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1
Awwadi, Firas Fandi. "A crystallographic and theoretical study of halogen---halogen and halogen---halide synthons." Online access for everyone, 2005. http://www.dissertations.wsu.edu/Dissertations/Summer2005/F%5FAwwadi%5F072705.pdf.
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Beckert, Marco. "Photodissociation dynamics of halogens and halogen-ions studied by ion imaging." Thesis, University of Bristol, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274674.
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Vulpe, Elena. "Molecular tectonics based on fluorinated porphyrins." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAF048/document.
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Les travaux décrits dans ce manuscrit utilisent les principes de la tectonique moléculaire pour générer des polymères de coordination hautement fluorés et /ou chiraux pour une application potentielle en séparation chirale. La synthèse de 13 porphyrines de type A2B2 substituées en position méso par deux pyridines et par deux chaines fluorées et/ou alkyles a été mise au point. Des réseaux de coordination ont été obtenus en présence de Zn(II) et de Cd(II) et caractérisés par diffraction des RX sur monocristal (DRX). Une analyse systématique des interactions supramoléculaires et notamment de interactions F---F présentes à l’état solide a été conduite. Des réseaux à base de liaisons halogènes ont également été obtenus en présence de di- et tri-iodoarènes et caractérisés par DRX.Le premier chapitre est une introduction générale sur la tectonique moléculaire, le deuxième chapitre décrit les voies des synthèses utilisées pour générer les ligands chiraux et fluorés et leur caractérisation à l’état solide. Le troisième chapitre présente la structure des réseaux mono, bi, et tridimensionnels formés en présence de Zn(II) ou de Cd(II), l’analyse structurale met en évidence un nombre croissant d’interaction F---F en fonction du nombre de fluors présents à la périphérie du macrocycle porphyrinique. Le dernier chapitre se concentre sur l’utilisation des liaisons halogènes de type N---I impliquant des porphyrines ou des tectons de type bipyridine et une série d’ iodofluoroarenesThis manuscript focuses on the use of molecular tectonics to generate chiral and / or fluorinated coordination polymers based on porphyrin building blocks for potential application in chiral separation. Synthesis of novel A2B2 fluorinated porphyrin tectons is described and their combinations with metal ions and haloarenes molecules are characterized by X-Ray diffraction.The first chapter gives a general introduction on molecular tectonics; the second chapter focuses on the synthetic routes used for the synthesis of highly fluorinated and/or chiral porphyrins and their solid state characterization by X-Ray diffraction analysis, highlighting the importance of the number of fluorine atoms present at the periphery of the tecton on the crystal packing. The third chapter presents the mono-, bi- and three dimensional networks formed by a combination of the porphyrins with Zn(II) or Cd(II). In the solid state, short F---F contacts were observed depending on the number of fluorine atoms present on the porphyrin backbone. The last chapter focuses on the use of halogen bonds, by merging the neutral porphyrin or bipyridine tectons with a series of iodofluoroarenes. The crystalline materials described in this work can be used as potential candidates for the separation of chiral and fluorinated molecules
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Liao, Jin. "Bromine and chlorine chemistry in the Arctic boundary layer." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/45932.
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Halogen chemistry plays an important role in spring time ozone and mercury depletion events (ODEs and MDEs) and may efficiently oxidize hydrocarbons such as the important greenhouse gas methane (CH4) in the polar marine boundary layer. This thesis presents a detailed study of bromine and chlorine chemistry in the Arctic boundary layer based on measurements of bromine and chlorine containing species using chemical ionization mass spectrometry (CIMS). The capability of CIMS to accurately measure bromine oxide (BrO) was demonstrated. The first direct measurements of hypobromous acid (HOBr) were achieved. Conditions that likely favor bromine activation (e.g. high wind speeds) was presented. To advance the understanding of bromine recycling, a time dependent model was built to simulate the bromine speciation. Unexpected high levels of molecular chlorine (Cl2) were observed at Barrow, AK, which had a large impact on methane oxidation and could contribute to ozone loss and mercury oxidation at Barrow, AK. Moreover, BrO levels observed at Summit, Greenland did not explain the under prediction of hydroxyl radical (OH). However, the enhanced OH was found to be coincident with elevated reactive gaseous mercury (RGM). In addition, airborne BrO measurements were found to be generally consistent with airborne observations of soluble bromide based on the response factors of mist chamber to the bromine species and bromine chemical mechanisms.
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Hogan, Simon William Leslie. "The role of halogen bonding in biomolecules." Thesis, University of St Andrews, 2018. http://hdl.handle.net/10023/13840.
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This study concerns halogen bonding between small molecules. Except where otherwise stated herein this investigation was performed exclusively using the M06-2X density functional, in conjunction with the 6-31+G* basis set except for iodine and astatine which were treated using the aug-cc-pVDZ-PP basis set with relativistic pseudopotentials. All calculations were performed in the gas phase. The counterpoise procedure was employed for all full geometry optimisations. Statistical analysis of the Cambridge Structural Database, wherein the frequency of structures as a function of halogen bond angle and distance constituted the sole part of this study not to be based on density functional theory. Except in chapter 5, all halogens from fluorine to astatine are investigated. In chapter 3, halogen bonding between halobenzene and a single water molecule is discussed. Competition between R – X•••OH2 halogen bonding and R – X•••H-O-H hydrogen bonding interactions is described. This system is analogous to the more elaborate microsolvated 1- methyl-5-halouracil system described in chapter 4. In this latter system one 1-methyl-5- halouracil molecule interacts with either one or two water molecules. A central feature of the investigation into this system is competition between R – X•••OH2 and R=O•••H-O-H hydrogen bonding. In chapter 5, halogen bonding is discussed in the context of the thyroid system. In particular halogen bonding between a thyroxine iodine atom and the protein backbone as well as crystal water molecules is the subject of this chapter. The effect of substitution of the iodine atom with an astatine atom is presented. Chapter 6 is concerned with halogen bonding in halogenated DNA base pairs. Interaction energies are compared with those of the canonical base pairs, and the effect of halogen bonding on geometry is also discussed. For each system, halogen bonding was found to become stronger and more tolerant of non- linear bond angles going down the halogen group.
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Amombo, Noa Francoise Mystere. "Halogen···Halogen interactions in host - guest systems." Doctoral thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/27462.
