, respectively. A small peak of dielectric constant along the b-direction exists just above the incommensurate-to-commensurate transition temperature. The anisotropic dielectric anomalies of [P(CH3)4]2CuBr4 at phase transitions were measured along the three crystallographic axes. The pressure-temperature phase diagram of [P(CH3)4]2CuCl4 was determined. The initial pressure coefficients of the normal-to-incommensurate and the incommensurate-to-commensurate transition temperatures are 0.19 K/MPa and 0.27 K/MPa, respectively. The incommensurate phase in [P(CH3)4]2CuCl4 disappears at a triple point which exists at 335 MPa and 443 K. The stability and the pressure effects of the incommensurate phases are much different among the four [Z(CH3)4]2CuY4 crystals (Z = N, P; Y = Cl, Br).

Synthesis, structure and reactivity of a terminal magnesium fluoride compound, [TpBut,Me]MgF: hydrogen bonding, halogen bonding and C-F bond formation.

PubMed

Rauch, Michael; Ruccolo, Serge; Mester, John Paul; Rong, Yi; Parkin, Gerard

2016-01-01

The bulky tris(3- tert -butyl-5-pyrazolyl)hydroborato ligand, [Tp Bu t ,Me ], has been employed to obtain the first structurally characterized example of a molecular magnesium compound that features a terminal fluoride ligand, namely [Tp Bu t ,Me ]MgF, via the reaction of [Tp Bu t ,Me ]MgMe with Me 3 SnF. The chloride, bromide and iodide complexes, [Tp Bu t ,Me ]MgX (X = Cl, Br, I), can also be obtained by an analogous method using Me 3 SnX. The molecular structures of the complete series of halide derivatives, [Tp Bu t ,Me ]MgX (X = F, Cl, Br, I) have been determined by X-ray diffraction. In each case, the Mg-X bond lengths are shorter than the sum of the covalent radii, thereby indicating that there is a significant ionic component to the bonding, in agreement with density functional theory calculations. The fluoride ligand of [Tp Bu t ,Me ]MgF undergoes halide exchange with Me 3 SiX (X = Cl, Br, I) to afford [Tp Bu t ,Me ]MgX and Me 3 SiF. The other halide derivatives [Tp Bu t ,Me ]MgX undergo similar exchange reactions, but the thermodynamic driving forces are much smaller than those involving fluoride transfer, a manifestation of the often discussed silaphilicity of fluorine. In accord with the highly polarized Mg-F bond, the fluoride ligand of [Tp Bu t ,Me ]MgF is capable of serving as a hydrogen bond and halogen bond acceptor, such that it forms adducts with indole and C 6 F 5 I. [Tp Bu t ,Me ]MgF also reacts with Ph 3 CCl to afford Ph 3 CF, thereby demonstrating that [Tp Bu t ,Me ]MgF may be used to form C-F bonds.

On the Structure of Some Pentaerythritol-Related Molecular Crystals with Pseudotetrahedral Molecular Structure. Ordered Structure of 2,2-Bis(bromomethyl)-1,3-propanediol and Orientationally Disordered Structure of 2-Chloromethyl-2-methyl-1,3-dichloropropane; 35Cl NQR

NASA Astrophysics Data System (ADS)

Dou, Shi-qi; Fuess, Hartmut; Strauß, Roman; Weiss, Alarich

1996-06-01

C(CH2Cl)3(CH3), melting point Tm = 291.3 K, shows in the DTA/DSC experiment a phase tran-sition from an orientationally disordered plastic phase I into an ordered phase II at TI ⃗ II = 235.9 K. From 77 K up to TII ⃗ I the 35Cl NQR spectrum is a triplet with (ν in MHz, T=77 K) ν1 = 34.213, ν2 = 34.183, ν3 = 33.786. The 35Cl NQR fade-out temperature Tf = 247 K coincides with TII ⃗ I found from the DSC experiment. The plastic phase of 2-chloromethyl-2-methyl-l,3-propanediol is cubic bcc, Im3m, Z = 2 and the lattice constant increases linearly 755 pm at 235 K to 768 pm at 283 K. In the heating cycle we found (ΔH in kJ/mol): ΔHII ⃗ I = 12.0, ΔSm/R = 1.0. The compound belongs to the group of plastic molecules formed by ellipsoid like distorted tetrahedra and is derived by substitution from methane. The crystal structure of 2,2-bis(bromomethyl)-1,3-propanediol was determined. DTA-DSC show that an orientationally disordered plastic phase does not exist. At room temperature C(CH2Br)2(CH2OH)2 crystallizes monoclinic, space group Cc, Z = 4, a = 628.2 pm, 6 = 2015.5 pm, c = 659.6 pm, β = 94.27°. The molecules interact by intermolecular hydrogen bonds between the OH-groups and by van der Waals forces Br…Br.

Anion dependent ion pairing in concentrated ytterbium halide solutions

NASA Astrophysics Data System (ADS)

Klinkhammer, Christina; Böhm, Fabian; Sharma, Vinay; Schwaab, Gerhard; Seitz, Michael; Havenith, Martina

2018-06-01

We have studied ion pairing of ytterbium halide solutions. THz spectra (30-400 cm-1) of aqueous YbCl3 and YbBr3 solutions reveal fundamental differences in the hydration structures of YbCl3 and YbBr3 at high salt concentrations: While for YbBr3 no indications for a changing local hydration environment of the ions were experimentally observed within the measured concentration range, the spectra of YbCl3 pointed towards formation of weak contact ion pairs. The proposed anion specificity for ion pairing was confirmed by supplementary Raman measurements.

Halo and Pseudohalo Cu(I)-Pyridinato Double Chains with Tunable Physical Properties.

PubMed

Hassanein, K; Amo-Ochoa, P; Gómez-García, C J; Delgado, S; Castillo, O; Ocón, P; Martínez, J I; Perles, J; Zamora, F

2015-11-16

The properties recently reported on the Cu(I)-iodide pyrimidine nonporous 1D-coordination polymer [CuI(ANP)]n (ANP = 2-amino-5-nitropyridine) showing reversible physically and chemically driven electrical response have prompted us to carry a comparative study with the series of [CuX(ANP)]n (X = Cl (1), X = Br (2), X = CN (4), and X = SCN (5)) in order to understand the potential influence of the halide and pseudohalide bridging ligands on the physical properties and their electrical response to vapors of these materials. The structural characterization of the series shows a common feature, the presence of -X-Cu(ANP)-X- (X = Cl, Br, I, SCN) double chain structure. Complex [Cu(ANP)(CN)]n (4) presents a helical single chain. Additionally, the chains show supramolecular interlinked interactions via hydrogen bonding giving rise to the formation of extended networks. Their luminescent and electrical properties have been studied. The results obtained have been correlated with structural changes. Furthermore, the experimental and theoretical results have been compared using the density functional theory (DFT). The electrical response of the materials has been evaluated in the presence of vapors of diethyl ether, dimethyl methylphosphonate (DMMP), CH2Cl2, HAcO, MeOH, and EtOH, to build up simple prototype devices for gas detectors. Selectivity toward gases consisting of molecules with H-bonding donor or acceptor groups is clearly observed. This selective molecular recognition is likely due to the 2-amino-5-nitropyridine terminal ligand.

A class of monolayer metal halogenides MX{sub 2}: Electronic structures and band alignments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Feng; Wang, Weichao; Luo, Xiaoguang

2016-03-28

With systematic first principles calculations, a class of monolayer metal halogenides MX{sub 2} (M = Mg, Ca, Zn, Cd, Ge, Pb; M = Cl, Br, I) has been proposed. Our study indicates that these monolayer materials are semiconductors with the band gaps ranging from 2.03 eV of ZnI{sub 2} to 6.08 eV of MgCl{sub 2}. Overall, the band gap increases with the increase of the electronegativity of the X atom or the atomic number of the metal M. Meanwhile, the band gaps of monolayer MgX{sub 2} (X = Cl, Br) are direct while those of other monolayers are indirect. Based on the band edge curvatures, the derived electronmore » (m{sub e}) and hole (m{sub h}) effective masses of MX{sub 2} monolayers are close to their corresponding bulk values except that the m{sub e} of CdI{sub 2} is three times larger and the m{sub h} for PbI{sub 2} is twice larger. Finally, the band alignments of all the studied MX{sub 2} monolayers are provided using the vacuum level as energy reference. These theoretical results may not only introduce the monolayer metal halogenides family MX{sub 2} into the emerging two-dimensional materials, but also provide insights into the applications of MX{sub 2} in future electronic, visible and ultraviolet optoelectronic devices.« less

TeX4 (X = F, Cl, Br) as Lewis acids--complexes with soft thio- and seleno-ether ligands.

PubMed

Hector, Andrew L; Jolleys, Andrew; Levason, William; Reid, Gillian

2012-08-28

TeF(4) reacts with OPR(3) (R = Me or Ph) in anhydrous CH(2)Cl(2) to give the colourless, square based pyramidal 1 : 1 complexes [TeF(4)(OPR(3))] only, in which the OPR(3) is coordinated basally in the solid state, (R = Me: d(Te-O) = 2.122(2) Å; R = Ph: d(Te-O) = 2.1849(14) Å). Variable temperature (19)F{(1)H}, (31)P{(1)H} and (125)Te{(1)H} NMR spectroscopic studies strongly suggest this is the low temperature structure in solution, although the systems are dynamic. The much softer donor ligands SMe(2) and SeMe(2) show a lower affinity for TeF(4), although unstable, yellow products with spectroscopic features consistent with [TeF(4)(EMe(2))] are obtained by the reaction of TeF(4) in neat SMe(2) or via reaction in CH(2)Cl(2) with SeMe(2). TeX(4) (X = F, Cl or Br) causes oxidation and halogenation of TeMe(2) to form X(2)TeMe(2). The Br(2)TeMe(2) hydrolyses in trace moisture to form [BrMe(2)Te-O-TeMe(2)Br], the crystal structure of which has been determined. TeX(4) (X = Cl or Br) react with the selenoethers SeMe(2), MeSe(CH(2))(3)SeMe or o-C(6)H(4)(SeMe)(2) (X = Cl) in anhydrous CH(2)Cl(2) to give the distorted octahedral monomers trans-[TeX(4)(SeMe(2))(2)], cis-[TeX(4){MeSe(CH(2))(3)SeMe}] and cis-[TeCl(4){o-C(6)H(4)(SeMe)(2)}], which have been characterised by IR, Raman and multinuclear NMR ((1)H, (77)Se{(1)H} and (125)Te{(1)H}) spectroscopy, and via X-ray structure determinations of representative examples. Tetrahydrothiophene (tht) can form both 1 : 1 and 1 : 2 Te : L complexes. For X = Br, the former has been shown to be a Br-bridged dimer, [Br(3)(tht)Te(μ-Br)(2)TeBr(3)(tht)], by crystallography with the tht ligands anti, whereas the latter are trans-octahedral monomers. Like its selenoether analogue, MeS(CH(2))(3)SMe forms distorted octahedral cis-chelates, [TeX(4){MeS(CH(2))(3)SMe}], whereas the more rigid o-C(6)H(4)(SMe)(2) unexpectedly forms a zig-zag chain polymer in the solid state, [TeCl(4){o-C(6)H(4)(SMe)(2)}](n), in which the dithioether adopts an extremely unusual bridging mode. This is in contrast to the chelating monomer, cis-[TeCl(4){o-C(6)H(4)(SeMe)(2)}], formed with the analogous selenoether and may be attributed to small differences in the ligand chelate bite angles. The wider bite angle xylyl-linked bidentates, o-C(6)H(4)(CH(2)EMe(2))(2) behave differently; the thioether forms cis-chelated [TeX(4){o-C(6)H(4)(CH(2)SMe)(2)}] confirmed crystallographically, whereas the selenoether undergoes C-Se cleavage and rearrangement on treatment with TeX(4), forming the cyclic selenonium salts, [C(9)H(11)Se](2)[TeX(6)]. The tetrathiamacrocycle, [14]aneS(4) (1,4,8,11-tetrathiacyclotetradecane), does not react cleanly with TeCl(4), but forms the very poorly soluble [TeCl(4)([14]aneS(4))](n), shown by crystallography to be a zig-zag polymer with exo-coordinated [14]aneS(4) units linked via alternate S atoms to a cis-TeCl(4) unit. Trends in the (125)Te{(1)H} NMR shifts for this series of Te(IV) halides chalcogenoether complexes are discussed.

Intermediate Temperature Fluids Life Tests - Experiments

DTIC Science & Technology

2007-06-01

TiCl4, TiBr4, and eutectic diphenyl/diphenyl oxide (Therminol VP-1/Dowtherm A). All of the life tests except for the GaCl3 are ongoing; the GaCl3...763 85.5 Eutectic Diphenyl/Diphenyl Oxide 285 530 770 31 Antimony Tribromide SbBr3 370 553 1178 55 Antimony Trichloride SbCl3 346 556 794 Cesium...From a Compatibility Standpoint) Have High Decomposition Potentials, While Halides/ Salts of Good Envelope Materials Have Low Decomposition Potentials

DFT investigation of electronic structures and magnetic properties of halides family MeHal3 (Me=Ti, Mo,Zr,Nb, Ru, Hal=Cl,Br,I) one dimensional structures

NASA Astrophysics Data System (ADS)

Kuzubov, A. A.; Kovaleva, E. A.; Popova, M. I.; Kholtobina, A. S.; Mikhaleva, N. S.; Visotin, M. A.; Fedorov, A. S.

2017-10-01

Using DFT GGA calculations, electronic structure and magnetic properties of wide family of transition metal trihalides (TMHal3) (Zr, Ti and Nb iodides, Mo, Ru, Ti and Zr bromides and Ti or Zr chlorides) are investigated. These structures consist of transition metal atoms chains surrounded by halides atoms. Chains are connected to each other by weak interactions. All TMHal3 compounds were found to be conductive along chain axis except of MoBr3 which is indirect gap semiconductor. It was shown that NbI3 and MoBr3 have large magnetic moments on metal atoms (1.17 and 1.81 μB, respectively) but other TMHal3 materials have small or zero magnetic moments. For all structures ferromagnetic and anti-ferromagnetic phases have almost the same energies. The causes of these properties are debated.

Crystal structure of {2,6-bis-[(di-methyl-amino)-meth-yl]phenyl-κ3N,C1,N'}(bromido/chlorido)-mercury(II).

PubMed

Gupta, Anand; Singh, Harkesh B; Butcher, Ray J

2017-11-01

In the mol-ecular structure of the title compound, {2,6-bis-[(di-methyl-amino)-meth-yl]phenyl-κ 3 N , C 1 , N '}[bromido/chlorido-(0.30/0.70)]mercury(II)-{2,6-bis-[(di-methyl-amino)-meth-yl]phenyl-κ 3 N , C 1 , N '}[bromido/chlorido-(0.24/0.76)]mer-cury(II) (1/1), [HgBr 0.30 Cl 0.70 (C 12 H 19 N 2 )]·[HgBr 0.24 Cl 0.76 (C 12 H 19 N 2 )], there are two mol-ecules in the asymmetric unit of formula L Hg X { L = 2,6-bis-[(di-methyl-amino)-meth-yl]phenyl and X = Cl/Br}. In each mol-ecule, the halide site is mixed Cl/Br, with occupancies of 0.699 (7):0.301 (7) and 0.763 (7):0.237 (7), respectively. The two mol-ecules are linked into dimers by a combination of Hg⋯Hg [Hg⋯Hg = 3.6153 (3) Å] and C-H⋯Cl and C-H⋯π inter-actions.

Electronic effects of Se and Pb dopants in TlBr

NASA Astrophysics Data System (ADS)

Smith, Holland M.; Phillips, David J.; Sharp, Ian D.; Beeman, Jeffrey W.; Chrzan, Daryl C.; Haegel, Nancy M.; Haller, Eugene E.; Ciampi, Guido; Kim, Hadong; Shah, Kanai S.

2012-05-01

Deep levels in Se- and Pb-doped bulk TlBr detectors were characterized with photo-induced conductivity transient spectroscopy (PICTS) and cathodoluminescence (CL). Se-doped TlBr revealed two traps with energies of 0.35 and 0.45 eV in PICTS spectra. The Pb-doped material revealed three levels with energies of 0.11, 0.45, and 0.75 eV. CL measurements in both materials correlate with optical transitions involving some of the identified levels. The ambipolar carrier lifetimes of Se-doped and Pb-doped TlBr were measured with microwave reflectivity transients and found to be significantly lower than the lifetime of undoped TlBr.

Solubility of alkali metal halides in the ionic liquid [C4C1im][OTf].

PubMed

Kuzmina, O; Bordes, E; Schmauck, J; Hunt, P A; Hallett, J P; Welton, T

2016-06-28

The solubilities of the metal halides LiF, LiCl, LiBr, LiI, NaF, NaCl, NaBr, NaI, KF, KCl, KBr, KI, RbCl, CsCl, CsI, were measured at temperatures ranging from 298.15 to 378.15 K in the ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([C4C1im][OTf]). Li(+), Na(+) and K(+) salts with anions matching the ionic liquid have also been investigated to determine how well these cations dissolve in [C4C1im][OTf]. This study compares the influence of metal cation and halide anion on the solubility of salts within this ionic liquid. The highest solubility found was for iodide salts, and the lowest solubility for the three fluoride salts. There is no outstanding difference in the solubility of salts with matching anions in comparison to halide salts. The experimental data were correlated employing several phase equilibria models, including ideal mixtures, van't Hoff, the λh (Buchowski) equation, the modified Apelblat equation, and the non-random two-liquid model (NRTL). It was found that the van't Hoff model gave the best correlation results. On the basis of the experimental data the thermodynamic dissolution parameters (ΔH, ΔS, and ΔG) were determined for the studied systems together with computed gas phase metathesis parameters. Dissolution depends on the energy difference between enthalpies of fusion and dissolution of the solute salt. This demonstrates that overcoming the lattice energy of the solid matrix is the key to the solubility of inorganic salts in ionic liquids.

Ab initio calculations of the lattice dynamics of silver halides

NASA Astrophysics Data System (ADS)

Gordienko, A. B.; Kravchenko, N. G.; Sedelnikov, A. N.

2010-12-01

Based on ab initio pseudopotential calculations, the results of investigations of the lattice dynamics of silver halides AgHal (Hal = Cl, Br, I) are presented. Equilibrium lattice parameters, phonon spectra, frequency densities and effective atomic-charge values are obtained for all types of crystals under study.

The crystal structures of six (2E)-3-aryl-1-(5-halogeno-thio-phen-2-yl)prop-2-en-1-ones.

PubMed

Naik, Vasant S; Yathirajan, Hemmige S; Jasinski, Jerry P; Smolenski, Victoria A; Glidewell, Christopher

2015-09-01

The structures of six chalcones containing 5-halogeno-thio-phen-2-yl substituents are reported: (2E)-1-(5-chloro-thio-phen-2-yl)-3-(4-ethyl-phen-yl)prop-2-en-1-one, C15H13ClOS, (I), and (2E)-1-(5-bromo-thio-phen-2-yl)-3-(4-ethyl-phen-yl)prop-2-en-1-one, C15H13BrOS, (II), are isostructural in space group P-1, while (2E)-1-(5-chloro-thio-phen-2-yl)-3-(4-eth-oxy-phen-yl)prop-2-en-1-one, C15H13ClO2S, (III), and (2E)-1-(5-bromo-thio-phen-2-yl)-3-(4-eth-oxy-phen-yl)prop-2-en-1-one C15H13BrO2S, (IV), are isostructural in space group P21/c. There are no hydrogen bonds of any kind in the structures of compounds (I) and (II), but in the structures of compounds (III) and (IV), the mol-ecules are linked into C(7) chains by means of C-H⋯O hydrogen bonds. In the structure of (2E)-3-(4-bromo-phen-yl)-1-(5-chloro-thio-phen-2-yl)prop-2-en-1-one, C13H8BrClOS, (V), there are again no hydrogen bonds nor π-π stacking inter-actions but in that of (2E)-1-(5-bromo-thio-phen-2-yl)-3-(3-meth-oxy-phen-yl)prop-2-en-1-one, C14H11BrO2S, (VI), the mol-ecules are linked into C(5) chains by C-H⋯O hydrogen bonds. In each of compounds (I)-(VI), the mol-ecular skeletons are close to planarity, and there are short halogen⋯halogen contacts in the structures of compounds (II) and (V) and a short Br⋯O contact in the structure of compound (VI). Comparisons are made with the structures of some similar compounds.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Linaburg, Matthew R.; McClure, Eric T.; Majher, Jackson D.

The structures of the lead halide perovskites CsPbCl3 and CsPbBr3 have been determined from X-ray powder diffraction data to be orthorhombic with Pnma space group symmetry. Their structures are distorted from the cubic structure of their hybrid analogs, CH3NH3PbX3 (X = Cl, Br), by tilts of the octahedra (Glazer tilt system a–b+a–). Substitution of the smaller Rb+ for Cs+ increases the octahedral tilting distortion and eventually destabilizes the perovskite structure altogether. To understand this behavior, bond valence parameters appropriate for use in chloride and bromide perovskites have been determined for Cs+, Rb+, and Pb2+. As the tolerance factor decreases, themore » band gap increases, by 0.15 eV in Cs1–xRbxPbCl3 and 0.20 eV in Cs1–xRbxPbBr3, upon going from x = 0 to x = 0.6. The band gap shows a linear dependence on tolerance factor, particularly for the Cs1–xRbxPbBr3 system. Comparison with the cubic perovskites CH3NH3PbCl3 and CH3NH3PbBr3 shows that the band gaps of the methylammonium perovskites are anomalously large for APbX3 perovskites with a cubic structure. This comparison suggests that the local symmetry of CH3NH3PbCl3 and CH3NH3PbBr3 deviate significantly from the cubic symmetry of the average structure.« less

Antireflection Coatings for Silicon in the 2.5-50-microm Region.

PubMed

Sherman, G H; Coleman, P D

1971-12-01

It has been found that vacuum-deposited films of CsI, AgCl, TlBr, and TlCl are useful as antireflection coatings for silicon over a broad spectral range in the infrared. Measurements performed on a plane-parallel silicon plate coated with various thicknesses of the above materials yield transmittance values ranging from 99% at lambda = 2.9 microm to 88% at lambda = 27 microm. Experimental details of the coating process and properties of the coatings are discussed.

Thallium halide radiation detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ijaz-ur-Rahman; Hofstadter, R.

1984-03-15

During a series of experiments on crystal conduction counters performed at Stanford University on thallium halide crystals, we have observed motion of both hole and electron carriers in a TlBr crystal. At a temperature near -90 /sup 0/C the hole motion produces larger pulses than electron motion. We have studied the behavior of TlBr, TlCl, and KRS-5 (40 mol % TlBr + 60 mol % TlI) crystals and examined them as possible crystal conduction detectors of ..cap alpha.. particles and ..gamma.. rays. TlBr appears to be a promising candidate for applications to nuclear physics and high-energy ..gamma..-ray physics. Modules ofmore » TlBr in ''crystal-ball'' geometry may lead to new detection possibilities. At -20 /sup 0/C space-charge accumulation in TlBr decreases to such an extent that operation at this temperature seems possible with moderate electrical gradients. In the long-neglected field of crystal conduction counters, we have potentially removed the space-charge limitation in TlBr and, allowing for both hole and electron motion, raised the possibility for spectroscopic performance of this material for ..gamma..-ray studies.« less

One-dimensional mercury(II) halide coordination polymers of 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine ligand: Synthesis, crystal structure, spectroscopic and DFT studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saghatforoush, Lotfali, E-mail: saghatforoush@gmail.com; Khoshtarkib, Zeinab; Amani, Vahid

2016-01-15

Three new coordination polymers, [Hg(μ-bptz)X{sub 2}]{sub n} (X=Cl (1), Br (2)) and [Hg{sub 2}(μ-bptz)(μ-I){sub 2}I{sub 2}]{sub n} (3) (bptz=3,6-bis(2-pyridyl)-1,2,4,5-tetrazine) were synthesized. X-ray structural analysis indicated that compounds 1 and 2 are composed of one-dimensional (1D) linear chains while the compound 3 has 1D stair-stepped structure. The electronic band structure along with density of states (DOS) calculated by the DFT method indicates that compound 1 and 2 are direct band gap semiconductors; however, compound 3 is an indirect semiconductor. The linear optical properties of the compounds are also calculated by DFT method. According to the DFT calculations, the observed emission bandmore » of the compounds in solid state is due to electron transfer from an excited bptz-π* state (CBs) to the top of VBs. {sup 1}H NMR spectra of the compounds indicate that, in solution phase, the compounds don’t decompose completely. Thermal stability of the compounds is studied using TG, DTA methods. - Graphical abstract: Synthesis, crystal structure and emission spectra of [Hg(μ-bptz)X{sub 2}]{sub n} (X=Cl and Br) and [Hg{sub 2}(μ-bptz)(μ-I){sub 2}I{sub 2}]{sub n} are presented. The electronic band structure and linear optical properties of the compounds are calculated by the DFT method. - Highlights: • Three 1D Hg(II) halide coordination polymers with bptz ligand have been prepared. • The structures of the compounds are determined by single crystal XRD. • DFT calculations show that [Hg(μ-bptz)X{sub 2}]{sub n} (X=Cl and Br) have a direct band gap. • DFT calculations show that [Hg{sub 2}(μ-bptz)(μ-I){sub 2}I{sub 2}]{sub n} has an indirect band gap. • The compounds show an intraligand electron transfer emission band in solid state.« less

Spectral studies related to dissociation of HBr, HCl and BrO

NASA Technical Reports Server (NTRS)

Ginter, M. L.

1986-01-01

Concern over halogen catalyzed decomposition of O3 in the upper atmosphere has generated need for data on the atomic and molecular species X, HX and XO (where X is Cl and Br). Of special importance are Cl produced from freon decomposition and Cl and Br produced from natural processes and from other industrial and agricultural chemicals. Basic spectral data is provided on HCl, HBr, and BrO necessary to detect specific states and energy levels, to enable detailed modeling of the processes involving molecular dissociation, ionization, etc., and to help evaluate field experiments to check the validity of model calculations for these species in the upper atmosphere. Results contained in four published papers and two major spectral compilations are summarized together with other results obtained.

Congener-specific determination of ultratrace levels of chlorinated and brominated polycyclic aromatic hydrocarbons in atmosphere and industrial stack gas by isotopic dilution gas chromatography/high resolution mass spectrometry method.

PubMed

Jin, Rong; Liu, Guorui; Zheng, Minghui; Fiedler, Heidelore; Jiang, Xiaoxu; Yang, Lili; Wu, Xiaolin; Xu, Yang

2017-08-04

Isotopic dilution gas chromatography combined with high resolution mass spectrometry (GC/HRMS) has overwhelming advantages with respect to the accuracy of congener-specific ultratrace analysis of complex persistent organic pollutants (POPs) in environmental matrices. However, an isotopic dilution GC/HRMS method for analysis of chlorinated and brominated polycyclic aromatic hydrocarbons (Cl-PAHs and Br-PAHs) using 13 C-labelled congeners as internal standards has not been established. In this study, a method for identification and quantification of 38 congeners of Cl-PAHs and Br-PAHs in atmosphere and stack gas samples from waste incinerators was developed using the isotopic dilution GC/HRMS technique. The instrumental detection limits of the GC/HRMS method ranged from 0.2pg to 1.8pg for Cl-PAH congeners, and 0.7pg to 2.7pg for Br-PAH congeners, which were about three orders of magnitude lower than those of the GC/quadrupole MS method. This new method developed was also the first to enable determination of Cl-PAH and Br-PAH homologs comprising congeners with the same molecular skeleton and chlorine or bromine substitution numbers. Among the detected congeners, seven Cl-PAH congeners and thirteen Br-PAH congeners that were abundant in the atmosphere and stack gases released from waste incinerators were firstly detected in real samples and reported using the established isotopic dilution GC/HRMS method. The developed isotopic dilution GC/HRMS is significant and needed for better studying the environmental behavior and health risk of Cl-PAHs and Br-PAHs. Copyright © 2017 Elsevier B.V. All rights reserved.

Mass-Dependent and -Independent Fractionation of Mercury Isotope during Gas-Phase Oxidation of Elemental Mercury Vapor by Atomic Cl and Br.

PubMed

Sun, Guangyi; Sommar, Jonas; Feng, Xinbin; Lin, Che-Jen; Ge, Maofa; Wang, Weigang; Yin, Runsheng; Fu, Xuewu; Shang, Lihai

2016-09-06

This study presents the first measurement of Hg stable isotope fractionation during gas-phase oxidation of Hg(0) vapor by halogen atoms (Cl(•), Br(•)) in the laboratory at 750 ± 1 Torr and 298 ± 3 K. Using a relative rate technique, the rate coefficients for Hg(0)+Cl(•) and Hg(0)+Br(•) reactions are determined to be (1.8 ± 0.5) × 10(-11) and (1.6 ± 0.8) × 10(-12) cm(3) molecule(-1) s(-1), respectively. Results show that heavier isotopes are preferentially enriched in the remaining Hg(0) during Cl(•) initiated oxidation, whereas being enriched in the product during oxidation by Br(•). The fractionation factors for (202)Hg/(198)Hg during the Cl(•) and Br(•) initiated oxidations are α(202/198) = 0.99941 ± 0.00006 (2σ) and 1.00074 ± 0.00014 (2σ), respectively. A Δ(199)Hg/Δ(201)Hg ratio of 1.64 ± 0.30 (2σ) during oxidation of Hg(0) by Br atoms suggests that Hg-MIF is introduced by the nuclear volume effect (NVE). In contrast, the Hg(0) + Cl(•) reaction produces a Δ(199)Hg/Δ(201)Hg-slope of 1.89 ± 0.18 (2σ), which in addition to a high degree of odd-mass-number isotope MIF suggests impacts from MIF effects other than NVE. This reaction also exhibits significant MIF of (200)Hg (Δ(200)Hg, up to -0.17‰ in the reactant) and is the first physicochemical process identified to trigger (200)Hg anomalies that are frequently detected in atmospheric samples.

Halocarbon emissions by selected tropical seaweeds: species-specific and compound-specific responses under changing pH.

PubMed

Mithoo-Singh, Paramjeet Kaur; Keng, Fiona S-L; Phang, Siew-Moi; Leedham Elvidge, Emma C; Sturges, William T; Malin, Gill; Abd Rahman, Noorsaadah

2017-01-01

Five tropical seaweeds, Kappaphycus alvarezii (Doty) Doty ex P.C. Silva, Padina australis Hauck, Sargassum binderi Sonder ex J. Agardh (syn. S. aquifolium (Turner) C. Agardh), Sargassum siliquosum J. Agardh and Turbinaria conoides (J. Agardh) Kützing, were incubated in seawater of pH 8.0, 7.8 (ambient), 7.6, 7.4 and 7.2, to study the effects of changing seawater pH on halocarbon emissions. Eight halocarbon species known to be emitted by seaweeds were investigated: bromoform (CHBr 3 ), dibro-momethane (CH 2 Br 2 ), iodomethane (CH 3 I), diiodomethane (CH 2 I 2 ), bromoiodomethane (CH 2 BrI), bromochlorometh-ane (CH 2 BrCl), bromodichloromethane (CHBrCl 2 ), and dibro-mochloromethane (CHBr 2 Cl). These very short-lived halocarbon gases are believed to contribute to stratospheric halogen concentrations if released in the tropics. It was observed that the seaweeds emit all eight halocarbons assayed, with the exception of K. alvarezii and S. binderi for CH 2 I 2 and CH 3 I respectively, which were not measurable at the achievable limit of detection. The effect of pH on halocarbon emission by the seaweeds was shown to be species-specific and compound specific. The highest percentage changes in emissions for the halocarbons of interest were observed at the lower pH levels of 7.2 and 7.4 especially in Padina australis and Sargassum spp., showing that lower seawater pH causes elevated emissions of some halocarbon compounds. In general the seaweed least affected by pH change in terms of types of halocarbon emission, was P. australis . The commercially farmed seaweed K. alvarezii was very sensitive to pH change as shown by the high increases in most of the compounds in all pH levels relative to ambient. In terms of percentage decrease in maximum quantum yield of photosynthesis ( F v ∕ F m ) prior to and after incubation, there were no significant correlations with the various pH levels tested for all seaweeds. The correlation between percentage decrease in the maximum quantum yield of photosynthesis ( F v ∕ F m ) and halocarbon emission rates, was significant only for CH 2 BrCl emission by P. australis ( r  = 0.47; p  ≤ 0.04), implying that photosynthesis may not be closely linked to halocarbon emissions by the seaweeds studied. Bromine was the largest contributor to the total mass of halogen emitted for all the seaweeds at all pH. The highest total amount of bromine emitted by K. alvarezii (an average of 98% of total mass of halogens) and the increase in the total amount of chlorine with decreasing seawater pH fuels concern for the expanding seaweed farming activities in the ASEAN region.

Halocarbon emissions by selected tropical seaweeds: species-specific and compound-specific responses under changing pH

PubMed Central

Leedham Elvidge, Emma C.; Sturges, William T.; Malin, Gill; Abd Rahman, Noorsaadah

2017-01-01

Five tropical seaweeds, Kappaphycus alvarezii (Doty) Doty ex P.C. Silva, Padina australis Hauck, Sargassum binderi Sonder ex J. Agardh (syn. S. aquifolium (Turner) C. Agardh), Sargassum siliquosum J. Agardh and Turbinaria conoides (J. Agardh) Kützing, were incubated in seawater of pH 8.0, 7.8 (ambient), 7.6, 7.4 and 7.2, to study the effects of changing seawater pH on halocarbon emissions. Eight halocarbon species known to be emitted by seaweeds were investigated: bromoform (CHBr3), dibro­momethane (CH2Br2), iodomethane (CH3I), diiodomethane (CH2I2), bromoiodomethane (CH2BrI), bromochlorometh­ane (CH2BrCl), bromodichloromethane (CHBrCl2), and dibro­mochloromethane (CHBr2Cl). These very short-lived halocarbon gases are believed to contribute to stratospheric halogen concentrations if released in the tropics. It was observed that the seaweeds emit all eight halocarbons assayed, with the exception of K. alvarezii and S. binderi for CH2I2 and CH3I respectively, which were not measurable at the achievable limit of detection. The effect of pH on halocarbon emission by the seaweeds was shown to be species-specific and compound specific. The highest percentage changes in emissions for the halocarbons of interest were observed at the lower pH levels of 7.2 and 7.4 especially in Padina australis and Sargassum spp., showing that lower seawater pH causes elevated emissions of some halocarbon compounds. In general the seaweed least affected by pH change in terms of types of halocarbon emission, was P. australis. The commercially farmed seaweed K. alvarezii was very sensitive to pH change as shown by the high increases in most of the compounds in all pH levels relative to ambient. In terms of percentage decrease in maximum quantum yield of photosynthesis (Fv∕Fm) prior to and after incubation, there were no significant correlations with the various pH levels tested for all seaweeds. The correlation between percentage decrease in the maximum quantum yield of photosynthesis (Fv∕Fm) and halocarbon emission rates, was significant only for CH2BrCl emission by P. australis (r = 0.47; p ≤ 0.04), implying that photosynthesis may not be closely linked to halocarbon emissions by the seaweeds studied. Bromine was the largest contributor to the total mass of halogen emitted for all the seaweeds at all pH. The highest total amount of bromine emitted by K. alvarezii (an average of 98% of total mass of halogens) and the increase in the total amount of chlorine with decreasing seawater pH fuels concern for the expanding seaweed farming activities in the ASEAN region. PMID:28149690

Insertion of terminal alkyne into Pt-N bond of the square planar [PtI2(Me2phen)] complex.

PubMed

Benedetti, Michele; De Castro, Federica; Lamacchia, Vincenza; Pacifico, Concetta; Natile, Giovanni; Fanizzi, Francesco P

2017-11-21

The reactivity of [PtX 2 (Me 2 phen)] complexes (X = Cl, Br, I; Me 2 phen = 2,9-dimethyl-1,10-phenanthroline) with terminal alkynes has been investigated. Although the dichlorido species [PtCl 2 (Me 2 phen)] exhibits negligible reactivity, the bromido and iodido derivatives lead in short time to the formation of five-coordinate Pt(ii) complexes of the type [PtX 2 (Me 2 phen)(η 2 -CH[triple bond, length as m-dash]CR)] (X = Br, I; R = Ph, n-Bu), in equilibrium with the starting reagents. Similar to analogous complexes with simple acetylene, the five coordinate species can also undergo dissociation of an halido ligand and formation of the transient square-planar cationic species [PtX(Me 2 phen)(η 2 -CH[triple bond, length as m-dash]CR)] + . This latter can further evolve to give an unusual, sparingly soluble square planar product where the former terminal alkyne is converted into a :C[double bond, length as m-dash]C(H)(R) moiety with the α-carbon bridging the Pt(ii) core with one of the two N-donors of coordinated Me 2 phen. The final product [PtX 2 {κ 2 -N,C-(Z)-N[combining low line]1-N10-C[combining low line][double bond, length as m-dash]C(H)(R)}] (N1-N10 = 2,9-dimethyl-1,10-phenanthroline; X = Br, I) contains a Pt-N-C-C-N-C six-membered chelate ring in a square planar Pt(ii) coordination environment.

Extraction behaviour and mechanism of Pt(iv) and Pd(ii) by liquid-liquid extraction with an ionic liquid [HBBIm]Br.

PubMed

Liu, Wenhui; Wang, Qi; Zheng, Yan; Wang, Shubin; Yan, Yan; Yang, Yanzhao

2017-06-06

In this study, a method of one-step separation and recycling of high purity Pd(ii) and Pt(iv) using an ionic liquid, 1-butyl-3-benzimidazolium bromate ([HBBIm]Br), was investigated. The effects of [HBBIm]Br concentration, initial metal concentration, and loading capacity of [HBBIm]Br were examined in detail. It was observed that [HBBIm]Br was a very effective extractant for selectively extracting Pd(ii) and precipitating Pt(iv). Through selectively extracting Pd(ii) and precipitating Pt(iv), each metal with high purity was separately obtained from mixed Pd(ii) and Pt(iv) multi-metal solution. The method of one-step separation of Pd(ii) and Pt(iv) is simple and convenient. The anion exchange mechanism between [HBBIm]Br and Pt(iv) was proven through Job's method and FTIR and 1 H NMR spectroscopies. The coordination mechanism between [HBBIm]Br and Pd(ii) was demonstrated via single X-ray diffraction and was found to be robust and distinct, as supported by the ab initio quantum-chemical studies. The crystals of the [PdBr 2 ·2BBIm] complex were formed first. Moreover, the influence of the concentrations of hydrochloric acid, sodium chloride, and sodium nitrate on the precipitation of Pt(iv) and extraction of Pd(ii) was studied herein. It was found that only the concentration of H + could inhibit the separation of Pt(iv) because H + could attract the anion PtCl 6 2- ; thus, the exchange (anion exchange mechanism) between the anions PtCl 6 2- and Br - was prevented. However, both the concentration of H + and Cl - can obviously inhibit the extraction of Pd(ii) because H + and Cl - are the reaction products and increasing their concentration can inhibit the progress of the reaction (coordination mechanism).

