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1
Drumright, Ray E. "Radical anion rearrangements. aryl cyclopropyl ketyl anions". Diss., This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-07282008-134853/.
Testo completo
2
Greenhall, Martin Paul. "Fluorinated anions". Thesis, Durham University, 1989. http://etheses.dur.ac.uk/6503/.
Testo completoAbstract (sommario):
Each of my four main areas of work is concerned with the formation and further reactions of organic fluorinated anions. a) We have investigated the fluoride ion induced reactions of 2H-pentafluoropropene with some perfluoro-aromatic compounds, forming a series of aryl substituted carbon acids and their corresponding carbanions. Also included is a study of an unusual product that was formed with pentafluoronitrobenzene as the aromatic substrate. b) Some fluorinated dienes have been generated from the fluoride ion induced reactions of dimethylacetylenedicarboxylate with a series of cyclic fluorinated alkenes. With perfluorocyclohexene, a variable temperature n.m.r. investigation indicated that one of the products was fluxional at room temperature. Products derived from, perfluorocyclopentene were then further reacted with mono- and bi-functional nucleophiles forming some new products including some interesting polycyclic compounds. c) We have studied the fluoride ion induced reactions of malononitrile and phenylsulphonylacetonitrile with a range of polyfluorinated aromatic and heteroaromatic systems. This study has yielded a series of stable fluorinated organic caesium salts which could be crystallised. Acidification of these salts yielded a series of conjugate acids and some acidity measurements were made. Analysis of n.m.r. data has shed some light on the n.m.r. consequences of tautomerisation which was observed in some of the conjugate acids. A highly unusual carbon-13 n.m.r. concentration effect was studied for several pyrimidyl salts in perdeuteroacetone solution. d) The reaction of bifunctional carbon acids with fluorinated dienes has been used to develop a route to new pentadienyl anions, cyclopentadienes, and cyclopentadienyl anions. FAB mass spectroscopy has proved to be an important tool in the study of our anionic species. Some unusual thermal isomerisation behaviour of the new cyclopentadienes has also been observed and investigated.
3
Wang, Zhiming 1958. "Anion Exchange and Competition in Layered Double Hydroxides". Thesis, University of North Texas, 1997. https://digital.library.unt.edu/ark:/67531/metadc332481/.
Testo completoAbstract (sommario):
Exchange reactions of anions, especially ferrocyanide and carbonate, with layered double hydroxides (LDHs) were investigated in relation to the origin of life on the early Earth. The effect on ferrocyanide exchange of concentration, pH, reaction time and cations are discussed. It was found that there were two different kinds of ferrocyanide species: one was that intercalated into the layered structure, occupying a site of D symmetry within the LDHs, while in the other, the ferrocyanide group retains full O symmetry. In addition, very low concentration, ferrocyanide associated with LDH will change its FTIR absorption shape. Carbonate was much more strongly intercalated than ferrocyanide into the LDHs, probably because of the strong hydrogen bonding.
4
Sekizaki, Shuichi. "Development of conducting cation radical salts with flexible organic anions : tetracyanoallyl anion derivatives". 京都大学 (Kyoto University), 2006. http://hdl.handle.net/2433/144214.
Testo completo
5
Buck, J. "Vinyl anions in synthesis". Thesis, University of Nottingham, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.353565.
Testo completo
6
Gillmore, Jason G. Jr. "Evaluation of 1,1-Dimethyl-5,7-Di-T-Butylspiro[2.5]Octa-4,7-Dien-6-One as a Mechanistic Probe for Single Electron Transfer". Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36888.
Testo completoAbstract (sommario):
Single electron transfer (SET) mechanisms are becoming ubiquitous in modern organic chemistry. However, it is often difficult to distinguish SET mechanisms from polar mechanisms. Kinetics, products and product distributions, and response to perturbation in solvent and substituents are often identical between the two mechanisms. Detection techniques such as EPR, CIDNP, and UV absorption can often detect "blind" pathways and thus cannot provide unambiguous evidence regarding the true mechanism of interest. In recent years mechanistic probes have been developed which can test for single electron transfer in the mechanism of interest in a more unambiguous manner, although a given probe is often applicable to a narrower range of reactions.
In this work 1,1-dimethyl-5,7-di-t-butylspiro[2.5]octa-4,7-dien-6-one (6) is presented as a new "hypersensitive" probe for single electron transfer to conjugated carbonyl compounds. This new probe functions in a rather unique fashion, allowing interpretation of the mechanism at work on the basis of the regiochemistry of spirocyclic ring opening. This "regiodifferentiation" based probe was studied with a variety of nucleophiles (particularly Grignard reagents) and has been found to be effective in differentiating SET from polar processes, although surprising results indicative of polar pathways in the case of reaction of 6 with Grignard reagents other than methyl Grignard were found. Additional insight into the mechanism of the reaction of Grignard reagents with conjugated ketones is also presented.
Master of Science
7
Wells, Debra J. "Extraction of the perrhenate and pertechnetate anions from aqueous solutions using inorganic anion exchangers". Thesis, University of Reading, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306851.
Testo completo
8
Brooks, Simon James. "From linear to cyclic anion receptors : high affinity receptors and sensors for oxo-anions". Thesis, University of Southampton, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438694.
Testo completo
9
Guangliang, Chen. "The Dissociation of Metalloporphyrin Anions". Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32517.
Testo completoAbstract (sommario):
ESI-MS spectra of Ni(II), Co(III), Mg(III), and Fe(II) porphyrin solutions in methanol show porphyrin monomer species with different charge states, such as [Ni(II)TPPS+H]3-, [Co(III)TPPS]3-, [Mn(III)TPPS]3-, [Mn(III)TPPS+H]2-, [Fe(II)TPPS+H]3-, and [Fe(II)TPPS+2H]2- ions. Collision-induced dissociation (CID) of these monomer species produced primarily losses of neutral SO3 and SO2. The mechanisms, in which these dissociation pathways took place, were investigated by the means of DFT calculations of the corresponding dissociation of neutral and ionized benzenesulfonate (B3-LYP/6-31+G(2d, p) level) and porphyrin monomer (B3-LYP/6-31+G(2d, p)+LANL2DZ//PM7 level). RRKM fitting of the CID breakdown curves showed that the activation energies of the reactions that experience a loss of SO2 from [Co(III)TPPS]3- and [Mn(III)TPPS]3- were similar, but of a lower magnitude than those for a loss of SO3. On the other hand, for [Ni(II)TPPS+H]3- and [Fe(II)TPPS+2H]2-, the activation energies of the reaction leading to a loss of SO2 were also similar, but this time were larger than those leading to SO3 loss. These results are consistent with a mechanism by which the SO2 loss starts with -C6H4SO3-, while the SO3 loss has to begin with -C6H4SO3H. To lose this SO3, extra energy is required for [Co(III)TPPS]3- and [Mn(III)TPPS]3- in order for them to overcome the barrier of H transfer from the porphyrin ring to -SO3-, but this is irrelevant when it comes to [Ni(II)TPPS+H]3- and [Fe(II)TPPS+2H]2- since the C6H4SO3H moiety already exists. In addition, the reaction of [Fe(II)TPPS+H]3- losing H leads to a unique dissociation mechanism.