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For a few decades now, halogen bonds which are non-covalent interactions, have gained a lot of interest in the science community due to their applications in diverse research areas. Halogen bonding (XB) is an interaction that occurs between electron deficient halogen compounds and electron donors. This is an established non-covalent interaction in the solid and gaseous phase. In this thesis, the work presented deals with the investigation of halogen bond interactions in host-guest complexes utilising both experimental and theoretical techniques. Two host compounds, tetrakis-4-(bromophenyl)ethylene and its iodo-analogue were synthesised for the studies reported in Chapter 3, 4 and 5. Chapter 3, deals with the classification of halogen···halogen interactions using halogenated methanes as guest solvents. Here, the inclusion complexes can be classified into different types of halogen bonds depending on their geometry. Type I, which are of van der Waals in nature usually have X···X distances greater than the sum of their van der Waals radii. Type IIa and IIb are interactions which are considered to be attractive and their X···X distances are usually shorter than those of type I. The compounds obtained in Chapter 3 were used to study both the kinetics of desolvation and the kinetics of enclathration for the solid host-methyl iodide vapour reactions, to obtain their rate law and determine activation energies. In Chapter 4, the two hosts mentioned above were utilised to form inclusion compounds with a series of halogenated compounds for guest exchange reactions. The structures of the starting inclusion compounds were exposed to the vapours of the second incoming guests to form intermediate complexes and final compounds, which were used to analyse the halogen···halogen interactions in their structures. NMR spectroscopy was performed on selected crystals to monitor the guest exchange experiment and the rate law of each exchange reaction was established. Tetrakis-4-(bromophenyl)ethylene and its iodo-analogue were also used as host compounds in Chapter 5. Here, halogen···halogen interactions are also classified and two novel polymorphs of tetrakis-4-(iodophenyl)ethylene with 3-picoline (3PIC) are reported. Kinetics of enclathration by suspension was conducted on two of the bromohost inclusion compounds (with 3-bromopyridine and 3-picoline) at 25 °C and 35 °C. Competition between hydrogen and halogen bonding was performed in Chapter 6, using three similar but subtly different host compounds with halogenated substituted pyridines as guests. IR spectroscopy and Hirshfeld surface analysis were utilised for further characterisation of these inclusion compounds. The synthesis of halogenated Werner clathrates containing Cl-, Br- and I- in Chapter 7, was conducted with various guests of substituted pyridines. Compounds, which were derived from NiI₂ yielded ionic complexes, forming iodide anions. Iodine was added to these complexes to form tri-iodide anions. The Werner clathrates obtained with the 4-picoline (4PIC) could also be directly synthesised by the exposure of NiCl₂/NiBr₂ to the vapour of 4PIC. Kinetics of enclathration of these two solid-vapour reaction compounds were also analysed. All the structures in this study were elucidated using single crystal X-ray diffraction. Thermal analyses such as thermogravimetry (TG), hot stage microscopy (HSM) and differential scanning calorimetry (DSC) were used for the determination of the thermal behaviour of the new compounds. Variable temperature powder X-ray diffraction was also carried out for the characterisation of the new compounds.
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Schindler, Severin [Verfasser]. "Grundlegende Studien zum Einsatz halogen-basierter Lewis-Säuren in Halogenid-Abstraktionsreaktionen sowie Synthese und Anwendung erster chiraler Halogenbrückendonoren / Severin Schindler." München : Verlag Dr. Hut, 2016. http://d-nb.info/1126297135/34.
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Yang, Jian. "Nouveaux développements de la chimie des proazaphosphatranes : de l’organocatalyse à la liaison halogène." Thesis, Ecole centrale de Marseille, 2018. http://www.theses.fr/2018ECDM0006/document.
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Au cours de ces travaux de thèse, nous avons exploré de nouvelles applications des proazaphosphatranes et de leurs dérivés, en particulier leur confinement dans une cage moléculaire. Dans la première partie, une bibliographie présente la littérature concernant (i) la découverte et les applications de proazaphosphatranes, (ii) les catalyseurs confinés dans des cages covalentes et (iii) la liaison halogène - une interaction non covalente émergente-. Par la suite, l’utilisation de proazaphosphatranes comme organocatalyseur très efficace pour la réaction de Strecker est décrit. Ensuite, un système FLP (paire de Lewis frustrée) comprenant un proazaphosphatrane encagé comme base de Lewis et du TiCl4 comme acide de Lewis a été utilisé pour catalyser la réaction de MBH (Morita-Baylis-Hillman). Finalement, un azaphosphatrane chloré a été synthétisé, et ses propriétés de reconnaissance vis à vis de différents anions halogénures, par liaison halogène, a été étudiéIn this dissertation, our goal is to explore new applications of proazaphosphatranes and their derivatives, especially in a confined space. In the first part, a comprehensive literature review regarding 1) discovery and application of proazaphosphatranes, 2) confined covalent cages based organo- and metal-catalysts, and 3) halogen bonding – an emergent noncovalent interaction has been demonstrated. Subsequently, proazaphosphatrane as highly efficient organocatalyst for the Strecker reaction is discussed. And a FLP (frustrated Lewis pair) system comprising an encaged proazaphosphatrane as Lewis base and TiCl4 as Lewis acid for MBH (Morita–Baylis–Hillman) reaction is reported. In the end, chlorinated azaphosphatrane is synthesized and studied in the recognition of different halide anions by halogen bonding, exhibiting a preferable affinity for chloride over bromide and iodide
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Pietzner, Verena. "Lernkontrolle im "Vernetzten Studium - Chemie" Entwicklung und Evaluation eines Konzepts am Beispiel des Kapitels "Addition von Halogenen an Doppelbindungen" /." [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=965380912.
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Keßenich, Ingo Elmar. "Beiträge zur Halogen- und Pseudohalogenchemie." Diss., lmu, 2001. http://nbn-resolving.de/urn:nbn:de:bvb:19-2342.
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Meerbach, Christian, Cong Wu, Steven C. Erwin, Zhiya Dang, Anatol Prudnikau, and Vladimir Lesnyak. "Halide-Assisted Synthesis of Cadmium Chalcogenide Nanoplatelets." American Chemical Association, 2019. https://tud.qucosa.de/id/qucosa%3A74323.
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Atomically flat colloidal semiconductor CdSe nanoplatelets (NPLs) with precisely controlled thickness possess a range of unique optoelectronic properties. Here, we study the growth of CdSe, CdTe, and CdS NPLs with the aim of synthesizing thicker NPLs in order to extend their optical activity further into the lower energy/larger wavelength range. We employ cadmium halides, which lead to faster reaction kinetics as confirmed by control experiments with cadmium hydroxide as a Cd-precursor. Addition of halides in all cases led to the formation of thicker NPL species, as compared with the corresponding syntheses without these additives. Analysis of a recent theoretical model of the platelet growth mechanism confirms an earlier suggestion that reducing both the reaction enthalpy and the surface energy of CdSe, by replacing acetate ligands with chloride ions, should indeed lead to thicker NPLs as observed. We noticed a formation of Cd0-metal nanoparticles in the first stage of the synthesis by preparing the Cd-precursor, which is another key finding of our work. We assume that these particles can serve as an active cadmium source facilitating the growth of the NPLs. The resulting 6 ML CdSe NPLs exhibited bright photoluminescence with quantum yield of up to 50%, exceptionally narrow spectrum centered at 582 nm with full width at half-maximum of approx. 11 nm, and small Stokes shift of 2 nm. Moreover, we demonstrated the synthesis of heterostructured core/shell CdSe/CdS NPLs based on 6 ML CdSe platelets, which also exhibited bright fluorescence. This work shows the possibility to overcome energetic barrier limiting the size (thickness) control by using appropriate promoters of the growth of CdSe, CdTe, and CdS 2D structures.