Stable Chloro- and Bromoxenate Cage Anions; [X3(XeO3)3]3- and [X4(XeO3)4]4- (X = Cl or Br).

PubMed

Goettel, James T; Haensch, Veit G; Schrobilgen, Gary J

2017-06-28

The number of isolable compounds which contain different noble-gas-element bonds is limited for xenon and even more so for krypton. Examples of Xe-Cl bonds are rare, and prior to this work, no Xe-Br bonded compound had been isolated in macroscopic quantities. The syntheses, isolation, and characterization of the first compounds to contain Xe-Br bonds and their chlorine analogues are described in the present work. The reactions of XeO 3 with [N(CH 3 ) 4 ]Br and [N(C 2 H 5 ) 4 ]Br have provided two bromoxenate salts, [N(C 2 H 5 ) 4 ] 3 [Br 3 (XeO 3 ) 3 ] and [N(CH 3 ) 4 ] 4 [Br 4 (XeO 3 ) 4 ], in which the cage anions have Xe-Br bond lengths that range from 3.0838(3) to 3.3181(8) Å. The isostructural chloroxenate anions (Xe-Cl bond lengths, 2.9316(2) to 3.101(4) Å) were synthesized by analogy with their bromine analogues. The bromo- and chloroxenate salts are stable in the atmosphere at room temperature and were characterized in the solid state by Raman spectroscopy and low-temperature single-crystal X-ray diffraction, and in the gas phase by quantum-chemical calculations. They are the only known examples of cage anions that contain a noble-gas element. The Xe-Br and Xe-Cl bonds are very weakly covalent and can be viewed as σ-hole interactions, similar to those encountered in halogen bonding. However, the halogen atoms in these cases are valence electron lone pair donors, and the σ* Xe-O orbitals are lone pair acceptors.

The association between content of the elements S, Cl, K, Fe, Cu, Zn and Br in normal and cirrhotic liver tissue from Danes and Greenlandic Inuit examined by dual hierarchical clustering analysis.

PubMed

Laursen, Jens; Milman, Nils; Pind, Niels; Pedersen, Henrik; Mulvad, Gert

2014-01-01

Meta-analysis of previous studies evaluating associations between content of elements sulphur (S), chlorine (Cl), potassium (K), iron (Fe), copper (Cu), zinc (Zn) and bromine (Br) in normal and cirrhotic autopsy liver tissue samples. Normal liver samples from 45 Greenlandic Inuit, median age 60 years and from 71 Danes, median age 61 years. Cirrhotic liver samples from 27 Danes, median age 71 years. Element content was measured using X-ray fluorescence spectrometry. Dual hierarchical clustering analysis, creating a dual dendrogram, one clustering element contents according to calculated similarities, one clustering elements according to correlation coefficients between the element contents, both using Euclidian distance and Ward Procedure. One dendrogram separated subjects in 7 clusters showing no differences in ethnicity, gender or age. The analysis discriminated between elements in normal and cirrhotic livers. The other dendrogram clustered elements in four clusters: sulphur and chlorine; copper and bromine; potassium and zinc; iron. There were significant correlations between the elements in normal liver samples: S was associated with Cl, K, Br and Zn; Cl with S and Br; K with S, Br and Zn; Cu with Br. Zn with S and K. Br with S, Cl, K and Cu. Fe did not show significant associations with any other element. In contrast to simple statistical methods, which analyses content of elements separately one by one, dual hierarchical clustering analysis incorporates all elements at the same time and can be used to examine the linkage and interplay between multiple elements in tissue samples. Copyright © 2013 Elsevier GmbH. All rights reserved.

Hydrogen bonding interactions in nicotinamide Ionic Liquids: A comparative spectroscopic and DFT studies

NASA Astrophysics Data System (ADS)

Shukla, Madhulata

2017-03-01

Being biodegradable in nature nicotinamide based Ionic Liquids (ILs) are gaining much attention now a day. Nicotinamide iodide (i.e 1-methyl-3ethoxy carbonyl pyridinium iodide (mNicI)) and 1-methyl-3ethoxy carbonyl pyridinium trifilimide (mNicNTf2) new ILs has been synthesized and has been characterized using different spectroscopic techniques like NMR, UV visible and infrared spectroscopy. Theoretical studies have been performed on several nicotinamide ILs. Geometry and spectral features were further characterized by Density Functional Theory (DFT) calculation. NBO charge distribution and electrostatic potential diagram presents in depth knowledge about interactions between cation and anion. A comparative theoretical study between mNicI and its other analogues i. e 1-methyl-3 ethoxy carbonyl pyridinium chloride and bromide i. e mNicCl and mNicBr has also been performed. Csbnd H⋯X hydrogen bonding along with C⋯X interaction has been reported for the first time for the nicotinamide based ILs. C2sbnd H stretching frequency shifts to higher wavenumber with change to a lesser electronegative anion. mNicCl and mNicBr are expected to be solid in nature with the evidence from the red shift in stretching frequency as compared to mNicI. TD-DFT calculation of mNicI proved that pale yellow color of liquid is due to inherent transition from anion to cation.

P3N-PIPO, a Frameshift Product from the P3 Gene, Pleiotropically Determines the Virulence of Clover Yellow Vein Virus in both Resistant and Susceptible Peas.

PubMed

Atsumi, Go; Suzuki, Haruka; Miyashita, Yuri; Choi, Sun Hee; Hisa, Yusuke; Rihei, Shunsuke; Shimada, Ryoko; Jeon, Eun Jin; Abe, Junya; Nakahara, Kenji S; Uyeda, Ichiro

2016-08-15

Peas carrying the cyv1 recessive resistance gene are resistant to clover yellow vein virus (ClYVV) isolates No.30 (Cl-No.30) and 90-1 (Cl-90-1) but can be infected by a derivative of Cl-90-1 (Cl-90-1 Br2). The main determinant for the breaking of cyv1 resistance by Cl-90-1 Br2 is P3N-PIPO produced from the P3 gene via transcriptional slippage, and the higher level of P3N-PIPO produced by Cl-90-1 Br2 than by Cl-No.30 contributes to the breaking of resistance. Here we show that P3N-PIPO is also a major virulence determinant in susceptible peas that possess another resistance gene, Cyn1, which does not inhibit systemic infection with ClYVV but causes hypersensitive reaction-like lethal systemic cell death. We previously assumed that the susceptible pea cultivar PI 226564 has a weak allele of Cyn1 Cl-No.30 did not induce cell death, but Cl-90-1 Br2 killed the plants. Our results suggest that P3N-PIPO is recognized by Cyn1 and induces cell death. Unexpectedly, heterologously strongly expressed P3N-PIPO of Cl-No.30 appears to be recognized by Cyn1 in PI 226564. The level of P3N-PIPO accumulation from the P3 gene of Cl-No.30 was significantly lower than that of Cl-90-1 Br2 in a Nicotiana benthamiana transient assay. Therefore, Cyn1-mediated cell death also appears to be determined by the level of P3N-PIPO. The more efficiently a ClYVV isolate broke cyv1 resistance, the more it induced cell death systemically (resulting in a loss of the environment for virus accumulation) in susceptible peas carrying Cyn1, suggesting that antagonistic pleiotropy of P3N-PIPO controls the resistance breaking of ClYVV. Control of plant viral disease has relied on the use of resistant cultivars; however, emerging mutant viruses have broken many types of resistance. Recently, we revealed that Cl-90-1 Br2 breaks the recessive resistance conferred by cyv1, mainly by accumulating a higher level of P3N-PIPO than that of the nonbreaking isolate Cl-No.30. Here we show that a susceptible pea line recognized the increased amount of P3N-PIPO produced by Cl-90-1 Br2 and activated the salicylic acid-mediated defense pathway, inducing lethal systemic cell death. We found a gradation of virulence among ClYVV isolates in a cyv1-carrying pea line and two susceptible pea lines. This study suggests a trade-off between breaking of recessive resistance (cyv1) and host viability; the latter is presumably regulated by the dominant Cyn1 gene, which may impose evolutionary constraints upon P3N-PIPO for overcoming resistance. We propose a working model of the host strategy to sustain the durability of resistance and control fast-evolving viruses. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Magnetic Transitions in Iron Porphyrin Halides by Inelastic Neutron Scattering and Ab-initio Studies of Zero-Field Splittings

DOE PAGES

Stavretis, Shelby E.; Atanasov, Mihail; Podlesnyak, Andrey A.; ...

2015-10-02

Zero-field splitting (ZFS) parameters of nondeuterated metalloporphyrins [Fe(TPP)X] (X = F, Br, I; H 2TPP = tetraphenylporphyrin) are determined by inelastic neutron scattering (INS). The ZFS values are D = 4.49(9) cm –1 for tetragonal polycrystalline [Fe(TPP)F], and D = 8.8(2) cm –1, E = 0.1(2) cm –1 and D = 13.4(6) cm –1, E = 0.3(6) cm –1 for monoclinic polycrystalline [Fe(TPP)Br] and [Fe(TPP)I], respectively. Along with our recent report of the ZFS value of D = 6.33(8) cm –1 for tetragonal polycrystalline [Fe(TPP)Cl], these data provide a rare, complete determination of ZFS parameters in a metalloporphyrin halide series.more » The electronic structure of [Fe(TPP)X] (X = F, Cl, Br, I) has been studied by multireference ab initio methods: the complete active space self-consistent field (CASSCF) and the N-electron valence perturbation theory (NEVPT2) with the aim of exploring the origin of the large and positive zero-field splitting D of the 6A 1 ground state. D was calculated from wave functions of the electronic multiplets spanned by the d 5 configuration of Fe(III) along with spin–orbit coupling accounted for by quasi degenerate perturbation theory. Results reproduce trends of D from inelastic neutron scattering data increasing in the order from F, Cl, Br, to I. A mapping of energy eigenvalues and eigenfunctions of the S = 3/2 excited states on ligand field theory was used to characterize the σ- and π-antibonding effects decreasing from F to I. This is in agreement with similar results deduced from ab initio calculations on CrX 6 3- complexes and also with the spectrochemical series showing a decrease of the ligand field in the same directions. A correlation is found between the increase of D and decrease of the π- and σ-antibonding energies e λ X (λ = σ, π) in the series from X = F to I. Analysis of this correlation using second-order perturbation theory expressions in terms of angular overlap parameters rationalizes the experimentally deduced trend. Furthermore, D parameters from CASSCF and NEVPT2 results have been calibrated against those from the INS data, yielding a predictive power of these approaches. Methods to improve the quantitative agreement between ab initio calculated and experimental D and spectroscopic transitions for high-spin Fe(III) complexes are proposed.« less

Magnetic Transitions in Iron Porphyrin Halides by Inelastic Neutron Scattering and Ab Initio Studies of Zero-Field Splittings.

PubMed

Stavretis, Shelby E; Atanasov, Mihail; Podlesnyak, Andrey A; Hunter, Seth C; Neese, Frank; Xue, Zi-Ling

2015-10-19

Zero-field splitting (ZFS) parameters of nondeuterated metalloporphyrins [Fe(TPP)X] (X = F, Br, I; H₂TPP = tetraphenylporphyrin) have been directly determined by inelastic neutron scattering (INS). The ZFS values are D = 4.49(9) cm⁻¹ for tetragonal polycrystalline [Fe(TPP)F], and D = 8.8(2) cm⁻¹, E = 0.1(2) cm⁻¹ and D = 13.4(6) cm⁻¹, E = 0.3(6) cm⁻¹ for monoclinic polycrystalline [Fe(TPP)Br] and [Fe(TPP)I], respectively. Along with our recent report of the ZFS value of D = 6.33(8) cm⁻¹ for tetragonal polycrystalline [Fe(TPP)Cl], these data provide a rare, complete determination of ZFS parameters in a metalloporphyrin halide series. The electronic structure of [Fe(TPP)X] (X = F, Cl, Br, I) has been studied by multireference ab initio methods: the complete active space self-consistent field (CASSCF) and the N-electron valence perturbation theory (NEVPT2) with the aim of exploring the origin of the large and positive zero-field splitting D of the ⁶A₁ ground state. D was calculated from wave functions of the electronic multiplets spanned by the d⁵ configuration of Fe(III) along with spin–orbit coupling accounted for by quasi degenerate perturbation theory. Results reproduce trends of D from inelastic neutron scattering data increasing in the order from F, Cl, Br, to I. A mapping of energy eigenvalues and eigenfunctions of the S = 3/2 excited states on ligand field theory was used to characterize the σ- and π-antibonding effects decreasing from F to I. This is in agreement with similar results deduced from ab initio calculations on CrX₆³⁻ complexes and also with the spectrochemical series showing a decrease of the ligand field in the same directions. A correlation is found between the increase of D and decrease of the π- and σ-antibonding energies e(λ)(X) (λ = σ, π) in the series from X = F to I. Analysis of this correlation using second-order perturbation theory expressions in terms of angular overlap parameters rationalizes the experimentally deduced trend. D parameters from CASSCF and NEVPT2 results have been calibrated against those from the INS data, yielding a predictive power of these approaches. Methods to improve the quantitative agreement between ab initio calculated and experimental D and spectroscopic transitions for high-spin Fe(III) complexes are proposed.

Theoretical studies of weak interactions of formamide with methanol and its derivates

NASA Astrophysics Data System (ADS)

Zheng, Xiao-Wen; Wang, Lu; Han, Shu-Min; Cui, Xiang-Yang; Du, Chong-Yang; Liu, Tao

2015-08-01

Theoretical calculations have been performed for the complexes of formamide (FA) with methanol and its derivates (MAX, X = F, Cl, Br, NO2, H, OH, CH3, and NH2) to study their structures and properties. Substituent effects on the hydrogen bond (H-bond) strength and cooperative effect by using water and its derivatives (HOZ, Z = H, NH2, and Br) as weak interaction probe were also explored. The calculation results show that electron-donating groups strengthen the weak interaction between formamide with methanol whereas electron-withdrawing groups weaken it. The cooperativity is present for the N-HïO H-bond in MAX-FA-HOZ and the cooperative effect increases in a series HONH2, HOH, and HOBr. In addition, we investigated the interaction between FA with hypohalous acids HOY (Y = F, Cl, and Br). It was found that the weak interaction between FA and HOY became stronger with the increase of the size of halogen atom. The nature of the halogen atom has negligible impact on the strength of the H-bond in MAX-FA (X = F, Cl, and Br), whereas it has an obvious influence on the strength of the H-bond in HOY-FA (Y = F, Cl, and Br).

The sources and evolution of mineralising fluids in iron oxide-copper-gold systems, Norrbotten, Sweden: Constraints from Br/Cl ratios and stable Cl isotopes of fluid inclusion leachates

NASA Astrophysics Data System (ADS)

Gleeson, S. A.; Smith, M. P.

2009-10-01

We have analysed the halogen concentrations and chlorine stable isotope composition of fluid inclusion leachates from three spatially associated Fe-oxide ± Cu ± Au mineralising systems in Norrbotten, Sweden. Fluid inclusions in late-stage veins in Fe-oxide-apatite deposits contain saline brines and have a wide range of Br/Cl molar ratios, from 0.2 to 1.1 × 10 -3 and δ 37Cl values from -3.1‰ to -1.0‰. Leachates from saline fluid inclusions from the Greenstone and Porphyry hosted Cu-Au prospects have Br/Cl ratios that range from 0.2 to 0.5 × 10 -3 and δ 37Cl values from -5.6‰ to -1.3‰. Finally, the Cu-Au deposits hosted by the Nautanen Deformation Zone (NDZ) have Br/Cl molar ratios from 0.4 to 1.1 × 10 -3 and δ 37Cl values that range from -2.4‰ to +0.5‰, although the bulk of the data fall within 0‰ ± 0.5‰. The Br/Cl ratios of leachates are consistent with the derivation of salinity from magmatic sources or from the dissolution of halite. Most of the isotopic data from the Fe-oxide-apatite and Greenstone deposits are consistent with a mantle derived source of the chlorine, with the exception of the four samples with the most negative values. The origin of the low δ 37Cl values in these samples is unknown but we suggest that there may have been some modification of the Cl-isotope signature due to fractionation between the mineralising fluids and Cl-rich silicate assemblages found in the alteration haloes around the deposits. If such a process has occurred then a modified crustal source of the chlorine for all the samples cannot be ruled out although the amount of fractionation necessary to generate the low δ 37Cl values would be significantly larger. The source of Cl in the NDZ deposits has a crustal signature, which suggests the Cl in this system may be derived from (meta-) evaporites or from input from crustal melts such as granitic pegmatites of the Lina Suite.

The origin of the conductivity maximum in molten salts. II. SnCl{sub 2} and HgBr{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aravindakshan, Nikhil P.; Kuntz, Colin M.; Gemmell, Kyle E.

2016-09-07

The phenomenon of electrical conductivity maxima of molten salts versus temperature during orthobaric (closed-vessel) conditions is further examined via ab initio simulations. Previously, in a study of molten BiCl{sub 3}, a new theory was offered in which the conductivity falloff at high temperatures is due not to traditional ion association, but to a rise in the activation energy for atomic ions hopping from counterion to counterion. Here this theory is further tested on two more inorganic melts which exhibit conductivity maxima: another high-conducting melt (SnCl{sub 2}, σ{sub max} = 2.81 Ω{sup −1} cm{sup −1}) and a low-conducting one (HgBr{sub 2},more » σ{sub max} = 4.06 × 10{sup −4} Ω{sup −1} cm{sup −1}). First, ab initio molecular dynamics simulations were performed and again appear successful in reproducing the maxima for both these liquids. Second, analysis of the simulated liquid structure (radial distributions, species concentrations) was performed. In the HgBr{sub 2} case, a very molecular liquid like water, a clear Grotthuss chain of bromide transfers was observed in simulation when seeding the system with a HgBr{sup +} cation and HgBr{sub 3}{sup −} anion. The first conclusion is that the hopping mechanism offered for molten BiCl{sub 3} is simply the Grotthuss mechanism for conduction, applicable not just to H{sup +} ions, but also to halide ions in post-transition-metal halide melts. Second, it is conjectured that the conductivity maximum is due to rising activation energy in network-covalent (halide-bridging) melts (BiCl{sub 3}, SnCl{sub 2}, PbCl{sub 2}), but possibly a falling Arrhenius prefactor (collision frequency) for molecular melts (HgBr{sub 2}).« less

Halide ions complex and deprotonate dipicolinamides and isophthalamides: assessment by mass spectrometry and UV-visible spectroscopy.

PubMed

Carasel, I Alexandru; Yamnitz, Carl R; Winter, Rudolph K; Gokel, George W

2010-12-03

The F(-), Cl(-), and Br(-) binding selectivity of bis(p-nitroanilide)s of dipicolinic and isophthalic acids was studied by using competitive electrospray mass spectrometry and UV-Visible spectroscopy. Both hosts prefer binding Cl(-) over either F(-) or Br(-). Host deprotonation was observed to some extent in all experiments in which the host was exposed to halide ions. When F(-) was present, host deprotonation was often the major process, whereas little deprotonation was observed by Cl(-) or Br(-), which preferred complexation. A solution of either host changed color when mixed with a F(-), H(2)PO(4)(-), di- or triphenylacetate solution.

Photon Reabsorption in Mixed CsPbCl3:CsPbI3 Perovskite Nanocrystal Films for Light-Emitting Diodes

PubMed Central

2017-01-01

Cesium lead halide nanocrystals, CsPbX3 (X = Cl, Br, I), exhibit photoluminescence quantum efficiencies approaching 100% without the core–shell structures usually used in conventional semiconductor nanocrystals. These high photoluminescence efficiencies make these crystals ideal candidates for light-emitting diodes (LEDs). However, because of the large surface area to volume ratio, halogen exchange between perovskite nanocrystals of different compositions occurs rapidly, which is one of the limiting factors for white-light applications requiring a mixture of different crystal compositions to achieve a broad emission spectrum. Here, we use mixtures of chloride and iodide CsPbX3 (X = Cl, I) perovskite nanocrystals where anion exchange is significantly reduced. We investigate samples containing mixtures of perovskite nanocrystals with different compositions and study the resulting optical and electrical interactions. We report excitation transfer from CsPbCl3 to CsPbI3 in solution and within a poly(methyl methacrylate) matrix via photon reabsorption, which also occurs in electrically excited crystals in bulk heterojunction LEDs. PMID:28316756

Multifrequency electron paramagnetic resonance and electron-nuclear double-resonance studies of photo-hole processes in AgBr and AgCl emulsion grains

NASA Astrophysics Data System (ADS)

Eachus, R. S.; Pawlik, Th D.; Baetzold, R. C.

2000-10-01

By using a combination of multifrequency EPR spectroscopy, ENDOR spectroscopy and calculations of structure and energy, the reactivities of photo-generated holes in microcrystalline AgBr and AgCl dispersions (photographic emulsions) have been followed in detail. Progress has been facilitated by the use of both gelatin and polyvinyl alcohol (PVA) as peptizers. The initial trapped hole centres produced by band-gap excitation have been identified. In AgBr, this species is [(Br4)3-.V], a neutral complex formed from hole trapping by the four nearest neighbours of a surface Ag+ vacancy (=V). [(Br4)3-.V] reacts with gelatin to produce a transient organic radical at the grain's surface. It does not, however, react with PVA. The formation of the oxidized gelatin radical might involve atomic bromine as an intermediate. In AgCl, the well-known self-trapped hole centre (AgCl6)4- is the initial hole species. The hole diffuses by an electron exchange process until it is trapped by a silver ion on the grain's surface or within its penultimate layer of lattice ions. It is subsequently released from this Ag2+ site to be retrapped at a centre containing four equivalent Cl- ions. The precise identity of this defect has yet to be determined, but its decay also results in the oxidation of gelatin.

Synthesis, structure, and magnetic properties of new layered phosphate halides Sr2Cu5(PO4)4X2·8H2O (X = Cl, Br) with a crown-like building unit.

PubMed

Qiu, Chaoqun; He, Zhangzhen; Cui, Meiyan; Tang, Yingying; Chen, Sihuai

2017-03-27

Two new compounds Sr 2 Cu 5 (PO 4 ) 4 X 2 ·8H 2 O (X = Cl and Br) are synthesized by a conventional hydrothermal method. Sr 2 Cu 5 (PO 4 ) 4 Cl 2 ·8H 2 O crystallizes in the tetragonal system with a space group of P42 1 2, while Sr 2 Cu 5 (PO 4 ) 4 Br 2 ·8H 2 O crystallizes in the space group P4/nmm, which are found to have a similar framework of layered structure, in which the crown-like {Cu 5 (PO 4 ) 4 X 2 } building units connect to each other forming a 2D corrugated sheet with vacancies, while the Sr 2+ cations are located along the vacancies. The spin lattice of two compounds built by Cu 2+ ions shows a new type of corrugated square. Magnetic measurements confirmed that both Sr 2 Cu 5 (PO 4 ) 4 X 2 ·8H 2 O (X = Cl and Br) exhibit antiferromagnetic ordering at low temperatures. A fit of theoretical model shows exchange interaction J = -25.62 K for the Cl-analogue and J/k B = -26.47 K for the Br-analogue.

A complex Ar⋯Agsbnd I produced by laser ablation and characterised by rotational spectroscopy and ab initio calculations: Variation of properties along the series Ar⋯Agsbnd X (X = F, Cl, Br and I)

NASA Astrophysics Data System (ADS)

Medcraft, Chris; Mullaney, John C.; Walker, Nicholas R.; Legon, Anthony C.

2017-05-01

A complex of argon with silver iodide (Ar⋯Agsbnd I) has been formed in the gas phase by laser ablation of a silver iodide rod in the presence of a pulse of argon gas and its ground-state rotational spectrum has been detected by means of a chirped-pulse, F-T microwave instrument. Ar⋯Agsbnd I was characterised both by experimental properties determined from its rotational spectrum and by ab initio calculations carried out at the CCSD(T)(F12c)/cc-pVTZ-F12 explicitly correlated level of theory. The molecule was shown to be linear in the ground state, with atoms in the order shown. The Ar⋯Ag and Agsbnd I bond lengths r0(Ar⋯Ag) = 2.6759 Å and r0(Agsbnd I) = 2.5356 Å, the dissociation energy De = 16.7 kJ mol-1 for the process Ar⋯Agsbnd I = Ar + Agsbnd I, the intermolecular quadratic stretching force constant FAr⋯Ag = F22 = 20.2(8) N m-1 and the increase 0.033 in the ionicity ic of Agsbnd I when it enters the complex are reported. The opportunity has been taken to compare the way in which these properties vary along the series Ar⋯Agsbnd X (X = F, Cl, Br and I).

Halogen and trace element geochemistry in Mid-Ocean Ridge basalts from the Australian-Antarctic Ridge (AAR)

NASA Astrophysics Data System (ADS)

Yang, Y. S.; Seo, J. H.; Park, S. H.; Kim, T.

2015-12-01

Australian-Antarctic Ridge (AAR) is an extension of easternmost SE Indian Mid-Ocean Ridge (MOR).We collected volcanic glasses from the "in-axis" of the KR1 and KR2 MOR, and the overlapping zones of the KR1 MOR and the nearby seamounts ("KR1 mixing"). We determined trace and halogen elements in the glasses. Halogen concentrations and its ratios in the glasses are important to understand the mantle metasomatism and volatile recycling. 52 of the collected glasses are "primitive" (higher than 6 wt% MgO), while 3 of them have rather "evolved" composition (MgO wt% of 1.72, 2.95 and 4.15). K2O concentrations and Th/Sc ratios in the glasses show a negative correlation with its MgO concentration. Incompatible element ratios such as La/Sm are rather immobile during a magma differentiation so the ratios are important to understand mantle composition (Hofmann et al. 2003). La/Sm ratios in the glasses are 0.95 ~ 3.28 suggesting that the AAR basalts can be classified into T-MORB and E-MORB (Schilling et al., 1983). La/Sm ratios are well-correlated with incompatible elements such as U, Ba, Nb, and negatively correlated with compatible elements such as Sc, Eu2+, Mg. The AAR glasses contain detectable halogen elements. The "KR1 mixing" glasses in halogen elements are more abundant than "in-axis" the glasses. Cl is the least variable element compared to the other halogens such as Br and I in the AAR. The "KR1 mixing" glasses have the largest variations of Br/Cl ratios compared to the "in-axis" glasses. The Cl/Br and Th/Sc ratios in the "in-axis" glasses and in the "KR1 mixing" glasses show positive and negative correlations, respectively. The Br-rich glasses in the "KR1 mixing" zone might be explained by a recycled Br-rich oceanic slab of paleo-subduction or by a hydrothermal alteration in the AAR. I composition in the glasses does not show a correlation other trace elements. The K/Cl and K/Ti ratios in the AAR glasses are similar to the basalts from the Galapagos Spreading Center (Geldmacher et al., 2010) and Pacific MORB. The AAR region closely located with Balleny hotspot (Lanyon et al., 1993) and Pacific-Antarctic Ridge. K2O/Nb and Zr/Nb ratios are very low compared with near Pacific-Antarctic Ridge and Southeast Indian Ridge. The ratios are close to the Balleny hotspot.

Structure and properties of the anions MF4-, MCl4- and MBr4- (M = C, Si, Ge)

NASA Astrophysics Data System (ADS)

Grein, Friedrich

2015-04-01

Density functional theory (DFT), Møller-Plesset (MP2) and coupled cluster with single and double substitutions including non-iterative triple excitations (CCSD(T)) calculations on the anions MX4-, with M = C, Si, Ge and X = F, Cl, Br, show that GeF4-, SiCl4-, GeCl4- and SiBr4- prefer a C2v conformation, but CCl4- is an elongated C3v structure. CBr4- has Td symmetry in MP2, but is slightly more stable in elongated C3v form with DFT and CCSD(T). GeBr4- has Td symmetry. CF4- and SiF4- are unstable with respect to loss of an electron. Vertical electron affinities (EAs) are negative also for CCl4 and SiCl4, and close to zero for GeF4 and SiBr4. Adiabatic EAs range from 0.47 eV for SiCl4 to 1.78 eV for GeBr4. The lowest excited states at Td symmetry are 2T2 resonances with energies of 2.1-3.5 eV, resulting from excitation of the a1 singly occupied molecular orbital to vacant t2 orbitals. Vertical excitation energies (VEEs) and vibrational frequencies are given for the most stable anionic geometries. Comparison with experimental VEEs for CCl4- is made. From dissociation energies of MX4, MX4-, MX3 and MX3-, appearance energies of X-, MX3-, X2- and MX2- were calculated. Most were found to be in reasonable agreement with experimental values. Theoretical spin densities and g-factors have been compared with experimental results available for CCl4-, SiCl4- and GeCl4-.

[The tasks and aims of hospital psychiatry today and in the future].

PubMed

Honig, A; Sierink, D; Verwey, B

Care provided by consultation-liaison (CL) psychiatry and general hospital (GH) psychiatry varies widely. This means that certain services are almost unrecognisable and therefore less readily available to patients.
AIM: To describe the core tasks of current CL- and GH-psychiatry care and to suggest how these tasks can best be performed and developed in the future.
METHOD: We conducted a selective review of relevant CL- and GH-related literature and combined the information we obtained with the results of a consultation with CL-psychiatrists about how CL- and GL psychiatry should function in the future.
RESULTS: Core tasks of CL- and GH-psychiatry are: 1. inpatient and outpatient care for complex patients with combined somatic and psychiatric problems (including addiction) and 2. acute care, diagnosis and treatment of patients referred to the Emergency Department. We gave an outline of how the quality of training can be maintained and/or improved and we suggest ways in which the funding of CL- and GH-psychiatry can be safeguarded and, if possible, increased in the future.
CONCLUSION: We strongly recommend that large teaching hospitals and all university hospitals should have at their disposal a psychiatric consultation service that includes psychiatric Emergency Department facilities and specialised CL and GH inpatient and outpatient facility such as a medical-psychiatric unit. The CL- and GH-service should have a psychiatrist as gatekeeper and should be integrated into the hospital's chain of care. Partners in this chain of care are interns who have other medical specialisms, mental health specialists employed at other (mainly psychiatric) hospitals and general practitioners (GPs).

Easy access to silicon(0) and silicon(II) compounds.

PubMed

Mondal, Kartik Chandra; Samuel, Prinson P; Tretiakov, Mykyta; Singh, Amit Pratap; Roesky, Herbert W; Stückl, A Claudia; Niepötter, Benedikt; Carl, Elena; Wolf, Hilke; Herbst-Irmer, Regine; Stalke, Dietmar

2013-04-15

Two different synthetic methodologies of silicon dihalide bridged biradicals of the general formula (L(n)•)2SiX2 (n = 1, 2) have been developed. First, the metathesis reaction between NHC:SiX2 and L(n): (L(n): = cyclic akyl(amino) carbene in a 1:3 molar ratio leads to the products 2 (n = 1, X = Cl), 4 (n = 2, X = Cl), 6 (n = 1, X = Br), and 7 (n = 2, X = Br). These reactions also produce coupled NHCs (3, 5) under C-C bond formation. The formation of the coupled NHCs (L(m) = cyclic alkyl(amino) carbene substituted N-heterocyclic carbene; m = 3, n = 1 (3) and m = 4, n =2 (5)) is faster during the metathesis reaction between NHC:SiBr2 and L(n): when compared with that of NHC:SiCl2. Second, the reaction of L(1):SiCl4 (8) (L(1): =:C(CH2)(CMe2)2N-2,6-iPr2C6H3) with a non-nucleophilic base LiN(iPr)2 in a 1:1 molar ratio shows an unprecedented methodology for the synthesis of the biradical (L(1)•)2SiCl2 (2). The blue blocks of silicon dichloride bridged biradicals (2, 4) are stable for more than six months under an inert atmosphere and in air for one week. Compounds 2 and 4 melt in the temperature range of 185 to 195 °C. The dibromide (6, 7) analogue is more prone to decomposition in the solution but comparatively more stable in the solid state than in the solution. Decomposition of the products has been observed in the UV-vis spectra. Moreover, compounds 2 and 4 were further converted to stable singlet biradicaloid dicarbene-coordinated (L(n):)2Si(0) (n = 1 (9), 2 (10)) under KC8 reduction. Compounds 2 and 4 were also reduced to dehalogenated products 9 and 10, respectively when treated with RLi (R = Ph, Me, tBu). Cyclic voltametry measurements show that 10 can irreversibly undergo both one electron oxidation and reduction.

Synthesis of Cesium Lead Halide Perovskite Quantum Dots

ERIC Educational Resources Information Center

Shekhirev, Mikhail; Goza, John; Teeter, Jacob D.; Lipatov, Alexey; Sinitskii, Alexander

2017-01-01

Synthesis of quantum dots is a valuable experiment for demonstration and discussion of quantum phenomena in undergraduate chemistry curricula. Recently, a new class of all-inorganic perovskite quantum dots (QDs) with a formula of CsPbX[subscript 3] (X = Cl, Br, I) was presented and attracted tremendous attention. Here we adapt the synthesis of…

Conductive hydrogel containing 3-ionene

NASA Technical Reports Server (NTRS)

Rembaum, Alan (Inventor); Yen, Shiao-Ping Siao (Inventor)

1977-01-01

Cationic polyelectrolytes formed by the polymerization in absence of oxygen of a monomer of the general formula: dispersed ##STR1## where x is 3 or more than 6 and Z is I, Br or Cl to form high charge density linear polymers are dispered in a water-soluble polymer such as polyvinyl alcohol to form a conductive hydrogel.

First-principles study of electronic and optical properties of lead-free double perovskites Cs2NaBX6 (B = Sb, Bi; X = Cl, Br, I)

NASA Astrophysics Data System (ADS)

Zhao, Shuai; Yamamoto, Kumiko; Iikubo, Satoshi; Hayase, Shuzi; Ma, Tingli

2018-06-01

Organolead halide perovskite is regarded as the most promising light-harvesting material for next-generation solar cells; however, the intrinsic instability and toxicity of lead are still of great concern. Bismuth is ecofriendly and has electronic properties similar to those of lead, which has gradually attracted interest for optoelectronic applications. However, the valence state of bismuth is different from that of lead, eliminating the possibility of replacing lead by bismuth in organolead halide perovskites. To address this matter, one feasible strategy is to construct B-site double perovskites by the combination of Bi3+ and B+ in 1:1 ratio. In this work, lead-free halide double perovskites of the form Cs2NaBX6 (B = Sb, Bi; X = Cl, Br, I) were investigated by first-principles calculations. The electronic properties, optical absorption coefficients, and thermodynamic stability of these compounds were investigated to ascertain their potential application in solar energy conversion. The results provide theoretical support for the exploration of lead-free perovskite materials in potential optoelectronic applications.

Lattice and Valence Electronic Structures of Crystalline Octahedral Molybdenum Halide Clusters-Based Compounds, Cs2[Mo6X14] (X = Cl, Br, I), Studied by Density Functional Theory Calculations.

PubMed

Saito, Norio; Cordier, Stéphane; Lemoine, Pierric; Ohsawa, Takeo; Wada, Yoshiki; Grasset, Fabien; Cross, Jeffrey S; Ohashi, Naoki

2017-06-05

The electronic and crystal structures of Cs 2 [Mo 6 X 14 ] (X = Cl, Br, I) cluster-based compounds were investigated by density functional theory (DFT) simulations and experimental methods such as powder X-ray diffraction, ultraviolet-visible spectroscopy, and X-ray photoemission spectroscopy (XPS). The experimentally determined lattice parameters were in good agreement with theoretically optimized ones, indicating the usefulness of DFT calculations for the structural investigation of these clusters. The calculated band gaps of these compounds reproduced those experimentally determined by UV-vis reflectance within an error of a few tenths of an eV. Core-level XPS and effective charge analyses indicated bonding states of the halogens changed according to their sites. The XPS valence spectra were fairly well reproduced by simulations based on the projected electron density of states weighted with cross sections of Al K α , suggesting that DFT calculations can predict the electronic properties of metal-cluster-based crystals with good accuracy.

Metal complexes of 3-(4-bromophenyl)-1-pyridin-2-ylprop-2-en-1-one thiosemicarbazone: cytotoxic activity and investigation on the mode of action of the gold(III) complex.

PubMed

Sâmia, Luciana B P; Parrilha, Gabrieli L; Da Silva, Jeferson G; Ramos, Jonas P; Souza-Fagundes, Elaine M; Castelli, Silvia; Vutey, Venn; Desideri, Alessandro; Beraldo, Heloisa

2016-06-01

Complexes [Au(PyCT4BrPh)Cl]Cl (1), [Pt(PyCT4BrPh)Cl]0.5KCl (2), and [Pd(PyCT4BrPh)Cl]KCl (3) were obtained with 3-(4-bromophenyl)-1-pyridin-2-ylprop-2-en-1-one thiosemicarbazone (HPyCT4BrPh). Although complexes (2) and (3) did not exhibit potent cytotoxic activity, HPyCT4BrPh and its gold(III) complex (1) proved to be highly cytotoxic against HL-60 (human promyelocytic leukemia) and THP-1 (human monocytic leukemia) cells, and against MDA-MB 231 and MCF-7 (human breast adenocarcinoma) solid tumor cells. Except for HL-60 cells, upon coordination to gold(III) a 2- to 3-fold increase in the cytotoxic effect was observed. An investigation on the possible biological targets of the gold(III) complex was carried out. Complex (1) but not the free thiosemicarbazone inhibits the enzymatic activity of thioredoxin reductase (TrxR). The affinity of 1 for TrxR suggests metal binding to a selenol residue in the active site of the enzyme. While HPyCT4BrPh was inactive, 1 was able to inhibit topoisomerase IB (Topo IB) activity. Hence, inhibition of TrxR and Topo IB could contribute to the mechanism of cytotoxic action of complex (1).

Temperature and Pressure Dependences of the Reactions of Fe+ with Methyl Halides CH3X (X = Cl, Br, I): Experiments and Kinetic Modeling Results.

PubMed

Ard, Shaun G; Shuman, Nicholas S; Martinez, Oscar; Keyes, Nicholas R; Viggiano, Albert A; Guo, Hua; Troe, Jürgen

2017-06-01

The pressure and temperature dependences of the reactions of Fe + with methyl halides CH 3 X (X = Cl, Br, I) in He were measured in a selected ion flow tube over the ranges 0.4 to 1.2 Torr and 300-600 K. FeX + was observed for all three halides and FeCH 3 + was observed for the CH 3 I reaction. FeCH 3 X + adducts (for all X) were detected in all reactions. The results were interpreted assuming two-state reactivity with spin-inversions between sextet and quartet potentials. Kinetic modeling allowed for a quantitative representation of the experiments and for extrapolation to conditions outside the experimentally accessible range. The modeling required quantum-chemical calculations of molecular parameters and detailed accounting of angular momentum effects. The results show that the FeX + products come via an insertion mechanism, while the FeCH 3 + can be produced from either insertion or S N 2 mechanisms, but the latter we conclude is unlikely at thermal energies. A statistical modeling cannot reproduce the competition between the bimolecular pathways in the CH 3 I reaction, indicating that some more direct process must be important.

Electrical properties and Raman studies of phase transitions in ferroelectric [N(CH3)4]2CoCl2Br2

NASA Astrophysics Data System (ADS)

Ben Mohamed, C.; Karoui, K.; Bulou, A.; Ben Rhaiem, A.