10
Newington, Ian M. "Azo-anions in organic synthesis". Thesis, University of Oxford, 1985. http://ora.ox.ac.uk/objects/uuid:690ab891-be13-4582-a029-47974d20adac.
Testo completoAbstract (sommario):
Novel synthetic applications of ambident azo-anions derived from hindered hydrazones have been investigated. Reaction with electrophiles occurred predominantly at carbon as the N-addition pathway was sterically retarded. Trityl, diphenyl-4-pyridylmethyl (DPP) benzhydryl, and t-butyldiphenylmethyl (BDP) hydrazones of various aldehydes and ketones were prepared in good yields from the corresponding hydrazines and carbonyls in aqueous methanol. The lithium salts derived from trityl and DPP hydrazones, by treatment with methyl lithium at -55°C, reacted with aldehydes and ketones to generate azo-alkoxides. These could be diverted to alcohols,by sequential protonation and spontaneous homolysis (about -20°C) in the presence of ethanethiol, or to alkenes,by treatment with phosphorus trichloride at -78 G followed by azo-homolysis. The reactions enabled efficient reductive cross-coupling of aldehydes and ketones. The mechanism of the alkene forming reaction was investigated. Anions of benzhydryl hydrazones were found to react inefficiently by a G-addition pathway giving mainly N-addition products. Anions of BDP hydrazones conveniently gave excellent yields of azo-alkanes upon treatment with alkyl halides,but no products were obtained on reaction with carbonyl electrophiles. The azo-alkanes could be isolated and purified and acted as key intermediates for several synthetically useful transformations. Homolysis in refluxing benzene with thiophenol gave alkanes in good yields. Phenylselenenyl-, bromo-, and chloro-alkanes,and β-alkylstyrenes were generated when thiol was replaced by diphenyl diselenide, N-bromosuccinimide, N-chlorosuccinimide and β-nitrostyrene respectively. Treatment of the azo-alkanes with trifluoroacetic acid generated benzophenone alkylhydrazones. These were dissolved in ethanol with concentrated hydrochloric acid, thereafter hydrolysis yielded alkylhydrazines or treatment with hydrogen (1 atm., 50°C, 20h) over 10% Pd/C generated primary amines by a novel use of carbonyls as α-aminocarbanion equivalents.
11
Allasia, Sara. "Dipyrromethane based receptors for anions". Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/67198/.
Testo completoAbstract (sommario):
This thesis is principally concerned with the synthesis of a range of dipyrromethane based receptors and their ability to bind anions, in particular carboxylates of amino acid derivatives. Chapter I provides a general introduction to the field of Supramolecular Chemistry and its applications. In this chapter a series of receptors for anions are presented their properties discussed. A particular attention is given to the aromatic heterocycles based receptors and to enantioselective receptors. Chapter II describes the synthesis of a series of acyclic receptors which are the results of subsequent modifications of a simple tweezer, based on a dipyrromethane unit coupled with two butyl amines, previously studied by the group.1 The binding properties with a series of anions are presented and, for the chiral receptors, the binding properties with Nprotected amino acids were investigated. Chapter III describes the synthesis and the binding properties of a series of macrocycles obtained by modifications of the tweezer receptors. The binding properties of the macrocyclic receptors with a series of anions and amino acids are also presented.
12
Horke, Daniel Alfred. "Femtosecond photoelectron imaging of anions". Thesis, Durham University, 2012. http://etheses.dur.ac.uk/5950/.
Testo completoAbstract (sommario):
Several recent results of a time-resolved photoelectron imaging experiment are presented. Following a broad introduction into the area of femtochemistry and time-resolved photoelectron spectroscopy, a detailed description of the spec- trometer is given. This utilises an electrospray ionisation source, coupled to an electrostatic ion trap. Ions are mass selected using time-of-flight methods and investigated using photoelectron imaging in a velocity-mapping geometry. Ultrafast dynamics are investigated by pump-probe spectroscopy with femtosec- ond laser pulses. Recent results are separated into three distinct projects: (i) The investigation of electron acceptor radical anions based on the quinone backbone. These commonly exhibit electron transfer rates exceeding those pre- dicted by Marcus theory by orders of magnitude. We show that an alternative pathway to electron transfer could involve the participation of electronic excited states, as these couple strongly to the anion ground state. Specifically, for p- Benzoquinone we show that electronic resonances located in the detachment continuum primarily undergo internal conversion via a number of conical inter- sections. (ii) Several polyanions have been investigated in the gas-phase. These systems exhibit unusual electronic properties, due to the presence of multiple excess charges, leading to the formation of a repulsive Coulomb barrier to photode- tachment. We investigate the effect of excess internal energy on this barrier and how it affects outgoing photoelectrons. We show that the trajectories of electrons are strongly influenced by this potential and demonstrate its use as a probe for large amplitude structural dynamics in polyanions. (iii) The isolated chromophore of the green fluorescent protein (GFP) has been studied, and the vertical and adiabatic detachment energies determined for the first time. Using time-resolved spectroscopy the excited state dynamics are in- vestigated. We show that the first singlet excited state of the anion primarily decays through internal conversion, explaining the absence of fluorescence in the gas-phase. Using high level quantum chemistry calculations we show the specific motion involved and hence confirm the function of the protein back- bone in GFP. This thesis is concluded with a few suggested experimental improvements and ideas for future studies of anions using the presented spectrometer.
13
Ogle, Mark Edward. "Spectroscopic studies of [alpha],[omega]-diphenylpolyenyl anions". Diss., Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/30363.
Testo completo
14
Spooner, Michael. "Anions and the bilayer : structural and mechanistic studies towards synthetic anion carriers for therapeutic applications". Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/410302/.
Testo completoAbstract (sommario):
Synthetic transmembrane anion transporters have attracted a great deal of interest due to their potential as therapeutic agents for the treatment of channelopathies such as cystic fibrosis or in the treatment of cancer. Despite a great deal of progress in the field over recent years, there are currently several hurdles that need to be overcome before anionophores become genuine therapeutic candidates. These include knowledge of how carriers behave in more cell-like bilayer systems, what molecular properties govern the rate determining step of the transport process and issues with solubility and deliverability. This thesis aims to explore some of these areas to help overcome some of these future barriers. The effect of lipid environment on the transport ability of a series of alkyl-substituted thioureas was investigated. The series covered a wide range of lipophilicity, to determine whether the optimum lipophilic range varied depending on the composition of the bilayer. Despite the different lipids appearing to modulate the overall transport rate, the relative order of the transporter efficacy appeared unaffected. Data is also presented demonstrating the use of dynamic covalent chemistry to generate an active transporter molecule in situ within the membrane. The compound formed by DCC was observed by measuring its transport response from vesicle experiments after the addition of two precursors (which do not facilitate transport alone) to the membrane. Comparison of the transport ability of the pre-formed compound and the rate of the DCC reaction measured by NMR spectroscopy gave insight into the balance required between these two factors in the design of these compounds. Finally, the effect of the fluorination of alkyl chains in tripodal tris-thiourea receptors was explored. Vesicle assays with and without accompanying protonophores to couple to the transport process were carried out to determine the mechanism of the transport process and discover whether fluorination had any effect on the selectivity of the transporter molecules. The activity of the compounds in FRT-YFP cell assays was also determined and comparison with the vesicle data gave insights into the vesicle tests required to accurately predict the transporters’ efficacy in cell epithelia.