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Arman, Hadi D. "Strategies for expanding the halogen bonding periodic table and designing complementary halogen/hydrogen bonding synthons." Connect to this title online, 2008. http://etd.lib.clemson.edu/documents/1219848304/.
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Pagé, Lilianne. "The Behaviour of Halogens (F, Cl, Br, I) and Other Fluid-Mobile Elements in Subduction Zones." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39261.
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The high abundance of fluid-mobile elements (FMEs) in arc magmas relative to the mantle attests to their recycling in subduction zones. Aqueous fluids released from the subducting slab transport these elements to the overlying mantle wedge for arc magma generation. However, some FME may be retained in the slab to the deeper mantle, incorporating into melts that form back-arc basalts, intraplate ocean island basalts (OIBs), carbonatites and kimberlites. This thesis reports the abundance and distribution of halogens (F, Cl, Br, I) and other FME (e.g., B, N) in various subducted lithologies to evaluate the behaviour of these elements during subduction, their partitioning among coexisting high pressure (HP) minerals and the role of these rocks and minerals in transporting these elements to the deeper mantle.
Abyssal lizardite-serpentinites, such as those from the Dominican Republic Tertiary subduction complex, are enriched in halogens and B from hydration by seawater and sediment-modified fluids. During the subduction and subsequent lizardite-antigorite transition of serpentinites, F and B are retained or replenished, while Cl, Br and I are expelled. Halogen compositions of shallow (<25 km) forearc mantle lizardite-serpentinites from the Dominican Republic suggest their hydration by fluids released from subducting altered oceanic crust, with only minor sediment contribution. This is in contrast with deep mantle wedge antigorite-serpentinites associated with the Tso Morari UHP unit, NW Himalaya where elevated F (avg. 185 ppm), Br (avg. 0.13 ppm), I (avg. 0.16 ppm), B (avg. 51 ppm) and N (avg. 23 ppm) contents and their ratios demonstrate significant contributions from subducted shallow water sediments. The latter results are significant because they demonstrate serpentinites can host FME to depths of at least 100 km in the mantle wedge, and possibly to 200 km (limit of antigorite stability) in the slab of cold subduction zones or to 300 km in phase A after antigorite decomposition.
A similar decoupling of F from Cl during subduction is also observed in the metamorphosed crust. Blueschists from the Tavsanli zone, NW Turkey and eclogites from the Tso Morari UHP unit and the Sulu UHP belt, China contain low bulk Cl and Br contents relative to their presumed protoliths, where as their F contents are similar or elevated. Iodine is also enriched in the blueschists and Tso Morari eclogites, but depleted in the Sulu eclogites relative to their protolith rocks. Enrichments of F and I in the metamorphosed crust are attributed to fluids released from subducting marine sediments, suggesting geochemical exchange among subducting lithologies. Shallow water trench sediments would be especially enriched in these elements given the close proximity of continents to these subduction zones. Apatite and phengite are the major host of halogens in these rocks as demonstrated by high F in these minerals; blueschists contain up to 3.5 wt% and 500 ppm F, respectively, and eclogites contain up to 2.3 wt% and 1600 ppm F, respectively. Other halogen-bearing minerals include lawsonite, Na-amphibole +/- chlorite in the blueschists and possibly titanite +/- Na-amphibole in the eclogites. Liberated F may be subsequently incorporated into antigorite-serpentinites of the overlying mantle wedge. Bulk B contents are generally low in the subducted crust, however phengite can host up to 100 ppm B to at least blueschists facies conditions.
Overall, Cl, Br and I are lost from the altered oceanic crust and lizardite-serpentinites during shallow (< 50 km) subduction, while F and some B are retained. Given the stability of minerals such as antigorite, phase A (after antigorite decomposition), apatite, lawsonite and phengite to depths of 200-300 km in cold subduction zones and their accommodation of FME, they may transport significant F, some B and N and minor Cl, Br and I beyond subarc depths (~ 100 km) and contribute to the their abundances in magmas derived from the deeper mantle.
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Impey, Gary A. "Photolyzable halogens in the Arctic troposphere." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0027/NQ39274.pdf.
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Huang, Jinqing, and 黃普卿. "A study of the reaction mechanisms and reactive intermediates involved in halogenated compounds : trichloroethylene oxide, halogenated benzophenones, and halogenated quinoline-based phototriggers." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/208036.
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UV/Vis absorption spectroscopy (UV/Vis), femtosecond transient absorption spectroscopy (fs-TA), nanosecond transient absorption spectroscopy (ns-TA), and nanosecond time-resolved resonance Raman spectroscopy (ns-TR3), as well as density functional theory (DFT) computations were employed to study the mechanisms and the intermediates in reactions of selected halogenated compounds, including trichloroethylene oxide (TCE oxide), halogenated benzophenones (4-FBP, 4-ClBP, 4-BrBP, 3-FBP, 33’-DFBP, 3-ClBP, 3-BrBP, 2-FBP, 2-ClBP, and 2-BrBP), and halogenated quinoline-based phototriggers (BHQ-OPh and BHQ-OAc). This study investigated the halogen substituent effect on the mechanisms of various water-involved reactions and the influences from the number of halogens present, the type of halogen and the substituent position of the halogen in the molecules of interest. The general mechanisms for the reactions of these halogenated compounds were summarized along with discussion of the driving forces from the substituted halogen. First, TCE oxide was hydrolyzed to release chloride ions one by one which led to a complicated water-catalyzed decomposition. To account for the dehalogenation and the formation of CO with three kinds of carboxylic acids (formic acid, glyoxylic acid, and dichloroacetic acid), the predominant decomposition pathways were examined by comparing the computed activation energies for the formation of different products. From these comparisons, the ring-opening reaction was identified as the rate-determining step, which is also supported by previous experimental observations reported in the literature. Based on all of these analyses, the mechanisms of the water-catalyzed decomposition reactions were determined and a water-assisted HCl elimination model has been proposed. Second, some halogen-substituted benzophenones demonstrated an efficiency for a photosubstitution reaction and the related photohydration reactions. Interestingly, the efficient photosubstitution reactions of 3-FBP and 33’-DFBP were dependent on the solution acidity and reached a maximum in 1 M HClO4 CH3CN/H2O (1/1) solution. Only the photohydration reaction took place for the 3-ClBP, 3-BrBP, 4-FBP, 4-ClBP, and 4-BrBP molecules. Nevertheless, no special photochemical reaction occurred for 2-FBP, 2-ClBP, and 2-BrBP. The mechanisms and intermediates were directly characterized by spectroscopic observations and rationalized by results from DFT computations. According to these results, the general mechanisms for the photosubstitution reaction and the related photohydration reactions of halogenated benzophenone derivatives were summarized. These results reveal that the efficiency in forming the corresponding hydroxy benzophenone is influenced by the solution acidity, substituent positions, and the character of the substituted halogens. The substituted halogen is the driving force of this photosubstitution reaction. This conclusion provides insight into several possible applications that are also briefly discussed in this thesis. Lastly, the BHQ-OPh system was found to undergo an extraordinary efficient excited-state proton transfer (ESPT) to initiate a dehalogenation reaction. The fs-TA and ns-TA spectra indicate clearly the interactions between four prototropic forms of BHQ-OPh, which were characterized by UV-Vis spectra under different pH values. These prototropic forms play important roles in inducing further dehalogenation, thus their structural configurations were also investigated by DFT computations. Besides, competing with the dehalogenation reaction, BHQ-OAc underwent another photodeprotection to release the OAc group. The comparison between BHQ-OPh and BHQ-OAc provides further information in understanding the mechanisms of dehalogenation reactions and photodeprotection reactions of these quinoline-based phototriggers.published_or_final_version
Chemistry
Doctoral
Doctor of Philosophy
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Wang, Qian. "Structure and Thermodynamic of Halogen Hydrates." Thesis, University of California, Irvine, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1535376.