2018-03-01

The present paper accounted for the synthesis, electric properties and vibrational spectroscopy of [N(CH3)4]2CoCl2Br2. The dielectric spectra were measured in the frequency range 10-1-105 Hz and temperature interval from 223 to 393 K. The dielectical properties confirm the ferroelectric-paraelectric phase transition at 290 K, which is reported by Abdallah Ben Rhaiem et al. (2013). The equivalent circuit based on the Z-View-software was proposed and the conduction mechanisms were determined. The obtained results have been discussed in terms of the correlated barrier hopping model (CBH) in phase I and non-overlapping small polaron tunneling model (NSPT) in phases II and III. Raman spectra as function temperature have been used to characterize the phase transitions and their nature, which indicates a change of the some peak near the transitions phase.

The anomalous halogen bonding interactions between chlorine and bromine with water in clathrate hydrates.

PubMed

Dureckova, Hana; Woo, Tom K; Udachin, Konstantin A; Ripmeester, John A; Alavi, Saman

2017-10-13

Clathrate hydrate phases of Cl 2 and Br 2 guest molecules have been known for about 200 years. The crystal structure of these phases was recently re-determined with high accuracy by single crystal X-ray diffraction. In these structures, the water oxygen-halogen atom distances are determined to be shorter than the sum of the van der Waals radii, which indicates the action of some type of non-covalent interaction between the dihalogens and water molecules. Given that in the hydrate phases both lone pairs of each water oxygen atom are engaged in hydrogen bonding with other water molecules of the lattice, the nature of the oxygen-halogen interactions may not be the standard halogen bonds characterized recently in the solid state materials and enzyme-substrate compounds. The nature of the halogen-water interactions for the Cl 2 and Br 2 molecules in two isolated clathrate hydrate cages has recently been studied with ab initio calculations and Natural Bond Order analysis (Ochoa-Resendiz et al. J. Chem. Phys. 2016, 145, 161104). Here we present the results of ab initio calculations and natural localized molecular orbital analysis for Cl 2 and Br 2 guests in all cage types observed in the cubic structure I and tetragonal structure I clathrate hydrates to characterize the orbital interactions between the dihalogen guests and water. Calculations with isolated cages and cages with one shell of coordinating molecules are considered. The computational analysis is used to understand the nature of the halogen bonding in these materials and to interpret the guest positions in the hydrate cages obtained from the X-ray crystal structures.

Gas-Phase Brønsted Superacidity of Some Derivatives of Monocarba-closo-Borates: a Computational Study

NASA Astrophysics Data System (ADS)

Lipping, Lauri; Leito, Ivo; Koppel, Ivar; Koppel, Ilmar A.

2009-10-01

The structures and gas-phase acidities (GA) of several CB11H12H-based carborane acid derivatives (HA) have been calculated with DFT B3LYP method using 6-311+G**, 6-311++G** basis sets. In order to verify the obtained GA values, several systems were also studied at G3(MP2) level of theory. Inserted substituents (CF3, F, Cl, Br, I, CN, CH3, etc.) followed the "belts" of the monocarborane cage starting from the boron antipodal to the carbon. In general, the predicted intrinsic gas-phase acidities of the systems varied according to the substituents in the following order of decreasing strength: CF3 > F > Cl > Br > I > CN > CH3. Nevertheless, some inconsistencies occurred. F and CN derivatives with lower degree of substitution had weaker intrinsic acidities than the respective Cl derivatives, but the situation was reversed in the case of a larger number of substituents. To obtain better understanding how the substituents influence the basicity of the carborane anion, three hypothetical reaction series were investigated, in which the protonation center was fixed on the boron atom (B12), antipodal to the carbon (C1), and a single substituent replaced the hydrogens at the vertexes of the three remaining positions (C1, B2, and B7). The intrinsic gas-phase acidities in these series of neutral carborane-based acids CB11X1H11H are found to clearly depend on the field-inductive and resonance effects of the substituent X. Some influence of the polarizability of X on the reaction center (B12) could be detected only in the alpha position (B7).

THE INTERSECTION OF STABLE AND NON-EQUILIBRIUM TETRAHEDRA IN A MUTUAL 7- COMPONENT SYSTEM OF Li, Na, Rb, T1/Br, C1, NO$sub 3$, SO$sub 4$ (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dombrovskaya, N.S.; Khakhlova, N.V.; Alekseeva, E.A.

1961-04-21

The most stable configuration of the mixture of the 16 salts formed from Li, Na, Rb, Tl/Br, Cl, NO/sub 3/, and S0/sub 4/ con ture which however interact, resulting in a stable mixture. On the basis of exchange reactions the following equation has been derived: LiBr + NaNO/sub 3/ + RbCl + 1/2Tl/sub 2/SO/sub 4/ = 1/ 2LiSO/sub 4/ + NaCl + RbNO/sub 3/ + TlBr. In addition, several binary complexes are also formed, such as Li/sub 2/SO/sub 4/ - Rb/sub 2/SO/sub 4/, 4Li/sub 2/SO/ sub 4/ - RbSO /sub 4/, RbCl - 2Li/sub 2/SO/sub 4/ and possible others. Inmore » view of the great interest, the intersection of stable and non-equilibrium tetrahedra consisting of components of both, was experimentally studied by thermai analysis. On the basis of cooling curves the following deflection points have been observed: 453 deg C, precipitation of the first Li/sub 2/SO/sub 4/ crystals; 409 deg , coprecipitation of Li/sub 2/SO/sub 4/ and NaCl; 391 deg , coprecipitation of Li/sub 2/SO/sub 4/, NaCl snd TlBr; and finally at 107 deg , formation of the quaternary eutectic with the previously mentioned salts + RbNO/sub 3/. The microstructures of the stable and non-equilibrium phases are quite similar. (TTT)« less

Brominated VSLSs in and over the East Pacific During the Halocarbon Air-Sea Transect - Pacific Cruise (HalocAST-P)

NASA Astrophysics Data System (ADS)

Liu, Y.; Yvon-Lewis, S. A.; Hu, L.; Smith, R. W.; Shen, L.; Bianchi, T. S.; Campbell, L.

2010-12-01

Brominated very short lived substances (VSLSs), such as bromoform (CHBr3), dibromomethane (CH2Br2), dibromochloromethane (CHClBr2), and dichlorobromomethane (CHBrCl2) can potentially supply a significant amount of inorganic bromine (Bry) to the troposphere and lower stratosphere. Bromine radicals are 50 - 100 times more efficient in depleting ozone (O3) than chlorine radicals; therefore, these compounds are important to the ozone chemistry in the atmosphere. CHBr3, CH2Br2, CHClBr2 and CHBrCl2 are thought to be produced mainly by phytoplankton in the open ocean. During the Halocarbon Air-Sea Transect - Pacific (HalocAST - P) cruise we examined the distributions of halocarbons in the East Pacific Ocean and in the overlying atmosphere. The cruise started from Punta Arenas, Chile on March 29, and finished at Seattle, WA, United States on April 29 2010. Continuous underway measurements of the atmospheric and surface seawater concentrations along with depth profiles of CHBr3, CH2Br2, CHClBr2, CHBrCl2, and a suite of other halogenated compounds were measured over a large cross latitudinal transect. The brominated VSLS measured during this cruise generally exhibit a correlation with chlorophyll a, supporting biogenic production as the predominate source for these compounds in the open ocean. Here, we will be discussing air and seawater concentrations, saturation anomalies, fluxes, and depth profiles for CHBr3, CH2Br2, CHClBr2, and CHBrCl2. Cyanobacteria counts, pigment compositions, nutrient and dissolved organic carbon (DOC) concentrations in the water column were also measured and serve as useful tools for understanding the biological production of these brominated VSLSs.

Mercury monohalides: suitability for electron electric dipole moment searches.

PubMed

Prasannaa, V S; Vutha, A C; Abe, M; Das, B P

2015-05-08

Heavy polar diatomic molecules are the primary tools for searching for the T-violating permanent electric dipole moment of the electron (eEDM). Valence electrons in some molecules experience extremely large effective electric fields due to relativistic interactions. These large effective electric fields are crucial to the success of polar-molecule-based eEDM search experiments. Here we report on the results of relativistic ab initio calculations of the effective electric fields in a series of molecules that are highly sensitive to an eEDM, the mercury monohalides (HgF, HgCl, HgBr, and HgI). We study the influence of the halide anions on E_{eff}, and identify HgBr and HgI as attractive candidates for future electric dipole moment search experiments.

Bromide supplementation exacerbated the renal dysfunction, injury and fibrosis in a mouse model of Alport syndrome.

PubMed

Yokota, Tsubasa; Omachi, Kohei; Suico, Mary Ann; Kojima, Haruka; Kamura, Misato; Teramoto, Keisuke; Kaseda, Shota; Kuwazuru, Jun; Shuto, Tsuyoshi; Kai, Hirofumi

2017-01-01

A seminal study recently demonstrated that bromide (Br-) has a critical function in the assembly of type IV collagen in basement membrane (BM), and suggested that Br- supplementation has therapeutic potential for BM diseases. Because salts of bromide (KBr and NaBr) have been used as antiepileptic drugs for several decades, repositioning of Br- for BM diseases is probable. However, the effects of Br- on glomerular basement membrane (GBM) disease such as Alport syndrome (AS) and its impact on the kidney are still unknown. In this study, we administered daily for 16 weeks 75 mg/kg or 250 mg/kg (within clinical dosage) NaBr or NaCl (control) via drinking water to 6-week-old AS mice (mouse model of X-linked AS). Treatment with 75 mg/kg NaBr had no effect on AS progression. Surprisingly, compared with 250 mg/kg NaCl, 250 mg/kg NaBr exacerbated the progressive proteinuria and increased the serum creatinine and blood urea nitrogen in AS mice. Histological analysis revealed that glomerular injury, renal inflammation and fibrosis were exacerbated in mice treated with 250 mg/kg NaBr compared with NaCl. The expressions of renal injury markers (Lcn2, Lysozyme), matrix metalloproteinase (Mmp-12), pro-inflammatory cytokines (Il-6, Il-8, Tnf-α, Il-1β) and pro-fibrotic genes (Tgf-β, Col1a1, α-Sma) were also exacerbated by 250 mg/kg NaBr treatment. Notably, the exacerbating effects of Br- were not observed in wild-type mice. These findings suggest that Br- supplementation needs to be carefully evaluated for real positive health benefits and for the absence of adverse side effects especially in GBM diseases such as AS.

Sticky ions in biological systems.

PubMed Central

Collins, K D

1995-01-01

Aqueous gel sieving chromatography on Sephadex G-10 of the Group IA cations (Li+, Na+, K+, Rb+, Cs+) plus NH4+ as the Cl- salts, in combination with previous results for the halide anions (F-, Cl-, Br-, I-) as the Na+ salts [Washabaugh, M.W. & Collins, K.D. (1986) J. Biol. Chem. 261, 12477-12485], leads to the following conclusions. (i) The small monovalent ions (Li+, Na+, F-) flow through the gel with water molecules attached, whereas the large monovalent ions (K+, Rb+, Cs+, Cl-, Br-, I-) adsorb to the nonpolar surface of the gel, a process requiring partial dehydration of the ion and implying that these ions bind the immediately adjacent water molecules weakly. (ii) The transition from strong to weak hydration occurs at a radius of about 1.78 A for the monovalent anions, compared with a radius of about 1.06 A for the monovalent cations (using ionic radii), indicating that the anions are more strongly hydrated than the cations for a given charge density. (iii) The anions show larger deviations from ideal behavior (an elution position corresponding to the anhydrous molecular weight) than do the cations and dominate the chromatographic behavior of the neutral salts. These results are interpreted to mean that weakly hydrated ions (chaotropes) are "pushed" onto weakly hydrated surfaces by strong water-water interactions and that the transition from strong ionic hydration to weak ionic hydration occurs where the strength of ion-water interactions approximately equals the strength of water-water interactions in bulk solution. PMID:7539920

Antiferromagnetism in a Family of S = 1 Square Lattice Coordination Polymers NiX 2 (pyz) 2 (X = Cl, Br, I, NCS; pyz = Pyrazine)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Junjie; Goddard, Paul A.; Singleton, John

The crystal structures of NiX2(pyz)(2) (X = Cl (1), Br (2), I (3), and NCS (4)) were determined by synchrotron X-ray powder diffraction. All four compounds consist of two-dimensional (2D) square arrays self-assembled from octahedral NiN4X2 units that are bridged by pyz ligands. The 2D layered motifs displayed by 1-4 are relevant to bifluoride-bridged [Ni(HF2) (pyz)(2)]EF6 (E = P, Sb), which also possess the same 2D layers. In contrast, terminal X ligands occupy axial positions in 1-4 and cause a staggered packing of adjacent layers. Long-range antiferromagnetic (AFM) order occurs below 1.5 (Cl), 1.9 (Br and NCS), and 2.5 Kmore » (I) as determined by heat capacity and muon-spin relaxation. The single-ion anisotropy and g factor of 2, 3, and 4 were measured by electron-spin resonance with no evidence for zero field splitting (ZFS) being observed. The magnetism of 1-4 spans the spectrum from quasi-two-dimensional (2D) to three-dimensional (3D) antiferromagnetism. Nearly identical results and thermodynamic features were obtained for 2 and 4 as shown by pulsed-field magnetization, magnetic susceptibility, as well as their Neel temperatures. Magnetization curves for 2 and 4 calculated by quantum Monte Carlo simulation also show excellent agreement with the pulsed-field data. Compound 3 is characterized as a 3D AFM with the interlayer interaction (j(perpendicular to)) being slightly stronger than the intralayer interaction along Ni-pyz-Ni segments (j(pyz)) within the two-dimensional [Ni(pyz)(2)](2+) square planes. Regardless of X, j(pyz), is similar for the four compounds and is roughly 1 K.« less

Method for production of hydrocarbons from hydrates

DOEpatents

McGuire, Patrick L.

1984-01-01

A method of recovering natural gas entrapped in frozen subsurface gas hydrate formations in arctic regions. A hot supersaturated solution of CaCl.sub.2 or CaBr.sub.2, or a mixture thereof, is pumped under pressure down a wellbore and into a subsurface hydrate formation so as to hydrostatically fracture the formation. The CaCl.sub.2 /CaBr.sub.2 solution dissolves the solid hydrates and thereby releases the gas entrapped therein. Additionally, the solution contains a polymeric viscosifier, which operates to maintain in suspension finely divided crystalline CaCl.sub.2 /CaBr.sub.2 that precipitates from the supersaturated solution as it is cooled during injection into the formation.

Rejection of Bromide and Bromate Ions by a Ceramic Membrane

PubMed Central

Moslemi, Mohammadreza; Davies, Simon H.; Masten, Susan J.

2012-01-01

Abstract Effects of pH and the addition of calcium chloride (CaCl2) on bromate (BrO3−) and bromide (Br−) rejection by a ceramic membrane were investigated. Rejection of both ions increased with pH. At pH 8, the rejection of BrO3− and Br− was 68% and 63%, respectively. Donnan exclusion appears to play an important role in determining rejection of BrO3− and Br−. In the presence of CaCl2, rejection of BrO3− and Br− ions was greatly reduced, confirming the importance of electrostatic interactions in determining rejection of BrO3− and Br−. The effect of Ca2+ is so pronounced that in most natural waters, rejection of both BrO3− and Br− by the membrane would be extremely small. PMID:23236251

Thioether coordination to divalent selenium halide acceptors--synthesis, properties and structures.

PubMed

Jolleys, Andrew; Levason, William; Reid, Gillian

2013-02-28

The tetravalent SeCl(4) and SeBr(4) are reduced in the presence of thioether ligands L (SMe(2), tht) or L-L (MeS(CH(2))(n)SMe (n = 2 or 3), o-C(6)H(4)(SMe)(2)) in MeCN solution at 0 °C, forming Se(II) thioether complexes, including the crystallographically characterised halo-bridged chain polymers [SeX(2)(SMe(2))] (X = Cl or Br), molecular trans-[SeX(2)(tht)(2)], cis-[SeBr(2){MeS(CH(2))(2)SMe}] and the thioether-bridged polymer [SeBr(2){MeS(CH(2))(3)SMe}], as the main products, together with halogenated ligand. The [SeX(2)(L)(2)] and [SeX(2)(L-L)] complexes are all based upon distorted square planar coordination, with two Se-based lone pairs assumed to occupy the (vacant) axial sites, and Se-S bond distances of ca. 2.4-2.6 Å. The 1:1 species [SeX(2)(SMe(2))] are T-shaped with trans X groups and weak intermolecular SeX contacts. The SeCl(2)-thioether complexes are less stable than the bromides, both in solution in CH(2)Cl(2) and as solids at ambient temperature. Reaction of SeBr(4) with o-C(6)H(4)(SMe(2))(2) leads to the red complex cis-[SeBr(2){κ(1)-o-C(6)H(4)(SMe)(2)}(2)] as the major product; together with a minor (yellow) product formed via bromination of the aromatic ring, [SeBr(2){4-Br-1,2-(SMe)(2)-C(6)H(3)}(2)]. The crystal structure confirms a V-shaped SeBr(2) unit with long (weak) κ(1)-interactions to one S donor (meta to the Br) from two brominated ligands--an extremely rare coordination mode for an o-phenylene dithioether. Similar reaction of o-C(6)H(4)(SMe(2))(2) with SeCl(4) leads to several species, including monosulfonium cation, [1](+) formed by coupling of one thioether group to the C4-position of the phenylene backbone in an adjacent molecule, confirmed crystallographically. Carbon-sulfur coupling is also evident in the reaction of SeX(4) with o-C(6)H(4)(CH(2)SMe)(2), leading to two related cyclic sulfonium species, [2](+) and [3](+), which were structurally characterised as [SeBr(4)](2-) and [Se(2)Cl(6)](2-) salts respectively. Reaction of SeX(4) with SeMe(2) leads to halogenation of the ligand to form Me(2)SeX(2) and reduction of the SeX(4) to elemental selenium.

MERCURY REMOVAL FROM STACK GAS BY AQUEOUS SCRUBBING

EPA Science Inventory

Fundamental results will be obtained on the reaction kinetics in mass transfer boundary layers for the following systems:

Hg(g)/Cl2(g)/SO2(g)/sulfite
Hg(g)/ClO2(g)/SO2...

• Temperature dependence of dissociative electron attachment to bromo-chlorotoluene isomers: Competition between detachment of Cl- and Br-

  NASA Astrophysics Data System (ADS)

  Mahmoodi-Darian, Masoomeh; Huber, Stefan E.; Mauracher, Andreas; Probst, Michael; Denifl, Stephan; Scheier, Paul; Märk, Tilmann D.

  2018-02-01

  Dissociative electron attachment to three isomers of bromo-chlorotoluene was investigated in the electron energy range from 0 to 2 eV for gas temperatures in the range of 392-520 K using a crossed electron-molecular beam apparatus with a temperature regulated effusive molecular beam source. For all three molecules, both Cl- and Br- are formed. The ion yields of both halogenides show a pronounced temperature effect. In the case of Cl- and Br-, the influence of the gas temperature can be observed at the threshold peak close to 0 eV. The population of molecules that have some of their out-of-plane modes excited varies strongly in the temperature range investigated, indicating that such vibrations might play a role in the energy transfer towards bond breaking. Potential energy curves for the abstraction of Cl- and Br- were calculated and extrapolated into the metastable domain. The barriers in the diabatic curves approximated in this way agree well with the ones derived from the temperature dependence observed in the experiments.

• Enhanced ionic conductivity with Li 7O 2Br 3 phase in Li 3OBr anti-perovskite solid electrolyte

  DOE Office of Scientific and Technical Information (OSTI.GOV)

  Zhu, Jinlong; Li, Shuai; Zhang, Yi

  Cubic anti-perovskites with general formula Li 3OX (X = Cl, Br, I) were recently reported as superionic conductors with the potential for use as solid electrolytes in all-solid-state lithium ion batteries. These electrolytes are nonflammable, low-cost, and suitable for thermoplastic processing. However, the primary obstacle of its practical implementation is the relatively low ionic conductivity at room temperature. In this work, we synthesized a composite material consisting of two anti-perovskite phases, namely, cubic Li 3OBr and layered Li 7O 2Br 3, by solid state reaction routes. The results indicate that with the phase fraction of Li 7O 2Br 3 increasingmore » to 44 wt. %, the ionic conductivity increased by more than one order of magnitude compared with pure phase Li 3OBr. Formation energy calculations revealed the meta-stable nature of Li 7O 2Br 3, which supports the great difficulty in producing phase-pure Li 7O 2Br 3 at ambient pressure. Here, methods of obtaining phase-pure Li 7O 2Br 3 will continue to be explored, including both high pressure and metathesis techniques.« less

Enhanced ionic conductivity with Li 7O 2Br 3 phase in Li 3OBr anti-perovskite solid electrolyte

DOE PAGES

Zhu, Jinlong; Li, Shuai; Zhang, Yi; ...

2016-09-07

Cubic anti-perovskites with general formula Li 3OX (X = Cl, Br, I) were recently reported as superionic conductors with the potential for use as solid electrolytes in all-solid-state lithium ion batteries. These electrolytes are nonflammable, low-cost, and suitable for thermoplastic processing. However, the primary obstacle of its practical implementation is the relatively low ionic conductivity at room temperature. In this work, we synthesized a composite material consisting of two anti-perovskite phases, namely, cubic Li 3OBr and layered Li 7O 2Br 3, by solid state reaction routes. The results indicate that with the phase fraction of Li 7O 2Br 3 increasingmore » to 44 wt. %, the ionic conductivity increased by more than one order of magnitude compared with pure phase Li 3OBr. Formation energy calculations revealed the meta-stable nature of Li 7O 2Br 3, which supports the great difficulty in producing phase-pure Li 7O 2Br 3 at ambient pressure. Here, methods of obtaining phase-pure Li 7O 2Br 3 will continue to be explored, including both high pressure and metathesis techniques.« less

Structural Characterization of Methanol Substituted Lanthanum Halides

PubMed Central

Boyle, Timothy J.; Ottley, Leigh Anna M.; Alam, Todd M.; Rodriguez, Mark A.; Yang, Pin; Mcintyre, Sarah K.

2010-01-01

The first study into the alcohol solvation of lanthanum halide [LaX3] derivatives as a means to lower the processing temperature for the production of the LaBr3 scintillators was undertaken using methanol (MeOH). Initially the de-hydration of {[La(µ-Br)(H2O)7](Br)2}2 (1) was investigated through the simple room temperature dissolution of 1 in MeOH. The mixed solvate monomeric [La(H2O)7(MeOH)2](Br)3 (2) compound was isolated where the La metal center retains its original 9-coordination through the binding of two additional MeOH solvents but necessitates the transfer of the innersphere Br to the outersphere. In an attempt to in situ dry the reaction mixture of 1 in MeOH over CaH2, crystals of [Ca(MeOH)6](Br)2 (3) were isolated. Compound 1 dissolved in MeOH at reflux temperatures led to the isolation of an unusual arrangement identified as the salt derivative {[LaBr2.75•5.25(MeOH)]+0.25 [LaBr3.25•4.75(MeOH)]−0.25} (4). The fully substituted species was ultimately isolated through the dissolution of dried LaBr3 in MeOH forming the 8-coordinated [LaBr3(MeOH)5] (5) complex. It was determined that the concentration of the crystallization solution directed the structure isolated (4 concentrated; 5 dilute) The other LaX3 derivatives were isolated as [(MeOH)4(Cl)2La(µ-Cl)]2 (6) and [La(MeOH)9](I)3•MeOH (7). Beryllium Dome XRD analysis indicated that the bulk material for 5 appear to have multiple solvated species, 6 is consistent with the single crystal, and 7 was too broad to elucidate structural aspects. Multinuclear NMR (139La) indicated that these compounds do not retain their structure in MeOD. TGA/DTA data revealed that the de-solvation temperatures of the MeOH derivatives 4 – 6 were slightly higher in comparison to their hydrated counterparts. PMID:20514349

17β-estradiol as precursors of Cl/Br-DBPs in the disinfection process of different water samples.

PubMed

Shao, Yanan; Pan, Zihan; Rong, Chuan; Wang, Yinghui; Zhu, Hongxiang; Zhang, Yuanyuan; Yu, Kefu

2018-05-21

During chlorine disinfection process, reactions between the disinfectant and 17β-estradiol (E2) lead to the formation of halogenated disinfection byproducts (DBPs) which can be a risk to both ecosystem and human health. The degradation and transformation products of E2 in sodium hypochlorite (NaClO) disinfection processes of different water samples were investigated. The reaction kinetics research showed that the degradation rates of E2 were considerably dependent on the initial pH value and the types of water samples. In fresh water, synthetic marine aquaculture water and seawater, the reaction rate constant was 0.133 min -1 , 2.067 min -1 and 2.592 min -1 , respectively. The reasons for the above phenomena may be due to the different concentrations of bromide ions (Br - ) in these three water samples which could promote the reaction between NaClO and E2. Furthermore, Br - could also cause the formation of brominated DBPs (Br-DBPs). The main DBPs, reaction centers and conceivable reaction pathways were explored. Seven halogenated DBPs have been observed including three chlorinated DBPs (Cl-DBPs) and four Br-DBPs. The active sites of E2 were found to be the pentabasic cyclic ring and the ortho position of the phenol moiety as well as C9-C10 position. The identified Cl/Br-DBPs were also confirmed in actual marine aquaculture water from a shrimp pond. The comparison of bio-concentration factors (BCF) values based on calculation of EPI-suite showed that the toxicities of the Br-DBPs were stronger than that of their chloride analogues. The absorbable organic halogens (AOX) analysis also suggested that the DBPs produced in the marine aquaculture water were more toxic than that in the fresh water system. Copyright © 2018 Elsevier Ltd. All rights reserved.

Structural properties of scandium inorganic salts

DOE PAGES

Sears, Jeremiah M.; Boyle, Timothy J.

2016-12-16

Here, the structural properties of reported inorganic scandium (Sc) salts were reviewed, including the halide (Cl, Br, and I), nitrate, sulfate, and phosphate salts. Additional analytical techniques used for characterization of these complexes (metrical data, FTIR and 45Sc NMR spectroscopy) were tabulated. A structural comparison of Sc to select lanthanide (La, Gd, Lu) salt complexes was briefly evaluated.

High Br- Content CsPb(Cl yBr1- y)3 Perovskite Nanocrystals with Strong Mn2+ Emission through Diverse Cation/Anion Exchange Engineering.

PubMed

Li, Fei; Xia, Zhiguo; Pan, Caofeng; Gong, Yue; Gu, Lin; Liu, Quanlin; Zhang, Jin Z

2018-04-11

The unification of tunable band edge (BE) emission and strong Mn 2+ doping luminescence in all-inorganic cesium lead halide perovskite nanocrystals (NCs) CsPbX 3 (X = Cl and Br) is of fundamental importance in fine tuning their optical properties. Herein, we demonstrate that benefiting from the differentiation of the cation/anion exchange rate, ZnBr 2 and preformed CsPb 1- x Cl 3 : xMn 2+ NCs can be used to obtain high Br - content Cs(Pb 1- x- z Zn z )(Cl y Br 1- y ) 3 : xMn 2+ perovskite NCs with strong Mn 2+ emission, and the Mn 2+ substitution ratio can reach about 22%. More specifically, the fast anion exchange could be realized by the soluble halide precursors, leading to anion exchange within a few seconds as observed from the strong BE emission evolution, whereas the cation exchange instead generally required at least a few hours; moreover, their exchange mechanism and dynamics process have been evaluated. The Mn 2+ emission intensity could be further varied by controlling the replacement of Mn 2+ by Zn 2+ with prolonged ion exchange reaction time. White light emission of the doped perovskite NCs via this cation/anion synergistic exchange strategy has been realized, which was also successfully demonstrated in a prototype white light-emitting diode (LED) device based on a commercially available 365 nm LED chip.

9,10-phenanthrenesemiquinone radical complexes of ruthenium(III), osmium(III) and rhodium(III) and redox series.

PubMed

Biswas, Manas Kumar; Patra, Sarat Chandra; Maity, Amarendra Nath; Ke, Shyue-Chu; Weyhermüller, Thomas; Ghosh, Prasanta

2013-05-14

Reactions of 9,10-phenanthrenequinone (PQ) in toluene with [M(II)(PPh3)3X2] at 298 K afford green complexes, trans-[M(PQ)(PPh3)2X2] (M = Ru, X = Cl, 1; M = Os, X = Br, 2) in moderate yields. Reaction of anhydrous RhCl3 with PQ and PPh3 in boiling ethanol affords the dark brown paramagnetic complex, cis-[Rh(PQ)(PPh3)2Cl2] (3) in good yields. Diffusion of iodine solution in n-hexane to the trans-[Os(PQ) (PPh3)2(CO)(Br)] solution in CH2Cl2 generates the crystals of trans-[Os(PQ)(PPh3)2(CO)(Br)](+)I3(-), (4(+))I3(-)), in lower yields. Single crystal X-ray structure determinations of 1·2toluene, 2·CH2Cl2 and 4(+)I3(-), UV-vis/NIR absorption spectra, EPR spectra of 3, electrochemical activities and DFT calculations on 1, 2, trans-[Ru(PQ)(PMe3)2Cl2] (1Me), trans-[Os(PQ)(PMe3)2Br2] (2Me), cis-[Rh(PQ)(PMe3)2Cl2] (3Me) and their oxidized and reduced analogues including trans-[Os(PQ)(PMe3)2(CO)(Br)](+) (4Me(+)) substantiated that 1-3 are the 9,10-phenanthrenesemiquinone radical (PQ(˙-)) complexes of ruthenium(III), osmium(III) and rhodium(III) and are defined as trans/cis-[M(III)(PQ(˙-))(PPh3)2X2] with a minor contribution of the resonance form trans/cis-[M(II)(PQ)(PPh3)2X2]. Two comparatively longer C-O (1.286(4) Å) and the shorter C-C lengths (1.415(7) Å) of the OO-chelate of 1·2toluene and 2·CH2Cl2 and the isotropic fluid solution EPR signal at g = 1.999 of 3 are consistent with the existence of the reduced PQ(˙-) ligand in 1-3 complexes. Anisotropic EPR spectra of the frozen glasses (g11 = g22 = 2.0046 and g33 = 1.9874) and solids (g11 = g22 = 2.005 and g33 = 1.987) instigate the contribution of the resonance form, cis-[Rh(II)(PQ)(PPh3)2Cl2] in 3. DFT calculations established that the closed shell singlet (CSS) solutions of 1Me and 2Me are unstable due to open shell singlet (OSS) perturbation. However, the broken symmetry (BS) (1,1) Ms = 0 solutions of 1Me and 2Me are respectively 22.6 and 24.2 kJ mole(-1) lower in energy and reproduced the experimental bond parameters well prompting the coordination of PQ(˙-) to the M(III) ions. The comparatively shorter C-O lengths, 1.268(4) and 1.266(5) Å and the longer C-C length, 1.466(6) Å, are consistent with the PQ chelation to osmium(II) ion in 4(+). The reversible anodic waves at 0.22, 0.22, and 0.18 V of 1-3, referenced by the Fc(+)/Fc couple, are assigned to the PQ(˙-)/PQ couple forming PQ complexes as trans/cis-[M(III)(PQ)(PPh3)2X2](+) while the cathodic waves at -0.92 and -0.89 V of 2 and 3 are due to formations of PQ(2-) complexes as trans-[M(III)(PQ(2-))(PPh3)2X2](-). 1 displays two overlapping cathodic waves at -0.72(89), -1.0(120) V. EPR spectrum of the frozen glass of 1(-) along with DFT calculations detected the contribution of both the valence tautomers, trans-[Ru(III)(PQ(2-))(PPh3)2Cl2](-) (g1 = g2 = 2.456; g3 = 1.983) and trans-[Ru(II)(PQ(˙-))(PPh3)2X2](-) (g(iso) = 1.999) in the anion. The characteristic lower energy absorption bands of 1 and 2 at 700 nm were assigned to CSS-OSS perturbation MLCT those are absent in paramagnetic 3, 1(+), 2(+), 1(-), 2(-) and 4(+) complexes, investigated by spectro-electrochemical measurements and time dependent (TD) DFT calculations on 1Me, 2Me, 1Me(+) and 1Me(-).

PREPUBERTAL EXPOSURES TO COMPOUNDS THAT INCREASE PROLACTIN SECRETION IN THE MALE RAT: EFFECTS ON ADULT PROSTATE

EPA Science Inventory

Prepubertal exposure to compounds that increase prolactin secretion in the male rat: effects on the adult prostate.

Stoker TE, Robinette CL, Britt BH, Laws SC, Cooper RL.

Endocrinology Branch, Reproductive Toxicology Division, National Health and Environmental Effec...

The 1988 Arctic Survey, Diurnal Study (Sunrise and Sunset) and Peak Altitude (22 km) Flights for the In Situ Detection of ClO and BrO from the NASA ER-2 Aircraft

NASA Technical Reports Server (NTRS)

Anderson, James G.

1996-01-01

Two critical areas of research were addressed successfully by this research. The first involves NASA ER-2 airborne observations of ClO and BrO radical destruction of ozone within the arctic vortex. The second involves the analysis of diurnal variations in ClO, to test the production and loss rates of ClO that constitutes the test for coupling reactions between the chlorine and nitrogen systems. We discuss results from this research in order.

ANALYSES OF THE INTERACTIONS WITHIN BINARY MIXTURES OF CARCINOGENIC PAHS USING MORPHOLOGICAL CELL TRANSFORMATION OF C3H10T1/2CL8 CELLS

EPA Science Inventory

ANALYSES OF THE INTERACTIONS WITHIN BINARY MIXTURES OF CARCINOGENIC PAHS USING MORPHOLOGICAL CELL TRANSFORMATION OF C3HIOT1/2 CL8 CELLS.

Studies of defined mixtures of carcinogenic polycyclic aromatic hydrocarbons (PAH) have identified three major categories of interacti...

Temperature Dependence of Thermodynamic Properties of Thallium Chloride and Thallium Bromide

NASA Astrophysics Data System (ADS)

Kavanoz, H. B.

2015-02-01

Thermodynamic properties as lattice parameters, thermal expansion, heat capacities Cp and Cv, bulk modulus, and Gruneisen parameter of ionic halides TlCl and TlBr in solid and liquid phases were studied using classical molecular dynamics simulation (MD) with interionic Vashistha-Rahman (VR) model potential. In addition to the static and transport properties which have been previously reported by the author [13], this study further confirms that temperature dependence of the calculated thermophysical properties of TlCl and TlBr are in agreement with the available experimental data at both solid and liquid phases in terms of providing an alternative rigid ion potential. The results give a fairly good description of TlCl and TlBr in the temperature range 10-1000 K.

Observations of Bromine Chloride (BrCl) at an Arctic Coastal Site

NASA Astrophysics Data System (ADS)

McNamara, S. M.; Garner, N.; Wang, S.; Raso, A. R. W.; Thanekar, S.; Fuentes, J. D.; Shepson, P. B.; Pratt, K.

2017-12-01

Chlorine and bromine chemistry in the Arctic boundary layer have significant impacts on tropospheric ozone depletion and the fates of atmospheric pollutants such as methane, a greenhouse gas, and mercury. However, there is sparse understanding of halogen production and removal pathways due to a lack of observations. Here, we report chemical ionization mass spectrometry measurements of bromine chloride (BrCl) observed at Utqiaġvik (Barrow), AK during March-May 2016. Over the course of the three-month study, two distinct BrCl diurnal trends were identified, and production mechanisms were explored using 0-dimensional modeling, constrained by a suite of reactive halogen measurements. The findings in this work highlight coupled chlorine and bromine chemistry, as well as halogen activation pathways in the Arctic.

Coastal water source of short-lived halocarbons in New England

NASA Astrophysics Data System (ADS)

Zhou, Yong; Varner, Ruth K.; Russo, Rachel S.; Wingenter, Oliver W.; Haase, Karl B.; Talbot, Robert; Sive, Barkley C.

2005-11-01

Short-lived halocarbon tracers were used to investigate marine influences on air quality in a coastal region of New England. Atmospheric measurements made at the University of New Hampshire's Observing Station at Thompson Farm (TF) in Durham, New Hampshire, indicate that relatively large amounts of halocarbons are emitted from local estuarine and coastal oceanic regions. Bromine-containing halocarbons of interest in this work include bromoform (CHBr3) and dibromomethane (CH2Br2). The mean mixing ratios of CHBr3 and CH2Br2 from 11 January to 5 March 2002 were 2.6 pptv and 1.6 pptv, and from 1 June to 31 August 2002 mean mixing ratios were 5.9 pptv and 1.4 pptv, respectively. The mean mixing ratio of CHBr3 was not only highest during summer, but both CHBr3 and CH2Br2 exhibited large variability in their atmospheric mixing ratios during this season. We attribute the greater variability to increased production combined with faster atmospheric removal rates. Other seasonal characteristics of CHBr3 and CH2Br2 in the atmosphere, as well as the impact of local meteorology on their distributions at this coastal site, are discussed. Tetrachloroethene (C2Cl4) and trichloroethene (C2HCl3) were used to identify time periods influenced by urban emissions. Additionally, measurements of CHBr3, CH2Br2, C2Cl4, methyl iodide (CH3I), and ethyl iodide (C2H5I) were made at TF and five sites throughout the nearby Great Bay estuarine area between 18 and 19 August 2003. These measurements were used to elucidate the effect of the tidal cycle on the distributions of these gases. The mean mixing ratios of CHBr3, CH2Br2, CH3I, and C2H5I were ˜82%, 46%, 14%, and 17% higher, respectively, near the coast compared to inland sites, providing evidence for a marine source of short-lived halocarbons at TF. Correlation between the tidal cycle and atmospheric concentrations of marine tracers on the night of 18 August 2003 showed that the highest values for the brominated species occurred ˜2-3 hours after high tide. Emission fluxes of CHBr3, CH2Br2, CH3I, and C2H5I on this night were estimated to be 26 ± 57, 4.7 ± 5.4, 5.9 ± 4.6, and 0.065 ± 0.20 nmol m-2 h-1, respectively. Finally, the anthropogenic source strength of CHBr3 was calculated to determine its impact on atmospheric levels observed in this region. Although our results indicate that anthropogenic contributions could potentially range from 15 to 60% of the total dissolved CHBr3 in the Great Bay, based on the observed ratio of CH2Br2/CHBr3 and surface seawater measurements in the Gulf of Maine, it appears unlikely that anthropogenic activities are a significant source of CHBr3 in the region.

Ionic Liquids and Solids with Paramagnetic Anions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Castner, Jr., E.W.; Wishart, J.; Krieger, B.M.