15
Sagamanova, Irina. "New Approaches to Catalyst Design and Immobilization". Doctoral thesis, Universitat Rovira i Virgili, 2015. http://hdl.handle.net/10803/401816.
Testo completoAbstract (sommario):
aplicació en transformacions enantioselectives amb l’objectiu de desenvolupar nous processos en flux i (b) catàlisi
homogènia centrada a millorar reaccions promogudes per anions sulfenat (la formació d’aril sulfòxids catalitzada per
pal·ladi i el desenvolupament d’un pre-catalitzador de segona generació per a processos sense metall).
La primera part de la feina tracta sobre l’aplicació del polinorbornè com a un suport robust per a immobilitzar
catalitzadors homogenis. A tal fi, s’ha seleccionat la reacció aldòlica. El material ha demostrat tenir potencial, amb
resultats comparables als obtinguts amb una matriu de poliestirè. Fóra interessant estudiar transformacions alternatives
per a aquest tipus de materials, especialment en aplicacions fotocatalítiques i processos de flux continu.
En els següents capítols s’han desenvolupat β-fluoroamines suportades en polímer emprant dues aproximacions: copolimerització
i química “click”. Tant el mètode d’activació via enamine com el que involucra ions imini s’han tingut en
compte per a estudiar reaccions enantioselectives.
L’addició asimètrica de Michael d’aldehids a nitroalquens ha estat especialment reeixida, ja que l’aplicació de flux
continu ha replicat les enantioselectivitats obtingudes en batch. L’estratègica instal·lació d’un fluorur en lloc del més
làbil èter de silici (catalitzador tipus Jørgensen-Hayashi) ha permès una millora substancial dels resultats.Pel que fa al mode d’activació d’ió imini, s’han estudiat l’epoxidació i l’aziridinació d’aldehids α,β-insaturats. Malgrat tot, caldrà repensar el disseny del catalitzador a causa de l’efecte negatiu en aquestes transformacions del triazole que fa d’unió. Finalment, en el camp de la catàlisi homogènia, s’ha estès la formació d’aril sulfòxids catalitzada per pal·ladi a clorurs d’aril, més assequibles que els corresponents bromurs. A més, s’ha desenvolupat un nou pre-catalitzador per a l’acoblament d’halurs per generar estirens sota catàlisi d’anió sulfenat. Esta Tesis contiene dos secciones: (a) estudios para la síntesis de nuevos organocatalizadores soportados y su aplicación en transformaciones enantioselectivas, a fin de desarrollar nuevos procesos de flujo y (b) catalisis homogénea para la optimización de reacciones de aniones sulfenato (formación de sulfóxidos de arilo catalizadas por Pd y desarrollo de una segunda generación de pre-catalizadores para procesos sin metales). La primera parte de este trabajo se centra en el desarrollo de resinas de polinorborneno robustas como soporte de catalizadores homogéneos. Se han estudiado reacciones aldólicas enantioselectivas con excelentes resultados, comparables a los obtenidos con poliestireno. Podría ser interesante estudiar aplicaciones de estos materiales en transformaciones fotocatalíticas y procesos en continuo. En los siguientes capítulos se presenta el desarrollo de nuevas resinas catalíticas basadas en β-fluoroaminas soportadas en poliestireno preparadas por copolimerización o siguiendo una estrategia de click-chemistry y su empleo en transformaciones asimétricas con activación via enamina e ión iminio. Se han aplicado en la adición de Michael de aldehídos a nitroalquenos, proceso que se ha implementado en flujo continuo con la misma enantioselectividad que en batch. La presencia de flúor, sustituyente más robusto que el lábil éter silílico de los catalizadores tipo Jørgensen-Hayashi, aumenta notablemente la vida útil del catalizador.
estos casos la presencia del triazol que conecta la matriz polímérica y la unidad catalítica tiene un efecto negativo en el proceso, por lo que será necesario rediseñar el catalizador. Finalmente se han estudiado dos procesos de catálisis homogénea. Se presentan metodologías mejoradas para la formación de sulfóxidos de arilo a partir de cloruros de arilo catalizada por Pd y el desarrollo de un nuevo precatalizador para el acoplamiento de haluros para generar estirenos mediada por aniones sulfenato. This Thesis covers two main sections: (a) studies towards the synthesis of new immobilized organocatalysts and their application in a wide range of enantioselective transformations with the main goal of developing new continuous flow processes and (b) homogenous catalysis aimed at improving recently reported reactions of sulfenate anions (a Pdcatalyzed aryl sulfoxide formation, and the development of a second generation pre-catalyst for metal-free processes). The first part of this work is devoted to the application of polynorbornene as a robust support for the immobilization of homogeneous catalysts. To this aim, the aldol reaction has been selected. This material has shown high potential, comparable to the results obtained with a polystyrene matrix. It will be interesting to study alternative transformations for this type of materials, especially in photocatalytic applications and continuous flow processes. In the following chapters, new polymer-supported β-fluoroamines have been developed with two different approaches: copolymerization and click chemistry. Both the enamine and iminium ion activation modes have been considered to study asymmetric transformations.
16
Gianola, Adam J. "Ultraviolet photoelectron spectroscopy of organic anions". Diss., Connect to online resource, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3219005.
Testo completo
17
Gray, Thomas Matthew. "Electrochemical and optical sensing of anions". Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442459.
Testo completo
18
Davies, M. K. "Synthetic applications of p block anions". Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.598378.