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So far to our knowledge, the bromine-xenon double clathrate hydrate has not yet been completely studied. In recent research in Janda lab at UC Irvine, we obtained the thermodynamic properties and structure of bromine-xenon double clathrate by applying UV-Vis spectroscopy and determining the total vapor pressure of the clathrate. In both of the TS-I and CS-II structures, bromine could only stay in the bigger size cages, while introducing xenon as a helper gas to occupy the smaller cages. Based on this concept, we hypothesize that the bromine-xenon double clathrate has the TS-I structure type below 273K, and the CS-II structure type above this temperature. Also we calculated the enthalpy of dissociation of the TS-I bromine-xenon double clathrate as 12.305±0.170kJ/mol/K, and the CS-II clathrate as 16.574±0.143 kJ/mol/K.
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Aubauer, Christoph. "Halogen-, Azid- und Koordinationsverbindungen des Phosphors." Diss., [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=963037900.
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Wagner, Thomas. "Satellite observations of atmospheric halogen oxides." [S.l. : s.n.], 1999. http://deposit.ddb.de/cgi-bin/dokserv?idn=961938161.
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Szwak, Małgorzata. "Halogen- und Pseudohalogen-Verbindungen des Tellurs." kostenfrei, 2006. http://www.diss.fu-berlin.de/2007/82/index.html.
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Davey, James Brian. "Microwave spectroscopy of halogen-bonded complexes." Thesis, University of Exeter, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249075.
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Oliferenko, P. "Understanding of hydrogen and halogen bonds." Thesis, Queen's University Belfast, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.680236.
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The goal of this work is to develop a fundamental formalism able to translate crystallographic information (contact distance and angle) into an accurate evaluation of whether a given pair of atoms participates in a hydrogen-bond or a van der Waals interaction, and, if so, what is its energy. The problem was tackled by using the enormous amount of structural data stored in the Cambridge Crystallographic Database. The distance and angle geometrical parameters were chosen for characterisation of non-covalent atom-atom contacts. Such contacts were searched within ' some pre-defined ranges of distance and angle and consequently arranged into a two-dimensional matrix form of contact counts against distance and angle. This distance/angle contact distribution matrix was fitted with a custom-designed two-dimensional analytical function, whose general form is a superposition of two terms: one describing maxima of contact density at short distances and the other capturing the continuum of disordered long-distanced contacts. The proposed analytical solution allows: 1) analysis of the statistics of short-distance contacts separately from the background noise; 2) the evaluation of analytical functions for the calculation of the probability of a contact to be a short-distance contact; 3) calculation of a pairwise statistical mean force potential through which the interaction energy of a contact can be evaluated. !twas demonstrated that the statistical mean force potential correlates well with the quantum chemically calculated energies of molecular complexes, and thus can serve as a reliable and simple means to estimate the strength of a hydrogen' bond or a van der Waals contact, provided that the contact distance and angle are known.
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Dominelli, Whiteley Nicholas. "Hydrogen-bonding and halogen-arene interactions." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/28824.
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Non-covalent interactions are fundamental to molecular recognition processes that underpin the structure and function of chemical and biological systems. Their study is often difficult due to the interplay of multiple interactions and solvent effects common in complex systems. Herein, chapter one provides some general background on the area before presenting a literature review of key, contemporary developments on the use of folding molecules for the quantification of non-covalent interactions. Chapter two investigates the magnitude and extent of energetic cooperativity in H-bond chains. Utilising supramolecular complexes and synthetic molecular torsion balances, direct measurements of energetic cooperativity are presented in an experimental system in which the geometry and number of H-bonds in a chain were systematically controlled. Strikingly, it was found that adding a second H-bond donor to form a chain can almost double the strength of the terminal H-bond, while further extension had very little effect. Computations provide insights into this strong, short-range cooperative effect in a range of H-bonding contexts. Chapters three and four build on the concepts and molecular models discussed in chapter two. Chapter three discusses the effects of interplay and competition between strong H-bond acceptors such as formyl groups and the weaker organofluorine H-bond acceptor. There has been some debate in recent literature about the latter’s ability to accept H-bonds, the work presented shows that although organofluorine is a weak H-bond acceptor, it can have a significant modulating effect on stronger interactions when in direct competition. Chapter four investigates deuterium isotope effects on conformational equilibria governed by non-covalent interactions. The results show that any deuterium isotope effect which exists is less than the margins of experimental error. Finally, chapter five discusses a molecular torsion balance designed to investigate halogen∙∙∙arene interactions. The interaction energies were investigated in a range of solvents and mixtures in order to dissect out the dispersive and solvophobic components of folding. Overall, these interactions were found to be weak. Nonetheless, a model was used to dissect trends in solvophobic and electronic contributions to the binding using multiple linear regression based upon the cohesive energy density and polarisabilities of the solvents.
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Rugg, Graham. "Carbon-halogen bond formation in enzymes." Thesis, University of Glasgow, 2016. http://theses.gla.ac.uk/7045/.