2010-06-18

Four paramagnetic ionic compounds have been prepared and their magnetic, structural and thermal properties have been investigated. The four compounds are methylbutylpyrrolidinium tetrachloroferrate(III) ([Pyrr{sub 14}]{sup +}/[FeCl{sub 4}]{sup -}), methyltributylammonium tetrachloroferrate(III) ([N{sub 1444}]{sup +}/[FeCl{sub 4}]{sup -}), butylmethylimidazolium tetrachloroferrate(III) ([bmim]{sup +}/[FeCl{sub 4}]{sup -}) and tetrabutylammonium bromotrichloroferrate(III) ([N{sub 4444}]{sup +}/[FeBrCl{sub 3}]{sup -}). Temperature-dependent studies of their magnetic behaviors show that all four compounds are paramagnetic at ambient temperatures. Glass transitions are observed for only two of the four compounds, [Pyrr{sub 14}]{sup +}/[FeCl{sub 4}]{sup -} and [bmim]{sup +}/[FeCl{sub 4}]{sup -}. Crystal structures for [Pyrr{sub 14}]{sup +}/[FeCl{sub 4}]{sup -} and [N{sub 1444}]{sup +}/[FeCl{sub 4}]{sup -}more » are compared with the previously reported [N{sub 4444}]{sup +}/[FeBrCl{sub 3}]{sup -}.« less

IDENTIFICATION OF STEREOCHEMICAL CONFIGURATIONS OF CYCLOPENTA[CD]PYRENE-DNA ADDUCTS IN STRAIN A/J MOUSE LUNG AND C3H10T1/2CL8 CELLS

EPA Science Inventory

Identification of Sterochemical Configurations of Cyclopent A[cd]Pyrene DNA Adducts in Strain A/J Mouse Lung and C3H10T1/2CL8 Cells.

Four major and several minor DNA adducts were resolved by 32P-postlabeling analysis of DNA from strain A/J mouse lung and C3H10T1/2CL8 (C3H...

Rate Constants for the Reactions of OH with CH(sub 3)Cl, CH(sub 2) C1(sub 2), CHC1(sub 3)and CH(sub 3)Br

NASA Technical Reports Server (NTRS)

Hsu, H-J.; DeMore, W.

1994-01-01

Rate constants for the reactions of OH with CH3C1, CH2Cl2, CHCl3 and CH3Br have been measured by a relative rate technique in which the reaction rate of each compound was compared to that of HFC-152a (CH3CHF2)and for CH2Cl2, HFC-161 (CH3CH2F).

The crystal structures of six (2E)-3-aryl-1-(5-halogeno­thio­phen-2-yl)prop-2-en-1-ones

PubMed Central

Naik, Vasant S.; Yathirajan, Hemmige S.; Jasinski, Jerry P.; Smolenski, Victoria A.; Glidewell, Christopher

2015-01-01

The structures of six chalcones containing 5-halogeno­thio­phen-2-yl substituents are reported: (2E)-1-(5-chloro­thio­phen-2-yl)-3-(4-ethyl­phen­yl)prop-2-en-1-one, C15H13ClOS, (I), and (2E)-1-(5-bromo­thio­phen-2-yl)-3-(4-ethyl­phen­yl)prop-2-en-1-one, C15H13BrOS, (II), are isostructural in space group P-1, while (2E)-1-(5-chloro­thio­phen-2-yl)-3-(4-eth­oxy­phen­yl)prop-2-en-1-one, C15H13ClO2S, (III), and (2E)-1-(5-bromo­thio­phen-2-yl)-3-(4-eth­oxy­phen­yl)prop-2-en-1-one C15H13BrO2S, (IV), are isostructural in space group P21/c. There are no hydrogen bonds of any kind in the structures of compounds (I) and (II), but in the structures of compounds (III) and (IV), the mol­ecules are linked into C(7) chains by means of C—H⋯O hydrogen bonds. In the structure of (2E)-3-(4-bromo­phen­yl)-1-(5-chloro­thio­phen-2-yl)prop-2-en-1-one, C13H8BrClOS, (V), there are again no hydrogen bonds nor π–π stacking inter­actions but in that of (2E)-1-(5-bromo­thio­phen-2-yl)-3-(3-meth­oxy­phen­yl)prop-2-en-1-one, C14H11BrO2S, (VI), the mol­ecules are linked into C(5) chains by C—H⋯O hydrogen bonds. In each of compounds (I)–(VI), the mol­ecular skeletons are close to planarity, and there are short halogen⋯halogen contacts in the structures of compounds (II) and (V) and a short Br⋯O contact in the structure of compound (VI). Comparisons are made with the structures of some similar compounds. PMID:26396857

Reactions of the linear tetranuclear complex Ru sub 4 (CO) sub 10 (CH sub 3 C double bond C(H)C(H) double bond N-i-Pr) sub 2 with oxidizing reagents. Syntheses of halide-bridged (Ru(CO) sub 2 X(CH sub 3 C double bond C(H)C(H) double bond N-i-Pr)) sub 2 and fac-Ru(CO) sub 3 X(CH sub 3 C double bond C(H)C(H) double bond N-i-Pr)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mul, W.P.; Elsevier, C.J.; van Leijen, M.

1991-01-01

The linear tetranuclear complex Ru{sub 4}(CO){sub 10}(CH{sub 3}C{double bond}C(H)C(H){double bond}N-i-Pr){sub 2} (1), containing two {eta}{sup 5}-azaruthenacyclopentadienyl systems, reacts with oxidizing reagents (I{sub 2}, Br{sub 2}, NBS, CCl{sub 4}) at elevated temperatures (40-90C) in heptane or benzene to give the new dimeric halide-bridged organoruthenium(II) complexes (Ru(CO){sub 2}X(CH{sub 3}C{double bond}C(H)C(H){double bond}N-i-Pr)){sub 2} (X = I (3a), X = Br (3b), Cl (3c); yield 30-80%) together with (Ru(CO){sub 3}X{sub 2}){sub 2}. The reactions of 1 with CX{sub 4} (X = I, Br, Cl) are accelerated by CO, probably because Ru{sub 4}(CO){sub 12}(CH{sub 3}C{double bond}C(H)C(H){double bond}N-i-Pr){sub 2} (5), which contains two unbridged metal-metal bonds,more » is formed prior to oxidation. The halide-bridged dimers 3a-c are obtained as mixtures of four isomers, the configurations of which are discussed. Splitting of the halide bridges takes place when a solution of 3a-c is saturated with CO, whereby mononuclear fac-Ru(CO){sub 3}X(CH{sub 3}C{double bond}C(H)C(H){double bond}N-i-Pr) (4a-c) is obtained. This process is reversible; ie., passing a stream of nitrogen through a solution of 4a-c or removal of the solvent under vacuum causes the reverse reaction with reformation of 3a-c. Compounds 3a-c and 4a-c have been characterized by IR (3, 4), FD mass (3), {sup 1}H (3, 4), and {sup 13}C{l brace}H{r brace} NMR (4) spectroscopy and satisfactory elemental analyses have been obtained for 3a-c. Compounds 3 and 4 are suitable precursors for the preparation of new homo- and heteronuclear transition-metal complexes.« less

Silver chlorobromide nanocubes with significantly improved uniformity: synthesis and assembly into photonic crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Zheng; Okasinski, John S.; Gosztola, David J.

2015-01-01

Silver chlorobromide (AgClxBr1-x, 0 < x < 1) nanocubes with a highly uniform size, morphology, and crystallinity have been successfully synthesized through a co-precipitation of Ag+ ions with both Cl- and Br- ions in ethylene glycol containing polyvinyl pyrrolidone at mild temperatures. Compositions of the synthesized nanocubes can be easily tuned by controlling the molar ratio of Cl- to Br- ions in the reaction solutions. The size of the nanocubes is determined by varying a number of parameters including the molar ratio of Cl- to Br- ions, injection rate of Ag+ ions, and reaction temperature. The real-time formation of colloidalmore » AgClxBr1-x nanocubes has been monitored, for the first time, by in situ highenergy synchrotron X-ray diffraction. The time-resolved results reveal that a fast injection rate of Ag+ ions is critical for the formation of AgClxBr1-x nanocubes with a highly pure face-centered cubic crystalline phase. The improved uniformity of the AgClxBr1-x nanocubes is beneficial for assembling them into order superlattices (e.g., photonic crystals) even by simply applying centrifugation forces. The stop band of the resulting photonic crystals can be easily tuned from the ultraviolet to the infrared region by using AgClxBr1-x nanocubes with different sizes. The variation of the dielectric constant of AgClxBr1-x associated with the change of the relative concentration of halide ions provides an additional knob to tune the optical properties of photonic crystals.« less

Synthesis and crystal structures of (2 E )-1,4-bis(4-chlorophenyl)but-2-ene-1,4-dione and (2 E )-1,4-bis(4-bromophenyl)but-2-ene-1,4-dione

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lastovickova, Dominika N.; La Scala, John J.; Sausa, Rosario C.

The molecular structure of (2 E )-1,4-bis(4-chlorophenyl)but-2-ene-1,4-dione [C 16 H 10 Cl 2 O 2 , ( 1 )] is composed of two p -chlorophenyl rings, each bonded on opposite ends to a near planar 1,4- trans enedione moiety [–C(=O)—CH=CH—(C=O)–] [r.m.s. deviation = 0.003 (1) Å]. (2 E )-1,4-Bis(4-bromophenyl)but-2-ene-1,4-dione [C 16 H 10 Br 2 O 2 , ( 2 )] has a similar structure to ( 1 ), but with two p -bromophenyl rings and a less planar enedione group [r.m.s. deviation = 0.011 (1) Å]. Both molecules sit on a center of inversion, thus Z ′ = 0.5. The dihedral angles between themore » ring and the enedione group are 16.61 (8) and 15.58 (11)° for ( 1 ) and ( 2 ), respectively. In the crystal, molecules of ( 1 ) exhibit C—Cl...Cl type I interactions, whereas molecules of ( 2 ) present C—Br...Br type II interactions. van der Waals-type interactions contribute to the packing of both molecules, and the packing reveals face-to-face ring stacking with similar interplanar distances of approximately 3.53 Å.« less

Synthesis and crystal structures of (2 E )-1,4-bis(4-chlorophenyl)but-2-ene-1,4-dione and (2 E )-1,4-bis(4-bromophenyl)but-2-ene-1,4-dione

DOE PAGES

Lastovickova, Dominika N.; La Scala, John J.; Sausa, Rosario C.

2018-02-13

The molecular structure of (2 E )-1,4-bis(4-chlorophenyl)but-2-ene-1,4-dione [C 16 H 10 Cl 2 O 2 , ( 1 )] is composed of two p -chlorophenyl rings, each bonded on opposite ends to a near planar 1,4- trans enedione moiety [–C(=O)—CH=CH—(C=O)–] [r.m.s. deviation = 0.003 (1) Å]. (2 E )-1,4-Bis(4-bromophenyl)but-2-ene-1,4-dione [C 16 H 10 Br 2 O 2 , ( 2 )] has a similar structure to ( 1 ), but with two p -bromophenyl rings and a less planar enedione group [r.m.s. deviation = 0.011 (1) Å]. Both molecules sit on a center of inversion, thus Z ′ = 0.5. The dihedral angles between themore » ring and the enedione group are 16.61 (8) and 15.58 (11)° for ( 1 ) and ( 2 ), respectively. In the crystal, molecules of ( 1 ) exhibit C—Cl...Cl type I interactions, whereas molecules of ( 2 ) present C—Br...Br type II interactions. van der Waals-type interactions contribute to the packing of both molecules, and the packing reveals face-to-face ring stacking with similar interplanar distances of approximately 3.53 Å.« less

Molecular orbital analysis of the inverse halogen dependence of nuclear magnetic shielding in LaX₃, X = F, Cl, Br, I.

PubMed

Moncho, Salvador; Autschbach, Jochen

2010-12-01

The NMR nuclear shielding tensors for the series LaX(3), with X = F, Cl, Br and I, have been computed using two-component relativistic density functional theory based on the zeroth-order regular approximation (ZORA). A detailed analysis of the inverse halogen dependence (IHD) of the La shielding was performed via decomposition of the shielding tensor elements into contributions from localized and delocalized molecular orbitals. Both spin-orbit and paramagnetic shielding terms are important, with the paramagnetic terms being dominant. Major contributions to the IHD can be attributed to the La-X bonding orbitals, as well as to trends associated with the La core and halogen lone pair orbitals, the latter being related to X-La π donation. An 'orbital rotation' model for the in-plane π acceptor f orbital of La helps to rationalize the significant magnitude of deshielding associated with the in-plane π donation. The IHD goes along with a large increase in the shielding tensor anisotropy as X becomes heavier, which can be associated with trends for the covalency of the La-X bonds, with a particularly effective transfer of spin-orbit coupling induced spin density from iodine to La in LaI(3). Copyright © 2010 John Wiley & Sons, Ltd.

Pressure dependence of band-gap and phase transitions in bulk CuX (X = Cl, Br, I)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Azhikodan, Dilna; Nautiyal, Tashi; Sharma, S.

2016-05-06

Usually a phase transition, in theoretical studies, is explored or verified by studying the total energy as a function of the volume considering various plausible phases. The intersection point, if any, of the free energy vs. volume curves for the different phases is then the indicator of the phase transition(s). The question is, can the theoretical study of a single phase alone indicate a phase transition? i.e. can we look beyond the phase under consideration through such a study? Using density-functional theory, we report a novel approach to suggest phase transition(s) through theoretical study of a single phase. Copper halidesmore » have been engaged for this study. These are direct band-gap semiconductors, with zinc blende structure at ambient conditions, and are reported to exhibit many phase transitions. We show that the study of volume dependence of energy band-gap in a single phase facilitates looking beyond the phase under consideration. This, when translated to pressures, reflects the phase transition pressures for CuX (X = Cl, Br, I) with an encouraging accuracy. This work thus offers a simple, yet reliable, approach based on electronic structure calculations to investigate new semiconducting materials for phase changes under pressure.« less

Crystal structure, electronic structure, temperature-dependent optical and scintillation properties of CsCe 2Br 7

DOE PAGES

Wu, Yuntao; Shi, Hongliang; Chakoumakos, Bryan C.; ...

2015-10-05

CsCe 2Br 7 is a self-activated inorganic scintillator that shows promising performance, but the understanding of the important structure-property relationships is lacking. In this work, we conduct a comprehensive study on CCsCe 2Br 7. The crystal structure of CsCe 2Br 7 is refined using single crystal X-ray study for the first time. It crystallizes into the orthorhombic crystal system with Pmnb space group. Its electronic structure is revealed by Density Functional Theory (DFT) calculations. Two cerium emission centers are identified and the energy barriers related to the thermal quenching to 4f ground states of Ce 3+ for these two Cemore » centers are evaluated. CsCe 2Br 7 single crystal has better light yield and energy resolution than CsCe 2Cl 7, but with an additional slow decay component of 1.7 s. The existence of a deep trap with a depth of 0.9 eV in CsCe 2Cl 7 contributes to its higher afterglow level in comparison to that of CsCe 2Br 7. The most possible point defects in CsCe 2Cl 7 and CsCe 2Br 7 are proposed by considering the vapour pressure in the growth atmosphere upon melting point.« less

The geochemistry of groundwater resources in the Jordan Valley: The impact of the Rift Valley brines

USGS Publications Warehouse

Farber, E.; Vengosh, A.; Gavrieli, I.; Marie, Amarisa; Bullen, T.D.; Mayer, B.; Polak, A.; Shavit, U.

2007-01-01

The chemical composition of groundwater in the Jordan Valley, along the section between the Sea of Galilee and the Dead Sea, is investigated in order to evaluate the origin of the groundwater resources and, in particular, to elucidate the role of deep brines on the chemical composition of the regional groundwater resources in the Jordan Valley. Samples were collected from shallow groundwater in research boreholes on two sites in the northern and southern parts of the Jordan Valley, adjacent to the Jordan River. Data is also compiled from previous published studies. Geochemical data (e.g., Br/Cl, Na/Cl and SO4/Cl ratios) and B, O, Sr and S isotopic compositions are used to define groundwater groups, to map their distribution in the Jordan valley, and to evaluate their origin. The combined geochemical tools enabled the delineation of three major sources of solutes that differentially affect the quality of groundwater in the Jordan Valley: (1) flow and mixing with hypersaline brines with high Br/Cl (>2 ?? 10-3) and low Na/Cl (<0.8) ratios; (2) dissolution of highly soluble salts (e.g., halite, gypsum) in the host sediments resulting in typically lower Br/Cl signal (<2 ?? 10-3); and (3) recharge of anthropogenic effluents, primarily derived from evaporated agricultural return flow that has interacted (e.g., base-exchange reactions) with the overlying soil. It is shown that shallow saline groundwaters influenced by brine mixing exhibit a north-south variation in their Br/Cl and Na/Cl ratios. This chemical trend was observed also in hypersaline brines in the Jordan valley, which suggests a local mixing process between the water bodies. ?? 2007 Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Cheng; Tsuge, Masashi; Khriachtchev, Leonid, E-mail: leonid.khriachtchev@helsinki.fi

Experimental and theoretical studies of HXeI and HXeH molecules in Ar, Kr, and Xe matrices are presented. HXeI exhibits the H–Xe stretching bands at 1238.0 and 1239.0 cm{sup −1} in Ar and Kr matrices, respectively, that are blue-shifted from the HXeI band observed in a Xe matrix (1193 cm{sup −1}) by 45 and 46 cm{sup −1}. These shifts are larger than those observed previously for HXeCl (27 and 16 cm{sup −1}) and HXeBr (37 and 23 cm{sup −1}); thus, the matrix effect is stronger for less stable molecules. The results for HXeI are qualitatively different from all previous results onmore » noble-gas hydrides with respect to the frequency order between Ar and Kr matrices. For previously studied HXeCl, HXeBr, and HXeCCH, the H–Xe stretching frequency is reliably (by >10 cm{sup −1}) higher in an Ar matrix than in a Kr matrix. In contrast, the H–Xe stretching frequency of HXeI in an Ar matrix is slightly lower than that in a Kr matrix. HXeH absorbs in Ar and Kr matrices at 1203.2 and 1192.1 cm{sup −1} (the stronger band for a Kr matrix), respectively. These bands are blue-shifted from the stronger band of HXeH in a Xe matrix (1166 cm{sup −1}) by 37 and 26 cm{sup −1}, and this frequency order is the same as observed for HXeCl, HXeBr, and HXeCCH but different from HXeI. The present hybrid quantum-classical simulations successfully describe the main experimental findings. For HXeI in the 〈110〉 (double substitution) site, the order of the H–Xe stretching frequencies (ν(Xe) < ν(Ar) < ν(Kr)) is in accord with the experimental observations, and also the frequency shifts in Ar and Kr matrices from a Xe matrix are well predicted (30 and 34 cm{sup −1}). Both in the theory and experiment, the order of the H–Xe stretching frequencies differs from the case of HXeCl, which suggests the adequate theoretical description of the matrix effect. For HXeH in the 〈100〉 (single substitution) site, the order of the frequencies is ν(Xe) < ν(Kr) < ν(Ar), which also agrees with the experiments. The calculated frequency shifts for HXeH in Ar and Kr matrices with respect to a Xe matrix (36 and 23 cm{sup −1}) are in a good agreement with the experiments. The present calculations predict an increase of the H–Xe stretching frequencies in the noble-gas matrices with respect to vacuum.« less

Heterobimetallic acetylide bridged Cu(I)/Ru(II)-halide/pseudohalide hybrid complexes: Synthesis, structural characterization, luminescence and electrochemical studies

NASA Astrophysics Data System (ADS)

Lolage, Sanjay; Pawal, Sandip; Chavan, Sanjay

2018-01-01

A new series of heterobimetallic complexes [Cu(PPh3)(NC5H4HCdbnd NC6H4Ctbnd CC6H4Ctbnd CRu (dppe)2Cl)X] (1a-5a) have been prepared by the reaction of trans-(NC5H4HCdbnd NC6H4Ctbnd CC6H4Ctbnd C Ru(dppe)2Cl) with copper salts in presence of triphenylphosphine (where X = Cl, Br, I, N3, NCS). Our synthetic attempts and successes are discussed in combination with spectroscopic and electronic characterization of the compounds. Comparison between halides and pseudohalides were studied by thermal and electrochemical analysis where, thermally robust complexes demonstrate quasireversible redox behaviour analogous to CuI/II/RuII/III couple. Room temperature luminescence with varying electron donating and quenching abilities of halides and pseudohalides in blue-green region were observed. Concentration and solvent dependant emission displays positive solvatochromism at ambient temperature.

Vibrational spectra of carboxylato complexes—III. Trinuclear 'basic' acetates and formates of chromium(III), iron(III) and other transition metals

NASA Astrophysics Data System (ADS)

Johnson, M. K.; Powell, D. B.; Cannon, R. D.

The i.r. and Raman spectra of a series of complexes [M III3O(OOCR) 6L 3]X· xH 2O (M = Cr, Fe, Mn, Ru, Rh; L = H 2O, pyridine, γ-picoline; X = Cl, Br, I, NO 3, ClO 3, ClO 4, BF 4) have been analysed in detail. The vibrational modes of the central M 3O and the three surrounding MO 4 units, are identified. The metal—nitrogen stretching vibrations and the MOH 2 modes are assigned. The 'basic' chromium(III) formate is shown to be [Cr 3O(OOCH) 6(OH 2) 2(OOCH)] xH 2O, containing monodentate, inner-sphere coordinated formate ion. The use of the symmetric and asymmetric OCO stretching frequencies in characterizing bridging carboxylate ions is discussed.

Synthetic and Spectroscopic Studies on N-(i,j-Disubstituted Phenyl)-4- Substituted Benzenesulphonamides, 4-X'C6H4SO2NH(i,j-X2C6H3), where X' = H, CH3, C2H5, F, Cl or Br; i, j = 2, 3; 2, 4; 2, 5; 2, 6 or 3, 4; and X = CH3 or Cl

NASA Astrophysics Data System (ADS)

Shetty, Mahesha; Gowda, B. Thimme

2005-02-01

Fifty four N-(i,j-disubstituted phenyl)-4-substituted benzenesulphonamides of the general formula 4-X'C6H4SO2NH(i,j-X2C6H3), where X' = H, CH3, C2H5, F, Cl or Br; i,j = 2,3; 2,4; 2,5; 2,6 or 3, 4; and X = CH3 or Cl, are prepared and characterized and their infrared, 1H and 13C NMR spectra in solution are studied. The N-H stretching vibrations νN-H absorb in the range 3305 - 3205 cm-1, while the asymmetric and symmetric SO2 vibrations vary in the ranges 1377 - 1307 cm-1 and 1184 - 1128 cm-1, respectively. The N-(i,j-disubstituted phenyl)-4-substituted benzenesulphonamides show C-S, S-N and C-N stretching vibrations in the ranges 844 - 800 cm-1, 945 - 891 cm-1 and 1309 - 1170 cm-1, respectively. The compounds do not exhibit particular trends in the variation of these frequencies on substitution either at ortho or meta positions with either a methyl group or Cl. The observed 1H and 13C chemical shifts of are assigned to protons and carbon atoms of the two benzene rings. Incremental shifts of the ring protons and carbon atoms due to -SO2NH(i,j-X2C6H3) groups in C6H5SO2NH(i,j-X2C6H3) and 4-X'C6H4SO2NH- groups in 4-X'C6H4SO2NH(C6H*) are computed and employed to calculate the chemical shifts of the ring protons and carbon atoms in the substituted compounds 4-X'C6H4SO2NH(i,j-X2C6H3). The different methods of calculation lead to almost the same values in most cases and agree well with the observed chemical shifts, indicating the validity of the principle of additivity of the substituent effects with chemical shifts in these compounds.

Radiocarbon evidence for a naturally produced, bioaccumulating halogenated organic compound.

PubMed

Reddy, Christopher M; Xu, Li; O'Neil, Gregory W; Nelson, Robert K; Eglinton, Timothy I; Faulkner, D John; Norstrom, Ross; Ross, Peter S; Tittlemier, Sheryl A

2004-04-01

Halogenated organic compounds (HOCs) such as 1,1'-dimethyl-3,3',4,4'-tetrabromo-5,5'-dichloro-2,2'-bipyrrole (DBP-Br4Cl2) and heptachloro-1'-methyl-1,2'-bipyrrole (Q1) have been detected worldwide, sometimes at high levels in Antarctic air, seabird eggs, the blubber of marine mammals, and, most notably, even human milk. To date, it has been difficult to determine whether these compounds are natural products or derived from industrial synthesis. Molecular-level 14C analysis of these compounds is particularly appealing because most industrial compounds are manufactured from petrochemicals (14C-free) and natural compounds should have "modern" or "contemporary" 14C levels. To investigate the source of DBP-Br4Cl2, we isolated 600 microg of this compound (150 microg of carbon) from marine animal extracts by employing gel permeation chromatography, Florisil column chromatography, and two-dimensional preparative capillary gas chromatography. The purified DBP-Br4Cl2 was split into two samples (75 microg of carbon each) and analyzed by accelerator mass spectrometry for 14C content. The delta14C values were -449 percent per thousand and -467 percent per thousand, corresponding to conventional 14C ages of 4740 and 5000 years before present (BP), respectively. The presence of detectable 14C in the DBP-Br4Cl2 strongly points to at least a natural or biogenic source. However, these delta14C values for DBP-Br4Cl2 are more depleted than expected for a recently synthesized natural product. Several explanations are discussed, but additional samples

Effect of halo-substituted aromatic salts on counterion binding constants obtained from cationic nanoparticle catalyzed reactions of piperidine and phenyl salicylate

NASA Astrophysics Data System (ADS)

Fagge, Ibrahim I.; Yusof, Nor Saadah M.; Zain, Sharifuddin Md; Khan, M. Niyaz

2017-12-01

Halo-substitutions at 3-position of benzene ring of the salts of aromatic carboxylate, MX, revealed the effect of two different halide ions (Br- and Cl-) on the counterion binding constants obtained from cationic nanoparticle catalyzed piperidinolysis of ionized phenyl salicylate (PhS-). The values of observed rate constant, kobs, determined at a constant total concentration of cetyltrimethylammonium bromide, [CTABr]T, piperidine, ([P]T), [PhS-]T, NaOH, and various concentration of MX (MX = 3-BrC6H4CO2Na and 3-ClC6H4CO2Na), were determined using UV-visible X spectrophotometric technique at 35 °C and 370 nm. The average value of nanoparticle binding constant, KXBr, for X- = 3-BrC6H4CO2- (RXBr = 57) was found to be about 2-fold larger than that for X- = 3-ClC6H4CO2- (RXBr = 30). These XX values were dependent of substituents 3-Br and 3-Cl, and independent of [CTABr]T. Both are related to the presence of different extent of viscoelastic worm-like nanoparticles formation in the [CTABr]T of 6 and 10 mM.

Laser cooling of MgCl and MgBr in theoretical approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wan, Mingjie; Shao, Juxiang; Huang, Duohui

Ab initio calculations for three low-lying electronic states (X{sup 2}Σ{sup +}, A{sup 2}Π, and 2{sup 2}Π) of MgCl and MgBr molecules, including spin-orbit coupling, are performed using multi-reference configuration interaction plus Davidson correction method. The calculations involve all-electronic basis sets and Douglas–Kroll scalar relativistic correction. Spectroscopic parameters well agree with available theoretical and experimental data. Highly diagonally distributed Franck-Condon factors f{sub 00} for A{sup 2}Π{sub 3/2,1/2} (υ′ = 0) → X{sup 2}Σ{sup +}{sub 1/2} (υ″ = 0) are determined for both MgCl and MgBr molecules. Suitable radiative lifetimes τ of A{sup 2}Π{sub 3/2,1/2} (υ′ = 0) states for rapid lasermore » cooling are also obtained. The proposed laser drives A{sup 2}Π{sub 3/2} (υ′ = 0) → X{sup 2}Σ{sup +}{sub 1/2} (υ″ = 0) transition by using three wavelengths (main pump laser λ{sub 00}; two repumping lasers λ{sub 10} and λ{sub 21}). These results indicate the probability of laser cooling MgCl and MgBr molecules.« less

Chloride (Cl-) ion-mediated shape control of palladium nanoparticles

NASA Astrophysics Data System (ADS)

Nalajala, Naresh; Chakraborty, Arup; Bera, Bapi; Neergat, Manoj

2016-02-01

The shape control of Pd nanoparticles is investigated using chloride (Cl-) ions as capping agents in an aqueous medium in the temperature range of 60-100 °C. With weakly adsorbing and strongly etching Cl- ions, oxygen plays a crucial role in shape control. The experimental factors considered are the concentration of the capping agents, reaction time and reaction atmosphere. Thus, Pd nanoparticles of various shapes with high selectivity can be synthesized. Moreover, the removal of Cl- ions from the nanoparticle surface is easier than that of Br- ions (moderately adsorbing and etching) and I- ions (strongly adsorbing and weakly etching). The cleaned Cl- ion-mediated shape-controlled Pd nanoparticles are electrochemically characterized and the order of the half-wave potential of the oxygen reduction reaction in oxygen-saturated 0.1 M HClO4 solution is of the same order as that observed with single-crystal Pd surfaces.

Effect of water on the fluorine and chlorine partitioning behavior between olivine and silicate melt.

PubMed

Joachim, Bastian; Stechern, André; Ludwig, Thomas; Konzett, Jürgen; Pawley, Alison; Ruzié-Hamilton, Lorraine; Clay, Patricia L; Burgess, Ray; Ballentine, Christopher J

2017-01-01

Halogens show a range from moderate (F) to highly (Cl, Br, I) volatile and incompatible behavior, which makes them excellent tracers for volatile transport processes in the Earth's mantle. Experimentally determined fluorine and chlorine partitioning data between mantle minerals and silicate melt enable us to estimate Mid Ocean Ridge Basalt (MORB) and Ocean Island Basalt (OIB) source region concentrations for these elements. This study investigates the effect of varying small amounts of water on the fluorine and chlorine partitioning behavior at 1280 °C and 0.3 GPa between olivine and silicate melt in the Fe-free CMAS+F-Cl-Br-I-H 2 O model system. Results show that, within the uncertainty of the analyses, water has no effect on the chlorine partitioning behavior for bulk water contents ranging from 0.03 (2) wt% H 2 O (D Cl ol/melt = 1.6 ± 0.9 × 10 -4 ) to 0.33 (6) wt% H 2 O (D Cl ol/melt = 2.2 ± 1.1 × 10 -4 ). Consequently, with the effect of pressure being negligible in the uppermost mantle (Joachim et al. Chem Geol 416:65-78, 2015), temperature is the only parameter that needs to be considered for the determination of chlorine partition coefficients between olivine and melt at least in the simplified iron-free CMAS+F-Cl-Br-I-H 2 O system. In contrast, the fluorine partition coefficient increases linearly in this range and may be described at 1280 °C and 0.3 GPa with ( R 2  = 0.99): [Formula: see text]. The observed fluorine partitioning behavior supports the theory suggested by Crépisson et al. (Earth Planet Sci Lett 390:287-295, 2014) that fluorine and water are incorporated as clumped OH/F defects in the olivine structure. Results of this study further suggest that fluorine concentration estimates in OIB source regions are at least 10% lower than previously expected (Joachim et al. Chem Geol 416:65-78, 2015), implying that consideration of the effect of water on the fluorine partitioning behavior between Earth's mantle minerals and silicate melt is vital for a correct estimation of fluorine abundances in OIB source regions. Estimates for MORB source fluorine concentrations as well as chlorine abundances in both mantle source regions are within uncertainty not affected by the presence of water.

Extended Fenske-Hall LCAO MO Calculations for Mixed Methylene Dihalides

NASA Astrophysics Data System (ADS)

Ziemann, Hartmut; Paulun, Manfred

1988-10-01

The electronic structure of mixed methylene dihalides CH2XY (X, Y = F, Cl, Br. I) has been studied using extended Fenske-Hall LCAO MO method. The comparison with available photoelec­tron spectra confirmes previous assignments of all bands with binding energies <100 eV. The electronic structure changes occurring upon varying the halogen substituents are discussed.

Method of selective reduction of halodisilanes with alkyltin hydrides

DOEpatents

D'Errico, John J.; Sharp, Kenneth G.

1989-01-01

The invention relates to the selective and sequential reduction of halodisilanes by reacting these compounds at room temperature or below with trialkyltin hydrides or dialkyltin dihydrides without the use of free radical intermediates. The alkyltin hydrides selectively and sequentially reduce the Si-Cl, Si-Br or Si-I bonds while leaving intact the Si-Si and Si-F bonds present.

CsPbBr3 nanocrystal saturable absorber for mode-locking ytterbium fiber laser

NASA Astrophysics Data System (ADS)

Zhou, Yan; Hu, Zhiping; Li, Yue; Xu, Jianqiu; Tang, Xiaosheng; Tang, Yulong

2016-06-01

Cesium lead halide perovskite nanocrystals (CsPbX3, X = Cl, Br, I) have been reported as efficient light-harvesting and light-emitting semiconductor materials, but their nonlinear optical properties have been seldom touched upon. In this paper, we prepare layered CsPbBr3 nanocrystal films and characterize their physical properties. Broadband linear absorption from ˜0.8 to over 2.2 μm and nonlinear optical absorption at the 1-μm wavelength region are measured. The CsPbBr3 saturable absorber (SA), manufactured by drop-casting of colloidal CsPbBr3 liquid solution on a gold mirror, shows modulation depth and saturation intensity of 13.1% and 10.7 MW/cm2, respectively. With this SA, mode-locking operation of a polarization-maintained ytterbium fiber laser produces single pulses with duration of ˜216 ps, maximum average output power of 10.5 mW, and the laser spectrum is centered at ˜1076 nm. This work shows that CsPbBr3 films can be efficient SA candidates for fiber lasers and also have great potential to become broadband linear and nonlinear optical materials for photonics and optoelectronics.

Electronic structure and nature of the ground state of the mixed-valence binuclear tetra(mu-1,8-naphthyridine-N,N')-bis(halogenonickel) tetraphenylborate complexes: experimental and DFT characterization.

PubMed

Bencini, Alessandro; Berti, Elisabetta; Caneschi, Andrea; Gatteschi, Dante; Giannasi, Elisa; Invernizzi, Ivana

2002-08-16

The ground state electronic structure of the mixed-valence systems [Ni(2)(napy)(4)X(2)](BPh(4)) (napy=1,8-naphthyridine; X=Cl, Br, I) was studied with combined experimental (X-ray diffraction, temperature dependence of the magnetic susceptibility, and high-field EPR spectroscopy) and theoretical (DFT) methods. The zero-field splitting (zfs) ground S=3/2 spin state is axial with /D/ approximately 3 cm(-1). The iodide derivative was found to be isostructural with the previously reported bromide complex, but not isomorphous. The compound crystallizes in the monoclinic system, space group P2(1)/n, with a=17.240(5), b=26.200(5), c=11.340(5) A, beta=101.320(5) degrees. DFT calculations were performed on the S=3/2 state to characterize the ground state potential energy surface as a function of the nuclear displacements. The molecules can thus be classified as Class III mixed-valence compounds with a computed delocalization parameter, B=3716, 3583, and 3261 cm(-1) for the Cl, Br, and I derivatives, respectively.

Optical studies of photoactive states in mixed organic-inorganic hybrid perovskites stabilized in polymers

NASA Astrophysics Data System (ADS)

Kardynal, Beata; Xi, Lifei; Salim, Teddy; Borghardt, Sven; Stoica, Toma; Lam, Yeng Ming

2015-03-01

Mixed organic-inorganic hybrid perovskites MAX-PbY2(X,Y =I, Br,Cl) have been demonstrated as very attractive materials for absorbers of solar cells and active layers of light emitting diodes and optically driven lasers. The bandgap of the perovskites can be tuned by mixing halogen atoms in different ratios. In this presentation we study mixed MAX-PbY2(X,Y =I, Br, Cl) particles synthesized directly in protective polymer matrices as light emitters. Both, time integrated and time resolved photoluminescence have been used to study the materials. So synthesized MAX-PbX2 are very stable when measured at room temperature and in air with radiative recombination of photogenerated carriers as the main decay path. In contrast, MAX-PbY2 with mixed halogen atoms display luminescence from sub-bandgap states which saturate at higher excitation levels. The density of these states depends on the used polymer matrix and increases upon illumination. We further compare the MAX-PbY2 synthesized in polymers and as films and show that these states are inherent to the material rather than its microstructure. This works has been supported by EU NWs4LIGHT grant.

Laser microprobe analyses of noble gas isotopes and halogens in fluid inclusions: Analyses of microstandards and synthetic inclusions in quartz

USGS Publications Warehouse

Böhlke, J.K.; Irwin, J.J.

1992-01-01

Ar, Kr, Xe, Cl, Br, I, and K abundances and isotopic compositions have been measured in microscopic fluid inclusions in minerals by noble gas mass spectrometry following neutron irradiation and laser extraction. The laser microprobe noble gas mass spectrometric (LMNGMS) technique was quantified by use of microstandards, including air-filled capillary tubes, synthetic basalt glass grains, standard hornblende grains, and synthetic fluid inclusions in quartz. Common natural concentrations of halogens (Cl, Br, and I) and noble gases (Ar and Kr) in trapped groundwaters and hydrothermal fluids can be analyzed simultaneously by LMNGMS in as little as 10−11 L of inclusion fluid, with accuracy and precision to within 5–10% for element and isotope ratios. Multicomponent element and isotope correlations indicate contaminants or persistent reservoirs of excess Xe and/or unfractionated air in some synthetic and natural fluid inclusion samples. LMNGMS analyses of natural fluid inclusions using the methods and calibrations reported here may be used to obtain unique information on sources of fluids, sources of fluid salinity, mixing, boiling (or unmixing), and water-rock interactions in ancient fluid flow systems.

Study of Pair and many-body interactions in rare-gas halide atom clusters using negative ion zero electron kinetic energy (ZEKE) and threshold photodetachment spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yourshaw, Ivan

1998-07-09

The diatomic halogen atom-rare gas diatomic complexes KrBr -, XeBr -, and KrCl - are studied in this work by zero electron kinetic energy (ZEKE) spectroscopy in order to characterize the weak intermolecular diatomic potentials of these species. Also, the ZEKE and threshold photodetachment spectra of the polyatomic clusters Ar nBr - (n = 2-9) and Ar nI - (n = 2-19) are studied to obtain information about the non-additive effects on the interactions among the atoms. This work is part of an ongoing effort to characterize the pair and many-body potentials of the complete series of rare gas halidemore » clusters. In these studies we obtain information about both the anionic and neutral clusters.« less

In Situ Detection of OH, HO2, ClO, BrO, NO2, ClONO2, BrONO2, ClOOCl, H2O, and O3 from the ER2

NASA Technical Reports Server (NTRS)

Anderson, James G.

2001-01-01

We review here the scientific progress that has emerged during the period January 1, 1998 through March 31, 2001. Results from the Sage III Ozone Loss and Validation Experiment (SOLVE) and Photochemistry of Ozone Loss in the Arctic Region in Summer (POLARIS) mission, and continuing work on prior missions, taken in order, including radical control of ozone on the northern hemisphere stratosphere, evolution of NO2 over the arctic winter and its effects on reactive chlorine, and the first measurements of ClOOCl in the stratosphere.

Rate constants for the reactions of OH with CH3Cl, CH2Cl2, CHCl3, and CH3Br

NASA Technical Reports Server (NTRS)

Hsu, K.-J.; Demore, W. B.

