Compounds labelled with 11C (β+, t1/2 = 20.4 min) are used in positron emission tomography (PET), which is a quantitative non-invasive molecular imaging technique. It utilizes computerized reconstruction methods to produce time-resolved images of the radioactivity distribution in living subjects. The feasibility of preparing [11C]methyl iodide from [11C]methane and iodine via a single pass through a non-thermal plasma reactor was explored. [11C]Methyl iodide with a specific radioactivity of 412 ± 32 GBq/µmol was obtained in 13 ± 3% decay-corrected radiochemical yield within 6 min via catalytic hydrogenation of [11C]carbon dioxide (24 GBq) and subsequent iodination, induced by electron impact. Labelled ethyl-, propyl- and butyl iodide was synthesized, within 15 min, via palladium-mediated carbonylation using [11C]carbon monoxide. The carbonylation products, labelled carboxylic acids, esters and aldehydes, were reduced to their corresponding alcohols and converted to alkyl iodides. [1-11C]Ethyl iodide was obtained via palladium-mediated carbonylation of methyl iodide with a decay-corrected radiochemical yield of 55 ± 5%. [1-11C]Propyl iodide and [1-11C]butyl iodide were synthesized via the hydroformylation of ethene and propene with decay-corrected radiochemical yields of 58 ± 4% and 34 ± 2%, respectively. [1-11C]Ethyl iodide was obtained with a specific radioactivity of 84 GBq/mmol from 10 GBq of [11C]carbon monoxide. [1-11C]Propyl iodide was synthesized with a specific radioactivity of 270 GBq/mmol from 12 GBq and [1-11C]butyl iodide with 146 GBq/mmol from 8 GBq. Palladium-mediated hydroxycarbonylation of acetylene was used in the synthesis of [1-11C]acrylic acid. The labelled carboxylic acid was converted to its acid chloride and subsequently treated with amine to yield N-[carbonyl-11C]benzylacrylamide. In an alternative method, [carbonyl-11C]acrylamides were synthesized in decay-corrected radiochemical yields up to 81% via palladium-mediated carbonylative cross-coupling of vinyl halides and amines. Starting from 10 ± 0.5 GBq of [11C]carbon monoxide, N-[carbonyl-11C]benzylacrylamide was obtained in 4 min with a specific radioactivity of 330 ± 4 GBq/µmol.

Title from PDF of title page. / Document formatted into pages; contains 64 pages. / Thesis (M.E.E.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: The ability of Mercuric Iodide (HgI2) to function as a highly efficient radiation detector at room temperature has generated great interest and has triggered further studies on this difficult material. This property is expected to enable significant enhancements to a far-ranging variety of applications and systems. HgI2 devices have shown superior performance at room temperature compared to elemental Si or Ge devices, which require to be cooled down to liquid nitrogen temperature when used as nuclear radiation detectors. While substantial studies have been conducted on single crystal HgI2, polycrystalline HgI2 remains a comparatively less studied form of this material. The primary use of HgI2 is as a direct radiation detector. It can also be used in applications with a scintillator intermediate to generate visible light from incident nuclear radiation. Hence its response to visible light can be used to study the electronic properties of HgI2 polycrystalline films. / ABSTRACT: The films are deposited on TEC-15 LOF glass with a Tin Oxide(Sn02) coating which acts as the growth surface. It also acts as the front contact with Palladium (Pd) being the back contact. Wire leads are attached to the palladium for electrical contact. The deposited films are circular in shape with a diameter of 2.5cm with thickness ranging from 50 to 600ìm. A maximum of 7 devices are contacted at various points on every film. For the measurements documented in this thesis, a tungsten-halogen lamp and an Oriel 1/4m grating monochromator are used as a light source. The incident flux on the sample is determined using a Si photodiode as reference. Device performance for both single crystal as well as polycrystalline films is documented. We have attempted to identify a set of optimum growth parameters using these measurements. / ABSTRACT: For a film to be considered favorably, not only should the individual devices show high quantum efficiencies and low dark currents, but the response of all devices on the same film should be uniform. A number of films are studied and the optimum film deposition conditions are commented upon. A powerful semiconductor device simulation tool, MEDICItm, is used to simulate the photoresponse of these films. The simulations are compared to the measurements and the transport and light absorption parameters of the polycrystalline films are determined. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This work describes the synthesis and characterization of thirteen new compounds belonging to the class of ditelluroethers iodides. The starting materials (ditelluroethers) were synthesized by a method few mentioned in the literature for the synthesis of this class of compounds. This methodology proved to be efficient once that ten new ditelluroethers were synthesized in satisfactory yields. Of these thirteen synthesized compounds, six had their structures determined by X-ray diffraction. From the structural analysis of these different ditelluroethers iodides we can conclude that the organization of the crystalline packing and the formation of the supramolecular assembling may vary with the carbon chain size between the tellurium atoms, aryl groups bond to the tellurium atom and the amount of molecular iodine used in the reaction. To ditelluroethers iodides of type [(PhTeI2)2(μ-CH2)] (1) with the participation of secondary bonds could be observed the formation of one-dimensional pseudo polymers. However, in ditelluroethers iodides in which the carbon chain contains four carbons, the formation of two-dimensional pseudo polymers to [(4-MeOC6H4TeI2)2(μ-C4H8)]·CH2Cl2 (12) or three-dimensional to [(PhTeI2)2(μ-C4H8)] (9) and [(2,6-MeOC6H3TeI2)2(μ-C4H8)] (13) were obtained. It was also verified the influence of the aryl group bonded to the tellurium atom, as the compound [(2,6-MeOC6H3TeI2)2](μ-CH2)] (4) which, instead of forming pseudo polymers, occurs the formation of molecular discrete structure. The use of different amounts of iodine also caused an influence on the crystalline packing as in [(PhTeI)2(μ-C3H6)(μ-O)] (5). / Este trabalho apresenta a síntese e caracterização de treze novos compostos pertencentes à classe dos iodetos de diteluroéteres. Os reagentes de partida (diteluroéteres) foram sintetizados por uma metodologia até então pouco citada na literatura para a síntese dessa classe de compostos. Essa metodologia mostrou-se eficiente uma vez que foram sintetizados dez novos diteluroéteres com rendimentos satisfatórios. Dos treze compostos sintetizados, seis tiveram sua estrutura determinada por difração de raios X. A partir da análise estrutural desses diferentes iodetos de diteluroéteres pode-se concluir que a organização do empacotamento cristalino e a formação de associações supramoleculares pode variar de acordo com o tamanho da cadeia carbônica entre os átomos de telúrio, os grupamentos arila ligados ao átomo de telúrio e a quantidade de iodo molecular utilizado na reação. Para iodetos de diteluroéteres do tipo [(PhTeI2)2(μ-CH2)] (1) com a participação das ligações secundárias observou-se a formação de pseudopolímeros unidimensionais. Entretanto, nos iodetos de diteluroéteres em que a cadeia carbônica é constituída por quatro carbonos, a formação de pseudopolímeros bidimensionais para [(4-MeOC6H4TeI2)2(μ-C4H8)]·CH2Cl2 (12) ou tridimensionais para [(PhTeI2)2(μ-C4H8)] (9) e [(2,6-MeOC6H3TeI2)2(μ-C4H8)] (13) foi obtida. Verificou-se também a influência do grupamento arila ligado ao átomo de telúrio, como no composto [(2,6-MeOC6H3TeI2)2](μ-CH2)] (4) no qual ao invés de formar pseudopolímeros ocorre a formação de uma estrutura molecular discreta. A utilização de diferentes quantidades de iodo também mostrou exercer influência no empacotamento cristalino como em [(PhTeI)2(μ-C3H6)(μ-O)] (5).

This thesis summarizes three novel and general reaction protocols for the synthesis of diaryliodonium salts. All protocols utilize mCPBA as oxidant and the acids used are either TfOH, to obtain triflate salts, or BF3•Et2O that gives the corresponding tetrafluoroborate salts in situ. Chapter two describes the reaction of various arenes and aryl iodides, delivering electron-rich and electron-deficient triflates in moderate to excellent yields. In chapter three, it is shown that the need of aryl iodides can be circumvented, as molecular iodine can be used together with arenes in a direct one-pot, three-step synthesis of symmetric diaryliodonium triflates. The final and fourth chapter describes the development of a sequential one-pot reaction from aryl iodides and boronic acids, delivering symmetric and unsymmetric, electron-rich and electron-deficient iodonium tetrafluoroborates in moderate to excellent yields. This protocol was developed to overcome mechanistic limitations existing in the protocols described in chapter two and three. The methodology described in this thesis is the most general, efficient and high-yielding existing up to date, making diaryliodonium salts easily available for various applications in synthesis.

No description available.