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SyrB2, a non-haem Fe halogenase first discovered in 2005, carries out a cryptic chlorination during the biosynthesis of syringomycin E in the bacterium Pseudomonas syringae. SyrB2 chlorinates its native substrate, l-Threonine (Thr), at an unactivated methyl group. It is able to activate this highly unreactive position using an oxoferryl intermediate of its active site complex, which abstracts a hydrogen from the substrate methyl group to form a bioradical. Whilst a provisional mechanism was quickly derived from the mechanisms of similar non-haem Fe enzymes, two features of this mechanism remain unclear: firstly, the structure or structures of the oxoferryl intermediate of its active-site complex, and secondly, why SyrB2 does not hydroxylate Thr in what would appear to be a plausible side-reaction. This latter problem is believed to be the result of substrate placement, as in reaction with two non-native substrates, α-aminobutyrate (Aba) and norvaline (Nva), SyrB2 is able to function as a hydroxylase. This thesis sets out to answer these two questions, as well as to pursue several preliminary goals. Firstly, a method validation study was carried out on several oxoferryl model complexes, which showed that B3LYP reproduced several parameters from CASPT2 benchmarks from the literature better than other tested functionals. Next, protein-substrate interactions were studied through docking and molecular dynamics simulations, which uncovered a new position for Thr. Finally, the mechanism of SyrB2 in reaction with these three substrates was investigated in a QM/MM study, which identified two likely structures of the oxoferryl active-site complex, as well as a new species in which the substrate radical intermediate coordinates to the iron complex.
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Rowland, Ian J. "Halogen 6* radicals : an ESR study." Thesis, University of Leicester, 1988. http://hdl.handle.net/2381/33878.
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The main objective of the study was to characterise, by electron spin resonance (ESR) spectroscopy, novel halogen containing a* radicals. These species are formed by ?-irradiation in a variety of halogen containing systems at liquid nitrogen temperatures. In Chapter One, a brief description of the first halogen a* radical to be identified, the Vx centre in potassium chloride (C12.-), is given in order to illustrate the general magnetic properties of the species. The dependence of these properties on the host matrix is also described. Accepted radiation damage mechanisms are presented with particular reference to dihalogen a* radicals. Some theoretical aspects of the ESR experiment is discussed in Chapter Two which explains briefly some of the phenomena encountered in the study. Sample preparation and analysis are also mentioned. Chapter Three describes the characteristics of the simplest halogen containing a* radical: the hydrogen halide radical anion. Hydrogen fluoride, hydrogen chloride, hydrogen bromide and hydrogen iodide radical anions isolated in a variety of host matrices are reported. The large matrix dependence of their magnetic parameters is explained in terms of intermolecular hydrogen bonding to the halogen. Attention is focused on nitrogen-halogen a* radicals in Chapter Four, where they are shown to be radiolytically formed in ammonium halides, mono, di and trialkylammonium iodides and monoalkylammonium bromides. Alkylamanium chloride radicals could not be identified. Chapter Five primarily explores the effect of the halide counter ion on the solid-state radiolysis of some tetraalkylammonium, trialkylsulphonium and trialkylsulphoxonium cations. During the course of the investigation, sulphur-halogen a* radicals are identified in the trialkylsulphonium salts after annealing. The last chapter investigates the factors which determine the type of species formed following electron capture by carbon halogen bonds. Both adducts and a* radicals are characterised and with particular reference to the specific example of iodoacetamide, consideration is given to the factors influencing their stability.
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OUVRARD, CAROLE. "Liaison hydrogene et tableau periodique. Liaison halogene." Nantes, 2001. http://www.theses.fr/2001NANT2002.
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La basicite de liaison hydrogene des derives alkyles des elements des groupes 15, 16 et 17 a ete mesuree a partir des parametres thermodynamiques (k, g, h et s) et spectroscopiques de leur complexation avec un phenol. Nous avons etabli rigoureusement l'existence d'une relation extrathermodynamique entre l'enthalpie et l'entropie de complexation permettant de discuter nos resultats sur l'echelle enthalpique. Le domaine de validite de la relation entre enthalpie de complexation et deplacement de la frequence v(oh) par liaison hydrogene a ete determine. Nous avons construit l'echelle de basicite pk h b pour 42 halogenoalcanes une vaste etude theorique, couvrant quatre periodes et trois groupes, des geometries et des energies des complexes de l'eau avec les derives methyles des elements des groupes 15, 16 et 17 a ete effectuee aux niveaux hf/6-311+g** et b3lyp/lanl2dz. Nous montrons que ces niveaux reproduisent bien les geometries experimentales extraites des bases de donnees mogadoc et csd, ainsi que les enthalpies de complexation determinees dans ce travail. Nous etablissons que les meilleurs descripteurs de la basicite de liaison hydrogene sont (i) la difference entre l'energie de premiere ionisation de la base et celle de l'atome de gaz rare de la periode correspondante et (ii) le potentiel electrostatique le caractere amphotere des halogenes lourds est souligne dans la derniere partie par l'etude des complexes yx. . . B et rx. . . B a l'etat solide dont nous etudions les similitudes et les differences structurales et energetiques avec la liaison hydrogene h. . . B.
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Weston, Bridget. "Noble gases and halogens in Icelandic basalts." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/noble-gases-and-halogens-in-icelandic-basalts(735b855b-bcb5-4528-9dc7-daaf2d7245d6).html.
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Noble gas and halogen data from a suite of Icelandic samples are presented. Iceland combines hotspot volcanism, a spreading ridge and abundant subglacially erupted samples. This combination allows for samples that erupted under high enough pressures to retain a measurable mantle volatile content, and also display signatures representing interaction between ocean island basalt (OIB) and mid-ocean ridge basalt (MORB) mantle sources.Erupted samples used to determine the mantle’s halogen and noble gas content have undergone a degassing process that can alter their volatile composition. An existing disequilibrium degassing model is developed with the modified model taking into account the evolution of the major volatiles over a multi-stage process and the different conditions present during magma ascent and quenching. The modified model allows substantially lower elemental noble gas ratios to be reached under disequilibrium conditions than allowed by the original model. Initial CO2 concentrations, pressure, diffusivity, ascent rate and degree of disequilibrium are shown to be critical parameters for this model. Final degassed noble gas concentrations are most affected by the surface quenching stage of an eruption, whereas noble gas elemental ratios can be primarily determined during magma ascent. In applying this model to MORB and OIB sample suites, the 3He/22Ne ratio of the MORB source mantle is constrained to be lower than 4.4, similar to estimates for the OIB source mantle. Additionally the most straightforward match between the degassing model and OIB helium and neon data suggest the OIB source mantle has 3He concentrations similar to or lower than the MORB source mantle. This finding requires a model for the OIB source mantle in which a high 3He/4He component is added to a helium-poor protolith.Noble gas studies are hampered by the large, isotopically atmospheric component typically found in Icelandic subglacial samples, which can swamp other signatures. Detailed analysis of a volatile rich sample from SW Iceland shows evidence for more than one ‘contaminant’ component and that two component fits used incorrectly can produce misleadingly precise source mantle noble gas ratios. Multi component best fits to noble gas elemental ratios find that four components are present in samples from this region. These components are unfractionated air, fractionated air and a mantle component which shows some variation due to degassing. Combining the disequilibrium degassing model with component resolution allows limits to be placed on the source mantle composition for this sample. The light noble gas source composition is compatible with mixing between a solar (‘direct nebula’) component and a MORB-like component. This direct nebula signature is at odds with an implanted signature seen in both Ne and Kr for the convecting mantle, and shows that both accretionary volatile origins must have contributed during the Earth’s formation. The heavy noble gases show an elemental abundance pattern which is distinct from air and solar patterns, and trends towards seawater. This confirms the presence of a recycled volatile signature in Iceland’s mantle but it is not possible to further constrain the origin of this signature.The Icelandic halogen data shows no evidence for significant fractionation during degassing or melt generation. Source estimates for the Br/Cl and I/Cl ratios for Iceland’s plume are found to be (1.56±0.03) x 10-3 and (3.1±0.3) x 10-5, compatible with estimates for the MORB source mantle. Halogen source concentrations in central Iceland are found to be approximately three times higher than estimates for the convecting mantle and correlate with the regions of Iceland that show high 3He/4He ratios and high source water contents. This may indicate a recycled halogen signature associated with Iceland’s proposed mantle plume.