1994-01-01

Rate constants for the reactions of OH with CH3Cl, CH2Cl2, CHCl3, and CH3Br have been measured by a relative rate technique in which the reaction rate of each compound was compared to that of HFC-152a (CH3CHF2) and (for CH2Cl2) HFC-161 (CH3CH2F). Using absolute rate constants for HFC-152a and HFC-161, which we have determined relative to those for CH4, CH3CCl3, and C2H6, temperature dependent rate constants of both compounds were derived. The derived rate constant for CH3Br is in good agreement with recent absolute measurements. However, for the chloromethanes all the rate constants are lower at atmospheric temperatures than previously reported, especially for CH2Cl2 where the present rate constant is about a factor of 1.6 below the JPL 92-20 value. The new rate constant appears to resolve a discrepancy between the observed atmospheric concentrations and those calculated from the previous rate constant and estimated release rates.

Controlled Pd(0)/t Bu3P Catalyzed Suzuki Cross-Coupling Polymerization of AB-Type Monomers with ArPd(t Bu3P)X or Pd2(dba)3/t Bu3P/ArX as the Initiator

DOE PAGES

Zhang, Honghai; Xing, Chun-Hui; Hu, Qiao-Sheng; ...

2015-02-05

The synthesis of well-defined and functionalized conjugated polymers, which are essential in the development of efficient organic electronics, through Suzuki cross-coupling polymerizations has been a challenging task. We developed controlled Pd(0)/t-Bu3P-catalyzed Suzuki cross-coupling polymerizations of AB-type monomers via the chain-growth mechanism with a series of in situ generated ArPd(t-Bu3P)X (X = I, Br, Cl) complexes as initiators. Among them, the combinations of Pd2(dba)3/t-Bu3P/p-BrC6H4I, Pd2(dba)3/t-Bu3P/p-BrC6H4CH2OH and Pd2(dba)3/t-Bu3P/p-PhCOC6H4Br were identified as highly robust initiator systems, resulting in polymers with predictable molecular weight and narrow polydispersity (PDI~1.13-1.20). In addition, Pd2(dba)3/t-Bu3P/p-BrC6H4CH2OH and Pd2(dba)3/t-Bu3P/p-PhCOC6H4Br initiator systems afforded functional polymers with >95% fidelity. Our results pavedmore » the road to access well-defined conjugated polymers, including conjugated polymers with complex polymer architectures such as block copolymers and branch copolymers.« less

Changes in Carbon Isotope Composition of Methyl Halides Resulting from Biological and Chemical Degradation

NASA Astrophysics Data System (ADS)

Baesman, S. M.; Miller, L. G.; Oremland, R. S.

2003-12-01

Methyl bromide (MeBr), methyl chloride (MeCl) and methyl iodide (MeI) are reactive trace gases that are produced and released to the atmosphere at the Earths surface. These methyl halides have the potential to influence ozone levels in the stratosphere. Current estimates of the relative contributions of natural and anthropogenic sources of these methyl halides are the subject of considerable debate. In addition, there is uncertainty in the magnitude of some of the largest sinks for these compounds. Hence, the atmospheric budgets of MeBr, MeCl and MeI, while uncertain at present, may be better constrained using stable isotope ratio (13C/12C) mass balances of sources and sinks. Our work has focused on characterizing the effects upon δ 13C values of methyl halides released after reactions which discriminate in favor of 12C during removal processes. Previously, we determined very large fractionations of carbon isotopes by pure cultures of soil bacteria. Further, we have documented large fractionations (kinetic isotope effects or KIEs) of methyl halides in live soils. In the case of MeBr and MeI, substantial fractionation also occurred in heat-killed soil, suggesting that chemical degradation resulted in a shift in the stable isotopic composition. At elevated concentrations, for instance during agricultural soil fumigations, the δ 13C value of MeBr or MeI released from soil can be determined by flux measurements or soil profiles. However, more information is needed regarding the processes responsible for isotope fractionation to be able to extrapolate to areas where the concentration is low or direct measurement is not otherwise possible. We report here on measurements of the fractionation of carbon isotopes in methyl halides during degradation by chemical processes that are likely to occur in soil or seawater. These processes include aqueous hydrolysis and halide exchange and the methylation of organic matter using humic acid as the model methyl acceptor. Results are compared with fractionation achieved during the uptake of methyl halides by live and heat-killed soils.

Hydrogeochemical and isotopic evidences of groundwater salinization in coastal aquifers: A case study in Jeju volcanic island, Korea

NASA Astrophysics Data System (ADS)

Kim, Y.; Lee, D.; Lee, K.; Koh, D.; Lee, S.; Park, W.; Koh, G.; Woo, N.

2001-12-01

In order to clearly identify the origin of saline groundwaters in the eastern part of Jeju volcanic island, Korea the hydrogeochemical and isotopic studies have been carried out for 18 observation wells located in east and southeast coastal regions. The total dissolved solid (TDS) contents of groundwater samples are highly variable (77 to 21,782 mg/L). Most of the groundwaters in the study area are classified into Na-Cl type except a few samples showing Ca-Cl type. Hydrochemical characteristics based on bivariate and triangular diagrams of major ions show that the changes of chemical compositions of groundwaters were mainly controlled by the salinization process linked to cation-exchange reactions. The oxygen, hydrogen, sulfur, and strontium isotopic data explicitly show a simple mixing trend of groundwater and seawater. Using two-components fractional mixing model on the basis of 18O contents as well as Br and Cl contents, the proportion of seawater in fresh groundwater was quantitatively determined as high as 60 %. Sr isotopic compositions and Br/Cl ratios strongly suggest that the source of groundwater salinization is present-day seawater intrusion rather than paleoseawater or formation water, which can also be supported by the I/Cl ratios. The highly permeable aquifers in the east coastal region characterized by low hydraulic gradient and recharge rate and high hydraulic conductivity comparing with other regions are advantageous to the groundwater salinization. Based on the Cl, ¥ä18O, and 87Sr/86Sr it was determined that seawater has intruded into inland 2.5 km from coastline.

Factors affecting the roles of reactive species in the degradation of micropollutants by the UV/chlorine process.

PubMed

Wu, Zihao; Guo, Kaiheng; Fang, Jingyun; Yang, Xueqin; Xiao, Hong; Hou, Shaodong; Kong, Xiujuan; Shang, Chii; Yang, Xin; Meng, Fangang; Chen, Liwei

2017-12-01

The UV/chlorine process is an emerging advanced oxidation process (AOP) that produces various reactive species, such as hydroxyl radicals (HO) and reactive chlorine species (RCS). The effects of the treatment conditions, such as chlorine dosage and pH, and the water matrix components of natural organic matter (NOM), alkalinity, ammonia and halides, on the kinetics and reactive species in the degradation of four micropollutants, metronidazole (MDZ), nalidixic acid (NDA), diethyltoluamide (DEET) and caffeine (CAF), by the UV/chlorine process were investigated. The degradation of MDZ and CAF was primarily attributable to HO and ClO, respectively, while that of NDA was primarily attributable to both ClO and CO 3 - . HO, Cl and CO 3 - are important for the degradation of DEET. The second-order rate constants for ClO with CAF and CO 3 - with NDA were determined to be 5.1 (±0.2) × 10 7  M -1 s -1 and 1.4 (±0.1) × 10 7  M -1 s -1 , respectively. Increasing chlorine dosage slightly changed the contribution of HO but linearly increased that of ClO to micropollutant degradation. Increasing pH decreased the contribution of either HO or Cl but not that of ClO. Both NOM and bicarbonate decreased the contributions of HO and Cl, whereas NOM but not bicarbonate significantly decreased that of ClO. The contribution of either HO or Cl first rose and then fell as the molar ratio of ammonia to chlorine increased from 0 to 1:1, while that of ClO decreased. The co-presence of high concentrations of Cl - and Br - enhanced the contribution of ClBr - and BrCl. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of the surface modification of silver nanoparticles on the surface-enhanced Raman spectroscopy of methylene blue for borohydride-reduced silver colloid

NASA Astrophysics Data System (ADS)

Dong, Xiao; Gu, Huaimin; Kang, Jian; Yuan, Xiaojuan; Wu, Jiwei

2010-12-01

The paper further investigated the relationship between the modification of the surface chemistry and the enhancement mechanisms of borohydride-reduced silver particles (BRSC). The bands of residual ions die down while the anomalous bands increase gradually with the increasing of the concentration of Cl - and Br -. It means the residual ions are displaced gradually by the added Cl - or Br - and the two halides can lead to the aggregation of the BRSC to a certain extent. However, the most strongly binding anions - I -, cannot cause any aggregation of silver particles. From the detection of methylene blue (MB), the relationship between the modification of silver surface chemistry and the enhancement mechanisms was discussed. Chloride gives the greatest enhancement while the iodide gives the lowest enhancement among the different kinds of anions. There are also some anomalous bands in the SERS spectra of MB, and these anomalous bands were given rational explanation in this paper.

Can Pb-Free Halide Double Perovskites Support High-Efficiency Solar Cells?

PubMed Central

2016-01-01

The methylammonium lead halides have become champion photoactive semiconductors for solar cell applications; however, issues still remain with respect to chemical instability and potential toxicity. Recently, the Cs2AgBiX6 (X = Cl, Br) double perovskite family has been synthesized and investigated as stable nontoxic replacements. We probe the chemical bonding, physical properties, and cation anti-site disorder of Cs2AgBiX6 and related compounds from first-principles. We demonstrate that the combination of Ag(I) and Bi(III) leads to the wide indirect band gaps with large carrier effective masses owing to a mismatch in angular momentum of the frontier atomic orbitals. The spectroscopically limited photovoltaic conversion efficiency is less than 10% for X = Cl or Br. This limitation can be overcome by replacing Ag with In or Tl; however, the resulting compounds are predicted to be unstable thermodynamically. The search for nontoxic bismuth perovskites must expand beyond the Cs2AgBiX6 motif. PMID:28066823

Can Pb-Free Halide Double Perovskites Support High-Efficiency Solar Cells?

PubMed

Savory, Christopher N; Walsh, Aron; Scanlon, David O

2016-11-11

The methylammonium lead halides have become champion photoactive semiconductors for solar cell applications; however, issues still remain with respect to chemical instability and potential toxicity. Recently, the Cs 2 AgBiX 6 (X = Cl, Br) double perovskite family has been synthesized and investigated as stable nontoxic replacements. We probe the chemical bonding, physical properties, and cation anti-site disorder of Cs 2 AgBiX 6 and related compounds from first-principles. We demonstrate that the combination of Ag(I) and Bi(III) leads to the wide indirect band gaps with large carrier effective masses owing to a mismatch in angular momentum of the frontier atomic orbitals. The spectroscopically limited photovoltaic conversion efficiency is less than 10% for X = Cl or Br. This limitation can be overcome by replacing Ag with In or Tl; however, the resulting compounds are predicted to be unstable thermodynamically. The search for nontoxic bismuth perovskites must expand beyond the Cs 2 AgBiX 6 motif.

PERINATAL EXPOSURE TO ESTROGENIC COMPOUNDS AND THE SUBSEQUENT EFFECTS ON THE PROSTRATE OF THE ADULT RAT: EVALUATION OF INFLAMMATION IN THE VENTRAL AND LATERAL LOBES

EPA Science Inventory

Perinatal exposure to estrogenic compounds and the subsequent effects on the prostate of the adult rat: evaluation of inflammation in the ventral and lateral lobes.

Stoker TE, Robinette CL, Cooper RL.

Endocrinology Branch, Reproductive Toxicology Division, National ...

First principles and experimental study of the electronic structure and phase stability of bulk thallium bromide

NASA Astrophysics Data System (ADS)

Smith, Holland M.; Zhou, Yuzhi; Ciampi, Guido; Kim, Hadong; Cirignano, Leonard J.; Shah, Kanai S.; Haller, E. E.; Chrzan, D. C.

2013-08-01

We apply state-of-art first principle calculations to study the polymorphism and electronic structure of three previously reported phases of TlBr. The calculated band structures of NaCl-structure phase and orthorhombic-structure phase have different features than that of commonly observed CsCl-structure phase. We further interpret photoluminescence spectra based on our calculations. Several peaks close to calculated band gap values of the NaCl-structure phase and the orthorhombic-structure phase are found in unpolished TlBr samples.

The crystal structures of BiTeO 3I, NdTeO 3X (X=Cl, Br) and Bi 5TeO 8.5I 2: some crystal chemistry peculiarities of layered Bi(Ln)Te oxyhalides

NASA Astrophysics Data System (ADS)

Berdonosov, Peter S.; Charkin, Dmitry O.; Kusainova, Ardak M.; Hervoches, Charles H.; Dolgikh, Valeriy A.; Lightfoot, Philip

2000-09-01

Four new layered oxyhalides related to the Sillen family have been prepared and characterized by Rietveld refinement of powder X-ray and neutron diffraction data. BiTeO 3I and NdTeO 3Br both adopt tetragonal symmetry, space group P4/ nmm (for BiTeO 3I, a=4.10811(8), c=27.988(1) Å; NdTeO 3Br, a=4.06603(7), c=26.922(1) Å, at 25°C). The structures are composed of triple and double fluorite-related mixed metal oxide layers separated by single and double halogen layers, in the sequence MTe 2O 5XXMTe 2O 5XM 2O 2X, which may be represented by the symbol X 13X 13X 22, where the subscript signifies the number of halogen layers and the superscript the number of metal sublayers within the fluorite block, by analogy with Sillen's notation. The double fluorite layers are occupied exclusively by Bi, whereas there is an ordered arrangement of Bi/Te within the triple fluorite layers, with Te exclusively occupying the outer sublayers of the block. NdTeO 3Cl adopts an orthorhombically distorted form of this structure type, space group Pmmn, a=4.08096(8), b=4.03441(8), c=25.7582(7) Å at 25°C. Bi 5TeO 8.5I 2 adopts a distorted, non-centrosymmetric version of the simpler X 13 structure type, space group Cmm2, a=5.6878(3), b=5.7230(3), c=9.7260(6) Å, consisting of single halogen layers sandwiched between triple fluorite layers, in which there is partial ordering of the Bi/Te cations.

Bonding in d9 complexes derived from EPR: Application to CuCl2-4, CuBr2-4, and CdCl2:Cu2+

NASA Astrophysics Data System (ADS)

Aramburu, J. A.; Moreno, M.

1985-12-01

In this work are reported the theoretical expressions for the [g], hyperfine, and superhyperfine (shf) tensors of a d9 square-planar complex within a molecular orbital (MO) scheme. These expressions include contributions arising from crystal field and charge transfer excitations calculated up to third and second order perturbations, respectively. This makes the present framework more general than those previously used. Through those expressions we have derived from the experimental EPR and optical data the MO coefficients corresponding to the valence b1g(x2-y2), b2g(xy), and eg(xz,yz) levels and also the core polarization contribution K to the hyperfine tensor for the systems CuCl2-4, CuBr2-4, and CdCl2:Cu2+. The 3d charge obtained for CuCl2-4 is equal to 0.61, 0.83, and 0.85 for the antibonding 3b1g, 2b2g, and 2eg levels, respectively. These figures are much closer to the Xα results by Bencini and Gatteschi [J. Am. Chem. Soc. 105, 5535 (1983)] than to those by Desjardins et al. [J. Am. Chem. Soc. 105, 4590 (1983)]. The σ and π covalency for CuBr2-4 are both higher than for CuCl2-4 in accord to the lower electronegativity for bromine. However, only for the antibonding 3b1g level of CuBr2-4 have we obtained an electronic charge lying mainly on ligands. The covalency of CdCl2:Cu2+ is smaller than that found for CuCl2-4, a fact associated to a higher metal-ligand distance for the former. Evidence of this statement are also given from the analysis of crystal-field spectra and isotropic shf constant. The values of K derived for CuCl2-4 (128.1×10-4 cm-1), CuBr2-4 (103.6×10-4 cm-1), and CdCl2:Cu2+ (123.9×10-4 cm-1) point out the dependence of K on the equatorial covalency but also on the existence of axial ligands. The [g] tensor of CuBr2-4 is dominated by the charge transfer contribution while the crystal field one is negative. Finally an analysis of the importance of each one of the involved contributions to the spin-Hamiltonian parameters is reported for the three systems, together with the results obtained through a full diagonalization within crystal field and charge transfer states.

Role of halogen and hydrogen bonds for stabilization of antithyroid drugs with hypohalous acids (HOX, X = I, Br, and Cl) adducts

NASA Astrophysics Data System (ADS)

El-Sheshtawy, Hamdy S.; El-Mehasseb, Ibrahim

2017-11-01

The mechanism for the inhibition of thyroid hormones by the thioamide-like antithyroid drug is a key process in the thyroid gland function. Therefore, in this study theoretical investigation of the molecular interaction between two antithyroid drugs, namely methimazol (MMI) and thiazoline-2-thione (T2T), with the hypohalous acids (HOX, X = I, Br, and Cl), which act as heme-linked halogenated species to tyrosine residue was discussed. The calculations were performed by M06-2X and MP2 using aug-cc-pVDZ level of theory. In addition, wB97xd/6-31G* level of theory was used in order to account for the dispersion forces. The results show the possible formation of three adducts, which is stabilized by halogen bond (I), both halogen and hydrogen bonds (II), two hydrogen bonds (III). The binding energies of the complexes reveals stabilization in the order III > II > I. The binding energies of the complexes was increased with increasing the electron affinity and polarizability of halogen atom, the dipole moment of the complexes (I and II), the electrostatic potential on halogen atom (Vmax:i.e σ-hole), and the charge-transfer process through the halogen bond in I. On the other hand, the binding energies of the complexes decreased with increasing the halogen atom electronegativity and the dipole moment of complex III. Natural bond orbital (NBO) analysis was used to investigate the molecular orbital interactions and the charge transfer process upon complexation.

Polarized Infrared Absorption of Dipole Centers in Cadmium Halide and PbI2 Crystals

NASA Astrophysics Data System (ADS)

Terakami, Mitsushi; Nakagawa, Hideyuki

2004-03-01

Polarized infrared (IR) absorption measurements on CN- or OH- centers in cadmium halide and PbI2 crystals were carried out at 6 K with a high spectral resolution of 0.025 cm-1 at 2000 cm-1 by using a FTIR spectrometer. Several sharp absorption lines with widths less than 0.1 cm-1 are observed in the energy region of the stretching vibration, i.e. 2000 to 2250 cm-1 for CN- and 2500 to 4500 cm-1 for OH-. These lines are classified into several groups attributed to (1) an isolated center simply substituted for a halogen ion, (2) an interstitial center located between the cadmium and halogen ion sheets and (3) a coupled center with an anion vacancy or a host metal ion. Almost all of the dipole axes (bond axes) of the CN- ions doped in MI2 (M = Cd or Pb) are parallel to the crystal c-axes, while those of the isolated and coupled CN- centers in CdX2 (X = Cl or Br) lean away from the direction of the c-axis. The most OH- ions doped in CdX2 (X = Cl, Br or I) and PbI2 are arranged in the halogen-ion planes with their dipole axes parallel to the crystal c-axes. The first overtone yields values of χe and ωeχe for CN- and OH- in CdX2 and PbI2. These values explain well the isotope shift of the main stretching band in CdX2 and PbI2.

Polymorphism in 2-X-adamantane derivatives (X = Cl, Br).

PubMed

Negrier, Philippe; Barrio, María; Tamarit, Josep Ll; Mondieig, Denise

2014-08-14

The polymorphism of two 2-X-adamantane derivatives, X = Cl, X = Br, has been studied by X-ray powder diffraction and normal- and high-pressure (up to 300 MPa) differential scanning calorimetry. 2-Br-adamantane displays a low-temperature orthorhombic phase (space group P212121, Z = 4) and a high-temperature plastic phase (Fm3̅m, Z = 4) from 277.9 ± 1.0 K to the melting point at 413.4 ± 1.0 K. 2-Cl-adamantane presents a richer polymorphic behavior through the temperature range studied. At low temperature it displays a triclinic phase (P1̅, Z = 2), which transforms to a monoclinic phase (C2/c, Z = 8) at 224.4 ± 1.0 K, both phases being ordered. Two high-temperature orientationally disordered are found for this compound, one hexagonal (P63/mcm, Z = 6) at ca. 241 K and the highest one, cubic (Fm3̅m, Z = 4), being stable from 244 ± 1.0 K up to the melting point at 467.5 ± 1.0 K. No additional phase appears due to the increase in pressure within the studied range. The intermolecular interactions are found to be weak, especially for the 2-Br-adamantane compound for which the Br···Br as well as C-Br···H distances are larger than the addition of the van der Waals radii, thus confirming the availability of this compound for building up diamondoid blocks.

Effect of non-stoichiometric solution chemistry on improving the performance of wide-bandgap perovskite solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Mengjin; Kim, Dong Hoe; Yu, Yue

A high-efficiency wide-bandgap (WBG) perovskite solar cell is critical for developing perovskite-related (e.g., all-perovskite, perovskite/Si, or perovskite/Cu(In,Ga)Se 2) tandem devices. Here, we demonstrate the use of non-stoichiometric precursor chemistry with excess methylammonium halides (MAX; X = I, Br, or Cl) for preparing high-quality ~1.75-eV FA 0.83Cs 0.17Pb(I 0.6Br 0.4) 3 perovskite solar cells. Among various methylammonium halides, using excess MABr in the non-stoichiometric precursor exhibits the strongest effect on improving perovskite crystallographic properties and device characteristics without affecting the perovskite composition. In contrast, using excess MAI significantly reduces the bandgap of perovskite due to the replacement of Br with I.more » Using 40% excess MABr, we demonstrate a single-junction WBG perovskite solar cell with stabilized efficiency of 16.4%. We further demonstrate a 20.3%-efficient 4-terminal tandem device by using a 14.7%-efficient semi-transparent WBG perovskite top cell and an 18.6%-efficient unfiltered (5.6%-efficient filtered) Si bottom cell.« less

Effect of non-stoichiometric solution chemistry on improving the performance of wide-bandgap perovskite solar cells

DOE PAGES

Yang, Mengjin; Kim, Dong Hoe; Yu, Yue; ...

2017-10-02

A high-efficiency wide-bandgap (WBG) perovskite solar cell is critical for developing perovskite-related (e.g., all-perovskite, perovskite/Si, or perovskite/Cu(In,Ga)Se 2) tandem devices. Here, we demonstrate the use of non-stoichiometric precursor chemistry with excess methylammonium halides (MAX; X = I, Br, or Cl) for preparing high-quality ~1.75-eV FA 0.83Cs 0.17Pb(I 0.6Br 0.4) 3 perovskite solar cells. Among various methylammonium halides, using excess MABr in the non-stoichiometric precursor exhibits the strongest effect on improving perovskite crystallographic properties and device characteristics without affecting the perovskite composition. In contrast, using excess MAI significantly reduces the bandgap of perovskite due to the replacement of Br with I.more » Using 40% excess MABr, we demonstrate a single-junction WBG perovskite solar cell with stabilized efficiency of 16.4%. We further demonstrate a 20.3%-efficient 4-terminal tandem device by using a 14.7%-efficient semi-transparent WBG perovskite top cell and an 18.6%-efficient unfiltered (5.6%-efficient filtered) Si bottom cell.« less

Mononuclear ruthenium(III) complexes containing chelating thiosemicarbazones: Synthesis, characterization and catalytic property

NASA Astrophysics Data System (ADS)

Raja, N.; Ramesh, R.

2010-02-01

Mononuclear ruthenium(III) complexes of the type [RuX(EPh 3) 2(L)] (E = P or As; X = Cl or Br; L = dibasic terdentate dehydroacetic acid thiosemicarbazones) have been synthesized from the reaction of thiosemicarbazone ligands with ruthenium(III) precursors, [RuX 3(EPh 3) 3] (where E = P, X = Cl; E = As, X = Cl or Br) and [RuBr 3(PPh 3) 2(CH 3OH)] in benzene. The compositions of the complexes have been established by elemental analysis, magnetic susceptibility measurement, FT-IR, UV-vis and EPR spectral data. These complexes are paramagnetic and show intense d-d and charge transfer transitions in dichloromethane. The complexes show rhombic EPR spectra at LNT which are typical of low-spin distorted octahedral ruthenium(III) species. All the complexes are redox active and display an irreversible metal centered redox processes. Complex [RuCl(PPh 3) 2(DHA-PTSC)] ( 5) was used as catalyst for transfer hydrogenation of ketones in the presence of isopropanol/KOH and was found to be the active species.

Trace elements retained in washed nuclear fuel reprocessing solvents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gray, L.W.; MacMurdo, K.W.

1979-09-01

Analysis of purified TBP extractant from solvent extraction processes at Savannah River Plant showed several stable elements and several long-lived radioisotopes. Stable elements Al, Na, Br, Ce, Hg, and Sm are found in trace quantities in the solvent. The only stable metallic element consistently found in the solvent was Al, with a concentration which varies from about 30 ppM to about 10 ppM. The halogens Br and Cl appear to be found in the solvent systems as organo halides. Radionuclides found were principally /sup 106/Ru, /sup 129/I, /sup 3/H, /sup 235/U, and /sup 239/Pu. The /sup 129/I concentration was aboutmore » 1 ppM in the first solvent extraction cycle of each facility. In the other cycles, /sup 129/I concentration varied from about 0.1 to 0.5 ppM. Both /sup 129/I and /sup 3/H appear to be in the organic solvent as a result of exchange with hydrogen.« less

Core-dependent and ligand-dependent relativistic corrections to the nuclear magnetic shieldings in MH4-n Y n (n = 0-4; M = Si, Ge, Sn, and Y = H, F, Cl, Br, I) model compounds.

PubMed

Maldonado, Alejandro F; Aucar, Gustavo A; Melo, Juan I

2014-09-01

The nuclear magnetic shieldings of Si, Ge, and Sn in MH(4-n) Y(n) (M = Si, Ge, Sn; Y = F, Cl, Br, I and n = 1-4) molecular systems are highly influenced by the substitution of one or more hydrogens by heavy-halogen atoms. We applied the linear response elimination of small components (LRESC) formalism to calculate those shieldings and learn whether including only a few of the leading relativistic correction terms is sufficient to be able to quantitatively reproduce the full relativistic value. It was observed that the nuclear magnetic shieldings change as the number of heavy halogen substituents and their weights vary, and the pattern of σ(M) generally does not exhibit the normal halogen dependence (NHD) behavior that can be seen in similar molecular systems containing carbon atoms. We also analyzed each relativistic correction afforded by the LRESC method and split them in two: core-dependent and ligand-dependent contributions; we then looked for the electronic mechanisms involved in the different relativistic effects and in the total relativistic value. Based on this analysis, we were able to study the electronic mechanism involved in a recently proposed relativistic effect, the "heavy atom effect on vicinal heavy atom" (HAVHA), in more detail. We found that the main electronic mechanism is the spin-orbit or σ p (T(3)) correction, although other corrections such as σ p (S(1)) and σ p (S(3)) are also important. Finally, we analyzed proton magnetic shieldings and found that, for molecules containing Sn as the central atom, σ(H) decreases as the number of heavy halogen substituents (of the same type: either F, Cl, or Br) increases, albeit at different rates for different halogens. σ(H) only increase as the number of halogen substituents increases if the halogen is iodine.

Kinetics of the Reactions of Cl((sup 2)P(sub J)) and Br((sup 2)P(sub 3/2)) with O3

NASA Technical Reports Server (NTRS)

Nicovich, J. M.; Kreutter, K. D.; Wine, P. H.

1997-01-01

A laser flash photolysis-resonance fluorescence technique has been employed to study the kinetics of the important stratospheric reactions Cl((sup 2)P(sub J)) + O3 yields ClO + O2 and Br((sup 2)P(sub 3/2)) + O3 yields BrO + O2 as a function of temperature. The temperature dependence observed for the Cl((sup 2)P(sub J)) + O3 reaction is nonArrhenius, but can be adequately described by the following two Arrhenius expressions (units are cu cm/(molecule.s), errors are 2 sigma and represent precision only): k(sub 1)(T) = (1.19 +/- 0.21) x 10(exp -11) exp[(-33 +/- 37)/T] for T = 189-269 K and k(sub 1)(T) = (2.49 +/- 0.38) x 10(exp -11) exp[(-233 +/- 46)/T] for 269-385 K. At temperatures below 230 K, the rate coefficients determined in this study are faster than any reported previously. Incorporation of our values for k(sub 1)(T) into stratospheric models would increase calculated ClO levels and decrease calculated HCI levels; hence the calculated efficiency of ClO catalyzed ozone destruction would increase. The temperature dependence observed for the Br((sup 2)P(sub 3/2)) + O3 reaction is adequately described by the following Arrhenius expression (units are cu cm/(molecule.s), errors are 2 sigma and represent precision only): k(sub 2)(T) = (1.50 +/- 0.16) x 10(exp -11)exp[(-775 +/- 30)/T for 195-392 K. While not in quantitative agreement with Arrhenius parameters reported in most previous studies, our results almost exactly reproduce the average of all earlier studies and therefore will not affect the choice of k(sub 2)(T) for use in modeling stratospheric BrO2 chemistry.

Controlled Synthesis and Functionalization of Vertically-Aligned Carbon Nanotubes for Multifunctional Applications

DTIC Science & Technology

2015-05-07

6 1.6 Lithium - Ion Batteries Based on Vertically-Aligned Carbon Nanotube Electrodes and Ionic...Cl, Br, or I) Prepared by Ball-Milling and Used as Anode Materials for Lithium - Ion Batteries ……………....................23 3.4 Well-Defined Two...9 1.6 Lithium - Ion Batteries Based on Vertically-Aligned Carbon Nanotube Electrodes and Ionic Liquid Electrolytes

Influence of the Li···π Interaction on the H/X···π Interactions in HOLi···C6H6···HOX/XOH (X=F, Cl, Br, I) complexes.

PubMed

Zeng, Yanli; Wu, Wenjie; Li, Xiaoyan; Zheng, Shijun; Meng, Lingpeng

2013-06-03

The influences of the Li···π interaction of C6H6···LiOH on the H···π interaction of C6H6···HOX (X=F, Cl, Br, I) and the X···π interaction of C6H6···XOH (X=Cl, Br, I) are investigated by means of full electronic second-order Møller-Plesset perturbation theory calculations and "quantum theory of atoms in molecules" (QTAIM) studies. The binding energies, binding distances, infrared vibrational frequencies, and electron densities at the bond critical points (BCPs) of the hydrogen bonds and halogen bonds prove that the addition of the Li···π interaction to benzene weakens the H···π and X···π interactions. The influences of the Li···π interaction on H···π interactions are greater than those on X···π interactions; the influences of the H···π interactions on the Li···π interaction are greater than X···π interactions on Li···π interaction. The greater the influence of Li···π interaction on H/X···π interactions, the greater the influences of H/X···π interactions on Li···π interaction. QTAIM studies show that the intermolecular interactions of C6H6···HOX and C6H6···XOH are mainly of the π type. The electron densities at the BCPs of hydrogen bonds and halogen bonds decrease on going from bimolecular complexes to termolecular complexes, and the π-electron densities at the BCPs show the same pattern. Natural bond orbital analyses show that the Li···π interaction reduces electron transfer from C6 H6 to HOX and XOH. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rotationally adiabatic pair interactions of para- and ortho-hydrogen with the halogen molecules F2, Cl2, and Br2.

PubMed

Berg, Matthias; Accardi, Antonio; Paulus, Beate; Schmidt, Burkhard

2014-08-21

The present work is concerned with the weak interactions between hydrogen and halogen molecules, i.e., the interactions of pairs H2-X2 with X = F, Cl, Br, which are dominated by dispersion and quadrupole-quadrupole forces. The global minimum of the four-dimensional (4D) coupled cluster with singles and doubles and perturbative triples (CCSD(T)) pair potentials is always a T shaped structure where H2 acts as the hat of the T, with well depths (De) of 1.3, 2.4, and 3.1 kJ/mol for F2, Cl2, and Br2, respectively. MP2/AVQZ results, in reasonable agreement with CCSD(T) results extrapolated to the basis set limit, are used for detailed scans of the potentials. Due to the large difference in the rotational constants of the monomers, in the adiabatic approximation, one can solve the rotational Schrödinger equation for H2 in the potential of the X2 molecule. This yields effective two-dimensional rotationally adiabatic potential energy surfaces where pH2 and oH2 are point-like particles. These potentials for the H2-X2 complexes have global and local minima for effective linear and T-shaped complexes, respectively, which are separated by 0.4-1.0 kJ/mol, where oH2 binds stronger than pH2 to X2, due to higher alignment to minima structures of the 4D-pair potential. Further, we provide fits of an analytical function to the rotationally adiabatic potentials.

Preparation and Single-Crystal X-Ray Structures of Four Related Mixed-Ligand 4-Methylpyridine Indium Halide Complexes

NASA Technical Reports Server (NTRS)

Hepp, Aloysius F.; Clark, Eric B.; Schupp, John D.; Williams, Jennifer N.; Duraj, Stan A.; Fanwick, Philip E.

2013-01-01

We describe the structures of four related indium complexes obtained during synthesis of solid-state materials precursors. Indium adducts of halides and 4-methylpyridine, InX3(pic)3 (X = Cl, Br; pic = 4-methylpyridine) consist of octahedral molecules with meridional (mer) geometry. Crystals of mer-InCl3(pic)3 (1) are triclinic, space group P1(bar) (No. 2), with a = 9.3240(3), b = 13.9580(6), c = 16.7268 (7) A, alpha = 84.323(2), beta = 80.938(2), gamma = 78.274(3)Z = 4, R = 0.035 for 8820 unique reflections. Crystals of mer-InBr3(pic)3 (2) are monoclinic, space group P21/n (No. 14), with a = 15.010(2), b = 19.938(2), c = 16.593(3), beta = 116.44(1)Z = 8, R = 0.053 for 4174 unique reflections. The synthesis and structures of related compounds with phenylsulfide (chloride) (3) and a dimeric complex with bridging hydroxide (bromide) (4) coordination is also described. Crystals of trans-In(SC6H5)Cl2(pic)3 (3) are monoclinic, space group P21/n (No. 14), with a = 9.5265(2), b = 17.8729(6), c = 13.8296(4), beta = 99.7640(15)Z = 4, R = 0.048 for 5511 unique reflections. Crystals of [In(mu-OH)Br2(pic)22 (4) are tetragonal, space group = I41cd (No. 110) with a = 19.8560(4), b = 19.8560(4), c = 25.9528(6), Z = 8, R = 0.039 for 5982 unique reflections.

New molecular assemblies of redox isomers, [CrIII(X4SQ)3-n(X4Cat)n]-n (X = Cl and Br; n = 0, 1, and 2), with metallocenium cations, [MIIICp2]+ (M = Co and Fe): X-ray crystal structures and physical properties.

PubMed

Chang, H C; Miyasaka, H; Kitagawa, S

2001-01-01

A series of redox isomers of [CrIII(X4SQ)(X4Cat)2]2-, [CrIII(X4SQ)2(X4Cat)]-, and [CrIII(X4SQ)3]0 (X = Cl and Br, SQ = semiquinonate, and Cat = catecholate) have been synthesized and characterized as charge-transfer (CT) compounds with metallocenium cations: (CoIIICp2)2[CrIII(Cl4SQ)(Cl4Cat)2] (1), (CoIIICp2)2[CrIII(Br4SQ)(Br4Cat)2] (2), (FeIIICp2)[CrIII(Cl4SQ)2(Cl4Cat)].C6H6 (4), (FeIIICp2)[CrIII(Br4SQ)2(Br4Cat)].CS2 (5), and (FeIIICp2)[CrIII(Cl4SQ)2(Cl4Cat)][CrIII(Cl4SQ)3] (6). First, the oxidation states of the chromium complexes are strongly dependent on the redox potentials of the metallocenes used. The CoIICp2, exhibiting stronger reduction power than FeIICp2, is useful for two-electron reduction of the [CrIII(X4SQ)3]0, affording [CrIII(X4SQ)(X4Cat)2]2- (1 and 2), which are first isolated and crystallographically characterized in the solid state. In contrast the reaction with FeIICp2 affords only [CrIII(X4SQ)2(X4Cat)]- (4 and 5). Second, solvents influence crystal structures of these compounds. The solvent set of C6H6/CS2 gives 1:1:C6H6 compound 4 with unique charged anions, [CrIII(Cl4SQ)2(Cl4Cat)]-, while the other set, n-C6H12/CS2, affords 1:2 compound 6 including the two redox isomers, [CrIII(Cl4SQ)2(Cl4Cat)]- and [CrIII(Cl4SQ)3]0. The [CrIII(X4SQ)(X4Cat)2]2- anions in 1 and 2 show no significant interconnection between them (discrete type), while the [CrIII(X4SQ)2(X4Cat)]- anions in 4-6 show one-dimensional column-type structures with the aid of intermolecular stacking interactions of the ligand moieties. The anions in 4 show additional stacking interaction with the [FeIIICp2]+ to form one-dimensional ...[D][A][S][D][A]... (D = [FeIIICp2]+, A = [CrIII(Cl4SQ)2(Cl4Cat)]-, and S = C6H6) type mixed-stack arrangements similar to that of previously reported (CoIIICp2)[CrIII(Cl4SQ)2(Cl4Cat)].C6H6 (3). Compound 6 forms a two-dimensional sheet structure where the two redox isomers, [CrIII(Cl4SQ)2(Cl4Cat)]- and [CrIII(Cl4SQ)3]0, are included. The sheet is regarded as a mixed-valence molecular assembly. Two types of the anions, [CrIII(X4SQ)(X4Cat)2]2- (1 and 2) and [CrIII(X4SQ)2(X4Cat)]- (4-6), exhibiting an intramolecular mixed-valence state, show intramolecular intervalence CT transition (IVCT) from the Cat to the SQ at near 5800 and 4300 cm-1, respectively, both in the solution and in the solid states. The intermolecular mixed-valence state of 6 was characterized by absorption spectroscopy, electric conductivity, and SQUID magnetometry. Interestingly, this mixed-valence state of the chromium module is dependent on the redox active nature of the coordinated ligands.

Further Analysis of Boiling Points of Small Molecules, CH[subscript w]F[subscript x]Cl[subscript y]Br[subscript z

ERIC Educational Resources Information Center

Beauchamp, Guy

2005-01-01

A study to present specific hypothesis that satisfactorily explain the boiling point of a number of molecules, CH[subscript w]F[subscript x]Cl[subscript y]Br[subscript z] having similar structure, and then analyze the model with the help of multiple linear regression (MLR), a data analysis tool. The MLR analysis was useful in selecting the…

EVALUATION OF BENZO[C]CHRYSENE DIHYDRODIOLS IN THE MORPHOLOGICAL CELL TRANSFORMATION OF MOUSE EMBRYO FIBROBLAST C3H10T1/2CL8 CELLS

EPA Science Inventory

EVALUATION OF BENZO[c]CHRYSENE DIHYDRODIOLS IN THE MORPHOLOGICAL CELL TRANSFORMATION OF MOUSE EMBRYO FIBROBLAST C3H10T?CL8 CELLS

Abstract The morphological cell transforming activities of three dihydrodiols of benzo[c]chrysene (B[c]C), trans-B[c]C-7,8-diol, trans-B[c]C-9...

Determination of Halide Concentrations at the Interface of Zwitterionic Micelles by Chemical Trapping: Influence of the Orientation of the Dipole and the Nature of the Cation.