Testo completoAbstract (sommario):
Chapter 1 surveys the chemistry and reactivity of Group 14 and relevant Group 15 complexes and introduces the analogies which exist between the well-established ligand behaviour of non-metallic systems and the configuration of donor functionality present in a range of main group metallo-organic compounds. Chapter 2 initially looks at the reactivity of the anion [Sn {μ-N=C(tBu)Ph}3]-, towards a variety of metals with the aim of using this complex as a tripodal ligand. However, the reaction of [Sn{μ-N=C(tBu)Ph}3Li.THF] with [CuCl] results in ligand transfer of one of the imido groups, to form [Cu{μ-N=C(tBu)Ph}]4.THF] and the presence of PPh3 fails to block this transfer, thus [Cu{μ-N=C(tBu)Ph}]4.2PPh3-THF is produced. The reaction of [Cp2Sn] with [2-LiPy] (2-Py = Pyridyl), formed from [nBuLi] with [2-PyBr], yields the Sn(IV) product [nBuSn(2-Py)3LiBr.0.5THF]. Investigations of this compound demonstrate the efficacy of the [nBuSn(2-Py)3] moiety as a robust neutral ligand. The reaction of [nBuSn(2-Py)3LiBr.0.5THF] with CuCl2 yields the Cu(I) product [nBuSn(2-Py)3CuBr.0.5THF]. However, an attempt to extend this reactivity to AgNO3 results in anion exchange, producing [nBuSn(2-Py)3LiNO3]. The Pb(II) complex [Pb(2-Py)3Li.THF] was synthesised from the reaction of [2-LiPy] with [Cp2Pb]. In Chapter 3, two alternative reaction pathways are identified in the nucleophilic substitution reactions of Group 14 metallocenes with lithiated primary amines [RNHLi]. These are exemplified by the synthesis of the primary tris(amido)stannate [(MANH)Sn(μ-NHMA)2Li.2THF] obtained from the reaction of [Cp2Sn] with [(MA)NHLi] (MA = 2-MeOC6H4), and the cubanes [ENCy4] [E = Sn, Pb ; Cy = C6H11] are prepared from [CyNHLi] and [Cp2E]. The later furnishes a new route to Group 14 imido cubanes. A study of the effects of two potent nucleophiles in the same molecule, [PhCH2N(Li)CH2)]2, with [Cp2Sn] was undertaken, yielding the dimer [{PhCH2N(CH2)2NCH2Ph}Sn]2.
19
Darr, Sameera Iqbal. "Electrochemical studies of substituted heteropolyoxometallate anions". Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.542959.
Testo completo
20
Moujaes, Elie A. "Intermolecular vibronic interactions in fullerene anions". Thesis, University of Nottingham, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438359.
Testo completo
21
West, Christopher William. "Ultrafast dynamics of gas phase anions". Thesis, Durham University, 2016. http://etheses.dur.ac.uk/11419/.
Testo completoAbstract (sommario):
The ultrafast dynamics of a number of molecules have been studied in the gas phase through the use of frequency- angle- and time-resolved photoelecron imaging. A particular emphasis has been applied to the behaviour of biologically relevant molecules following photoexcitation. The gaseous ions were produced from an electrospray ionisation source and interrogated by a purpose-built velocity-map imaging photoelectron spectrometer with a minimum temporal resolution of ~50 fs. Firstly, the details of a global kinetic fitting routine for a time-resolved photoelectron spectrum are presented. Through fitting the constituent photoelectron images to a kinetic fit, the photoelectron angular anisotropy of the constituent features of the time-resolved spectrum is preserved. Secondly, the dynamics of the green fluorescent protein model chromophore following UV excitation were explored, identifying internal conversion of the initially produced excited state population to a lower lying excited state before photodetachment. Thirdly, frequency- and angle-resolved photoelectron imaging is employed to investigate the dynamics of anionic resonances of para-benzoquinone, that have been implicated in facilitating electron attachment to this moiety. Fourthly, the photoelectron spectra of a series of carboxylic acids are presented in order to assess the feasibility of producing anions by attaching carboxylic acids to neutral chromophores. Fifthly, a time-resolved photoelectron spectrum of the biological chromophore and carboxylic acid, all-trans¬-retinoic acid is presented. Finally, highly anisotropic photoelectron spectra of the dianion, antimony tartrate are presented. In order to explain the anisotropy, classical trajectories of electrons on the molecular electrostatic potential energy surface are calculated. From this, the observed anisotropy can be assigned the the shape of the molecular repulsive Coulomb barrier.
22
Kawachi, Atsushi. "The Chemistry of Functionalized Silyl Anions". Kyoto University, 1995. http://hdl.handle.net/2433/77813.
Testo completo
23
Hiscock, Jennifer R. "Binding anions using simple neutral molecules". Thesis, University of Southampton, 2010. https://eprints.soton.ac.uk/171157/.
Testo completoAbstract (sommario):
This thesis reports a number of novel neutral, hydrogen bond donating anion receptors and describes their anion coordination properties in both the solution and solid states. A set of ten urea/thiourea linked indole/carbazole groups were found to have high affinities for a variety of oxo-anions in highly competitive DMSO solutions. Of these receptors, the diindolylurea motif was found to be excellent for the binding of dihydrogen phosphate. This group of receptors were found to form 1:1 complexes in solution with various anions but more complex 2:1 and 3:1 receptor:anion complexes were observed in the solid state. Deprotonation of the bound protonated oxo-anion was observed with these 2:1 and 3:1 complexes. The basic diindolylurea motif was then extended by the incorporation of further NH bond donor groups from amide, indole and carbazole functionalities. This group of receptors were found to form 1:1 complexes in both the solution and solid states, with the binding mode dependent of the geometry of the anion. These compounds also showed spontaneous crystallisation with sulfate in as little as 20 minutes. These receptors showed high affinities for the oxo-anions and gave the first examples of solution state deprotonation of bound protonated oxo-anions. A set of three dimensional indole-based receptors was also synthesised, utilising the TREN and pin-wheel scaffolds. These receptors contain between six and fifteen NH bond donor groups that give a range of anion binding modes, some too complex to be defined, that generally show a preference for the oxo-anions. Again, an example of deprotonation of the bound protonated oxo-anion was observed.
24
Müller, Lutz O. "Weakly coordinating anions and lewis superacidity". [S.l. : s.n.], 2008. http://nbn-resolving.de/urn:nbn:de:bsz:25-opus-49292.
Testo completo
25
Berryman, Orion Boyd. "Anions and electron-deficient aromatic rings /". Connect to title online (Scholars' Bank) Connect to title online (ProQuest), 2008. http://hdl.handle.net/1794/8159.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--University of Oregon, 2008.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 265-281). Also available online in Scholars' Bank; and in ProQuest, free to University of Oregon users.
26
You, Shaochun. "CuCl₂-induced oxidative coupling of Anions /". Bern, 1992. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
Testo completo
27
Berryman, Orion Boyd 1981. "Anions and electron-deficient aromatic rings". Thesis, University of Oregon, 2008. http://hdl.handle.net/1794/8159.