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Matheson, Leah J. "Abiotic and biotic reductive dehalogenation of halogenated methanes /." Full text open access at:, 1994. http://content.ohsu.edu/u?/etd,241.
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Dohle, Wolfgang. "Funktionalisierte Heterocyclen durch eine Halogen-Magnesium-Austauschreaktion." Diss., [S.l.] : [s.n.], 2002. http://edoc.ub.uni-muenchen.de/archive/00001352.
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Saiz-Lopez, Alfonso. "Halogen chemistry in the marine boundary layer." Thesis, University of East Anglia, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426341.
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Mössinger, Juliane Cornelia. "Heterogeneous reaction kinetics of atmospheric halogen species." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621294.
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Lounsbury, Katherine Edline. "Halogen Atom Transfer Reactions Via Metalloradical Catalysis." Thesis, Boston College, 2018. http://hdl.handle.net/2345/bc-ir:108260.
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Thesis advisor: X. Peter ZhangHalogenated compounds are useful synthetic organic molecules. One valuable tool for synthesizing halogen containing molecules are atom transfer radical addition (ATRA) reactions which can difunctionalize olefins with a halogen moiety. Many transition complexes can catalyze these reactions but have drawbacks such as the need for harsh conditions and additives. Herein we describe the first ATRA reaction catalyzed by cobalt metalloradical catalysis (Co-MRC) which shows a broad substrate scope, moderate temperatures and uses no additives. This reaction showed excellent regioselectivity, when applicable, and low levels of enantioselectivity (up to 33% ee)
Thesis (MS) — Boston College, 2018
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
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Enami, Shinichi. "Halogen cycles in the stratosphere and troposphere." 京都大学 (Kyoto University), 2006. http://hdl.handle.net/2433/136139.
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Ding, Luying. "Kinetic Studies of the Reactions of Cl and Br with Silane and Trimethylsilane." Thesis, University of North Texas, 1992. https://digital.library.unt.edu/ark:/67531/metadc500233/.
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The temperature dependence of the reactions of halogen atoms Cl and Br with SiH4 and (CH3)3SiH have been investigated with the flash photolysis-resonance fluorescence technique. CCI4 and CH2Br2 were used as precursors to produce Cl and Br atoms, respectively. Experiments gave {k(Cl + SiH4) (295 - 472 K)} = (1.56 +0.11) x 10-1 exp[(2.0 + 0.2) kJ mol'/RT] cm3 s4, {k(Br + SiH4)(295 - 575 K)} = (9.0 + 1.5) x 10-" exp[-(17.0 + 0.6) Id mol'/RT] cm3 s', {k(Cl + (CH3)3SiH)(295 - 468 K)} = (1.24 0.35) x 104 exp[(1.3 + 0.8) Id mol4/RT] cm3 s', and {k(Br + (CH3)3SiH)(295 - 456 K)} = (7.6 + 3.3) x 1010 exp[-(28.4 + 1.3) Id mol'/RT] cm3 s'. The results were compared with values from earlier work.
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Guilbaud, Johan. "Synthèses d'(arylsulfanyl)pyridines halogénées et leurs dérivés par couplages C-S et C-X catalysés par des complexes du palladium." Thesis, Bourgogne Franche-Comté, 2018. http://www.theses.fr/2018UBFCK047/document.
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L’activation C–H d’aryle dirigée par des groupements directeurs 2-sulfonylpyridine et 2-sulfanylpyridine vers la formation de liaisons C–X (X = F, Cl, Br, I) a été étudiée. Pour cette étude, il a été nécessaire au préalable de développer des méthodes de synthèse de thioéthers (2-(arylsulfanyl)pyridines) et de sulfones (2 (arylsulfonyl)pyridines) simples et variées. La synthèse des thioéthers s’est effectuée à l’aide d’un couplage C–S catalysé au palladium entre des thioaryles et des hétérocycles halogénés. Ce couplage a pour avantage d’utiliser un ligand commercial et peu onéreux : la bis(diphénylphosphino)ferrocène (dppf). L’oxydation des thioéthers a ensuite été étudiée pour former des sulfones dans des conditions les plus performantes possibles. Enfin, l’halogénation de ces différents composés a pu être étudiée par activation de liaison C–H d’aryle ortho-dirigée en présence de complexes de palladium. Différents systèmes catalytiques ont été mis au point permettant la formation de liaisons C–Br, C–I, C–Cl et même C–F. Ces couplages ont l’avantage d’être sélectifs en positions ortho du groupement directeur et de pouvoir fonctionnaliser une seule ou les deux positionsC–H activation of aryl compounds directed by 2-sulfonylpyridine and 2-sulfanylpyridine moiety for the formation of C–X (X = F, Cl, Br, I) bonds was studied. First, the syntheses of thioethers (2-(arylsulfanyl)pyridines) and sulfones (2-(arylsulfonyl)pyridines) were necessary for the progress of this project. A C–S coupling catalyzed by palladium complexe between thioaryls and halogenated heterocycles was performed for the synthesis of thioethers. The cheap ligand bis(diphenylphosphino)ferrocene (dppf) was used for this convenient reaction. Then, oxidation of thioethers was performed to synthesize sulfones. Halogenation of these compounds was studied with ortho-directed C–H activation catalyzed with palladium. Different catalytic systems were elaborated allowing the formations of C–Br, C–I, C–Cl and C–F bonds. These couplings are selective in ortho position of directing group and one or both positions can be functionalized
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Wilson, Ruth Irene. "Pesticide and pharmaceutical photolysis, fate of the halogens." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0016/MQ53368.pdf.