PubMed

Cuccovia; Romsted; Chaimovich

1999-12-01

The interfacial concentrations of Cl(-) and Br(-) in aqueous zwitterionic micelles were determined by chemical trapping by analyzing product yields from spontaneous dediazoniation of micelle-bound 2,6-dimethyl-4-hexadecylbenzenediazonium ion. Interfacial concentrations of Cl(-) and Br(-) in 3-(N-hexadecyl-N, N-dimethylammonio) propane sulfonate, HPS, micelles were higher than in bulk solutions prepared with Li(+), Na(+), Rb(+), Cs(+), tetramethylammonium (TMA(+)), Mg(+2), and Ca(+2) salts. In contrast, the interfacial concentrations of Cl(-) and Br(-) were generally lower than in bulk solution in hexadecylphosphoryl choline, HDPC, micelles for all salts except Mg(+2) and Ca(+2). In both HPS and HDPC micelles the interfacial concentration of Br(-) was higher than that of Cl(-), showing that binding is anion selective. The cation had a large effect on the interfacial concentration of halide ions with HDPC micelles decreasing in the order Ca(2+) > Mg(2+) > Li(+) > Na(+) > K(+) > Cs(+) > Rb(+) > TMA(+). These results are the first direct and extensive determination of local halide ion concentration at the surface of zwitterionic micelles, and they demonstrate that chemical trapping methodology will work in membranes at physiologically relevant salt concentrations. Copyright 1999 Academic Press.

Anion dependent self-assembly of 56-metal Cd-Ln nanoclusters with enhanced near-infrared luminescence properties

NASA Astrophysics Data System (ADS)

Yang, Xiaoping; Schipper, Desmond; Zhang, Lijie; Yang, Keqin; Huang, Shaoming; Jiang, Jijun; Su, Chengyong; Jones, Richard A.

2014-08-01

Two series of Cd-Ln clusters: nano-drum [Ln8Cd24L12(OAc)48] and nano-double-drum [Ln12Cd44L20Cl30(OAc)54] (Ln = Nd and Yb) were prepared using a flexible Schiff base ligand bearing two aryl-Br groups. Chloride (Cl-) ions, together with the interactions of Br with other electronegative atoms, play a key role in the formation of the nano-double-drums. The structures were studied by TEM and photophysical properties were determined.Two series of Cd-Ln clusters: nano-drum [Ln8Cd24L12(OAc)48] and nano-double-drum [Ln12Cd44L20Cl30(OAc)54] (Ln = Nd and Yb) were prepared using a flexible Schiff base ligand bearing two aryl-Br groups. Chloride (Cl-) ions, together with the interactions of Br with other electronegative atoms, play a key role in the formation of the nano-double-drums. The structures were studied by TEM and photophysical properties were determined. Electronic supplementary information (ESI) available: Full experimental and characterization details for 1-4. CCDC 972369-972372. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4nr03075c

Transmittance of optical materials from 0.17 micro to 3.0 micro.

PubMed

McCarthy, D E

1967-11-01

The transmittance of thirty-one optical materials is given from 0.17, micro to 3.0 micro. Included are NaCl, KBr, CsBr, CsI, CaF(2), BaF(2), NaF, TlBr, TICL, KRS-5, KRS-6, T-12, KC, CuC, T O(2), ADP, KDP, SrTiO(3), GaP, CaCO(3), CdSe, As(2)S(3), ruby, Al(2)O(3), Irtran 1-6, and quartz. All are synthetic with the exception of CaCO(3). In many cases, the short wavelength cutoff of the synthetic materials is less than that which has been reported for naturally occurring materials.

Structure modeling and manufacturing PCFs for the range of 2-25 μm

NASA Astrophysics Data System (ADS)

Lvov, Alexandr; Salimgareev, Dmitrii; Korsakov, Michail; Korsakov, Alexandr; Zhukova, Liya

2017-11-01

Photostable and flexible materials transparent at the wide spectral range are necessary for the development of optical fiber units. Solid solutions of silver and monadic thallium halides are the most suitable crystal media for this purpose. The goal of our research was the search of optimum structure for the fibers with a single mode operation and a rather large core diameter. We modelled fiber structures (solid-core, hollow-core, active-core PCF) with various ratio of inserts diameters and increments between the inserts, basing on two crystal systems: AgCl-AgBr and AgBr-TlI. Then we chose the single mode fiber structure and manufactured it by means of extrusion.

Reactions of N2O5 with Salty and Surfactant-Coated Glycerol: Interfacial Conversion of Br- to Br2 Mediated by Alkylammonium Cations.

PubMed

Shaloski, Michael A; Gord, Joseph R; Staudt, Sean; Quinn, Sarah L; Bertram, Timothy H; Nathanson, Gilbert M

2017-05-18

Gas-liquid scattering and product-yield experiments are used to investigate reactions of N 2 O 5 with glycerol containing Br - and surfactant ions. N 2 O 5 oxidizes Br - to Br 2 for every solution tested: 2.7 M NaBr, 0.03 M tetrahexylammonium bromide (THABr), 0.03 M THABr + 0.5 M NaBr, 0.03 M THABr + 0.5 M NaCl, 0.03 M THABr + 0.01 M sodium dodecyl sulfate (SDS), and 0.01 M cetyltrimethylammonium bromide (CTABr). N 2 O 5 also reacts with glycerol itself to produce mono- and dinitroglycerin. Surface tension measurements indicate that 0.03 M THABr and 2.7 M NaBr have similar interfacial Br - concentrations, though their bulk Br - concentrations differ by 90-fold. We find that twice as much Br 2 is produced in the presence of THA + , implying that the conversion of Br - to Br 2 is initiated at the interface, perhaps mediated by the charged, hydrophobic pocket within the surface THA + cation. The addition of 0.5 M NaBr, 0.5 M NaCl, or 0.01 M SDS to 0.03 M THABr lowers the Br 2 production rate by 23%, 63%, and 67% of the THABr value, respectively. When CTA + is substituted for THA + , Br 2 production drops to 12% of the THABr value. The generation of Br 2 under such different conditions implies that trace amounts of surface-active alkylammonium ions can catalyze interfacial N 2 O 5 reactions, even when salts and other surfactants are present.

RESIDENTIAL PESTICIDE USE AND URINARY ORGANOPHOSPHATE METABOLITES IN PRE-SCHOOL CHILDREN

EPA Science Inventory

Residential Pesticide Use and Urinary Organophosphate Metabolites in Pre-School Children
CL Carty1, P Mendola1, D Barr2, L Needham2, D Walsh1

1Epidemiology and Biomarkers Branch, Human Studies Division, National Health and Environmental Effects Research Laboratory, U.S....

Catalytic valorization of starch-rich food waste into hydroxymethylfurfural (HMF): Controlling relative kinetics for high productivity.

PubMed

Yu, Iris K M; Tsang, Daniel C W; Yip, Alex C K; Chen, Season S; Wang, Lei; Ok, Yong Sik; Poon, Chi Sun

2017-08-01

This study aimed to maximize the valorization of bread waste, a typical food waste stream, into hydroxymethylfurfural (HMF) by improving our kinetic understanding. The highest HMF yield (30mol%) was achieved using SnCl 4 as catalyst, which offered strong derived Brønsted acidity and moderate Lewis acidity. We evaluated the kinetic balance between these acidities to facilitate faster desirable reactions (i.e., hydrolysis, isomerization, and dehydration) relative to undesirable reactions (i.e., rehydration and polymerization). Such catalyst selectivity of SnCl 4 , AlCl 3 , and FeCl 3 was critical in maximizing HMF yield. Higher temperature made marginal advancement by accelerating the undesirable reactions to a similar extent as the desirable pathways. The polymerization-induced metal-impregnated high-porosity carbon was a possible precursor of biochar-based catalyst, further driving up the economic potential. Preliminary economic analysis indicated a net gain of USD 43-236 per kilogram bread waste considering the thermochemical-conversion cost and chemical-trading revenue. Copyright © 2017 Elsevier Ltd. All rights reserved.

Design, Synthesis and Characterisation of New Chimeric Ruthenium(II)-Gold(I) Complexes as Improved Cytotoxic Agents

PubMed Central

Massai, Lara; Fernández-Gallardo, Jacob; Guerri, Annalisa; Arcangeli, Annarosa; Pillozzi, Serena

2015-01-01

Two heterobimetallic complexes, i.e. [RuCl2(p-cymene)(µ-dppm)AuC] (1) and [RuCl2(p-cymene)(µ-dppm)Au S(thiazoline)] (3), based on known cytotoxic [Ru(p-cymene)Cl2(PR3)] and [AuX(PR3)] (X = Cl, SR) molecular scaffolds, with the diphosphane linker 1,1-bis(diphenylphosphino) methane, dppm, were conveniently prepared and characterised. Remarkably, the new compounds manifested a more favourable in vitro pharmacological profile toward cancer cells than individual ruthenium and gold species being either more cytotoxic or more selective. The interactions of the study compounds with (pBR322) DNA and their inhibitory effects on cathepsin B were also assessed. In addition, their reactivity toward suitable models of protein targets was explored and clear evidence gained for disruption of the bimetallic motif and for protein binding of monometallic fragments. Overall, the data reported here strongly support the concept of multifunctional heterometallic compounds as “improved” candidate agents for cancer treatment. The mechanistic and pharmacological implications of the present findings are discussed. PMID:25996553

Design, synthesis and characterisation of new chimeric ruthenium(II)-gold(I) complexes as improved cytotoxic agents.

PubMed

Massai, Lara; Fernández-Gallardo, Jacob; Guerri, Annalisa; Arcangeli, Annarosa; Pillozzi, Serena; Contel, María; Messori, Luigi

2015-06-28

Two heterobimetallic complexes, i.e. [RuCl2(p-cymene)(μ-dppm)AuC] (1) and [RuCl2(p-cymene)(μ-dppm)Au(S-thiazoline)] (3), based on known cytotoxic [Ru(p-cymene)Cl2(PR3)] and [AuX(PR3)] (X = Cl, SR) molecular scaffolds, with the diphosphane linker 1,1-bis(diphenylphosphino)methane, dppm, were conveniently prepared and characterised. Remarkably, the new compounds manifested a more favourable in vitro pharmacological profile toward cancer cells than individual ruthenium and gold species being either more cytotoxic or more selective. The interactions of the studied compounds with (pBR322) DNA and their inhibitory effects on cathepsin B were also assessed. In addition, their reactivity toward suitable models of protein targets was explored and clear evidence gained for disruption of the bimetallic motif and for protein binding of monometallic fragments. Overall, the data reported here strongly support the concept of multifunctional heterometallic compounds as "improved" candidate agents for cancer treatment. The mechanistic and pharmacological implications of the present findings are discussed.

Multifunctional silicon surfaces: reaction of dichlorocarbene generated from Seyferth reagent with hydrogen-terminated silicon (111) surfaces.

PubMed

Liu, Wenjun; Sharp, Ian D; Tilley, T Don

2014-01-14

Insertion of dichlorocarbene (:CCl2), generated by decomposition of the Seyferth reagent PhHgCCl2Br, into the Si-H bond of a tertiary silane to form a Si-CCl2H group is an efficient homogeneous, molecular transformation. A heterogeneous version of this reaction, between PhHgCCl2Br and a silicon (111) surface terminated by tertiary Si-H bonds, was studied using a combination of surface-sensitive infrared and X-ray photoelectron spectroscopies. The insertion of dichlorocarbene into surface Si-H bonds parallels the corresponding reaction of silanes in solution, to produce surface-bound dichloromethyl groups (Si-CCl2H) covering ∼25% of the silicon surface sites. A significant fraction of the remaining Si-H bonds on the surface was converted to Si-Cl/Br groups during the same reaction, with PhHgCCl2Br serving as a halogen atom source. The presence of two distinct environments for the chlorine atoms (Si-CCl2H and Si-Cl) and one type of bromine atom (Si-Br) was confirmed by Cl 2p, Br 3d, and C 1s X-ray photoelectron spectroscopy. The formation of reactive, halogen-terminated atop silicon sites was also verified by reaction with sodium azide or the Grignard reagent (CH3MgBr), to produce Si-N3 or Si-Me functionalities, respectively. Thus, reaction of a hydrogen-terminated silicon (111) surface with PhHgCCl2Br provides a facile route to multifunctional surfaces possessing both stable silicon-carbon and labile silicon-halogen sites, in a single pot synthesis. The reactive silicon-halogen groups can be utilized for subsequent transformations and, potentially, the construction of more complex organic-silicon hybrid systems.

A novel strategy to construct Janus metallamacrocycles with both a Ru-arene face and an imidazolium face.

PubMed

Li, Ji; Zhang, Peipei; Xu, Yan; Su, Zhi; Qian, Yong; Li, Shunli; Yu, Tao; Sadler, Peter J; Liu, Hong-Ke

2017-11-28

The bottom-up construction of highly functional metallamacrocycles from simple building blocks is a challenge of much current interest. We have used solvothermal reactions of a bifunctional p-bitmb ligand with [Ru(arene)X 2 ] 2 in CH 2 Cl 2 or CH 2 Br 2 to generate the novel mononuclear metallamacrocyclic [RuX(arene)L 2 CH 2 ]X 3 complexes 1-3 (1, arene = p-cym, X = Cl; 2, arene = bip, X = Cl; 3, arene = p-cym, X = Br), which were characterized by various techniques. These complexes are "bowl-like" and have two faces: one coordinative Ru centre (arene)Ru(N,N)X bridged by L (L = 1,4-bis(imidazol-1-ylmethyl)-2,3,5,6-tetramethylbenzene, p-bitmb) to a dipositive bis-imidazolinium centre. Cl - or Br - anions can be trapped inside the cavity of the "bowl-like" structure, forming H-bonds with the backbone. Experimental (NMR and ESI-MS) and computational (DFT calculations) studies show that the source of the bridging -CH 2 - group is the dihalogenated solvent (CH 2 Cl 2 or CH 2 Br 2 ) that links the two arms of an initially formed non-cyclic complex (arene)RuX 2 L 2 by a mechanism of nucleophilic substitution. Optimization of the reaction conditions afforded the macrocyclic complexes in almost quantitative yields. The applications of these complexes as anti-proliferative agents towards cancer cells and for selective anion sensing have been explored.

Laser flash photolysis studies of atmospheric free radical chemistry using optical diagnostic techniques

NASA Technical Reports Server (NTRS)

Wine, Paul H.; Nicovich, J. M.; Hynes, Anthony J.; Stickel, Robert E.; Thorn, R. P.; Chin, Mian; Cronkhite, Jeffrey A.; Shackelford, Christie J.; Zhao, Zhizhong; Daykin, Edward P.

1993-01-01

Some recent studies carried out in our laboratory are described where laser flash photolytic production of reactant free radicals has been combined with reactant and/or product detection using time-resolved optical techniques to investigate the kinetics and mechanisms of important atmospheric chemical reactions. Discussed are (1) a study of the radical-radical reaction O + BrO yields Br + O2 where two photolysis lasers are employed to prepare the reaction mixture and where the reactants O and BrO are monitored simultaneously using atomic resonance fluorescence to detect O and multipass UV absorption to detect BrO; (2) a study of the reaction of atomic chlorine with dimethylsulfide (CH3SCH3) where atomic resonance fluorescence detection of Cl is employed to elucidate the kinetics and tunable diode laser absorption spectroscopy is employed to investigate the HCl product yield; and (3) a study of the aqueous phase chemistry of Cl2(-) radicals where longpath UV absorption spectroscopy is employed to investigate the kinetics of the Cl2(-) + H2O reaction.

Major element compositions of fluid inclusions from hydrothermal vein-type deposits record eroded sedimentary units in the Schwarzwald district, SW Germany

NASA Astrophysics Data System (ADS)

Walter, Benjamin F.; Burisch, Mathias; Marks, Michael A. W.; Markl, Gregor

2017-12-01

Mixing of sedimentary formation fluids with basement-derived brines is an important mechanism for the formation of hydrothermal veins. We focus on the sources of the sediment-derived fluid component in ore-forming processes and present a comprehensive fluid inclusion study on 84 Jurassic hydrothermal veins from the Schwarzwald mining district (SW Germany). Our data derive from about 2300 fluid inclusions and reveal differences in the average fluid composition between the northern, central, and southern Schwarzwald. Fluids from the northern and southern Schwarzwald are characterised by high salinities (18-26 wt% NaCl+CaCl2), low Ca/(Ca+Na) mole ratios (0.1-0.4), and variable Cl/Br mass ratios (30-1140). In contrast, fluids from the central Schwarzwald show even higher salinities (23-27 wt% NaCl+CaCl2), higher Ca/(Ca+Na) mole ratios (0.2-0.9), and less variable Cl/Br mass ratios (40-130). These fluid compositions correlate with the nature and thickness of the now eroded sedimentary cover rocks. Compared to the northern and the southern Schwarzwald, where halite precipitation occurred during the Middle Triassic, the sedimentary basin in the central Schwarzwald was relatively shallow at this time and no halite was precipitated. Accordingly, Cl/Br ratios of fluids from the central Schwarzwald provide no evidence for the reaction of a sedimentary brine with halite, whereas those from the northern and southern Schwarzwald do. Instead, elevated Ca/(Ca+Na), high SO4 contents, and relatively low Cl/Br imply the presence of a gypsum dissolution brine during vein formation in the central Schwarzwald which agrees with the reconstructed regional Triassic geology. Hence, the information archived in fluid inclusions from hydrothermal veins in the crystalline basement has the potential for reconstructing sedimentary rocks in the former overburden.

Syntheses of monomeric (. eta. sup 5 -pentamethylcyclopentadienyl)platinum(IV) methyl and bromo complexes and of (hydrotris(3,5-dimethyl-1-pyrazolyl)borato)trimethylplatinum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roth, S.; Ramamoorthy, V.; Sharp, P.R.

1990-09-05

The reaction of Cp*MgCl{center dot}THF (Cp* = C{sub 5}Me{sub 5}) with 1 equiv of PtMe{sub 3}I and PtMe{sub 2}Br{sub 2} produces Cp*PtMe{sub 3} (1) and Cp*PtMe{sub 2}Br (2), respectively. Reaction of 2 with Br{sub 2} produces Cp*PtMeBr{sub 2} (3) in good yield. The structures of 2 and 3 have been determined by x-ray crystallography, and the crystal structure data are reported. Complex 2 crystallizes in the monoclinic space group, P2{sub 1}/m, and complex 3 crystallizes in the monoclinic space group, P2{sub 1}/m. The molecules reside on mirror planes and are monomeric pseudotetrahedral Pt(IV) complexes with piano stool type geometries andmore » {eta}{sup 5}-Cp* groups. Both molecules have Br atoms on the mirror. This leads to a disorder of the Me and the second Br positions in complex 3. The average Pt-C(Cp*) bond length is 2.25 (7) {angstrom} in 2 and 2.22 (4) {angstrom} in 3. The Pt-C(Me) and Pt-Br bond lengths in 2 are 2.07 (2) and 2.498 (2) {angstrom}, respectively. The ordered Pt-Br bond length in 3 is 2.496 (2) {angstrom}. Treatment of 1 with halogens results in the cleavage of the Pt-Cp* bond. The reaction of PtMe{sub 3}I with KTp* (Tp* = (HB(3,5-dimethylpyrazolyl){sub 3}){sup {minus}}) in thf gives Tp*PtMe{sub 3} (4) in almost quantitative yield. The reaction of 4 with Br{sub 2} brominates the 4-position of the pyrazolyl ring only. 28 refs., 2 figs., 5 tabs.« less

Sensitivity of Tropospheric Chemical Composition to Halogen-Radical Chemistry Using a Fully Coupled Size-Resolved Multiphase Chemistry-Global Climate System: Halogen Distributions, Aerosol Composition, and Sensitivity of Climate-Relevant Gases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Long, M.; Keene, W. C.; Easter, Richard C.

Observations and model studies suggest a significant but highly non-linear role for halogens, primarily Cl and Br, in multiphase atmospheric processes relevant to tropospheric chemistry and composition, aerosol evolution, radiative transfer, weather, and climate. The sensitivity of global atmospheric chemistry to the production of marine aerosol and the associated activation and cycling of inorganic Cl and Br was tested using a size-resolved multiphase coupled chemistry/global climate model (National Center for Atmospheric Research’s Community Atmosphere Model (CAM); v3.6.33). Simulation results showed strong meridional and vertical gradients in Cl and Br species. The simulation reproduced most available observations with reasonable confidence permittingmore » the formulation of potential mechanisms for several previously unexplained halogen phenomena including the enrichment of Br- in submicron aerosol, and the presence of a BrO maximum in the polar free troposphere. However, simulated total volatile Br mixing ratios were generally high in the troposphere. Br in the stratosphere was lower than observed due to the lack of long-lived organobromine species in the simulation. Comparing simulations using chemical mechanisms with and without reactive Cl and Br species demonstrated a significant temporal and spatial sensitivity of primary atmospheric oxidants (O3, HOx, NOx), CH4, and non-methane hydrocarbons (NMHC’s) to halogen cycling. Simulated O3 and NOx were globally lower (65% and 35%, respectively, less in the planetary boundary layer based on median values) in simulations that included halogens. Globally, little impact was seen in SO2 and non-sea-salt SO42- processing due to halogens. Significant regional differences were evident: The lifetime of nss-SO42- was extended downwind of large sources of SO2. The burden and lifetime of DMS (and its oxidation products) were lower by a factor of 5 in simulations that included halogens, versus those without, leading to a 20% reduction in nss-SO42- in the southern hemisphere planetary boundary layer based on median values.« less

CsPbBr{sub 3} nanocrystal saturable absorber for mode-locking ytterbium fiber laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Yan; Li, Yue; Xu, Jianqiu

Cesium lead halide perovskite nanocrystals (CsPbX{sub 3}, X = Cl, Br, I) have been reported as efficient light-harvesting and light-emitting semiconductor materials, but their nonlinear optical properties have been seldom touched upon. In this paper, we prepare layered CsPbBr{sub 3} nanocrystal films and characterize their physical properties. Broadband linear absorption from ∼0.8 to over 2.2 μm and nonlinear optical absorption at the 1-μm wavelength region are measured. The CsPbBr{sub 3} saturable absorber (SA), manufactured by drop-casting of colloidal CsPbBr{sub 3} liquid solution on a gold mirror, shows modulation depth and saturation intensity of 13.1% and 10.7 MW/cm{sup 2}, respectively. With this SA, mode-locking operationmore » of a polarization-maintained ytterbium fiber laser produces single pulses with duration of ∼216 ps, maximum average output power of 10.5 mW, and the laser spectrum is centered at ∼1076 nm. This work shows that CsPbBr{sub 3} films can be efficient SA candidates for fiber lasers and also have great potential to become broadband linear and nonlinear optical materials for photonics and optoelectronics.« less

Naked-eye determination of oxalate anion in aqueous solution with copper ion and pyrocatechol violet.

PubMed

Su, Jing; Sun, Yuan-Qiang; Huo, Fang-Jun; Yang, Yu-Tao; Yin, Cai-Xia

2010-11-01

A novel strategy for the determination of oxalate anions was successfully established using a copper ion and pyrocatechol violet (PV) ensemble. The sensor ensemble can discriminate oxalate over other common anions including F(-), Cl(-), I(-), Br(-), HPO(4)(2-), PO(4)(3-), AcO(-), CO(3)(2-), SO(4)(2-), ClO(4)(-), P(2)O(7)(4-), S(2-) (deposited by Ag(+)), CN(-) (shielded by Fe(3+)) and can detect oxalate at low microgram levels in quasi-physiological aqueous solutions. The detection of the oxalate anion gives rise to a rapid observable visual color change from blue to yellow.

Formation of iodinated trihalomethanes during UV/chloramination with iodate as the iodine source.

PubMed

Zhang, Tian-Yang; Lin, Yi-Li; Wang, An-Qi; Tian, Fu-Xiang; Xu, Bin; Xia, Sheng-Ji; Gao, Nai-Yun

2016-07-01

Iodinated trihalomethanes (I-THMs) are a group of emerging disinfection by-products with high toxicity, and iodide (I(-)) as well as iodinated organic compounds are expected to be their iodine sources. Nevertheless, in this study, iodate (IO3(-)) was proven to be a new iodine source of I-THM formation during UV/chloramination. In the iodate-containing waters (without any other iodine sources), I-THM formation increased with the increase of UV dose, IO3(-) and NH2Cl concentrations. With the increase of Br(-)/IO3(-) molar ratio, I-THM formation (especially for the brominated species) increased. Besides, NOM species could affect I-THM formation from IO3(-) during UV/chloramination. Fulvic acid could promote IO3(-) phototransformation to I(-) but humic acid impeded the production of I(-) during UV irradiation. Under realistic drinking water treatment conditions (DOC = 5.0 mg-C/L, IO3(-) = 12.7 μg-I/L, UV dose = 50 mJ/cm(2), NH2Cl = 5 mg-Cl2/L), CHCl2I was detected as 0.17 μg/L using solid-phase microextraction method, and the production rate of I-THMs from IO3(-) was about 7% of that from I(-). Copyright © 2016 Elsevier Ltd. All rights reserved.

Enhanced ionic conductivity with Li{sub 7}O{sub 2}Br{sub 3} phase in Li{sub 3}OBr anti-perovskite solid electrolyte

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Jinlong, E-mail: jlzhu04@physics.unlv.edu, E-mail: yusheng.zhao@unlv.edu, E-mail: zhaoys@sustc.edu.cn; Li, Shuai; Zhang, Yi

Cubic anti-perovskites with general formula Li{sub 3}OX (X = Cl, Br, I) were recently reported as superionic conductors with the potential for use as solid electrolytes in all-solid-state lithium ion batteries. These electrolytes are nonflammable, low-cost, and suitable for thermoplastic processing. However, the primary obstacle of its practical implementation is the relatively low ionic conductivity at room temperature. In this work, we synthesized a composite material consisting of two anti-perovskite phases, namely, cubic Li{sub 3}OBr and layered Li{sub 7}O{sub 2}Br{sub 3,} by solid state reaction routes. The results indicate that with the phase fraction of Li{sub 7}O{sub 2}Br{sub 3} increasing to 44 wt.more » %, the ionic conductivity increased by more than one order of magnitude compared with pure phase Li{sub 3}OBr. Formation energy calculations revealed the meta-stable nature of Li{sub 7}O{sub 2}Br{sub 3}, which supports the great difficulty in producing phase-pure Li{sub 7}O{sub 2}Br{sub 3} at ambient pressure. Methods of obtaining phase-pure Li{sub 7}O{sub 2}Br{sub 3} will continue to be explored, including both high pressure and metathesis techniques.« less

Structures and properties of spherical 90-vertex fullerene-like nanoballs.

PubMed

Scheer, Manfred; Schindler, Andrea; Bai, Junfeng; Johnson, Brian P; Merkle, Roger; Winter, Rainer; Virovets, Alexander V; Peresypkina, Eugenia V; Blatov, Vladislav A; Sierka, Marek; Eckert, Hellmut

2010-02-15

By applying the proper stoichiometry of 1:2 to [Cp(R)Fe(eta(5)-P(5))] and CuX (X=Cl, Br) and dilution conditions in mixtures of CH(3)CN and solvents like CH(2)Cl(2), 1,2-Cl(2)C(6)H(4), toluene, and THF, nine spherical giant molecules having the simplified general formula [Cp(R)Fe(eta(5)-P(5))]@[{Cp(R)Fe(eta(5)-P(5))}(12){CuX}(25)(CH(3)CN)(10)] (Cp(R)=eta(5)-C(5)Me(5) (Cp*); eta(5)-C(5)Me(4)Et (Cp(Et)); X=Cl, Br) have been synthesized and structurally characterized. The products consist of 90-vertex frameworks consisting of non-carbon atoms and forming fullerene-like structural motifs. Besides the mostly neutral products, some charged derivatives have been isolated. These spherical giant molecules show an outer diameter of 2.24 (X=Cl) to 2.26 nm (X=Br) and have inner cavities of 1.28 (X=Cl) and 1.20 nm (X=Br) in size. In most instances the inner voids of these nanoballs encapsulate one molecule of [Cp*Fe(eta(5)-P(5))], which reveals preferred orientations of pi-pi stacking between the cyclo-P(5) rings of the guest and those of the host molecules. Moreover, pi-pi and sigma-pi interactions are also found in the packing motifs of the balls in the crystal lattice. Electrochemical investigations of these soluble molecules reveal one irreversible multi-electron oxidation at E(p)=0.615 V and two reduction steps (-1.10 and -2.0 V), the first of which corresponds to about 12 electrons. Density functional calculations reveal that during oxidation and reduction the electrons are withdrawn or added to the surface of the spherical nanomolecules, and no Cu(2+) species are involved.

An isopiestic study of aqueous NaBr and KBr at 50 °C: Chemical equilibrium model of solution behavior and solubility in the NaBr-H 2O, KBr-H 2O and Na-K-Br-H 2O systems to high concentration and temperature

NASA Astrophysics Data System (ADS)

Christov, Christomir

2007-07-01

The isopiestic method has been used to determine the osmotic coefficients of the binary solutions NaBr-H 2O (from 0.745 to 5.953 mol kg -1) and KBr-H 2O (from 0.741 to 5.683 mol kg -1) at the temperature t = 50 °C. Sodium chloride solutions have been used as isopiestic reference standards. The isopiestic results obtained have been combined with all other experimental thermodynamic quantities available in literature (osmotic coefficients, water activities, bromide mineral's solubilities) to construct a chemical model that calculates solute and solvent activities and solid-liquid equilibria in the NaBr-H 2O, KBr-H 2O and Na-K-Br-H 2O systems from dilute to high solution concentration within the 0-300 °C temperature range. The Harvie and Weare [Harvie C., and Weare J. (1980) The prediction of mineral solubilities in naturalwaters: the Na-K-Mg-Ca-Cl-SO 4-H 2O system from zero to high concentration at 25 °C. Geochim. Cosmochim. Acta44, 981-997] solubility modeling approach, incorporating their implementation of the concentration-dependent specific interaction equations of Pitzer [Pitzer K. (1973) Thermodynamics of electrolytes. I. Theoretical basis and general equations. J. Phys. Chem.77, 268-277] is employed. The model for binary systems is validated by comparing activity coefficient predictions with those given in literature, and not used in the parameterization process. Limitations of the mixed solutions model due to data insufficiencies are discussed. This model expands the variable temperature sodium-potassium model of Greenberg and Moller [Greenberg J., and Moller N. (1989) The prediction of mineral solubilities in natural waters: a chemical equilibrium model for the Na-K-Ca-Cl-SO 4-H 2O system to high concentration from 0 to 250 °C. Geochim. Cosmochim. Acta53, 2503-2518] by evaluating Br - pure electrolyte and mixing solution parameters and the chemical potentials of three bromide solid phases: NaBr-2H 2O (cr), NaBr (cr) and KBr (cr).

Synthesis, Structure, and Antiproliferative Activity of Three Gallium(III) Azole Complexes

PubMed Central

Zanias, Stergios; Papaefstathiou, Giannis S.; Raptopoulou, Catherine P.; Papazisis, Konstantinos T.; Vala, Vasiliki; Zambouli, Dimitra; Kortsaris, Alexandros H.; Kyriakidis, Dimitrios A.; Zafiropoulos, Theodoros F.

2010-01-01

As part of our interest into the bioinorganic chemistry of gallium, gallium(III) complexes of the azole ligands 2,1,3-benzothiadiazole (btd), 1,2,3-benzotriazole (btaH), and 1-methyl-4,5-diphenylimidazole (L) have been isolated. Reaction of btaH or btd with GaBr3 or GaCl3 resulted in the mononuclear complexes [GaBr3(btaH)2] (1) and [GaCl3(btd)2] (2), respectively, while treatment of GaCl3 with L resulted in the anionic complex (LH)2[GaCl4] (3). All three complexes were characterized by single-crystal X-ray crystallography and IR spectroscopy, while their antiproliferative activities were investigated against a series of human and mouse cancer cell lines. PMID:20721278

BIOTRANSFORMATION AND GENOTOXICITY OF THE DRINKING WATER DISINFECTION BYPRODUCT BROMODICHLOROMETHANE: DNA BINDING MEDIATED BY GLUTATHIONE TRANSFERASE THETA 1-1

EPA Science Inventory

The drinking water disinfection byproduct bromodichloromethane (CHBrCl2) was
previously shown to be mutagenic in Salmonella typhimurium that overexpress rat glutathione
transferase theta 1-1 (GSTT1-1). Several experimental approaches were undertaken in this study
to inve...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Varley, J. B.; Conway, A. M.; Voss, L. F.

Thallium bromide (TlBr) crystals subjected to hydrochloric acid (HCl) chemical treatments have been shown to advantageously affect device performance and longevity in TlBr-based room temperature radiation detectors, yet the exact mechanisms of the improvements remain poorly understood. Here in this paper, we investigate the influence of several HCl chemical treatments on device-grade TlBr and describe the changes in the composition and electronic structure of the surface. Composition analysis and depth profiles obtained from secondary ion mass spectrometry (SIMS) identify the extent to which each HCl etch condition affects the detector surface region and forms of a graded TlBr/TlBr 1-xCL xmore » surface heterojunction. Using a combination of X-ray photoemission spectroscopy (XPS) and hybrid density functional calculations, we are able to determine the valence band offsets, band gaps, and conduction band offsets as a function of Cl content over the entire composition range of TIBr 1-xC1 X. This study establishes a strong correlation between device process conditions, surface chemistry, and electronic structure with the goal of further optimizing the long-term stability and radiation response of TlBr-based detectors.« less

Insights into the intramolecular donor stabilisation of organostannylene palladium and platinum complexes: syntheses, structures and DFT calculations.

PubMed

Wagner, Michael; Deáky, Vajk; Dietz, Christina; Martincová, Jana; Mahieu, Bernard; Jambor, Roman; Herres-Pawlis, Sonja; Jurkschat, Klaus

2013-05-17

The syntheses of the transition metal complexes cis-[(4-tBu-2,6-{P(O)(OiPr)2}2C6H2SnCl)2MX2] (1, M = Pd, X = Cl; 2, M = Pd, X = Br; 3, M = Pd, X = I; 4, M = Pt, X = Cl), cis-[{2,6-(Me2NCH2)2C6H3SnCl}2MX2] (5, M = Pd, X = I; 6, M = Pt, X = Cl), trans-[{2,6-(Me2NCH2)2C6H3SnI}2PtI2] (7) and trans-[(4-tBu-2,6-{P(O)(OiPr)2}2C6H2SnCl)PdI2]2 (8) are reported. Also reported is the serendipitous formation of the unprecedented complexes trans-[(4-tBu-2,6-{P(O)(OiPr)2}2C6H2SnCl)2Pt(SnCl3)2] (10) and [(4-tBu-2,6-{P(O)(OiPr)2}2C6H2SnCl)3Pt(SnCl3)2] (11). The compounds were characterised by elemental analyses, (1)H, (13)C, (31)P, (119)Sn and (195)Pt NMR spectroscopy, single-crystal X-ray diffraction analysis, UV/Vis spectroscopy and, in the cases of compounds 1, 3 and 4, also by Mössbauer spectroscopy. All the compounds show the tin atoms in a distorted trigonal-bipyramidal environment. The Mössbauer spectra suggest the tin atoms to be present in the oxidation state III. The kinetic lability of the complexes was studied by redistribution reactions between compounds 1 and 3 as well as between 1 and cis-[{2,6-(Me2 NCH2)2C6H3SnCl}2PdCl2]. DFT calculations provided insights into both the bonding situation of the compounds and the energy difference between the cis and trans isomers. The latter is influenced by the donor strength of the pincer-type ligands. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Product control by halide ions of ionic liquids in the ionothermal syntheses of Ni-(H)BTC metal-organic frameworks.

PubMed

Xu, Ling; Yan, Shihai; Choi, Eun-Young; Lee, Jin Yong; Kwon, Young-Uk

2009-06-21

Ni(OAc)(2)-H(3)BTC system in various ionic liquids, [RMI]X (R = ethyl, n-propyl, n-butyl; X = Cl, Br, I), produced five MOFs in two structure types; their relative thermodynamic stability varies with the size of RMI(+), and the X(-) ions govern the kinetic factors so that their combination effects determine the final product.

Highly stable and water-soluble monodisperse CsPbX3/SiO2 nanocomposites for white-LED and cells imaging.

PubMed

Ding, Nan; Zhou, Donglei; Sun, Xuke; Xu, Wen; Xu, Hongwei; Pan, Gencai; Li, Dongyu; Zhang, Shuang; Dong, Biao; Song, Hongwei

2018-08-24

In spite of the excellent optical properties of all-inorganic halide perovskite quantum dots (PQDs), they still suffer from inherent poor stability even when exposed to moisture from the atmosphere, restricting their applications, especially in white-light-emitting diodes (LEDs) and cells imaging. Here, we proposed a strategy by encapsulating the CsPbX 3 (X = Cl, Br, I) PQDs into silica nanoplates to prepare highly stable and water-soluble CsPbX 3 /SiO 2 nanocomposites. First, the 120 nm monodisperse CsPbX 3 /SiO 2 nanocomposites inlayed with several CsPbX 3 PQDs were fabricated via the modified Stöber method. After coating, their stability exposed in the air was largely improved for all the CsPbX 3 (X = Cl, Br, I) PQDs without changing their emission peaks and full-width at half-maximum, attributed to the suppression of the anion-exchange and decomposition. Moreover, further experiments demonstrated that the CsPbX 3 /SiO 2 nanocomposites were highly water-soluble and stable in the water. Their applications in LEDs and cell imaging demonstrated their ultrastability and high biocompatibility. Therefore, this study shows the possibility of their use in photoelectric devices and biological applications.

Partitioning of mercury in aqueous biphasic systems and on ABEC resins.

PubMed

Rogers, R D; Griffin, S T

1998-06-26

Poly(ethylene glycol)-based aqueous biphasic systems (PEG-ABS) can be utilized to separate and recover metal ions in environmental and hydrometallurgical applications. A concurrent study was conducted comparing the partitioning of mercury between aqueous layers in an ABS [Me-PEG-5000/(NH4)2SO4] and partitioning of mercury from aqueous solutions to aqueous biphasic extraction chromatographic (ABEC-5000) resins. In ammonium sulfate solutions, mercury partitions to the salt-rich phase in ABS, but by using halide ion extractants, mercury will partition to the PEG-rich phase after formation of a chloro, bromo or iodo complex. The efficacy of the extractant increases in the order Cl-

Electron induced inelastic and ionization cross section for plasma modeling

NASA Astrophysics Data System (ADS)

Verma, Pankaj; Mahato, Dibyendu; Kaur, Jaspreet; Antony, Bobby

2016-09-01

The present paper reports electron impact total inelastic and ionization cross section for silicon, germanium, and tin tetrahalides at energies varying from ionization threshold of the target to 5000 eV. These cross section data over a wide energy domain are very essential to understand the physico-chemical processes involved in various environments such as plasma modeling, semiconductor etching, atmospheric sciences, biological sciences, and radiation physics. However, the cross section data on the above mentioned molecules are scarce. In the present article, we report the computation of total inelastic cross section using spherical complex optical potential formalism and the estimation of ionization cross section through a semi-empirical method. The present ionization cross section result obtained for SiCl4 shows excellent agreement with previous measurements, while other molecules have not yet been investigated experimentally. Present results show more consistent behaviour than previous theoretical estimates. Besides cross sections, we have also studied the correlation of maximum ionization cross section with the square root of the ratio of polarizability to ionization potential for the molecules with known polarizabilities. A linear relation is observed between these quantities. This correlation is used to obtain approximate polarizability volumes for SiBr4, SiI4, GeCl4, GeBr4, and GeI4 molecules.