Testo completoAbstract (sommario):
xx, 281 p. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.More than two-thirds of all enzyme substrates and cofactors are anionic, emphasizing the essential role that anions play in biological processes. Moreover, anions can have detrimental effects on the environment by causing ground water contamination when anions such as perchlorate, phosphate and nitrate develop in intolerable levels. Owing to the prevalent nature of anions, traditional strategies employed to target anions--including hydrogen bonding, metal ion coordination and electrostatic interactions--have been extensively studied. An alternative approach to anion binding would complement the powerful array of existing techniques. Recently, in the supramolecular chemistry community, new insight has been cast on how anions attractively interact with electron-deficient arenes, suggesting that aromatic rings are a viable anion binding strategy to balance existing methods. Chapter I provides a historical perspective of anions interacting with electron- deficient arenes. This outlook has its origins in the late 1800s with the discovery of colored charge-transfer complexes between donor and acceptor molecules and continues with the progression of the field leading up to the recent supramolecular fascination. Chapter II represents our initial efforts at measuring anion/arene interactions in solution. In particular, sulfonamide based hydrogen bonding receptors were developed with pendant aromatic rings to test the strength of anion/arene interactions in solution. Complementary computational chemistry and crystallography were utilized to supplement the solution studies. Chapter III describes our quantum calculations and crystallographic efforts at using only electron-deficient arenes to bind halides. A Cambridge Structure Database survey supports our emphasis of understanding multiple anion/arene interactions. Chapter IV illustrates how tripodal anion receptors can be developed to bind anions using only electron-deficient aromatic rings. Furthermore, subtle changes in anion binding geometries are observed with isomeric receptors and corroborated with Density Functional Theory calculations. Chapter V is dedicated to the preparation of electron-deficient anion receptors that are conformationally stabilized by hydrogen bonds. Chapter VI is committed to using our knowledge of anion binding to study a series of ethynyl-pyridine sulfonamides capable of hydrogen bonding to small molecules and anions. In conclusion, Chapter VII is a summary and future prospective for the field of anion/arene interactions. This dissertation includes previously published and co-authored material.
Adviser: Darren W. Johnson
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Hevko, John Michael. "Migration and cyclisation reactions of selected organic anions /". Title page, table of contents and abstract only, 1998. http://web4.library.adelaide.edu.au/theses/09PH/09phh596.pdf.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--University of Adelaide, Dept. of Chemistry, 1999?Includes 5 leaves of errata. Includes reprints of author's previously published articles. Includes bibliographical references (leaves 228-245).
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Cowie, David. "Differential induction of organic anion transporting polypeptides in rat liver". Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources. Restricted: no access until April 24, 2020, 2008. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=25707.
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Miranda, Margarida Sofia Quintanilha. "Transmembrane transport of anions by synthetic transporters". Master's thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/22273.
Testo completoAbstract (sommario):
Mestrado em QuímicaThe chloride transport across the phospholipid bilayer assisted by small synthetic molecules were studied by computational methods including quantum calculations followed by molecular dynamics simulations and free energy calculations. A series of twelve tris-thiourea aryl substituted putative transporters, with three different six-membered rings as scaffolds (desmethyl cyclohexane, hexamethyl cyclohexane and benzene) and each of them with four possible aryl substituents (3,5-trifluoromethyl, p-trifluoromethyl, p-nitro and phenyl), were studied in silico in order to understand the experimental transport data previously reported for these molecules. The computational study started with the DFT optimization of twelve chloride complexes in gas phase and in DMSO at the M062X/6-31+G** theory level. The strength of the N-H···Cl- interactions were ascertained through the E2 values obtained from the second order perturbation theory, the Wiberg bond Indexes and the most positive value of the electrostatic potential (VS,max). Overall, these descriptors increases with the binding affinity constants reflecting the electron withdrawing character of the aryl substituents. Thus, the 3,5-trifluoromethyl substituted transporters presented the highest values for the quantum descriptors as well as the highest binding affinity for chloride anion, indicating that these molecules are able to successfully uptake the anion from the water phase and further proceed to its transport across the phospholipid bilayer. Subsequently, the passive diffusion of these chloride complexes were then investigated by MD simulations positioning them either in the bilayer core and water phase. Overall, the MD simulation runs reveal that the transporters were able to promote chloride uptake and release events, consistent with anion carrier transport mechanism. Furthermore, free energy profile for 3,5-trifluoromethyl hexamethyl cyclohexane complex and free chloride were constructed from the potential mean force calculations. The chloride complex has to surpass an energy barrier to cross the middle of the phospholipid bilayer of 2 kcal mol-1 while for the free chloride this energy increases to 19.5 kcal mol-1 indicating that the chloride transport assisted by this receptor is energetically favoured. Another remarkable feature from the MD simulations is that the chloride complexes fit comfortably well below the membrane’s interface which seems to indicate that the receptors are able to operate as a chloride shuttle without leaving the phospholipid bilayer.
O transporte de cloreto pela bicamada fosfolipídica, assistido por pequenas moléculas sintéticas, foi estudado através de métodos computacionais, incluindo cálculos quânticos, simulações de dinâmica molecular e cálculos de energia livre. As propriedades de transporte de um conjunto de doze tris-tioureias contendo um anel central de seis membros (cicloexano, cicloexano hexametilado e benzeno) derivatizado com grupos arilo (3,5-trifluorometilo, p-trifluorometilo, pnitro e fenilo), foram estudados in silico tendo como objetivo a compreensão de dados experimentais de transporte reportados. O estudo computacional iniciou-se com a otimização dos doze complexos em fase gasosa e em dimetilsulfóxido (DMSO), ao nível de teoria de M06-2X/6- 31+G**. A força das interações NH···Cl- foi determinada através dos valores de E2 obtidos da teoria de perturbação de segunda ordem, dos índices de ligação de Wiberg e do valor mais positivo de potencial electroestático (VS,max). Estes descritores aumentam com as constantes de afinidade, refletindo o carácter electroatractor dos substituintes arilo. Assim, os três transportadores com grupos 3,5-trifluorometilo apresentaram os valores mais altos para estes descritores e para afinidade ao cloreto, demonstrando que estas moléculas conseguem de facto capturar um anião da fase aquosa e proceder ao seu transporte através da bicamada fosfolipídica. Seguiu-se o estudo do processo de difusão passiva para estes três complexos por dinâmica molecular, tendo estes sido colocados tanto na fase aquosa como no centro da bicamada fosfolipídica. Estas simulações revelaram que os transportadores eram capazes de promover os processos de captura e libertação de cloreto. Além disso, os perfis de energia livre para o complexo do ligando cicloexano hexametilado derivatizado com 3,5-trifluorometilo e para o cloreto livre foram obtidos através de cálculos de potencial de força média. O complexo tem que superar uma barreira energética de 2 kcal mol-1 para atravessar o meio da bicamada enquanto o cloreto livre tem que ultrapassar uma barreira de energia livre de 19.5 kcal mol-1, i.e. o transporte assistido pelo recetor é energeticamente mais favorável. Outra caraterística importante das simulações está relacionada com o facto dos complexos de cloreto de inserirem confortavelmente abaixo da interface da membrana, indicando que os recetores conseguem operar como transportadores de cloreto sem sair da bicamada fosfolipídica.
31
Sivertsen, Edvard. "Membrane Separation of Anions in Concentrated Electrolytes". Doctoral thesis, Norwegian University of Science and Technology, Department of Chemical Engineering, 2001. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-2100.
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Gachuiri, Elizabeth Wanjiku. "Competitive adsorption of anions on Kenyan soils". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ33224.pdf.
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Hopkins, Peter K. "Novel tripodal ligands designed to complex anions". Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249200.
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34
Qureshi, Naseem. "Calixarene and coordination complex hosts for anions". Thesis, Durham University, 2009. http://etheses.dur.ac.uk/18/.