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Upstill-Goddard, R. C. "Geochemistry of the halogens in the Tamar estuary." Thesis, University of Leeds, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.354529.
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Manke, David. "Toward the photo-induced reductive elimination of halogens." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33651.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2005.Vita.
Includes bibliographical references.
Light-driven energy conversion schemes have been proposed as alternative energy to fossil fuels. The target fuel of these schemes is hydrogen. For photocatalytic hydrogen production to be feasible, it must be performed on energy-poor substrates and must possess high quantum efficiency. The controlling aspect of this quantum efficiency is not hydrogen evolution, but rather activation of stable M-X bonds that are generated from the reaction of catalyst with the low energy substrate. This thesis examines the activation of such bonds, by examining high oxidation state transition metal dimers as potential platforms for the reductive elimination of halogen. Early transition metals were explored with bis(alkylamido)phenylborane ligands. These systems did not demonstrate halogen elimination, but an interesting transition metal chemistry was developed for this ligand set. Alternatively, bimetallic gold systems were also studied as potential platforms, and have shown efficient photoreactivity toward M-X bond activation.
by David R. Manke.
Ph.D.
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Shepler, Benjamin C. "Ab initio investigation of the thermochemistry, spectroscopy and dynamics of reactions between mercury and reactive halogen species." Online access for everyone, 2006. http://www.dissertations.wsu.edu/Dissertations/summer2006/b%5Fshepler%5F072806.pdf.
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Hind, Kelvin. "Mulliken 'charge-transfer' complexes : an investigation by rotational spectroscopy." Thesis, University of Exeter, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337767.
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MANGANAS, MURIEL. "Gestion informatique des donnees d'un analyseur de vapeurs halogenees par seringue auto pulsee pour obtenir en circuit ferme ou semi-ferme la concentration choisie d'un anesthetique volatil." Amiens, 1990. http://www.theses.fr/1990AMIEM016.
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Otto, Ronald. "Untersuchungen zu Phasen im System Nickel/Silicium/Halogen." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2009. http://nbn-resolving.de/urn:nbn:de:swb:105-9452127.
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Nickel-Silicidphasen wurden auf neuen Synthesewegen bei relativ niedrigen Temperaturen und kurzen Reaktionszeiten präpariert. Die Belastung von dispersem Metall mit Siliciumtetrachlorid liefert Produkte, die mit den thermodynamischen Berechnungen korrelieren. Bei der direkten Umsetzung von Nickelhalogeniden mit Silicium beeinflussen die Versuchsbedingungen wesentlich die Zusammensetzung der resultierenden Phasengemische. Durch Temperungen reduziert sich der Bestand an Silicidphasen. Die Umsetzung von Nickelchlorid und Silicium gelang erstmals auch in einer KCl/LiCl-Salzschmelze als Reaktionsmedium, wodurch sich thermodynamisch vorhersagbare Silicidphasen erhalten lassen. In einigen Fällen deuten die Ergebnisse auf die Bildung halogenhaltiger, bei Raumtemperatur metastabiler Silicidphasen hin. Zum Reaktionsmechanismus werden zwei über die Oxidationsstufe +2 des Siliciums verlaufende Routen diskutiert.
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Demirekler, Pinar. "Optimization Of Microwave-halogen Lamp Baking Of Bread." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605074/index.pdf.
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The main objective of this study was to optimize the processing conditions of breads baked in halogen lamp-microwave combination oven by using response surface methodology. It was also aimed to construct neural network models for the prediction of quality parameters of bread as a function of processing conditions.
Different baking time and power combinations were used in order to find the optimum baking conditions of bread in halogen lamp-microwave combination oven. The independent variables were the baking time (4, 4.5, 5, 5.5, and 6 min), power of upper and lower halogen lamps (40, 50, 60, 70, and 80%), and power of the microwave (20, 30, 40, 50, and 60%). As control, breads baked in conventional oven at 200ºC for 13 min were used. The measured quality parameters were the weight loss, color change, specific volume, porosity, and texture profile of the breads. Baking time, upper halogen lamp power, and microwave power were found to be significant on affecting most of the quality parameters. On the other hand, lower halogen lamp power was found to be an insignificant factor for all of the responses. For the optimization process, Response Surface Methodology (RSM) was used. The optimum baking conditions were determined as 5 min of baking time at 70% upper halogen lamp power, 50% lower halogen lamp power, and 20% microwave power. Breads baked at the optimum condition had comparable quality with conventionally baked ones. When halogen lamp-microwave combination oven was used, conventional baking time of breads was reduced by 60%. Artificial neural network models were developed for each of the quality parameters in order to observe the effects of the baking time and different oven conditions on the quality of the breads. High regression coefficients were calculated between the experimental data and predicted values showing that this method is capable in predicting quality parameters of breads during halogen lamp-microwave combination baking. In addition, the results were comparable to the RSM study.
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Schütt, Thomas. "Halogen-, Azid- und Koordinationsverbindungen des Arsens und Antimons." Diss., lmu, 2001. http://nbn-resolving.de/urn:nbn:de:bvb:19-3668.
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Seidel, Stefan. "Chemie im Supersauren Halogen-Kationen, Xenon als Komplexligand /." [S.l.] : [s.n.], 2001. http://www.diss.fu-berlin.de/2001/125/index.html.
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Schütt, Thomas. "Halogen-, Azid- und Koordinationsverbindungen des Arsens und Antimons." [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=963037811.
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Higham, Michael David. "Theoretical Studies of Heterogeneous Catalysis for Halogen Chemistry." Doctoral thesis, Universitat Rovira i Virgili, 2017. http://hdl.handle.net/10803/586085.
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En la present tesi s’han emprat tècniques computacionals per investigar la utilització de materials basats en òxids de metalls de transició amb estructura de rutil com a catalitzadors per a compostos halogenats. Els estudis exploren la interacció entre l’estructura i composició de la superfície, l’activitat catalítica i la selectivitat de formació de productes.