Widely Applicable n-Type Molecular Doping for Enhanced Photovoltaic Performance of All-Polymer Solar Cells.

PubMed

Xu, Yalong; Yuan, Jianyu; Sun, Jianxia; Zhang, Yannan; Ling, Xufeng; Wu, Haihua; Zhang, Guobing; Chen, Junmei; Wang, Yongjie; Ma, Wanli

2018-01-24

A widely applicable doping design for emerging nonfullerene solar cells would be an efficient strategy in order to further improve device photovoltaic performance. Herein, a family of compound TBAX (TBA= tetrabutylammonium, X = F, Cl, Br, or I, containing Lewis base anions are considered as efficient n-dopants for improving polymer-polymer solar cells (all-PSCs) performance. In all cases, significantly increased fill factor (FF) and slightly increased short-circuit current density (J sc ) are observed, leading to a best PCE of 7.0% for all-PSCs compared to that of 5.8% in undoped devices. The improvement may be attributed to interaction between different anions X - (X = F, Cl, Br, and I) in TBAX with the polymer acceptor. We reveal that adding TBAX at relatively low content does not have a significantly impact on blend morphology, while it can reduce the work function (WF) of the electron acceptor. We find this simple and solution processable n-type doping can efficiently restrain charge recombination in all-polymer solar cell devices, resulting in improved FF and J sc. More importantly, our findings may provide new protocles and insights using n-type molecular dopants in improving the performance of current polymer-polymer solar cells.

Enormous excitonic effects in bulk, mono- and bi- layers of cuprous halides using many-body perturbation technique

NASA Astrophysics Data System (ADS)

Azhikodan, Dilna; Nautiyal, Tashi

2017-10-01

Cuprous halides (CuX with X = Cl, Br, I), intensely studied about four decades ago by experimentalists for excitons, are again drawing attention of researchers recently. Potential of cuprous halide systems for device applications has not yet been fully explored. We go beyond the one-particle picture to capture the two-particle physics (electron-hole interaction to form excitons). We have deployed the full tool kit of many-body perturbation technique, GW approximation + Bethe Salpeter equation, to unfurl the rich excitonic physics of the bulk as well as layers of CuX. The negative spin-orbit contribution at the valence band top in CuCl, compared to CuBr and CuI, is in good agreement with experiments. We note that CuX have exceptionally strong excitons, defying the linear fit (between the excitonic binding energy and band gap) encompassing many semiconductors. The mono- and bi- layers of cuprous halides are predicted to be rich in excitons, with exceptionally large binding energies and the resonance energies in UV/visible region. Hence this work projects CuX layers as good candidates for optoelectronic applications. With advancement of technology, we look forward to experimental realization of CuX layers and harnessing of their rich excitonic potential.

Room Temperature Quantum Spin Hall Insulator in Ethynyl-Derivative Functionalized Stanene Films

PubMed Central

Zhang, Run-wu; Zhang, Chang-wen; Ji, Wei-xiao; Li, Sheng-shi; Yan, Shi-shen; Hu, Shu-jun; Li, Ping; Wang, Pei-ji; Li, Feng

2016-01-01

Quantum spin Hall (QSH) insulators feature edge states that topologically protected from backscattering. However, the major obstacles to application for QSH effect are the lack of suitable QSH insulators with a large bulk gap. Based on first-principles calculations, we predict a class of large-gap QSH insulators in ethynyl-derivative functionalized stanene (SnC2X; X = H, F, Cl, Br, I), allowing for viable applications at room temperature. Noticeably, the SnC2Cl, SnC2Br, and SnC2I are QSH insulators with a bulk gap of ~0.2 eV, while the SnC2H and SnC2F can be transformed into QSH insulator under the tensile strains. A single pair of topologically protected helical edge states is established for the edge of these systems with the Dirac point locating at the bulk gap, and their QSH states are confirmed with topological invariant Z2 = 1. The films on BN substrate also maintain a nontrivial large-gap QSH effect, which harbors a Dirac cone lying within the band gap. These findings may shed new light in future design and fabrication of large-gap QSH insulators based on two-dimensional honeycomb lattices in spintronics. PMID:26728874

Spin-orbit coupling calculations with the two-component normalized elimination of the small component method

NASA Astrophysics Data System (ADS)

Filatov, Michael; Zou, Wenli; Cremer, Dieter

2013-07-01

A new algorithm for the two-component Normalized Elimination of the Small Component (2cNESC) method is presented and tested in the calculation of spin-orbit (SO) splittings for a series of heavy atoms and their molecules. The 2cNESC is a Dirac-exact method that employs the exact two-component one-electron Hamiltonian and thus leads to exact Dirac SO splittings for one-electron atoms. For many-electron atoms and molecules, the effect of the two-electron SO interaction is modeled by a screened nucleus potential using effective nuclear charges as proposed by Boettger [Phys. Rev. B 62, 7809 (2000), 10.1103/PhysRevB.62.7809]. The use of the screened nucleus potential for the two-electron SO interaction leads to accurate spinor energy splittings, for which the deviations from the accurate Dirac Fock-Coulomb values are on the average far below the deviations observed for other effective one-electron SO operators. For hydrogen halides HX (X = F, Cl, Br, I, At, and Uus) and mercury dihalides HgX2 (X = F, Cl, Br, I) trends in spinor energies and SO splittings as obtained with the 2cNESC method are analyzed and discussed on the basis of coupling schemes and the electronegativity of X.

NMR longitudinal relaxation enhancement in metal halides by heteronuclear polarization exchange during magic-angle spinning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shmyreva, Anna A.; Safdari, Majid; Furó, István

2016-06-14

Orders of magnitude decrease of {sup 207}Pb and {sup 199}Hg NMR longitudinal relaxation times T{sub 1} upon magic-angle-spinning (MAS) are observed and systematically investigated in solid lead and mercury halides MeX{sub 2} (Me = Pb, Hg and X = Cl, Br, I). In lead(II) halides, the most dramatic decrease of T{sub 1} relative to that in a static sample is in PbI{sub 2}, while it is smaller but still significant in PbBr{sub 2}, and not detectable in PbCl{sub 2}. The effect is magnetic-field dependent but independent of the spinning speed in the range 200–15 000 Hz. The observed relaxation enhancementmore » is explained by laboratory-frame heteronuclear polarization exchange due to crossing between energy levels of spin-1/2 metal nuclei and adjacent quadrupolar-spin halogen nuclei. The enhancement effect is also present in lead-containing organometal halide perovskites. Our results demonstrate that in affected samples, it is the relaxation data recorded under non-spinning conditions that characterize the local properties at the metal sites. A practical advantage of fast relaxation at slow MAS is that spectral shapes with orientational chemical shift anisotropy information well retained can be acquired within a shorter experimental time.« less

Crystal structures of 6-chloro­indan-1-one and 6-bromo­indan-1-one exhibit different inter­molecular packing inter­actions

PubMed Central

Caruso, Alessio; Blair, Benjamin; Tanski, Joseph M.

2016-01-01

The two title compounds are analogs of 1-indanone that are substituted at the 6-position with chlorine and bromine. Although very similar in mol­ecular structure, the crystal structures are not isomorphous and reveal that 6-chloro­indan-1-one, C9H7ClO (I), and 6-bromo­indan-1-one, C9H7BrO (II), exhibit unique inter­molecular packing motifs. The mol­ecules of the chloro analog (I) pack with a herringbone packing motif of C—H⋯O inter­actions, whereas the bromo derivative (II) packs with offset face-to-face π-stacking, C—H⋯O, C—H⋯Br and Br⋯O inter­actions. Compound (II) was refined as a two-component non-merohedral twin, BASF 0.0762 (5). PMID:27840702

Methyl chloride and methyl bromide emissions from baking: an unrecognized anthropogenic source.

PubMed

Thornton, Brett F; Horst, Axel; Carrizo, Daniel; Holmstrand, Henry

2016-05-01

Methyl chloride and methyl bromide (CH3Cl and CH3Br) are the largest natural sources of chlorine and bromine, respectively, to the stratosphere, where they contribute to ozone depletion. We report the anthropogenic production of CH3Cl and CH3Br during breadbaking, and suggest this production is an abiotic process involving the methyl ester functional groups in pectin and lignin structural polymers of plant cells. Wide variations in baking styles allow only rough estimates of this flux of methyl halides on a global basis. A simple model suggests that CH3Br emissions from breadbaking likely peaked circa 1990 at approximately 200tonnes per year (about 0.3% of industrial production), prior to restrictions on the dough conditioner potassium bromate. In contrast, CH3Cl emissions from breadbaking may be of similar magnitude as acknowledged present-day CH3Cl industrial emissions. Because the mechanisms involve functional groups and compounds widely found in plant materials, this type of methyl halide production may occur in other cooking techniques as well. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of chlorination on the TlBr band edges for improved room temperature radiation detectors: Effect of chlorination on the TlBr band edges for radiation detectors

DOE PAGES

Varley, J. B.; Conway, A. M.; Voss, L. F.; ...

2015-02-09

Thallium bromide (TlBr) crystals subjected to hydrochloric acid (HCl) chemical treatments have been shown to advantageously affect device performance and longevity in TlBr-based room temperature radiation detectors, yet the exact mechanisms of the improvements remain poorly understood. Here in this paper, we investigate the influence of several HCl chemical treatments on device-grade TlBr and describe the changes in the composition and electronic structure of the surface. Composition analysis and depth profiles obtained from secondary ion mass spectrometry (SIMS) identify the extent to which each HCl etch condition affects the detector surface region and forms of a graded TlBr/TlBr 1-xCL xmore » surface heterojunction. Using a combination of X-ray photoemission spectroscopy (XPS) and hybrid density functional calculations, we are able to determine the valence band offsets, band gaps, and conduction band offsets as a function of Cl content over the entire composition range of TIBr 1-xC1 X. This study establishes a strong correlation between device process conditions, surface chemistry, and electronic structure with the goal of further optimizing the long-term stability and radiation response of TlBr-based detectors.« less

Five-coordinate Co(II) complexes with nitrilotriacetic acid: Crystal structures of Ca[Co(Nta)X] . nH{sub 2}O (X{sup -} = Cl, Br, or NCS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Polyakova, I. N.; Poznyak, A. L.; Sergienko, V. S.

2006-07-15

The synthesis and X-ray diffraction study of three Ca[Co(Nta)X] . nH{sub 2}O complexes [X{sup -} = Cl, n = 2.3 (I); X{sup -} = Br, n = 2 (II); and X{sup -} = NCS, n = 2 (III)] are performed. The main structural units of crystals I-III are the [CoX(Nta)]{sup 2-} anionic complexes and hydrated Ca{sup 2+} cations. The anionic complexes have similar structures. The coordination of the Co{sup 2+} atom in the shape of a trigonal bipyramid is formed by N + 3O atoms of the Nta{sup 3-} ligand and the X{sup -} anion in the trans position withmore » respect to N. In structures I-III, the Co-O and Co-N bond lengths lie in the ranges 1.998-2.032 and 2.186-2.201 A, respectively. The Co-X bond lengths are 2.294 (I), 2.436 and 2.445 (II), and 1.982 A (III). The environments of the Ca{sup 2+} cations include oxygen atoms of one or two water molecules and six or seven O(Nta) atoms with the coordination number of 9 in I or 8 in II and III. The Ca-O(Nta) bonds form a three-dimensional framework in I or layers in II and III. Water molecules are involved in the hydrogen bonds O(w)-H...O(Nta), O(w)-H...X, and O(w)-H...O(w). Structural data for crystals I-III are deposited with the Cambridge Structural Database (CCDC nos. 287 814-287 816)« less

Synergy of ammonium chloride and moisture on perovskite crystallization for efficient printable mesoscopic solar cells

PubMed Central

Rong, Yaoguang; Hou, Xiaomeng; Hu, Yue; Mei, Anyi; Liu, Linfeng; Wang, Ping; Han, Hongwei

2017-01-01

Organometal lead halide perovskites have been widely used as the light harvester for high-performance solar cells. However, typical perovskites of methylammonium lead halides (CH3NH3PbX3, X=Cl, Br, I) are usually sensitive to moisture in ambient air, and thus require an inert atmosphere to process. Here we demonstrate a moisture-induced transformation of perovskite crystals in a triple-layer scaffold of TiO2/ZrO2/Carbon to fabricate printable mesoscopic solar cells. An additive of ammonium chloride (NH4Cl) is employed to assist the crystallization of perovskite, wherein the formation and transition of intermediate CH3NH3X·NH4PbX3(H2O)2 (X=I or Cl) enables high-quality perovskite CH3NH3PbI3 crystals with preferential growth orientation. Correspondingly, the intrinsic perovskite devices based on CH3NH3PbI3 achieve an efficiency of 15.6% and a lifetime of over 130 days in ambient condition with 30% relative humidity. This ambient-processed printable perovskite solar cell provides a promising prospect for mass production, and will promote the development of perovskite-based photovoltaics. PMID:28240286

Structural study of salt forms of amides; paracetamol, benzamide and piperine

NASA Astrophysics Data System (ADS)

Kennedy, Alan R.; King, Nathan L. C.; Oswald, Iain D. H.; Rollo, David G.; Spiteri, Rebecca; Walls, Aiden

2018-02-01

Single crystal x-ray diffraction has been used to investigate the structures of six complexes containing O-atom protonated cations derived from the pharmaceutically relevant amides benzamide (BEN), paracetamol (PAR) and piperine (PIP). The structures of the salt forms [PAR(H)][SO3C6H4Cl], [BEN(H)][O3SC6H4Cl] and [BEN(H)][Br]·H2O are reported along with those of the hemi-halide salt forms [PAR(H)][I3]. PAR, [PIP(H)][I3]·PIP and [PIP(H)][I3]0·5[I]0.5. PIP. The structure of the cocrystal BEN. HOOCCH2Cl is also presented for comparison. The geometry of the amide group is found to systematically change upon protonation, with the Cdbnd O distance increasing and the Csbnd N distance decreasing. The hemi-halide species all feature strongly hydrogen bonded amide(H)/amide pairs. The amide group Cdbnd O and Csbnd N distances for both elements of each such pair are intermediate between those found for simple neutral amide and protonated amide forms. It was found that crystallising paracetamol from aqueous solutions containing Ba2+ ions gave orthorhombic paracetamol.

Methyl halide production associated with kelp

NASA Technical Reports Server (NTRS)

Dastoor, Minoo N.; Manley, Steven L.

1985-01-01

Methyl halides (MeX) are important trace constituents of the atmosphere because they, mostly MeCl, have a major impact on the atmospheric ozone layer. Also, MeCl may account for 5 pct. of the total Cl budget and MeI may have a central role in the biogeochemical cycling of iodine. High MeI concentrations were found in seawater from kelp beds and it has been suggested that MeI is produced by kelps and that MeI and MeBr along with numerous other halocarbons were released by non-kelp marine macroalgae. The objective was to determine if kelps (and other seaweeds) are sources of MeX and to assess their contribution to the estimated global source strength (EGSS) of MeX. Although the production of MeX appears to be associated with kelp, microbes involved with kelp degradation also produce MeX. Microbial MeX production may be of global significance. The microbial MeX production potential, assuming annual kelp production equals kelp degradation and 100 pct. conversion of kelp halides to MeX, is approx. 2 x the EGSS. This is not achieved but indicates that microbial production of MeX may be of global significance.

Quantitative and Qualitative Involvement of P3N-PIPO in Overcoming Recessive Resistance against Clover Yellow Vein Virus in Pea Carrying the cyv1 Gene

PubMed Central

Choi, Sun Hee; Hagiwara-Komoda, Yuka; Atsumi, Go; Shimada, Ryoko; Hisa, Yusuke; Naito, Satoshi

2013-01-01

In pea carrying cyv1, a recessive gene for resistance to Clover yellow vein virus (ClYVV), ClYVV isolate Cl-no30 was restricted to the initially infected cells, whereas isolate 90-1 Br2 overcame this resistance. We mapped the region responsible for breaking of cyv1-mediated resistance by examining infection of cyv1 pea with chimeric viruses constructed from parts of Cl-no30 and 90-1 Br2. The breaking of resistance was attributed to the P3 cistron, which is known to produce two proteins: P3, from the main open reading frame (ORF), and P3N-PIPO, which has the N-terminal part of P3 fused to amino acids encoded by a small open reading frame (ORF) called PIPO in the +2 reading frame. We introduced point mutations that were synonymous with respect to the P3 protein but nonsynonymous with respect to the P3N-PIPO protein, and vice versa, into the chimeric viruses. Infection of plants with these mutant viruses revealed that both P3 and P3N-PIPO were involved in overcoming cyv1-mediated resistance. Moreover, P3N-PIPO quantitatively affected the virulence of Cl-no30 in cyv1 pea. Additional expression in trans of the P3N-PIPO derived from Cl-no30, using White clover mosaic virus as a vector, enabled Cl-no30 to move to systemic leaves in cyv1 pea. Susceptible pea plants infected with chimeric ClYVV possessing the P3 cistron of 90-1 Br2, and which were therefore virulent toward cyv1 pea, accumulated more P3N-PIPO than did those infected with Cl-no30, suggesting that the higher level of P3N-PIPO in infected cells contributed to the breaking of resistance by 90-1 Br2. This is the first report showing that P3N-PIPO is a virulence determinant in plants resistant to a potyvirus. PMID:23616656

Electromodulation spectroscopy of excitons in simple cubic TlCl and TlBr

DOE Office of Scientific and Technical Information (OSTI.GOV)

McClelland, J.F.; Lynch, D.W.

1979-03-15

Transmission and electromodulated transmission spectra have been measured in the direct Wannier exciton region for TlCl and TlBr. The spectra were obtained at a sample temperature between 5 and 6 K for a range of applied electric fields. The data have been reduced to obtain the electric-field-induced changes in the dielectric function and compared in detail to the calculations of Blossey. The experimental results support the trends predicted by the calculations.

THE K-REGION DIHYDRODIOL OF BENZO[A]PYRENE INDUCES DNA DAMAGE AND MORPHOLOGICAL CELL TRANSFORMATION IN C3H10T1/2CL8 MOUSE EMBRYO CELLS WITHOUT THE FORMATION OF DETECTABLE STABLE COVALENT DNA ADDUCTS

EPA Science Inventory

The K -region dihydrodiol ofbenzo[ a ]pyrene induces DNA damage and morphological cell transformation in C3HlOTY2CL8 mouse embryo cells without the formation of detectable stable covalent DNA adducts

Benzo[ a ]pyrene (B[ a ]P) is the most thoroughly studied polycyclic aro...

Chemical Ignition of Flame Throwers

DTIC Science & Technology

1944-04-20

fluorinating agents such as fluorine, antimony penta- fluoride, oxygen fluoride or bromine and chlorine trifluoride mixtures be evaluated. The use...0F2), and bromine and chlorine trifluoride mixtures (BrF3-ClF3). Oxygen fluoride, a gas boiling at -l67°C., has the interesting property of being...ShFc), oxygen fluoride (0F2), and bromine and chlorine fluoride mixtures (BrF3-ClFsJ. Oxygen fluoride Is stable In the presence of moisture. 4

Interplay of metals and bromine with dioxin-related compounds concentrated in e-waste open burning soil from Agbogbloshie in Accra, Ghana.

PubMed

Fujimori, Takashi; Itai, Takaaki; Goto, Akitoshi; Asante, Kwadwo A; Otsuka, Masanari; Takahashi, Shin; Tanabe, Shinsuke

2016-02-01

Open burning of electronic waste (e-waste) releases various metals and organohalogen compounds in the environment. Here we investigated the interplay of metals (Cu, Pb, Zn, Fe, Co, and Sr) and bromine (Br) in the formation of dioxin-related compounds (DRCs), including polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs), as well as non-regulated DRCs such as polybrominated dibenzo-p-dioxins/furans (PBDD/Fs) and their monobrominated PCDD/Fs in soils sampled from open burning e-waste sites at Agbogbloshie in Accra, Ghana. The predominant DRCs were PBDFs, PCDFs, PCDDs, and DL-PCBs. Statistical analyzes, X-ray absorption spectroscopy, and the PCDF/PCDD ratio suggested possible formation paths of PCDD/Fs and DL-PCBs by catalytic behaviors of copper chlorides (CuCl, CuCl2, and Cu2(OH)3Cl) and thermal breakdown of polyvinyl chloride. Predominant formation of brominated furans may be derived from electron transfer from intermediates of PBDE to copper, Cu(II) → Cu(I). Lead chloride also contributed to generate DRCs and may become highly bioaccessible through the open burning of e-waste. The main zinc species (ZnCl2 and ZnS) suggested a possible relationship to generate DRCs and specific zinc source such as tire burning. Cu, Pb, Zn, and Br contained in various e-wastes, wires/cables, plastics, and tires strongly influenced generation of many DRCs. Copyright © 2015 Elsevier Ltd. All rights reserved.

Low-Bandgap Cs4CuSb2Cl12 Layered Double Perovskite: Synthesis, Reversible Thermal Changes, and Magnetic Interaction.

PubMed

Singhal, Nancy; Chakraborty, Rayan; Ghosh, Prasenjit; Nag, Angshuman

2018-05-29

Double perovskites (DPs) with a generic formula A2M'(I)M(III)X6 (A and M are metal ions, and X = Cl, Br, I) are now being explored as potential alternatives to Pb-halide perovskite for solar cell and other optoelectronic applications. However, these DPs typically suffer from wide (~ 3 eV) and/or indirect band gaps. In 2017, a new structural variety, namely layered DP halide Cs4CuSb2Cl12 (CCSC) with bivalent Cu(II) ion in place of M'(I) was reported exhibiting a band gap ~1 eV. Here, we report a mechanochemical synthesis of CCSC, its thermal- and chemical stability, and magnetic response of Cu(II) d9 electrons controlling optoelectronic properties. A simple grinding of precursor salts at ambient conditions provides stable and scalable product CCSC. CCSC is stable in water-acetone solvent mixture (~30% water) and many other polar solvents unlike Pb-halide perovskites. It decomposes to Cs3Sb2Cl9, Cs2CuCl4 and SbCl3 at 210 oC, but the reaction can be reversed back to produce CCSC at lower temperatures and high humidity. A long range magnetic ordering is observed in CCSC even at room temperature. Role of such magnetic ordering in controlling the dispersion of conduction band, and therefore, controlling the electronic and optoelectronic properties of CCSC has been discussed. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Premelting phenomena in pseudo-binary ionic crystals

NASA Astrophysics Data System (ADS)

Matsunaga, Shigeki

2010-04-01

The theory of the premelting phenomena in ionic crystals on the basis of the concept of the heterophase fluctuation has been applied to the pseudo-binary ionic crystals, KCl-NaCl, AgBr-AgCl and AgBr-CuBr systems. Molecular dynamics simulations (MD) have been performed to examine the ionic configurations in their premelting region in the vicinity of their melting points. Liquid-like clusters have been observed in the results of MD utilizing the Lindemann instability condition. The sizes of liquid-like clusters have been estimated by theory and MD. The characteristics of the dynamical behavior of ions in the premelting region have been examined by the mean square displacement and the velocity correlation functions.

Cyclic nucleotides induce long-term augmentation of glutamate-activated chloride current in molluscan neurons.

PubMed

Bukanova, Julia V; Solntseva, Elena I; Skrebitsky, Vladimir G

2005-12-01

1. Literature data indicate that serotonin induces the long-term potentiation of glutamate (Glu) response in molluscan neurons. The aim of present work was to elucidate whether cyclic nucleotides can cause the same effect. 2. Experiments were carried out on isolated neurons of the edible snail (Helix pomatia) using a two-microelectrode voltage-clamp method. 3. In the majority of the cells examined, the application of Glu elicited a Cl- -current. The reversal potential (Er) of this current lied between -35 and -55 mV in different cells. 4. Picrotoxin, a blocker of Cl- -channels, suppressed this current equally on both sides of Er. Furosemide, an antagonist of both Cl- -channels and the Na+/K+/Cl- -cotransporter, had a dual effect on Glu-response: decrease in conductance, and shift of Er to negative potentials. 5. A short-term (2 min) cell treatment with 8-Br-cAMP or 8-Br-cGMP caused long-term (up to 30 min) change in Glu-response. At a holding potential of -60 mV, which was close to the resting level, an increase in Glu-activated inward current was observed. This potentiation seems to be related to the right shift of Er of Glu-activated Cl- -current rather than to the increase in conductance of Cl- -channels. The blocking effect of picrotoxin rested after 8-Br-cAMP treatment. 6. The change in the Cl- -homeostasis as a possible mechanism for the observed effect of cyclic nucleotides is discussed.

Novel ternary molten salt electrolytes for intermediate-temperature sodium/nickel chloride batteries

NASA Astrophysics Data System (ADS)

Li, Guosheng; Lu, Xiaochuan; Coyle, Christopher A.; Kim, Jin Y.; Lemmon, John P.; Sprenkle, Vincent L.; Yang, Zhenguo

2012-12-01

The sodium-nickel chloride (ZEBRA) battery is operated at relatively high temperature (250-350 °C) to achieve adequate electrochemical performance. Reducing the operating temperature in the range of 150200 °C can not only lead to enhanced cycle life by suppressing temperature-related degradations, but also allow the use of lower cost materials for construction. To achieve adequate electrochemical performance at lower operating temperatures, reduction in ohmic losses is required, including the reduced ohmic resistance of β″-alumina solid electrolyte (BASE) and the incorporation of low melting point secondary electrolytes. In present work, planar-type Na/NiCl2 cells with a thin BASE (600 μm) and low melting point secondary electrolyte were evaluated at reduced temperatures. Molten salts used as secondary electrolytes were fabricated by the partial replacement of NaCl in the standard secondary electrolyte (NaAlCl4) with other lower melting point alkali metal salts such as NaBr, LiCl, and LiBr. Electrochemical characterization of these ternary molten salts demonstrated improved ionic conductivity and sufficient electrochemical window at reduced temperatures. Furthermore, Na/NiCl2 cells with 50 mol% NaBr-containing secondary electrolyte exhibited reduced polarizations at 175 °C compared to the cell with the standard NaAlCl4 catholyte. The cells also exhibited stable cycling performance even at 150 °C.

Chaos in the classical mechanics of bound and quasi-bound HX-4He complexes with X = F, Cl, Br, CN.

PubMed

Gamboa, Antonio; Hernández, Henar; Ramilowski, Jordan A; Losada, J C; Benito, R M; Borondo, F; Farrelly, David

2009-10-01

The classical dynamics of weakly bound floppy van der Waals complexes have been extensively studied in the past except for the weakest of all, i.e., those involving He atoms. These complexes are of considerable current interest in light of recent experimental work focussed on the study of molecules trapped in small droplets of the quantum solvent (4)He. Despite a number of quantum investigations, details on the dynamics of how quantum solvation occurs remain unclear. In this paper, the classical rotational dynamics of a series of van der Waals complexes, HX-(4)He with X = F, Cl, Br, CN, are studied. In all cases, the ground state dynamics are found to be almost entirely chaotic, in sharp contrast to other floppy complexes, such as HCl-Ar, for which chaos sets in only at relatively high energies. The consequences of this result for quantum solvation are discussed. We also investigate rotationally excited states with J = 1 which, except for HCN-(4)He, are actually resonances that decay by rotational pre-dissociation.

CALCULATED MOLECULAR STRUCTURES AND POTENTIAL ENERGY FUNCTIONS OF PAHS WITH METHYL CROWDING IN THE BAY REGION AND THEIR METABOLITES: COMPARISON TO EXPERIMENTAL STRUCTURES

EPA Science Inventory

Abstract Title: Calculated molecular structures and potential energy functions of P AHs with methyl crowding in the bay region and their metabolites: Comparison to experimental structures.

Abstract:
PAHs with methyl group substitution near a bay region represent a cl...

Crystal growth and near infrared optical properties of Pr 3+ doped lead halide materials for resonantly pumped eye safe laser applications

NASA Astrophysics Data System (ADS)

Jones, Ivy Krystal

In this dissertation the material development and optical spectroscopy of Pr3+ activated low phonon energy halide crystals is presented for possible applications in resonantly pumped eye-safe solid-state laser gain media. In the last twenty years, the developments in fiber and diode lasers have enabled highly efficient resonant pumping of Pr3+ doped crystals for possible lasing in the 1.6--1.7 microm region. In this work, the results of the purification, crystal growth, and near-infrared (NIR) spectroscopic characterization of Pr3+ doped lead (II) chloride, PbCl2 and lead (II) bromide, PbBr2 are presented. The investigated PbCl2 and PbBr2 crystals are non-hygroscopic with maximum phonon energies between ~180--200 cm-1, which enable efficient emission in the NIR spectral region (~ 1.6 microm) from the 3F3/3F4 → 3H4 transition of Pr3+ ions. The commercial available starting materials were purchased as ultra dry, high purity (~ 99.999 %) beads and purified through a combination of zone-refinement and halogenation. The crystal growth of Pr3+ doped PbCl 2 and PbBr2 was performed via vertical Bridgman technique using a two-zone furnace. The resulting Pr3+ doped PbCl 2 and PbBr2 crystals exhibited characteristic IR absorption bands in the 1.5--1.7 microm region (3H4 → 3F3/3F4), which allow for resonant pumping using commercial diode lasers. A broad IR emission band centered at ~1.6 microm was observed under ~1445 nm diode laser excitation from both Pr3+ doped halides. This dissertation presents comparative spectroscopic results for Pr 3+:PbCl2 and Pr3+:PbBr2 including NIR absorption and emission studies, lifetime measurements, modelling of radiative and non-radiative decay rates, determination of transition cross-section, and the net effective gain cross sections.

Influence of ligand polarizability on the reversible binding of O2 by trans-[Rh(X)(XNC)(PPh3)2] (X = Cl, Br, SC6F5, C2Ph; XNC = xylyl isocyanide). Structures and a kinetic study.

PubMed

Carlton, Laurence; Mokoena, Lebohang V; Fernandes, Manuel A

2008-10-06

The complexes trans-[Rh(X)(XNC)(PPh 3) 2] (X = Cl, 1; Br, 2; SC 6F 5, 3; C 2Ph, 4; XNC = xylyl isocyanide) combine reversibly with molecular oxygen to give [Rh(X)(O 2)(XNC)(PPh 3) 2] of which [Rh(SC 6F 5)(O 2)(XNC)(PPh 3) 2] ( 7) and [Rh(C 2Ph)(O 2)(XNC)(PPh 3) 2] ( 8) are sufficiently stable to be isolated in crystalline form. Complexes 2, 3, 4, and 7 have been structurally characterized. Kinetic data for the dissociation of O 2 from the dioxygen adducts of 1- 4 were obtained using (31)P NMR to monitor changes in the concentration of [Rh(X)(O 2)(XNC)(PPh 3) 2] (X = Cl, Br, SC 6F 5, C 2Ph) resulting from the bubbling of argon through the respective warmed solutions (solvent chlorobenzene). From data recorded at temperatures in the range 30-70 degrees C, activation parameters were obtained as follows: Delta H (++) (kJ mol (-1)): 31.7 +/- 1.6 (X = Cl), 52.1 +/- 4.3 (X = Br), 66.0 +/- 5.8 (X = SC 6F 5), 101.3 +/- 1.8 (X = C 2Ph); Delta S (++) (J K (-1) mol (-1)): -170.3 +/- 5.0 (X = Cl), -120 +/- 13.6 (X = Br), -89 +/- 18.2 (X = SC 6F 5), -6.4 +/- 5.4 (X = C 2Ph). The values of Delta H (++) and Delta S (++) are closely correlated (R (2) = 0.9997), consistent with a common dissociation pathway along which the rate-determining step occurs at a different position for each X. Relative magnitudes of Delta H (++) are interpreted in terms of differing polarizabilities of ligands X.

Using Cl/Br ratios and other indicators to assess potential impacts on groundwater quality from septic systems: A review and examples from principal aquifers in the United States

USGS Publications Warehouse

Katz, B.G.; Eberts, S.M.; Kauffman, L.J.

2011-01-01

A detailed review was made of chemical indicators used to identify impacts from septic tanks on groundwater quality. Potential impacts from septic tank leachate on groundwater quality were assessed using the mass ratio of chloride-bromide (Cl/Br), concentrations of selected chemical constituents, and ancillary information (land use, census data, well depth, soil characteristics) for wells in principal aquifers of the United States. Chemical data were evaluated from 1848 domestic wells in 19 aquifers, 121 public-supply wells in 6 aquifers, and associated monitoring wells in four aquifers and their overlying hydrogeologic units. Based on previously reported Cl/Br ratios, statistical comparisons between targeted wells (where Cl/Br ratios range from 400 to 1100 and Cl concentrations range from 20 to 100 mg/L) and non-targeted wells indicated that shallow targeted monitoring and domestic wells (0.5. mg/L) shallow groundwater from target domestic wells, relative to non-target wells (1.5. mg/L), corresponded to significantly higher potassium, boron, chloride, dissolved organic carbon, and sulfate concentrations, which may also indicate the influence of septic-tank effluent. Impacts on groundwater quality from septic systems were most evident for the Eastern Glacial Deposits aquifer and the Northern High Plains aquifer that were associated with the number of housing units using septic tanks, high permeability of overlying sediments, mostly oxic conditions, and shallow wells. Overall, little or no influence from septic systems were found for water samples from the deeper public-supply wells.The Cl/Br ratio is a useful first-level screening tool for assessing possible septic tank influence in water from shallow wells (<20 m) with the range of 400-1100. The use of this ratio would be enhanced with information on other chloride sources, temporal variability of chloride and bromide concentrations in shallow groundwater, knowledge of septic-system age and maintenance, and the use of multiple tracers (combination of additional chemical and microbiological indicators). ?? 2010.

Monohalogenated ferrocenes C5H5FeC5H4 X (X = Cl, Br and I) and a second polymorph of C5H5FeC5H4I

PubMed Central

Romanov, Alexander S.; Mulroy, Joseph M.; Khrustalev, Victor N.; Antipin, Mikhail Yu.; Timofeeva, Tatiana V.

2009-01-01

The structures of the three title monosubstituted ferrocenes, namely 1-chloro­ferrocene, [Fe(C5H5)(C5H4Cl)], (I), 1-bromo­ferrocene, [Fe(C5H5)(C5H4Br)], (II), and 1-iodo­ferrocene, [Fe(C5H5)(C5H4I)], (III), were determined at 100 K. The chloro- and bromo­ferrocenes are isomorphous crystals. The new triclinic polymorph [space group P , Z = 4, T = 100 K, V = 943.8 (4) Å3] of iodo­ferrocene, (III), and the previously reported monoclinic polymorph of (III) [Laus, Wurst & Schottenberger (2005 ▶). Z. Kristallogr. New Cryst. Struct. 220, 229–230; space group Pc, Z = 4, T = 100 K, V = 924.9 Å3] were obtained by crystallization from ethanolic solutions at 253 and 303 K, respectively. All four phases contain two independent mol­ecules in the unit cell. The relative orientations of the cyclo­penta­dienyl (Cp) rings are eclipsed and staggered in the independent mol­ecules of (I) and (II), while (III) demonstrates only an eclipsed conformation. The triclinic and monoclinic polymorphs of (III) contain nonbonded inter­molecular I⋯I contacts, causing different packing modes. In the triclinic form of (III), the mol­ecules are arranged in zigzag tetra­mers, while in the monoclinic form the mol­ecules are arranged in zigzag chains along the a axis. Crystallographic data for (III), along with the computed lattice energies of the two polymorphs, suggest that the monoclinic form is more stable. PMID:19893225

Aspects of the history of 66095 based on trace elements in clasts and whole rock

NASA Technical Reports Server (NTRS)

Jovanovic, S.; Reed, G. W., Jr.

1982-01-01

Halogens, P, U and Na are reported in anorthositic and basaltic clasts and matrix from rusty rock 66095. Large fractions of Cl and Br associated with the separated phases from 66095 are soluble in H2O. Up to two orders of magnitude variation in concentrations of these elements in the breccia components and varying H2O-soluble Cl/Br ratios indicate different sources of volatiles. An approximately constant ratio of the H2O- to 0.1 M HNO3-soluble Br in the various components suggests no appreciable alteration in the original distributions of this element in the breccia forming processes. Up to 50% or more of the phosphorus and of the non-H2O-soluble Cl was dissolved from most of the breccia components by 0.1 M HNO3. Clast and matrix residues from the leaching steps contain, in most cases, the Cl/P2O5 ratio found in 66095 whole rock and in a number of other Apollo 16 samples. Evidence that phosphates are the major P-phases in the breccia is based on the 0.1 M acid solubility of Cl and P in the matrix sample and on elemental concentrations which are consistent with those of KREEP.

Chemical and isotopic constrains on the origin of brine and saline groundwater in Hetao plain, Inner Mongolia.

PubMed

Liu, Jun; Chen, Zongyu; Wang, Lijuan; Zhang, Yilong; Li, Zhenghong; Xu, Jiaming; Peng, Yurong

2016-08-01

The origin and evolution of brine and saline groundwater have always been a challenged work for geochemists and hydrogeologists. Chemical and isotopic data of brine and saline waters were used to trace the sources of salinity and therefore to understand the transport mechanisms of groundwater in Xishanzui, Inner Mongolia. Both Cl/Br (molar) versus Na/Br (molar) and Cl (meq/L) versus Na (meq/L) indicated that salinity was from halite dissolution or at least a significant impact by halite dissolution. The logarithmic plot of the concentration trends of Cl (mg/L) versus Br (mg/L) for the evaporation of seawater and the Qinghai Salt Lake showed that the terrestrial halite dissolution was the dominated contribution for the salinity of this brine. The stable isotope ratios of hydrogen and oxygen suggested that the origin of brine was from paleorecharge water which experienced mixing of modern water in shallow aquifer. δ(37)Cl values ranged from -0.02 to 3.43 ‰ (SMOC), and reflecting mixing of different sources. The Cl isotopic compositions suggest that the dissolution of halite by paleometeoric water had a great contribution to the salinity of brine, and the contributions of the residual seawater and the dissolution of halite by the Yellow River water could be excluded.