Testo completoAbstract (sommario):
My Ph.D research is mainly based on ‘calixarene and coordination complex hosts for anion’. The research is to make synthetic chloride ion channels for possible treatment of cystic fibrosis. Our approach is based on derivatives of larger calix[n]arenes. Calixarenes are chalice-shaped molecules that form readily under base catalyzed-condensation of tert-butyl phenol with formaldehyde. We have synthesized calixarenes which were tuned at the lower rim with bromo alkyl nitrile and reduced followed by reaction with a series of different isocyanates bearing fluorescent functional groups capable of binding and sensing chloride and nitrate. We are also interested how the host ligand binds with metal anions in solution and solid state chemistry. We synthesised simple pyridyl urea ligands and isomorphs. Their anion binding studies are discussed in terms of solid state and solution chemistry. Solid state structures based on silver and copper metal forming contact ion pairs with series of anions like nitrate, chloride, bromide, trifluoroacetate and boron tetrafluoride. Their solution based anion binding studies were performed and control titration results show that these hosts bind anions in a one to one fashion which was confirmed with solid state structures. An interesting aspect is that 2-ureidopyridine ligand exists in four different anhydrous crystal forms (I – IV0), which can be crystallized by several techniques. It was found that forms I and II only crystallize without another polymorph from methanol solution or in presence of inorganic salts. Thermoanalysis shows that all the modifications melt without previous transition and applying the heat of fusion rule proves this system to be completely monotropic. The crystal structures show that the molecule forms one intramolecular and two intermolecular hydrogen bonds to give S(6) and dimeric R (8) graph synthons in all four structures. However packing arrangements differ strikingly and since the hydrogen-bonding arrangement is the same for all the four forms, the differences in energy measured by thermoanalytical methods can only be caused by the different packing arrangements involving combinations of the weaker interactions, with the CH.¼S contacts being among the obvious differences. Thus, this system is a clear example in which the presence of robust, reproducible hydrogen bonded synthons does not lead to any control or predictability of polymorphic form.
35
Sookhun, Shatrugan. "Jahn-Teller effects in C₆₀ anions". Thesis, University of Nottingham, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.411506.
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Leedham, Angela Priscilla. "Imido analogues of main group oxo-anions". Thesis, University of Bristol, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247865.
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Stanley, Laurence Harry. "Dynamics of anions probed by photoelectron imaging". Thesis, Durham University, 2017. http://etheses.dur.ac.uk/12404/.
Testo completoAbstract (sommario):
This work comprises of the design and construction of a novel ion trap and guide system for the existing photoelectron spectrometer along with the study of two molecular systems. The redesigning of the system was to address shortcomings in the previous design and to open the door to new possibilities of research. The new components have been installed and proof-of-concept data has been taken that shows the success of the new cryogenic cooling system upon the ions. The anionic resonances of anthracene, a polyaromatic hydrocarbon (PAH), were studied using the new apparatus. This allowed for the use of a new methodology to produce ions of interest that were previously impossible to study. While we found that photodissociation gave better regioselectivity, it was possible to generate the most stable deprotonated from of the anthracenyl anion. Considering the formation of the anions in the interstellar medium, it was shown that it is likely that the anthracenyl resonances preferred to decay by autodetachment. This would result in little formation of the anion from the approach of an electron upon the neutral. The chromophore of the Green Fluorescent Protein (GFP) has been extensively studied by other researchers. We investigated the dynamics of an isomer of that chromophore. The movement of a single functional group from the para- to the meta- position completely alters the energetics of the system along with the dynamics. It was shown that this structural change would make for a significantly poorer choice as a chromophore for a fluorescent protein.
38
Peasey, Sonja Janet. "Complexes of lithium salts with inorganic anions". Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621685.
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House, Stewart Nicholas. "Studies on chiral allenyl and vinyl anions". Thesis, University of Leicester, 1989. http://hdl.handle.net/2381/33738.
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Morris, Daniel S. "Redox chemistry of perrhenate and other anions". Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/31480.
Testo completoAbstract (sommario):
This thesis discusses reduction and oxidation reactions catalysed by the perrhenate anion and oxidation reactions catalysed by other oxo-anions i.e. sulfate and nitrate. Chapter one introduces catalytic hydrosilylation, hydroboration, deoxydehydration and alkene epoxidation and some of their applications, with a focus on high oxidation state complexes. Chapter two describes the synthesis of a salt of perrhenate [N(hexyl)4][ReO4] which is highly soluble in organic solvents. The use of this salt as a catalyst for both the hydrosilylation and hydroboration of carbonyl compounds and carbon dioxide is discussed. Catalytic methylation of amines and anilines with carbon dioxide and hydrosilanes is also reported. Labelled carbon dioxide reactions and DFT calculations are conducted in order to understand the mechanism of carbon dioxide reduction using hydrosilanes. Chapter three outlines the synthesis of a number of alkylammonium and pyridinium perrhenate salts and their application in the deoxydehydration reaction, converting vicinal diols to alkenes. The role of the counterion is discussed with pyridinium perrhenates shown to be more effective catalysts. DFT calculations are conducted to identify the most likely pathway of the catalytic cycle. Alternative reducing agents to the triphenylphosphine initially used are also studied. Chapter four reports results of organic salts of perrhenate, sulfate and nitrate as oxidation catalysts, specifically their ability to catalyse epoxidations of alkenes. By the formation of supramolecular ion pairs (SIPs), these anions are made organic soluble which is found to significantly enhance their catalytic ability, however, the organic counterions used to form these SIPs were found to be of importance. Ionic liquids are also used for the epoxidation of alkenes. Solution studies are presented to further understanding of how these compounds interact with one another in solution. Chapter five contains experimental conditions and characterisation for compounds discussed in this work.
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ZAHNEISEN, THOMAS. "Reactivite nucleophile et electrophile des anions chloroallyliques". Paris 6, 1992. http://www.theses.fr/1992PA066372.
Testo completoAbstract (sommario):
Des carbenoides allyliques peuvent etre crees par simple deprotonation de l'halogenure allylique correspondant avec une base forte telle que le litmp, lda ou sec buli. L'addition du litmp a temperature ambiante dans un melange de chlorure ou bromure de prenyle et d'olefine conduit aux cyclopropanes vinyliques avec des rendements de 30 a 60%. Le carbenoide (carbene) intermediaire est electrophile, reagissant plus facilement avec des olefines riches en electrons. Les halogenures allyliques moins substitues donnent des rendements inferieurs. La meme technique par creation in situ du carbenoide, permet egalement une reaction nucleophile a basse temperature mais necessite que l'electrophile soit moins acide et plus reactif vis-a-vis du carbenoide que l'halogenure allylique precurseur. Dans le cas contraire, il est possible de preparer a basse temperature une solution de chloroallyl et chlorocrotyl lithium par addition lente du chlorure dans la base, suivi de l'addition de l'electrophile. Les regioselectivite et diastereoselectivite de la condensation de ces anions haloallyliques sur des carbonyles peuvent etre considerablement ameliorees par transmetallation. Les titanates bromoallyliques et chlorocrotyliques ainsi crees conduisent a une excellente anti-diastereoselectivite. Par contre, les diastereoisomeres syn sont obtenus de maniere hautement selective a partir des anions chloroallyliques de zinc
42
Xu, Fei. "Ionic Liquid Crystals Based on Fluorocomplex Anions". Kyoto University, 2012. http://hdl.handle.net/2433/160955.