El treball se centra en diòxids de ruteni i titani com catalitzadors per les reaccions d’oxidació d’halurs d’hidrogen i oxicloració d’etilè. Els càlculs amb la teoria del funcional de la densitat demostren com pot tindre lloc la substitució d’oxígens superficials, sota condicions de reacció per la oxidació d’halurs d’hidrogen. Particularment, una important absorció de brom va ser determinada en òxid de ruteni, amb la substitució de brom extenent-se des de la superfície fins les capes sub-superficials, i introduint una gran reorganització estructural de la superfície. Per tant, es proposa que el mecanisme de reacció estigui estretament vinculat al grau de substitució a la superfície. Les investigacions també examinen sistemes basats en diòxids de titani dopats. Ha estat explorada la relació entre els defectes a l’estructura electrònica induïts pel dopant, i l’activitat catalítica cap a processos elementals associats a l’oxidació d’halurs d’hidrogen. Particularment, ha estat determinat que es pot realitzar una elecció racional del dopant per optimitzar el nombre de defectes, i les seves energies associades, amb la finalitat de modificar de forma acurada l’estructura electrònica de la superfície, i així, obtenir una activitat òptima. Finalment, el diòxid de ruteni es investigat com un potencial catalitzador per a la oxicloració d’etilè. Es va determinar que la competició entre els processos de combustió i oxicloració es millorada pel confinament dimensional dels adsorbats sobre la superfície del catalitzador, i que el recobriment superficial és un factor essencial per determinar la viabilitat de certs processos elementals, i així, la selectivitat dels productes. La tesi proporciona una clara visió general dels rutils com catalitzadors per la química dels halògens. A més, també proporciona coneixements detallats que poden ser utilitzats per al desenvolupament de millors catalitzadors al futur.En la presente tesis se han empleado técnicas computacionales para investigar el uso de materiales basados en óxidos de metales de transición con estructura de rutilo como catalizadores para la química de halógenos. Los estudios exploran la interacción entre la estructura y composición de la superficie, la actividad catalítica y la selectividad de los productos. El trabajo se enfoca en sistemas basados en dióxidos de rutenio y titanio como catalizadores para las reacciones de oxidación de haluros de hidrógeno y oxicloración de etileno. Los cálculos con métodos de la teoría del funcional de la densidad muestran como, bajo condiciones de reacción para la oxidación de haluros de hidrógeno, la sustitución de oxígenos superficiales puede tener lugar. Particularmente, una importante absorción de bromo fue encontrada en dióxido de rutenio, con la sustitución de bromo extendiéndose desde la superficie hacia las capas subsuperficiales, e induciendo una gran reorganización estructural de la superficie. Por lo tanto, se propone que el mecanismo de reacción está estrechamente vinculado al grado de sustitución en la superficie. Las investigaciones también examinan sistemas basados en dióxidos de titanio dopados. La relación entre los defectos en la estructura electrónica inducidos por el dopante, y la actividad catalítica hacia procesos elementales asociados con la oxidación de haluros de hidrógeno, es explorada. Particularmente, se encontró que una elección racional del dopante puede ser realizada para optimizar el número de defectos, y sus energías asociadas, con la finalidad de modificar de forma precisa la estructura electrónica de la superficie y, así, obtener una actividad óptima. Finalmente, se investigó el dióxido de rutenio como un potencial catalizador para la oxicloración de etileno. Se encontró que la competición entre los procesos combustión y oxicloración es mejorada por el confinamiento dimensional de adsorbatos sobre la superficie del catalizador, y que la recubrimiento superficial es un factor esencial para determinar la viabilidad de ciertos procesos elementales y, así, la selectividad de los productos. La tesis proporciona una clara visión general de los rutilos como catalizadores para la química de los halógenos. Además, también proporciona conocimientos detallados que pueden ser usados para el desar
Computational techniques are applied to investigate the utility of rutile transition metal oxide based systems as catalysts for halogen chemistry. The studies explore the interplay between surface structure and composition, catalytic activity and product selectivity. The work focuses on ruthenium dioxide and titanium dioxide based systems as catalysts for hydrogen halide oxidation and ethylene oxychlorination reactions. DFT calculations show that under hydrogen halide oxidation conditions, replacement of surface oxygen atoms in the rutile catalyst can occur. In particular, significant bromine uptake was found to occur in ruthenium dioxide, with bromine replacement extending beyond the surface to the subsurface layers and inducing a major structural rearrangement at the surface. It is thus proposed that the reaction mechanism is closely linked to the extent of surface replacement. The investigations also examine doped titanium dioxide based systems. The relationship between dopant-induced electronic structure defect states, and the catalyst activity towards elementary processes associated with hydrogen halide oxidation, is explored. In particular, it was found that a judicious choice of dopant atom can be made to optimise the number of defect states, and their associated energies, in order to fine-tune the electronic structure of the system for optimal activity. Finally, ruthenium dioxide is investigated as a potential catalyst for ethylene oxychlorination. It was found that competition between combustion and oxychlorination processes is enhanced by dimensional confinement of adsorbates on the catalyst surface, and that surface coverage is an essential factor in determining the feasibility of certain elementary processes, and thus product selectivity. The thesis provides a clear overview of rutile catalysts for halogen chemistry and provides detailed insights which can inform the future development of superior catalysts.
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Otto, Ronald. "Untersuchungen zu Phasen im System Nickel, Silicium, Halogen." Doctoral thesis, [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=968652425.
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Mahajan, Anoop Sharad. "Reactive halogen species in the marine boundary layer." Thesis, University of Leeds, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539689.
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Robinson, Sean W. "Interlocked halogen bonding host systems for anion recognition." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:9cc6c40c-3df7-4f23-b905-c4f164a57707.
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This thesis describes the synthesis and anion recognition properties of acyclic and mechanically interlocked anion receptors containing either the 3,5-bis-iodotriazole pyridinium or pyridine-N-oxide motifs. Chapter One introduces the field of supramolecular chemistry, highlighting areas of particular relevance to this thesis, viz. anion coordination, recognition, templation, halogen bonding and synthesis of interlocked structural frameworks. Chapter Two describes the synthesis of acyclic, [2]catenane and water-soluble [2]rotaxane anion receptors containing the novel 3,5-bis-iodotriazole pyridinium motif and details their anion recognition properties. X-ray crystal structures of the [2]catenane bearing this motif are provided in support of the anion binding results. X-ray Absorption Spectroscopy is used to probe the nature, and quantify the degree of covalency, of halogen-bonding interactions. Chapter Three details further work incorporating the 3,5-bis-iodotriazole pyridinium motif into elaborate symmetric and asymmetric [2]rotaxane anion hosts designed for nitrate binding in competitive aqueous solvent media. Moreover, the synthesis of an analogous water-soluble [2]rotaxane is presented and its anion recognition properties investigated. Chapter Four focuses on the synthesis of acyclic and symmetric interlocked anion receptors bearing the novel neutral 3,5-bis-iodotriazole pyridine-N-oxide motif. The anion recognition properties of these hosts are presented with an emphasis on [2]rotaxane species capable of binding chloride and nitrate in competitive aqueous solvent media. Chapter Five provides a summary of the major conclusions of this thesis. Chapter Six furnishes procedures pertaining to chemicals, instrumentation, data handling and analytical protocols, as well as detailing synthetic methods and characterisation of novel compounds. Chapter Seven provides the references cited within Chapters One to Six. Full crystallographic information and details of molecular modeling experiments are provided in Digital Appendices on an enclosed DVD.
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Yoshimura, Toshio. "Polymerization and Polymer Properties of Halogen-Containing Acetylenes." Kyoto University, 1999. http://hdl.handle.net/2433/181330.
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