Dans le cadre des recherches menées dans le domaine de la sûreté des réacteurs nucléaires, la problématique de la formation des oxydes d'iode dans l'enceinte de confinement par la destruction d'iodures organiques lors d'un accident grave a été étudiée avec les moyens du domaine de la chimie atmosphérique.La cinétique de destruction d'iodures organiques (tels que CH3I, CH2I2, CHI3, C2H5I, n-C3H7I et i-C3H7I) par les radicaux OH et O a d'abord été étudiée avec un système de Photolyse Flash – Résonance Fluorescente, dans des conditions représentatives de l'enceinte d'un accident de réacteur nucléaire accidenté. Des constantes cinétiques et leurs énergies d'activation ont été déterminées, dont certaines pour la première fois dans la littérature. Les mécanismes d'oxydation par OH et O des iodures organiques sont soit par abstraction d'un atome d'hydrogène, soit par la formation d'un complexe, menant à l'arrachement de l'atome d'iode. Ensuite, une analyse avec le code IODAIR a permis de réactualiser certaines cinétiques et de compléter ce code avec l'ajout de nouvelles réactions publiées récemment. Une comparaison de la cinétique globale de destruction de CH3I par OH et O dans le code IODAIR et de la constante cinétique globale inclue dans le code ASTEC/IODE a mis en évidence une différence d'un facteur environ 2, ce qui montre l'influence de ces deux radicaux (et principalement de O) sur la destruction des iodures organiques. L'autre voie de destruction majoritaire serait par rayonnement électronique. Les autres radicaux comme H ou N ne contribueraient que très peu à leur disparition. / Within the framework of the research in the nuclear reactor safety field, the iodine oxides formation by organic iodides destruction in the containment has been studied with the means of the atmospheric chemistry field. The destruction kinetics and their activation energy of organic iodides by OH and O radical has been quantified by a Flash Photolysis system able to monitor the oxidant radicals by resonance fluorescence. Those results have been published and some of them for the first time in the literature. The mechanisms leading to the organic iodides destruction are either by a hydrogen atom abstraction, either by the formation of a complex, depending on the organic iodide involved. Then, certain kinetics reactions have been updated in the IODAIR code. Other reactions have been added based on the recent literature available. A comparison of the kinetics destruction of CH3I by OH and O with IODAIR and the global kinetics of destruction in ASTEC/IODE showed a difference of about 2 which shows the importance of these two radicals (and mainly O) in those destruction processes. The other main path of destruction would be by electron radiation. Other radicals like H and N would not contribute significantly to organic iodides destruction. A sensitivity analysis highlighted that organic iodides would mostly be destroyed into iodine oxides with a almost complete conversion within a few hours. Finally, an atmospheric chamber has been used to quantify iodine oxides growth, density and composition. Under the conditions studied, their formation is fast. Particles sizes of about 200- 400 nm are formed within a few hours.

A reação entre a N,N,N\',N\'-tetrametilmalonamida e os iodetos de lantanídeos e ítrio em acetona conduziu a formação dos compostos de adição de fórmula geral LnI3.xTMMA (x = 5, Ln= La, Ce; x = 4, Ln = Pr - Lu, V). Os produtos da reação são cristalinos e apresentam a coloração característica dos correspondentes íons lantanídeos , porém bem menos pronunciadas; não são, em geral, higroscópicos; são bastante solúveis em água, nitrometano e acetonitrila, menos solúveis em metanol e etanol, fracamente solúveis em nitrobenzeno, acetona e praticamente insolúveis em benzeno, tetracloreto de carbono e clorofórmio. Fundem com decomposição na faixa entre 200 e 2500 C°. Os compostos obtidos foram caracterizados por análise elementar, espectros na região do infra-vermelho, difração de raios-X (método do pó), condutância molar. Foram obtidos espectros na região do visível dos compostos de neodímio, hólmio e érbio, em solução; o espectro do composto de neodímio foi também obtido no estado sólido em temperaturas diferentes. Foi registrado o espectro de fluorescência do composto de eurôpio , no estado sólido, em temperatura do nitrogênio líquido. Os espectros na região do infra-vermelho indicaram que a