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43
Surber, Sean Eric. "Photoelectron Imaging of Molecular and Cluster Anions". Diss., The University of Arizona, 2005. http://hdl.handle.net/10150/194908.
Testo completoAbstract (sommario):
Femtosecond negative-ion photoelectron imaging spectroscopy allows the probing of dynamics resulting from solvation and photodissociation in both the time-resolved and solvent domains. First, the basic premise of photoelectron imaging shall be presented, followed by a discussion of qualitative approaches for interpreting photoelectron angular distributions as illustrated by application to the photoelectron images of S₂⁻ and CS₂⁻. The photoelectron images of CS₂⁻ serve as a reference for interpreting the results for homogeneous and heterogeneous solvation in CO₂ and OCS cluster anions. The effects of solvation upon the photoelectron angular distribution and the photoelectron energy spectrum are discussed in relation to (OCS)n⁻, OCS⁻·H₂O, (CO2)n⁻, and (CO₂)n(H₂O)m⁻. The (OCS)₂⁻ cluster anion images show evidence of competition of excited state decay pathways and coexistence of isomers. The evolution of photoelectron images, resulting from I₂Br⁻ dissociation shows the evolving electronic structure of the I⁻ channel as the anion dissociates.
44
Scott, David M. "Low-energy collisions of alkali-metal anions". W&M ScholarWorks, 1986. https://scholarworks.wm.edu/etd/1539623761.
Testo completoAbstract (sommario):
Measurements of the total cross section for electron detachment, (sigma)(,e)(E), are presented for low-energy (E(,1ab) < 300 eV) collisions of Na('-), K('-), and Cs('-) with atomic and molecular targets. For many of the atomic (rare-gas) targets, the energy dependence of (sigma)(,e)(E) is striking: virtually no detachment is observed until relatively high collision energies (50 eV in the center-of-mass frame) are reached, in contradistinction to what has been observed for similar collisions involving H('-). The thresholds for alkali anion detachment are approximately equal to the thresholds for excitation observed in collisions of neutral alkali atoms with these same targets. The similarity between the dynamics of the neutral system and that of the negative ion system, together with the observation (at greater energies) of detachment accompanied by excitation of the alkali parent, suggests that electron detachment may be mediated by a two-electron process in some cases. A simple curve-crossing mechanism adequately reproduces the observed (sigma)(,e)(E) for several of these rare-gas targets.;Measurements of both (sigma)(,e)(E) and the cross section for charge transfer (sigma)(,i)(E) have also been completed for H(,2), D(,2), N(,2), O(,2), CO, CO(,2), SO(,2), N(,2)O, CH(,4), and SF(,6) targets. Electron detachment is the dominant process for all of these targets except O(,2), SO(,2), and SF(,6), with thresholds on the order of a few eV. Structure in (sigma)(,e)(E) for the CO(,2) target has been attributed to charge transfer to a metastable state of CO(,2)('-)(('2)A(,1)). Similarly, in the case of N(,2)O, both (sigma)(,e)(E) and (sigma)(,i)(E) exhibit behavior which suggests that a temporary negative ion state is formed during the collision. In the case of the O(,2), SO(,2), and SF(,6) targets, charge transfer is observed to have particularly large cross sections (>100 (ANGSTROM)('2)) at low collision energies.
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Dieng, Pape Sylla. "Recognition of chiral anions by ruthenacyclic complexes". Strasbourg, 2009. http://www.theses.fr/2009STRA6258.
Testo completoAbstract (sommario):
La mise au point de récepteurs énantiosélectifs d’oxy-anions chiraux représente un défi majeur de la chimie supramoléculaire. Au cours des dernières décennies, plusieurs stratégies ont été développées qui visaient à la séparation énantiosélective de molécules chirales. La plupart des récepteurs décrits dans la littérature sont cependant de nature organique. Au laboratoire de Synthèses Métallo-Induites, les propriétés de reconnaissance d’anion d’un complexe du Co (III) lié par un ligand monoanionique tridentate NCN symétrique (connu sous le nom de pince de van Koten) ont été établies. Ainsi, ce travail a été dédié à la préparation d’une version chirale de ce type de récepteur. Nous avons réalisé la synthèse de deux types de ligands chiraux NCN’ non symétriques présentant une structure différente : l’un avec un bras diméthylamine, l’autre avec un bras pyridine. Les différentes fonctionnalisations apportées au ligand NCN ont eu pour but de générer un environnement pseudo-tétraédrique chiral au niveau du métal inséré à l’intérieur de la pince, mais également de tirer profit de la possibilité d’intéraction hydrogène avec un des bras aminés du ligand-pince. La cyclométallation du premier ligand aminé a donné lieu à un mélange de composés diastéréomères instables où le métal est retrouvé à l’extérieur de la pince. La lithiation puis la transmétallation sur l’or (I) a conduit à un complexe métallé à l’intérieur de la pince. La cyclométallation du deuxième ligand contenant une pyridine a permis l’activation C-H à l’intérieur de la pince conduisant à deux complexes organométalliques instables et s’isomérisant l’un vers l’autre. Une étude DFT a permis de proposer, entre autres hypothèses, une isomérisation entre un complexe NCN’ de coordination faciale et un complexe NCN’ de coordination méridionale. Nous avons également dédié ces travaux à l’étude des propriétés de reconnaissance énantiosélective d’un composé cycloruthéné (préparé à partir du ligand (R)-1-(1-naphtyl éthylamine)) vis-à-vis de carboxylates de Mosher. Les expériences de complexation effectuées en solution dans le dichloromethane ont permis de mettre en évidence une sélectivité de 3. 4 en faveur du carboxylate R. Dans une expérience d’extraction, la sélectivité en faveur du substrat R a été portée à 6The development of enantioselective receptors for chiral oxy-anions represents a major challenge in supramolecular chemistry. In recent decades, several strategies have been developed aimed at enantioselective separation of chiral molecules. However, most of the receptors described in the literature are organic based receptors. In our laboratory, the anion recognition properties of a Co (III) complex bound by a symmetrical monoanionic tridentate NCN ligand (known as van Koten pincer) were established. This work was then focused on the preparation of a chiral version of this type of receptors. We have synthesized two types of non-symmetrical chiral NCN’ ligands with different structures: one with a dimethylamine arm and the other with a pyridine arm. The different ligand designs were made to generate a pseudo-tetrahedral chiral environment at the metal center inserted into the pincer, but also to take advantage of the possibility of hydrogen interaction with one arm of the pincer ligand. The cyclometallation of the first amine ligand resulted in a mixture of unstable diastereomeric compounds where the metal was found outside of the pincer. Lithiation and transmetallation to gold (I) led to a complex with the metal inside the pincer. Cyclometallation of the second pyridine-containing ligand resulted in a CH activation within the pincer leading to two unstable organometallic complexes isomerizing one towards the other. DFT studies have allowed to propose, among other assumptions, an isomerization between NCN’ facial coordination complex and NCN’ meridional coordination complex. This work was also dedicated to the study of enantioselective recognition properties of a cycloruthenated compound (prepared from the ligand (R) -1 - (1-naphtylethylamine)) vis-à-vis Mosher carboxylates. Complexation experiments carried out in solution in dichloromethane allowed the demonstration of a selectivity of 3. 4 for the R-carboxylate. In an extraction experiment, the selectivity towards the R-substrate was increased to 6
46
Davis, Julian Murray. "Sapphyrins aggregation and anion binding behavior in polar, protic media /". Access restricted to users with UT Austin EID UMI Company copy, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3036590.