Synthesis and Characterization of Atomically Precise Copper Nanoclusters

NASA Astrophysics Data System (ADS)

Nguyen, Thuy-Ai Dang

The reactivity of MCl3(eta1-TEMPO) (M = Fe, Al; TEMPO = 2,2,6,6-tetramethylpiperidine-N-oxyl) with a variety of lignin models, including 3,4-dimethoxybenzyl alcohol, 1-phenyl-2-phenoxyethanol and 1,2-diphenyl-2-methoxyethanol is investigated. FeCl3(TEMPO) is effective in cleanly converting these substrates to the corresponding aldehyde or ketone. AlCl3(eta1-TEMPO) is also able to oxidize these substrates, however in a few instances the products of over-oxidation are also observed. In contrast, 2-phenoxyethanol is not oxidized by MCl 3(eta1-TEMPO); instead it likely coordinates to the metal center, forming a 2-phenoxyethoxide complex. Oxidation of activated alkanes by MCl3(eta1-TEMPO) suggests that the reactions proceed via an initial 1-electron concerted proton-electron transfer (CPET) event. Finally, reaction of TEMPO with FeBr3 in Et 2O results in oxidation of the solvent. The copper hydride clusters [Cu14H12(phen) 6(PPh3)4][X]2 (X = Cl, OTf) are obtained in good yields by reaction of [(Ph3P)CuH]6 with 1,10-phenanthroline, in the presence of a halide or pseudohalide source. [Cu14H 12(phen)6(PPh3)4][Cl]2 reacts with CO2 in CH2Cl2, in the presence of excess Ph3P, to form the formate complex, [(Ph3P)2Cu(kappa 2-O2CH)], along with [(phen)(Ph3P)CuCl]. [Cu25H22(PPh3)12]Cl and [Cu 18H17(PPh3)10]Cl, are isolated from the reaction of Cu(OAc) and CuCl with Ph2SiH2, in the presence of PPh3. [Cu25H22(PPh3) 12]Cl formally features partial Cu(0) character. Subsequent reaction with Ph2phen resulted in the isolation of [Cu29Cl 4H22(Ph2phen)12]Cl (Ph2phen = 4,7-diphenyl-1,10-phenanthroline), in good yields. A time-resolved kinetic evaluation of the formation of [Cu29Cl4H22(Ph 2phen)12]Cl reveals that the mechanism of cluster growth is initiated by rapid ligand exchange, followed by slower extrusion of CuCl monomer, transport, and subsequent capture by intact clusters. Two Cu26 nanoclusters, tentatively formulated as [Cu 26H17(PPh3)9(OAc)3] and [Cu26H22(PPh3)10(OAc)2], are isolated from the reaction of Cu(OAc) with Ph2SiH2, in the presence of PPh3. As formulated, [Cu26H 17(PPh3)9(OAc)3] features a magic number N* = 6, which is unprecedented for a copper nanocluster. XANES supports an assignment of more Cu(0) character than [Cu25H 22(PPh3)12]Cl (N* = 2) for this complex. A critical reevaluation of the synthesis and characterization of Cu 8(MPP)4 is reported. This product was reportedly formed by reaction of Cu(NO3)2 with 2-mercapto-5-n-propylpyrimidine (HMPP) and NaBH4, in ethanol, in the presence of [N(C8H 17)4][Br]. However, upon reevaluation, no experimental evidence to support the existence of Cu8(MPP)4 was found. Instead, the material isolated from this reaction is a complex mixture containing [N(C8H17)4]+, Br -, NO3-, 2-mercapto-5-n-propyl-1,6-dihydropyrimidine (H2MPP*), along with the Cu(I) coordination polymer, [Cu(MPP)]n. H2MPP* and [Cu(MPP)]n, as well as the related Cu(I) coordination complexes, [Cu(HMPP*)]n and [Cu2(MPP*)]n are independently synthesized to support these conclusions.

Physical Chemistry of Energetic Nitrogen Compounds

DTIC Science & Technology

1993-10-01

2177 (1981). 8. R.F. Heiner, III, H . Helvajian , G.ý. Holloway,-and J.B. Koffend, J. Phys. Chem . 93, 7813 (1989). 9. D.D. Bell and R.D. Coombe, J. Chem...Deuterium Atom Reactions with NFC12 . . . . . . . . . . . . . . . . . . . . . . . . . 15 3. The Reaction of H Atomps with NF2Cl .............. 22 V...or Br,) was admitted downstream such that a portion of the F atoms were converted to H , Cl or Br atoms prior to the admission of HN3 to the flow. When

Subthreshold parallel pumping experiments on the quasi one-dimensional S = {1}/{2} ferromagnets [C 6H 11NH 3]CuBr 3 and [C 6H 11NH 3]CuCl 3

NASA Astrophysics Data System (ADS)

Hoogerbeets, R.; Wiegers, S. A. J.; Van Duyneveldt, A. J.

1985-04-01

Subthreshold parallel pumping experiments on [C 6H 11NH 3]CuBr 3 (abbreviated as CHAB) and [C 6H 11NH 3]CuCl 3 (CHAC) at 9.6 and 18.3 GHz are reported. It is shown that the experimental results can be explained using the values of the parameters as have been obtained from previously reported FMR measurements.

Surface properties of thermionic electrodes

NASA Technical Reports Server (NTRS)

Stickney, R. E.

1972-01-01

A quasi-equilibrium model which provides semiquantitative predictions of the oxygen reaction with refractory metals was developed at high temperature and low pressure. Extensive experimental data was obtained on adsorption and work function properties for a wide variety of adsorbates (Cs, K, Na, I, Br, Cl, and O) on several refractory metals (W, Ta, Mo, and Re). Conclusions and recommendations for research on alkali metal adsorption, oxygen adsorption, and adsorption of cesium - oxygen mixtures are included.

Mutual Neutralization of Atomic Rare-Gas Cations (Ne+, Ar+, Kr+, Xe+) with Atomic Halide Anions (Cl-, Br-, I-)

DTIC Science & Technology

2015-01-07

DOCUMENTATION PAGE Form Approved OMB No. 0704-0188 Public reporting burden for this collection of information is estimated to average 1 hour per...reviewing this collection of information . Send comments regarding this burden estimate or any other aspect of this collection of information , including...suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports

Atomic emission spectroscopy

NASA Technical Reports Server (NTRS)

Andrew, K. H.

1975-01-01

The relationship between the Slater-Condon theory and the conditions within the atom as revealed by experimental data was investigated. The first spectrum of Si, Rb, Cl, Br, I, Ne, Ar, and Xe-136 and the second spectrum of As, Cu, and P were determined. Methods for assessing the phase stability of fringe counting interferometers and the design of an autoranging scanning system for digitizing the output of an infrared spectrometer and recording it on magnetic tape are described.

Method of selective reduction of polyhalosilanes with alkyltin hydrides

DOEpatents

Sharp, Kenneth G.; D'Errico, John J.

1989-01-01

The invention relates to the selective and stepwise reduction of polyhalosilanes by reacting at room temperature or below with alkyltin hydrides without the use of free radical intermediates. Alkyltin hydrides selectively and stepwise reduce the Si--Br, Si--Cl, or Si--I bonds while leaving intact any Si--F bonds. When two or more different halogens are present on the polyhalosilane, the halogen with the highest atomic weight is preferentially reduced.

C–H bond halogenation catalyzed or mediated by copper: an overview

PubMed Central

Hao, Wenyan

2015-01-01

Summary Carbon–halogen (C–X) bonds are amongst the most fundamental groups in organic synthesis, they are frequently and widely employed in the synthesis of numerous organic products. The generation of a C–X bond, therefore, constitutes an issue of universal interest. Herein, the research advances on the copper-catalyzed and mediated C–X (X = F, Cl, Br, I) bond formation via direct C–H bond transformation is reviewed. PMID:26664634

Quasicharacteristic radiation of relativistic electrons at orientation motion in lithium halides crystals along charged planes and axes

NASA Astrophysics Data System (ADS)

Maksyuta, N. V.; Vysotskii, V. I.; Efimenko, S. V.

2016-07-01

The paper deals with the investigation of the orientation motion of relativistic electrons in charged (111) planes and charged [110] axes of lithium halides ionic crystals of LiF, LiCl, LiBr and LiI. On the basis of these investigations the spectra of quasicharacteristic radiation for the electron beams with various Lorentz-factors both in planar and axial cases have been calculated numerically.

Scanning Tunneling Microscopy

DTIC Science & Technology

1992-03-17

tihodoluminescence spectroscopy , coupled with pulsed laser annealing-to reveal systematics between interface chemical and electronic structure. The...Duke and Y. C. Chanf "The atomic geometries of ZnSe (110) a~e GaAs (110): determination by photoemissic spectroscopy ," to be published...resonances in the conduction band), Be, Tl, In, Ga , AI, Pb, Sn, Ge, Si, B, Bi, Sb, Po, Te, As, At, P, Se, I, C, S, and Br (in the gap), with Cl, N, 0

Amino acids as novel nucleophiles for silver nanoparticle-luminol chemiluminescence.

PubMed

Li, Na; Ni, Shubiao

2014-12-01

The use of noble metal nanoparticles (NPs) as reductants in chemiluminescence (CL) has been reported only rarely owing to their high oxidation potentials. Interestingly, nucleophiles could dramatically lower the oxidation potential of Ag NPs, such that in the presence of nucleophiles Ag NPS could be used as reductants to induce the CL emission of luminol, an important CL reagent widely used in forensic analysis for the detection of trace amounts of blood. Although nucleophiles are indispensible in Ag NP-luminol CL, only inorganic nucleophiles such as Cl(-), Br(-), I(-) and S2O3 (2-) have been shown to be efficient. The effects of organic nucleophiles on CL remain unexplored. In this study, 20 standard amino acids were evaluated as novel organic nucleophiles in Ag NP-luminol CL. Histidine, lysine and arginine could initiate CL emission; the others could not. It is proposed that the different behaviors of 20 standard amino acids in the CL reactions derive from the interface chemistry between Ag NPs and these amino acids. UV/vis absorption spectra were studied to validate the interface chemistry. In addition, imidazole and histidine were chosen as a model pair to compare the behavior of the monodentate nucleophile with that of the corresponding multidentate nucleophile in Ag NP-luminol CL. Copyright © 2014 John Wiley & Sons, Ltd.

Halogen Substitution Effects on N2 O Schiff Base Ligands in Unprecedented Abrupt FeII Spin Crossover Complexes.

PubMed

Phonsri, Wasinee; Macedo, David S; Vignesh, Kuduva R; Rajaraman, Gopalan; Davies, Casey G; Jameson, Guy N L; Moubaraki, Boujemaa; Ward, Jas S; Kruger, Paul E; Chastanet, Guillaume; Murray, Keith S

2017-05-23

A family of halogen-substituted Schiff base iron(II) complexes, [Fe II (qsal-X) 2 ], (qsal-X=5-X-N-(8-quinolyl)salicylaldimines)) in which X=F (1), Cl (2), Br (3) or I (4) has been investigated in detail. Compound 1 shows a temperature invariant high spin state, whereas the others all show abrupt spin transitions, at or above room temperature, namely, 295 K (X=I) up to 342 K (X=Br), these being some of the highest T 1/2 values obtained, to date, for Fe II N/O species. We have recently reported subtle symmetry breaking in [Fe II (qsal-Cl) 2 ] 2 with two spin transition steps occurring at 308 and 316 K. A photomagnetic study reveals almost full HS conversion of [Fe II (qsal-I) 2 ] 4 at low temperature (T(LIESST)=54 °K). The halogen substitution effects on the magnetic properties, as well as the crystal packing of the [Fe II (qsal-X) 2 ] compounds and theoretical calculations, are discussed in depth, giving important knowledge for the design of new spin crossover materials. In comparison to the well known iron(III) analogues, [Fe III (qsal-X) 2 ] + , the two extra π-π and P4AE interactions found in [Fe II (qsal-X) 2 ] compounds, are believed to be accountable for the spin transitions occurring at ambient temperatures. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Vapour growth of argyrodite-type ionic conductors Cu 6PS 5Hal

NASA Astrophysics Data System (ADS)

Fiechter, S.; Eckstein, J.; Nitsche, R.

1983-03-01

Cu 6PS 5Hal compounds (with Hal = Cl, Br or I) have been crystallized around 950 K by CVT with P, S and Hal (and combinations thereof). Chemical insight into the transport processes was gained from dissociation pressure measurements and spectroscopic vapour analysis. Lacking thermochemical data of the compounds were obtained from Cp measurements. Models, derived for the CVT mechanisms, yield transport rates and directions which agree qualitatively with experiments. The main vapour species (for Hal = C1) are PSCI 3, S 2, PCI 3, P 4S 3 and (CuCl) 3. With a surplus of CuHal, VLS growth via liquid CuHal/Cu 2S phases was observed.

MORPHOLOGICAL CELL TRANSFORMATION OF C3H10T1/2CL8 MOUSE EMBRYO CELLS BY THE K-REGION DIHYDRODIOL OF BENZO[A]PYRENE OCCURS IN COINCIDENCE WITH DNA DAMAGE, BUT WITHOUT THE FORMATION OF DETECTABLE STABLE COVALENT DNA ADDUCTS

EPA Science Inventory

Abstract:

Benzo[a]pyrene (B[a]P) has been the most thoroughly studied polycyclic aromatic hydrocarbon (PAH). Many mechanisms have been suggested to explain its carcinogenic activity, yet many questions still remain. K-region diols of PAHs are common metabolic inter...

The interaction of mercury with halogenated graphene

NASA Astrophysics Data System (ADS)

Kirchofer, Abigail; Sasmaz, Erdem; Wilcox, Jennifer

2011-03-01

The interaction of mercury with halogenated graphene was studied using plane-wave density functional theory. Various configurations of H, Hg, O and Br or Cl on the zigzag edge sites of graphene were investigated. Although Hg-Br (or -Cl) complexes were found to be stable on the surface, the most stable configurations found were those with Hg adjacent to O. The surface atoms Hg, O, and Br tend to repel each other during geometric optimization, moving towards an H atom nearest-neighbor where possible. The strength of the Hg-graphene interaction is very sensitive to the local environment. The Hg-graphene binding energy is strongest when the Hg is located next to a surface O but not immediately next to a bound Br. DOS analysis revealed that Hg adsorption involves a gain in Hg 6 p-states and a loss in Hg 5 s electron density, resulting in an oxidized surface-bound Hg complex. DOS analysis suggests that Br strengthens the Hg-graphene interaction by modifying the surface carbon electron density; however, when Br is adjacent to Hg, a direct Hg-Br interaction weakens the Hg-C bond. These investigations provide insight into the mechanism associated with enhanced Hg adsorption on Br-functionalized carbon materials for Hg emissions reductions from coal-fired power plant applications. The authors acknowledge the financial support by Electric Power Research Institute (EPRI).

Effects of a Reservoir Water on the GW Quality in a Coastal Aquifer of Semi-arid Region, North-east of Tunisia

NASA Astrophysics Data System (ADS)

Uchida, C.; Kawachi, A.; Tsujimura, M.; Tarhouni, J.

2015-12-01

This study investigated effects of a reservoir water in a salinized shallow aquifer based on spatial distribution of geochemical properties in groundwater (GW). In many coastal shallow aquifers of arid and semi-arid regions, groundwater table (GWT) depression and salinization have occurred due to GW overexploitation. In Korba aquifer, north-east of Tunisia, after a dam reservoir has been constructed in order to assure a water resource for irrigation, improvement of GW level and quality have been observed in the downstream area of the dam (area-A), while the GW in the other area (area-B) still has high salinity. This study, therefore, aimed to investigate the effects of the reservoir water on the GW quality. In June 2013, water quality survey and sampling were carried out at 60 wells (GW), a dam reservoir, river and the sea. Major ions, boron, bromide, and oxygen-18 and deuterium in collected samples were analyzed. From the results, in the area-B, the GWT was lower than the sea level and the high salinity were observed. The Br- concentration of the GW was correlated with the Cl- concentration, and the values of B/Cl- and Br-/Cl- of the GW were similar to the seawater. Since the GWT depression allowed the seawater to intrude into the aquifer, the GW salinization occurred in this area. On the other hand, in the area-A, GWT was higher than the seawater level, and the Na+ and Cl- concentrations were lower than the area-B. Especially, in the irrigated areas by using the reservoir water, the isotopic values, B/Cl- and Br-/Cl- of the GW were relatively higher than the others. The reservoir water has high isotopic values due to evaporation effect, and the B/Cl- and Br-/Cl- values become higher due to organic matters in sediment of the reservoir or soil in the filtration process. Thus, in addition to the direct infiltration from the reservoir into the aquifer, irrigation using a reservoir water probably has a positive impact on the GW quality in this area.

Chlorate Formation Mechanism in the Presence of Sulfate Radical, Chloride, Bromide and Natural Organic Matter.

PubMed

Hou, Shaodong; Ling, Li; Dionysiou, Dionysios D; Wang, Yuru; Huang, Jiajia; Guo, Kaiheng; Li, Xuchun; Fang, Jingyun

2018-06-05

Halides and natural organic matter (NOM) are inevitable in aquatic environment and influence the degradation of contaminants in sulfate radical (SO 4 •- )-based advanced oxidation processes. This study investigated the formation of chlorate in the coexposure of SO 4 •- , chloride (Cl - ), bromide (Br - ) and/or NOM in UV/persulfate (UV/PDS) and cobalt(II)/peroxymonosulfate (Co/PMS) systems. The formation of chlorate increased with increasing Cl - concentration in the UV/PDS system, however, in the Co/PMS system, it initially increased and then decreased. The chlorate formation involved the formation of hypochlorous acid/hypochlorite (HOCl/OCl - ) as an intermediate in both systems. The formation was primarily attributable to SO 4 •- in the UV/PDS system, whereas Co(III) played a significant role in the oxidation of Cl - to HOCl/OCl - and SO 4 •- was important for the oxidation of HOCl/OCl - to chlorate in the Co/PMS system. The pseudo-first-order rate constants ( k') of the transformation from Cl - to HOCl/OCl - were 3.32 × 10 -6 s -1 and 9.23 × 10 -3 s -1 in UV/PDS and Co/PMS, respectively. Meanwhile, k' of HOCl/OCl - to chlorate in UV/PDS and Co/PMS were 2.43 × 10 -3 s -1 and 2.70 × 10 -4 s -1 , respectively. Br - completely inhibited the chlorate formation in UV/PDS, but inhibited it by 45.2% in Co/PMS. The k' of SO 4 •- reacting with Br - to form hypobromous acid/hypobromite (HOBr/OBr - ) was calculated to be 378 times higher than that of Cl - to HOCl/OCl - , but the k' of Co(III) reacting with Br - to form HOBr/OBr - was comparable to that of Cl - to HOCl/OCl - . NOM also significantly inhibited the chlorate formation, due to the consumption of SO 4 •- and reactive chlorine species (RCS, such as Cl·, ClO· and HOCl/OCl - ). This study demonstrated the formation of chlorate in SO 4 •- -based AOPs, which should to be considered in their application in water treatment.

AN APPROACH TO THE DEVELOPMENT OF MODELS TO QUANTITATIVELY ASSESS THE EFFECTS OF EXPOSURE TO ENVIRONMENTALLY RELEVANT LEVELS OF ENDOCRINE DISRUPTORS

EPA Science Inventory

An approach to the development of quantitative models to assess the effects of exposure to environmentally relevant levels of endocrine disruptors on homeostasis in adults.

Ben-Jonathan N, Cooper RL, Foster P, Hughes CL, Hoyer PB, Klotz D, Kohn M, Lamb DJ, Stancel GM.
<...

Effect of ionic liquid treatment on the ultrastructural and topochemical features of compression wood in Japanese cedar (Cryptomeria japonica).

PubMed

Kanbayashi, Toru; Miyafuji, Hisashi

2016-07-18

The morphological and topochemical changes in wood tissues in compression wood of Japanese cedar (Cryptomeria japonica) upon treated with two types of ionic liquids, 1-ethyl-3-methylimidazolium chloride ([C2mim][Cl]) and 1-ethylpyridinium bromide ([EtPy][Br]) were investigated. Compression wood tracheids were swollen by both ionic liquids but their swelling behaviors were different in the types of ionic liquids used. Under the polarized light, we confirmed that crystalline cellulose in compression wood is amorphized by [C2mim][Cl] treatment whereas it changes slightly by [EtPy][Br] treatment. Raman microscopic analyses revealed that [C2mim][Cl] can preferentially liquefy polysaccharides in compression wood whereas [EtPy][Br] liquefy lignin. In addition, the interaction of compression wood with ionic liquids is different for the morphological regions. These results will assist in the use of ionic liquid treatment of woody biomass to produce valuable chemicals, bio-fuels, bio-based composites and other products.

Effect of ionic liquid treatment on the ultrastructural and topochemical features of compression wood in Japanese cedar (Cryptomeria japonica)

PubMed Central

Kanbayashi, Toru; Miyafuji, Hisashi

2016-01-01

The morphological and topochemical changes in wood tissues in compression wood of Japanese cedar (Cryptomeria japonica) upon treated with two types of ionic liquids, 1-ethyl-3-methylimidazolium chloride ([C2mim][Cl]) and 1-ethylpyridinium bromide ([EtPy][Br]) were investigated. Compression wood tracheids were swollen by both ionic liquids but their swelling behaviors were different in the types of ionic liquids used. Under the polarized light, we confirmed that crystalline cellulose in compression wood is amorphized by [C2mim][Cl] treatment whereas it changes slightly by [EtPy][Br] treatment. Raman microscopic analyses revealed that [C2mim][Cl] can preferentially liquefy polysaccharides in compression wood whereas [EtPy][Br] liquefy lignin. In addition, the interaction of compression wood with ionic liquids is different for the morphological regions. These results will assist in the use of ionic liquid treatment of woody biomass to produce valuable chemicals, bio-fuels, bio-based composites and other products. PMID:27426470

Synthesis and characterization of monomeric Mn (IV) and pseudo-tetrameric Mn (III) complexes: magnetic properties of Mn (III) complex.

PubMed

Yahsi, Yasemin; Kara, Hulya

2014-06-05

Two novel monomer Mn (IV) [Mn(3,5-ClL1)2]⋅(CH3OH), (1), [3,5-ClL1H2=N-(2-hydroxyethyl)-3,5-dichlorosalicylaldimine] (1) and hydrogen-bonded pseudo-tetramer Mn (III) [Mn(5-BrL2)(H2O)2]2⋅[Mn(5-BrL2)(H2O)]2⋅2⋅(ClO4), (2), [5-BrL2H2=N,N'-bis(5-bromosalicylidenato)-1,2-diamino-2-methylpropane)] (2) Schiff base complexes have been synthesized and their crystal structures have been determined by single crystal X-ray diffraction analysis. A variable temperature magnetic susceptibility measurement study has been performed for complex (2) and the result indicates there is a very weak antiferromagnetic interaction (J=-0.40±0.016cm(-1)) between the two manganese (III) centers. Copyright © 2014 Elsevier B.V. All rights reserved.

Salts in the dry valleys of Antartica

NASA Technical Reports Server (NTRS)

Gibson, E. K., Jr.; Presley, B. J.; Hatfield, J.

1984-01-01

The Dry Valleys of Antarctica are examples of polar deserts which are rare geological features on the Earth. Such deserts typically have high salinities associated with their closed-basin waters and on many surficial materials throughout them. In order to examine the possible sources for the salts observed in association with the soils in the Dry Valleys. The chloride and bromide concentrations of the water leachates from 58 soils and core samples were measured. The Cl/Br ratio for seawater is 289 and ratios measured for most of the 58 soils studied (greater than 85% of the soils studied) was larger than the seawater ratio (ratios typically were greater than 1000 and ranged up to 50,000). The enrichment in Cl relative to Br is strong evidence that the alts present within the soils were derived from seawater during ordinary evaporation processes, and not from the deposition of Cl and Br from aerosols or from rock weathering as has often been suggested.

Halogens as tracers of protosolar nebula material in comet 67P/Churyumov-Gerasimenko

NASA Astrophysics Data System (ADS)

Dhooghe, Frederik; De Keyser, Johan; Altwegg, Kathrin; Briois, Christelle; Balsiger, Hans; Berthelier, Jean-Jacques; Calmonte, Ursina; Cessateur, Gaël; Combi, Michael R.; Equeter, Eddy; Fiethe, Björn; Fray, Nicolas; Fuselier, Stephen; Gasc, Sébastien; Gibbons, Andrew; Gombosi, Tamas; Gunell, Herbert; Hässig, Myrtha; Hilchenbach, Martin; Le Roy, Léna; Maggiolo, Romain; Mall, Urs; Marty, Bernard; Neefs, Eddy; Rème, Henri; Rubin, Martin; Sémon, Thierry; Tzou, Chia-Yu; Wurz, Peter

2017-12-01

We report the first in situ detection of halogens in a cometary coma, that of 67P/Churyumov-Gerasimenko. Neutral gas mass spectra collected by the European Space Agency's Rosetta spacecraft during four periods of interest from the first comet encounter up to perihelion indicate that the main halogen-bearing compounds are HF, HCl and HBr. The bulk elemental abundances relative to oxygen are ∼8.9 × 10-5 for F/O, ∼1.2 × 10-4 for Cl/O and ∼2.5 × 10-6 for Br/O, for the volatile fraction of the comet. The cometary isotopic ratios for 37Cl/35Cl and 81Br/79Br match the Solar system values within the error margins. The observations point to an origin of the hydrogen halides in molecular cloud chemistry, with frozen hydrogen halides on dust grains, and a subsequent incorporation into comets as the cloud condensed and the Solar system formed.

Nuclear magnetic resonance shielding constants and chemical shifts in linear 199Hg compounds: a comparison of three relativistic computational methods.

PubMed

Arcisauskaite, Vaida; Melo, Juan I; Hemmingsen, Lars; Sauer, Stephan P A

2011-07-28

We investigate the importance of relativistic effects on NMR shielding constants and chemical shifts of linear HgL(2) (L = Cl, Br, I, CH(3)) compounds using three different relativistic methods: the fully relativistic four-component approach and the two-component approximations, linear response elimination of small component (LR-ESC) and zeroth-order regular approximation (ZORA). LR-ESC reproduces successfully the four-component results for the C shielding constant in Hg(CH(3))(2) within 6 ppm, but fails to reproduce the Hg shielding constants and chemical shifts. The latter is mainly due to an underestimation of the change in spin-orbit contribution. Even though ZORA underestimates the absolute Hg NMR shielding constants by ∼2100 ppm, the differences between Hg chemical shift values obtained using ZORA and the four-component approach without spin-density contribution to the exchange-correlation (XC) kernel are less than 60 ppm for all compounds using three different functionals, BP86, B3LYP, and PBE0. However, larger deviations (up to 366 ppm) occur for Hg chemical shifts in HgBr(2) and HgI(2) when ZORA results are compared with four-component calculations with non-collinear spin-density contribution to the XC kernel. For the ZORA calculations it is necessary to use large basis sets (QZ4P) and the TZ2P basis set may give errors of ∼500 ppm for the Hg chemical shifts, despite deceivingly good agreement with experimental data. A Gaussian nucleus model for the Coulomb potential reduces the Hg shielding constants by ∼100-500 ppm and the Hg chemical shifts by 1-143 ppm compared to the point nucleus model depending on the atomic number Z of the coordinating atom and the level of theory. The effect on the shielding constants of the lighter nuclei (C, Cl, Br, I) is, however, negligible. © 2011 American Institute of Physics

Singlet Excited States of Cl and Br Molecules: New Theories Applied to the -XO and -XO2 (X=C1 and Br) Chromophores

NASA Technical Reports Server (NTRS)

Lee, Timothy J.; Srinivasan, Parthiban; Head-Gordon, Martin; Huo, Winifred (Technical Monitor)

1998-01-01

Electronic excitation energies are determined using single-reference based theories derived from response equations involving perturbation theory and coupled-cluster theory. These methods are applied to the singlet manifold of excited electronic states of the HClO, HBrO, HOClO, HOBrO, HClO2, and HBrO2 molecules. The reliability of the various perturbation theory approaches is assessed by comparison to the linear-response singles and doubles coupled-cluster (LRCCSD) method. The excitation energies for the Y-XO compounds are compared and contrasted for Y=H and HO, and X=Cl and Br. A similar comparison is performed for the H-XO2 compounds.

Reactions of rhenium(V) and molybdenum(V) oxypentahalides with 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ashurova, N.Kh.; Yakubov, K.G.

1993-11-01

The author studied complexation reactions of rhenium(V) and molybdenum(V) with a macrocyclic ligand 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane (Tet a). The authors found that in hydrohalic acid medium, the onium complexes [H{sub 2}(Tet a)][EOX{sub 5}] are formed, with E = Re, Mo; X = Cl, Br. Reactions of [EOX{sub 5}]{sup 2{minus}} with (Tet a) in nitrometane yield complexes of molecular and cation types [EO(Tet a)Cl{sub 3}] and [EO(Tet a)Br]Br{sub 2}. Composition and structure of the obtained compounds are established by elemental analysis, conductometry, and mid- and far-IR spectroscopy.

Tracing recharge to aquifers beneath an Asian megacity with Cl/Br and stable isotopes: the example of Dhaka, Bangladesh

NASA Astrophysics Data System (ADS)

Hoque, M. A.; McArthur, J. M.; Sikdar, P. K.; Ball, J. D.; Molla, T. N.

2014-06-01

Dhaka, the capital of Bangladesh, is home to a population of 15 million people, whose water supply is 85% drawn from groundwater in aquifers that underlie the city. Values of Cl/Br >500 are common in groundwater beneath western Dhaka in areas <3 km from the river, and in rivers and sewers around and within the city. The study shows that groundwater beneath western Dhaka is strongly influenced by infiltration of effluent from leaking sewers and unsewered sanitation, and by river-bank infiltration from the Turag-Buriganga river system which bounds the western limit of the city. River-bank infiltration from other rivers around Dhaka is minor. Values of Cl/Br and Cl concentrations reveal that 23 % of wells sampled in Dhaka are influenced by saline connate water in amounts up to 1%. This residual natural salinity compromises the use of electrical conductivity of groundwater as a method for defining pathways of recharge by contaminated surface waters. Concentrations of As, B, Ba, Cd, Cu, F, Ni, NO3, Pb, Sb, Se and U in groundwater samples are less than WHO health-based guideline values for drinking water.

High-Resolution THz Measurements of BrO Generated in AN Inductively Coupled Plasma

NASA Astrophysics Data System (ADS)

Nemchick, Deacon J.; Drouin, Brian

2017-06-01

Building upon the foundation provided by previous work, the X_{1}^{2}Π_{3/2} and X_{2}^{2}Π_{1/2} states of the transient radical, BrO, were interrogated in previously unprobed spectral regions (0.5 to 1.7 THz) by employing JPL developed high-resolution cascaded frequency multiplier sources. Like other members of the halogen monoxides (XO), this species has been the target of several recent atmospheric remote sensing studies and is a known participant in a catalytic ozone degradation cycle. For the current work, BrO is generated in an inductively coupled plasma under dynamic flow conditions and rotational lines are observed directly at their Doppler-limited resolution. New spectral transitions including those owing to both the ground (ν=0) and excited (ν=1 and 2) vibrational states of isotopologues composed of permutations of natural abundance ^{16}O, ^{18}O, ^{79}Br, and ^{81}Br are fit to a global Hamiltonian containing both fine and hyperfine terms. In addition to further refining existing spectroscopic parameters, new observations will be made available to remote detection communities through addition to the JPL catalog. New findings will be discussed along with future plans to extend these studies to other halogen monoxides (X=Cl and I) and the more massive halogen dioxides (OXO & XOO).

High-Temperature Photoluminescence of CsPbX 3 (X = Cl, Br, I) Nanocrystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Diroll, Benjamin T.; Nedelcu, Georgian; Kovalenko, Maksym

2017-03-30

Recent synthetic developments have generated intense interest in the use of cesium lead halide perovskite nanocrystals for light-emitting applications. This work presents the photoluminescence (PL) of cesium lead halide perovskite nanocrystals with tunable halide composition recorded as function of temperature from 80 to 550 K. CsPbBr 3 nanocrystals show the highest resilience to temperature while chloride-containing samples show relatively poorer preservation of photoluminescence at elevated temperatures. Thermal cycling experiments show that PL loss of CsPbBr 3 is largely reversible at temperatures below 450 K, but shows irreversible degradation at higher temperatures. Time-resolved measurements of CsPbX 3 samples show an increasemore » in the PL lifetime with temperature elevation, consistent with exciton fission to form free carriers, followed by a decrease in the apparent PL lifetime due to trapping. In conclusion, PL persistence measurements and time-resolved spectroscopies implicate thermally assisted trapping, most likely to halogen vacancy traps, as the mechanism of reversible PL loss.« less

Performance of an alkalophilic and halotolerant laccase from gamma-proteobacterium JB in the presence of industrial pollutants.

PubMed

Singh, Gursharan; Sharma, Prince; Capalash, Neena

2009-08-01

An alkalophilic and halotolerant laccase from gamma-proteobacterium JB catalyzed in high concentrations of organic solvents and various salts. The enzyme retained 80-100% activity in 10% concentration of dimethylsulfoxide (DMSO), ethanol, acetone or methanol; 100, 85 and 50% activity in 20 mM MgCl(2), 5.0 mM MnCl(2) and 0.1 mM CuCl(2); 140, 120 and 110% activity in 5.0 mM MnSO(4), 10 mM MgSO(4) and 1mM CaSO(4), respectively. Sodium halides inhibited the enzyme in the order: F(-)> Br(-)> I(-)> Cl(-). In 0.5 M NaCl, pH 6.0, laccase was approximately 60% active. Decolorization of indigo carmine by laccase at pH 9.0 was not inhibited even in the presence of 0.5 M NaCl. Release of chromophoric, reducing and hydrophobic compounds during biobleaching of straw rich-soda pulp by laccase was not inhibited when the enzyme was applied in the presence of 1 M NaCl at pH 8.0. Laccase retained 50% residual activity even when incubated with 5% calcium hypochlorite for 30 min.

Synthesis, characterization and optical non-linearity of two heterobimetallic copper clusters containing tetraselenometalates

NASA Astrophysics Data System (ADS)

Zhang, Qian-Feng; Zhang, Chi; Song, Ying-Lin; Xin, Xin-Quan

2000-07-01

Cluster [{MoCu 3Se 3Br}(PPh 3) 3Se]·3THF·H 2O ( 1·3THF·H 2O) was prepared from reaction of [Et 4N] 2[MoSe] 4, Cu(PPh 3) 2NO 3 and Et 4N·Br in CH 2Cl 2 solution; also, 1 can be also obtained from the reaction of [MoSe 4Cu 4Py 6Br 2] and excess PPh 3 in a DMF-CH 2Cl 2 mixture solvent. The 95Mo NMR technique was used to monitor the above two reaction processes. X-ray crystallographic structure determination shows that it contains a strongly distorted cubane-like {MoCu 3Se 3Br} core. The coordination of the central Mo atom and each Cu atom are distorted from tetrahedral. Cluster [{WCu 3Se 3Cl}(PPh 3) 3Se] ( 2) was synthesized by the reaction of [Et 4N] 2[WSe] 4 and Cu(PPh 3) 2Cl in the solid state for nonlinear optical (NLO) studies. Its structure was reported by Ibers (Inorg. Chem. 31 (1992) 4365). The NLO properties of clusters 1 and 2 were studied. Both NLO absorption and refraction were obtained, and their effective third-order non-linearities were detected with α2=3.4×10 -10 and 5.9×10 -10 m/W and n2=-1.5×10 -17 and -1.3×10 -17 m 2/W , respectively, for the same concentration CH 2Cl 2 solution of 1 and 2. Influence of skeletal atoms to nonlinear absorption is also discussed in the paper.

Gyroscope-like molecules consisting of PdX₂/PtX₂ rotators within three-spoke dibridgehead diphosphine stators: syntheses, substitution reactions, structures, and dynamic properties.

PubMed

Nawara-Hultzsch, Agnieszka J; Stollenz, Michael; Barbasiewicz, Michał; Szafert, Sławomir; Lis, Tadeusz; Hampel, Frank; Bhuvanesh, Nattamai; Gladysz, John A

2014-04-14

Threefold intramolecular ring-closing metatheses of trans-[MCl2(P{(CH2)(m)CH=CH2}3)2] are effected with Grubbs' catalyst. Following hydrogenation catalyzed by [RhCl(PPh3)3], the title complexes trans-[MCl2(P((CH2)n)3P)] (n=2m+2; M/n=Pt/14, 4 c; Pt/16, 4 d; Pt/18, 4 e; Pd/14, 5 c; Pd/18, 5 e) and sometimes isomers partly derived from intraligand metathesis, trans-[MCl2{P(CH2)n(CH2)n}P(CH2)n)] (4'c-e, 5'e), are isolated. These react with LiBr, NaI, and KCN to give the corresponding MBr2, MI2, and M(CN)2 species (58-99%). (13)C NMR data show that the MX2 moieties rapidly rotate within the diphosphine cage on the NMR timescale, even at -120 °C. The reaction of 4 c and KSCN gives separable Pt(NCS)2 and Pt(NCS)(SCN) adducts (13 c, 28%; 14 c, 20%), and those of 4 c,e and Ph2Zn give PtPh2 species (15 c, 61%; 15 e, 90%). (13)C NMR spectra of 13 c-15 c show two sets of CH2 signals (ca. 2:1 intensity ratios), indicating that MX2 rotation is no longer rapid. Reactions of 4 c or 4'c and excess NaC≡CH afford the free diphosphines P{(CH2)14}3P (91%) and (CH2)14P(CH2)14P(CH2)14 (90%). The latter has been crystallographically characterized as a bis(BH3) adduct. The crystal structures of eight complexes with P(CH2)14P linkages (PtCl2, PtBr2, PtI2, Pt(NCS)2, PtPh2, PdCl2, PdBr2, PdI2) and 15 e have been determined, and intramolecular distances analyzed with respect to MX2 rotation. The conformations of the (CH2)14 moieties and features of the crystal lattices are also discussed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Constraining the global bromomethane budget from carbon stable isotopes

NASA Astrophysics Data System (ADS)

Bahlmann, Enno; Wittmer, Julian; Greule, Markus; Zetzsch, Cornelius; Seifert, Richard; Keppler, Frank

2016-04-01

Despite intense research in the last two decades, the global bromomethane (CH3Br) budget remains unbalanced with the known sinks exceeding the known sources by about 25%. The reaction with OH is the largest sink for CH3Br. We have determined the kinetic isotope effects for the reactions of CH3Br with the OH and Cl radical in order to better constrain the global CH3Br budget from an isotopic perspective. The isotope fractionation experiments were performed at 20±1°C in a 3500 L Teflon smog-chamber with initial CH3Br mixing ratios of about 2 and 10 ppm and perflourohexane (25 ppb) as internal standard. Atomic chlorine (Cl) was generated via photolysis of molecular chlorine (Cl2) using a solar simulator with an actinic flux comparable to that of the sun in mid-summer in Germany. OH radicals were generated via the photolysis of ozone (O3) at 253.7 nm in the presence of water vapor (RH = 70%).The mixing ratios of CH3Br, and perflourohexane were monitored by GC-MS with a time resolution of 15 minutes throughout the experiments. From each experiment 10 to 15 sub samples were taken in regular time intervals for subsequent carbon isotope ratio determinations by GC-IRMS performed at two independent laboratories in parallel. We found a kinetic isotope effect (KIE) of 17.6±3.3‰ for the reaction of CH3Br with OH and a KIE of 9.8±1.4 ‰ for the reaction with Cl*. We used these fractionation factors along with new data on the isotopic composition of CH3Br in the troposphere (-34±7‰) and the surface ocean (-26±7‰) along with reported source signatures, to constrain the unknown source from an isotopic perspective. The largest uncertainty in estimating the isotopic composition of the unknown source arises from the soil sink. Microbial degradation in soils is the second largest sink and assigned with a large fractionation factors of about 50‰. However, field experiments revealed substantially smaller apparent fractionation factors ranging from 11 to 22‰. In addition, simple model studies suggest that the soil uptake of CH3Br and hence its isotopic effect is largely controlled by diffusion resulting in an even smaller apparent isotopic fractionation. As a consequence, the estimated source signature for the unknown source is discussed with respect to the assumptions made for the soil sink.