coordenação do ligante se efetua através dos átomos de oxigênio da carbonila. Os difratogramas de raios-X permitiram a identificação de quatro tipos de estruturas: o primeiro e constituído dos compostos de lantânio e cério; o segundo forma uma série isomorfa que se estende do composto de praseodímio ao do disprósio, o terceiro é constituído do composto de hôlmio e o último tipo é formado pelos compostos de érbio a lutécio, incluíndo ítrio. Os valores obtidos para as medidas de condutância molar mostram que os compostos comportam-se como eletrólitos 1: 3 em acetonitrila e nitrometano e como eletrólitos 1:2 em metanol. Os espectros de absorção eletrônicos dos compostos de neodímio, hólmio e érbio em solução de acetonitrila, não são essencialmente modificados nas diferentes concentrações em que os mesmos foram registrados. O estudo do espectro do composto de neodímio permitiu mostrar que a interação entre o ligante e o Nd3+ é essencialmente eletrostática. Os valores do parâmetro nefelauxético, β e do fator de covalência, b1/2 e de SINHA, δ, indicaram este fato. A força do oscilador foi calculada em solução de nitrometano e comparada com os valores obtidos para outros compostos O espectro de fluorescência do composto de európio sugere simetria D2d para o Eu3+, Foi admitida esta mesma simetria para os compostos que apresentam estruturas cristalinas iguais. Um estudo comparativo sobre espectroscopia de absorção e emissão na região do visivél foi realizado utilizando-se de compostos de adição contendo perclorato, hexafluorfosfato, nitrato, isotiocianato e cloreto de neodímio e európio com a N,N,N\',N\'-tetrametilmalonamida. Dados sobre os parâmetros nefelauxéticos, fatores de covalência e forças do oscilador foram determinados para cada composto de neodímio. As simetrias possíveis e os poliedros de coordenação para os compostos de európio foram sugeridos. / Addition compounds of formula Lni3.xTMMA (x = 5 for Ln = La, Ce and x = 4 for Ln = Pr - Lu, Y) were prepared by reaction of N,N.N\',N\'-tetramethylmalonamide (TMMA) and lanthanide iodides in acetone. The crystalline adducts present the same, but fainter colors of the corresponding lanthanide ions; they are in general practically not hygroscopic and melt with decomposition between 200-250°. They are soluble in water, nitromethane, acetonitrile, slightly soluble in methanol, ethanol, nitrobenzene, acetone and practically insoluble in benzene, carbon tetrachloride and chloroform. The compounds were characterized by elemental analysis, infrared spectra, X-ray powder patterns, electrolytic molar conductance, visible spectra of neodymium, holmium and erbium in acetonitrile, absorption spectrum of the solid neodymium compound at different temperatures and emission spectrum of the solid europium compound at liquid nitrogen temperature. lnfrared spectra indicate that coordination of the ligand occurs through the carbonyl oxygens. X-ray patterns show four types of structures: the first contains the lanthanum and cerium compounds; the second the adducts for praseodymium to dysprosium, the third the holmium compound and the fourth type the adducts from erbium to lutecium and yttrium. Conductance data indicate a behaviour of 1:3 electrolytes in acetonitrile and nitromethane, and 1:2 electrolytes in methanol. The visible spectra of neodymium, holmium and erbium adducts in acetonitrile are not essentially modified at different concentrations. The nephelauxetic parameter, β, the covalency factor, b1/2 and the SINHA\'s parameter, δ, were determined from the neodymium spectrum. The values obtained show that the interaction between Nd3+ and the ligand is essentially electrostatic. The oscillator strenght was calculated from the neodymium spectrum in nitromethane solution and the value was compared with those obtained for other neodymium adducts. The number of bands and shape of the emission spectrum of the europium compound may suggest the D2d symmetry for the adducts of the same isomorphous series. A comparative study concerning absorption and emission spectra of the perchlorate, hexafluorphosphate, nitrate, isothiocyanate and chloride neodymium and europium adducts with TMMA was realized. The parameters, β, b1/2 and δ and the oscillator strenghts. P, were determined for the neodymium adducts. The emission spectra of the corresponding europium compounds were also determined. Suggestions concerning symmetry and geometry of the adducts are given.