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Stevanovic, Stéphane. "Absorption sélective de gaz par des liquides ioniques basés sur des anions carboxylates ou des anions tris (pentafluoroethyl) trifluorophosphates". Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2012. http://tel.archives-ouvertes.fr/tel-00822155.
Testo completoAbstract (sommario):
Différentes familles de liquides ioniques ont été sélectionnées pour leur capacité d'absorption de gaz et plus particulièrement de dioxyde de carbone. L'objectif de ces travaux est de définir les liquides ioniques les plus à même d'être utilisés en tant qu'absorbants dits alternatifs dans les procédés de captage de gaz, l'enjeu principal étant à terme de diminuer les coûts de production des procédés industriels. Les systèmes retenus sont des liquides ioniques purs issus de la combinaison de cations imidazolium, pyrrolidinium et phosphonium avec des anions de type carboxylate ou tris (pentafluoroethyl) trifluorophosphate ainsi que des mélanges binaires de liquides ioniques avec anion carboxylate + eau. L'absorption de différents gaz - dioxyde de carbone, azote, protoxyde d'azote et éthane - dans les liquides ioniques purs ainsi que dans les mélanges liquide ionique +eau a été mesurée dans une gamme de températures comprises entre 303.15 et 353.15 K et pour des pressions proches de l'atmosphérique. La sélectivité des liquides ioniques pour l'absorption de dioxyde de carbone par rapport aux autres gaz a pu être déterminée. La caractérisation de l'absorption de gaz est fonction des systèmes étudiés, les interactions entre les gaz et certains liquides ioniques (ou certains mélanges liquide ionique + eau) étant uniquement de type physique alors que dans d'autres systèmes, l'absorption est le résultat à la fois d'interactions physiques mais également de la présence de réaction chimique.
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Garsany, Yannick. "Understanding steel corrosion in oilfield brines". Thesis, University of Southampton, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252197.
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Simion, Cristian. "Anions 1-aza et 2-azaallyliques, modèles-clés dans l'élaboration de charpentes cycliques azotées à cinq, six et sept chainons". Lille 1, 1994. http://www.theses.fr/1994LIL10072.
Testo completoAbstract (sommario):
Le travail presente dans le memoire de these concerne l'etude de la reactivite d'anions 1-aza et 2-azaallyliques et leur implication dans l'edification de charpentes heterocycliques a cinq, six et sept chainons. Les reactions qui sont decrites s'appuient sur l'excellente nucleophilie de ces especes et sont associees aux proprietes reactionnelles des differents intermediaires intervenant dans les processus d'annelation: les o-ethyl thiocarboxylates (thioesters) pour leur aptitude a generer des anions sulfures transitoires, les pyridines alpha-halogenees pour la labilite de l'atome d'halogene dans les reactions de substitution nucleophile aromatique permettant ainsi une tres bonne regioselectivite de la cyclisation. L'association de ces trois proprietes a permis l'elaboration de structures de type pyrido 3,2-f 1,4 thiazepine, pyrido 2,3-b 1,4 thiazepine, 1,5 naphtyridine, 1,7 naphtyridine. Une utilisation plus classique des anions 2-azallyliques et leur engagement dans un processus de cycloaddition 1,3-anionique a egalement permis la construction de modeles a cinq chainons tels que les delta-2-thiazolines.
50
Kelsen, Vinciane. "Greffage de complexes organométalliques sur anions hydroxyborates : application à la transformation des oléfines". Thesis, Lyon 1, 2010. http://www.theses.fr/2010LYO10280.
Testo completoAbstract (sommario):
Cette thèse présente le greffage de complexes organométalliques sur des anions hydroxyborates. Ces ligands originaux sont susceptibles de conférer des propriétés particulières à la sphère de coordination du métal. Leur caractère anionique pourrait permettre l'immobilisation des catalyseurs dans une phase liquide ionique. La majeure partie des travaux a porté sur la réactivité des anions hydroxyborates avec les métaux du groupe IV de la classification périodique. Les complexes alkyles du zirconium et de l'hafnium réagissent avec la fonction hydroxyle de l'anion par protonolyse de la liaison métal-alkyle. La résolution par diffraction des rayons X de la structure des complexes métallocènes [Cp2MMe(OB(C6F5)3)]- [PPN]+ (M = Zr et Hf) a confirmé la nature covalente des liaisons M-O et B-O et donc l'intérêt des anions hydroxyborates comme ligands de complexes organométalliques. Cette réactivité a ensuite été déclinée sur différents précurseurs du zirconium et de l'hafnium. Le complexe ionique [Ti(OiPr)3(OB(C6F5)3]-[PPN]+ a été synthétisé à partir d'un complexe alkoxy du titane par une réaction d'échange de ligands. Ce complexe activé par le triéthylaluminium dimérise sélectivement l'éthylène en butène-1 en milieu liquide ionique. L'extension du concept à d'autres métaux de la classification périodique : aluminium, fer, molybdène, a été abordée. Deux complexes anioniques du molybdène ont notamment été isolés et sont des catalyseurs de métathèse des oléfinesThis thesis presents the use of hydroxyborate anions as anchors for organometallic complexes. These original ligands might confer particular properties to the coordination sphere of the metal. Their anionic nature might also allow the immobilization of catalysts in ionic liquids. The main part of this work dealt with the reactivity of hydroxyborate anions with group IV metals. Zirconium and hafnium complexes reacted with the hydroxyl function of the anion by protonolysis of the metal-alkyl bond. Resolution of the structure of metallocene complexes [Cp2MMe(OB(C6F5)3)]-[PPN]+ (M = Zr and Hf) by X-Ray diffraction confirmed the covalent nature of M-O and B-O bonds and so the relevance of hydroxyborate anions as ligands for organometallic complexes. Then, this reactivity was extended to different zirconium and hafnium precursors. The ionic complex [Ti(OiPr)3(OB(C6F5)3)]- [PPN]+ was synthesized from an alkoxy titanium complex by a ligand exchange reaction. This complex activated by triethylaluminium selectively dimerized ethylene into 1-butene in ionic liquids. Extension of the concept to other metals such as aluminum, iron and molybdenum, was studied. Two anionic molybdenum complexes were isolated and are catalysts for olefin metathesis