A reação entre a N,N,N\',N\'-tetrametilmalonamida e os iodetos de lantanídeos e ítrio em acetona conduziu a formação dos compostos de adição de fórmula geral LnI3.xTMMA (x = 5, Ln= La, Ce; x = 4, Ln = Pr - Lu, V). Os produtos da reação são cristalinos e apresentam a coloração característica dos correspondentes íons lantanídeos , porém bem menos pronunciadas; não são, em geral, higroscópicos; são bastante solúveis em água, nitrometano e acetonitrila, menos solúveis em metanol e etanol, fracamente solúveis em nitrobenzeno, acetona e praticamente insolúveis em benzeno, tetracloreto de carbono e clorofórmio. Fundem com decomposição na faixa entre 200 e 2500 C°. Os compostos obtidos foram caracterizados por análise elementar, espectros na região do infra-vermelho, difração de raios-X (método do pó), condutância molar. Foram obtidos espectros na região do visível dos compostos de neodímio, hólmio e érbio, em solução; o espectro do composto de neodímio foi também obtido no estado sólido em temperaturas diferentes. Foi registrado o espectro de fluorescência do composto de eurôpio , no estado sólido, em temperatura do nitrogênio líquido. Os espectros na região do infra-vermelho indicaram que a coordenação do ligante se efetua através dos átomos de oxigênio da carbonila. Os difratogramas de raios-X permitiram a identificação de quatro tipos de estruturas: o primeiro e constituído dos compostos de lantânio e cério; o segundo forma uma série isomorfa que se estende do composto de praseodímio ao do disprósio, o terceiro é constituído do composto de hôlmio e o último tipo é formado pelos compostos de érbio a lutécio, incluíndo ítrio. Os valores obtidos para as medidas de condutância molar mostram que os compostos comportam-se como eletrólitos 1: 3 em acetonitrila e nitrometano e como eletrólitos 1:2 em metanol. Os espectros de absorção eletrônicos dos compostos de neodímio, hólmio e érbio em solução de acetonitrila, não são essencialmente modificados nas diferentes concentrações em que os mesmos foram registrados. O estudo do espectro do composto de neodímio permitiu mostrar que a interação entre o ligante e o Nd3+ é essencialmente eletrostática. Os valores do parâmetro nefelauxético, β e do fator de covalência, b1/2 e de SINHA, δ, indicaram este fato. A força do oscilador foi calculada em solução de nitrometano e comparada com os valores obtidos para outros compostos O espectro de fluorescência do composto de európio sugere simetria D2d para o Eu3+, Foi admitida esta mesma simetria para os compostos que apresentam estruturas cristalinas iguais. Um estudo comparativo sobre espectroscopia de absorção e emissão na região do visivél foi realizado utilizando-se de compostos de adição contendo perclorato, hexafluorfosfato, nitrato, isotiocianato e cloreto de neodímio e európio com a N,N,N\',N\'-tetrametilmalonamida. Dados sobre os parâmetros nefelauxéticos, fatores de covalência e forças do oscilador foram determinados para cada composto de neodímio. As simetrias possíveis e os poliedros de coordenação para os compostos de európio foram sugeridos. / Addition compounds of formula Lni3.xTMMA (x = 5 for Ln = La, Ce and x = 4 for Ln = Pr - Lu, Y) were prepared by reaction of N,N.N\',N\'-tetramethylmalonamide (TMMA) and lanthanide iodides in acetone. The crystalline adducts present the same, but fainter colors of the corresponding lanthanide ions; they are in general practically not hygroscopic and melt with decomposition between 200-250°. They are soluble in water, nitromethane, acetonitrile, slightly soluble in methanol, ethanol, nitrobenzene, acetone and practically insoluble in benzene, carbon tetrachloride and chloroform. The compounds were characterized by elemental analysis, infrared spectra, X-ray powder patterns, electrolytic molar conductance, visible spectra of neodymium, holmium and erbium in acetonitrile, absorption spectrum of the solid neodymium compound at different temperatures and emission spectrum of the solid europium compound at liquid nitrogen temperature. lnfrared spectra indicate that coordination of the ligand occurs through the carbonyl oxygens. X-ray patterns show four types of structures: the first contains the lanthanum and cerium compounds; the second the adducts for praseodymium to dysprosium, the third the holmium compound and the fourth type the adducts from erbium to lutecium and yttrium. Conductance data indicate a behaviour of 1:3 electrolytes in acetonitrile and nitromethane, and 1:2 electrolytes in methanol. The visible spectra of neodymium, holmium and erbium adducts in acetonitrile are not essentially modified at different concentrations. The nephelauxetic parameter, β, the covalency factor, b1/2 and the SINHA\'s parameter, δ, were determined from the neodymium spectrum. The values obtained show that the interaction between Nd3+ and the ligand is essentially electrostatic. The oscillator strenght was calculated from the neodymium spectrum in nitromethane solution and the value was compared with those obtained for other neodymium adducts. The number of bands and shape of the emission spectrum of the europium compound may suggest the D2d symmetry for the adducts of the same isomorphous series. A comparative study concerning absorption and emission spectra of the perchlorate, hexafluorphosphate, nitrate, isothiocyanate and chloride neodymium and europium adducts with TMMA was realized. The parameters, β, b1/2 and δ and the oscillator strenghts. P, were determined for the neodymium adducts. The emission spectra of the corresponding europium compounds were also determined. Suggestions concerning symmetry and geometry of the adducts are given.

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