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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
161

Reagentes organometálicos: preparação e reatividade de compostos orgânicos de telúrio / Organometallic reagents: preparation and reactivity of organic compounds of tellurium

Silva, Márcio Santos da 18 November 2011 (has links)
Nesta tese foram desenvolvidas metodologias sintéticas para a preparação de compostos orgânicos de telúrio empregando reagentes organometálicos. Primeiramente, foi estudada a abertura tipo SN2 de lactonas, por organoiltelurolatos de lítio ou magnésio para obtenção dos respectivos ácidos telurocarboxílicos. Os organoiltelurolatos foram preparados a partir da reação do telúrio elementar com o organometálico desejado, evitando a manipulação de diteluretos alquílicos que apresentam odores desagradáveis. As reações de abertura de lactonas são de fácil execução e levam aos produtos em bons rendimentos (60 - 88 %). Além disso, há a possibilidade de transformação funcional dos produtos para alcoóis, a partir de uma redução in situ, ou para acil derivados, por meio da esterificação de Steglich. Os alcoóis obtidos são precursores sintéticos das respectivas espécies dilitiadas. Adicionalmente, foram preparados teluretos de alquil arila funcionalizados a partir da reação entre alquiltelurolatos de lítio com iodetos de arila catalisada por CuI (5 mol %). Também foi explorada a influência de ligantes, o que levou a um aumento do rendimento das reações testadas. Também foi estudada a reatividade de n-butilteluretos vinílicos e arílicos com reagentes organometálicos. Ou seja, foi estudada a reação de troca telúrio/metal com compostos organoilzinco e organoilmanganês. As reações com compostos de organoilzinco apresentaram resultados insatisfatórios, devido à baixa seletividade de transferência de grupos ligados ao zinco. As reações com compostos de manganês apresentaram bons resultados, com seletividade na transferência de ligantes e bons rendimentos dos produtos de captura dos compostos de organoilmanganês com eletrófilos. Foi estudada também a reação de acoplamento cruzado entre compostos de aril Grignard e teluretos de butil-vinila na presença de cloreto de manganês e iodeto de cobre (MnCl2/CuI). A reação ocorreu com elevada estereosseletividade e com rendimentos de moderados a bons. / In this PhD thesis synthetic methodologies for the preparation of organic compounds of tellurium employing organometallic reagents were developed. Initially, the SN2 type opening reaction of lactones by means of lithium or magnesium organotellurolates leading to the corresponding carboxylic acids was studied. The metal organotellurolates were prepared by reacting elemental tellurium with organolithium or Grignard reagents, avoiding the manipulation of bad smelling dialkylditellurides. The opening reactions occured easily, leading to the products in good yields (60 - 88 %). The tellurocarboxylic acids were transformed into alcohols by in situ reduction or into acyl derivatives, by a Steglich esterification. The obtained alcohols are precursors of the corresponding dilithium species by reaction with n-butyllithium. Additionally, functionalized arylbutyltellurides were prepared by reacting lithium alkyltellurolates with functionalized aryl iodides in the presence of CuI (5 mol %). The influence of ligands was also explored, leading to improved yields. It was also investigated the reactivity of vinyl butyltellurides with organometallic reagents. The tellurium/metal exchange reaction with organozinc and organomanganese compounds was studied. The reactions with organozinc compounds presented unsatisfactory results, in view of the low selectivity transfer of the groups linked to zinc. The reaction with organomanganese compounds presented better results in view of the fast Te/Mn exchange reaction, selectivity in the ligand transfer and good yields of the organomanganese capture products with electrophiles. It was also studied the cross-coupling reaction between aryl Grignard reagents and vinyl butyl tellurides in the presence of manganese chloride and copper iodide (MnCl2/CuI). The reaction occuried with high stereosselectivity and in moderate to good yields.
162

Reagentes organometálicos: preparação e reatividade de compostos orgânicos de telúrio / Organometallic reagents: preparation and reactivity of organic compounds of tellurium

Márcio Santos da Silva 18 November 2011 (has links)
Nesta tese foram desenvolvidas metodologias sintéticas para a preparação de compostos orgânicos de telúrio empregando reagentes organometálicos. Primeiramente, foi estudada a abertura tipo SN2 de lactonas, por organoiltelurolatos de lítio ou magnésio para obtenção dos respectivos ácidos telurocarboxílicos. Os organoiltelurolatos foram preparados a partir da reação do telúrio elementar com o organometálico desejado, evitando a manipulação de diteluretos alquílicos que apresentam odores desagradáveis. As reações de abertura de lactonas são de fácil execução e levam aos produtos em bons rendimentos (60 - 88 %). Além disso, há a possibilidade de transformação funcional dos produtos para alcoóis, a partir de uma redução in situ, ou para acil derivados, por meio da esterificação de Steglich. Os alcoóis obtidos são precursores sintéticos das respectivas espécies dilitiadas. Adicionalmente, foram preparados teluretos de alquil arila funcionalizados a partir da reação entre alquiltelurolatos de lítio com iodetos de arila catalisada por CuI (5 mol %). Também foi explorada a influência de ligantes, o que levou a um aumento do rendimento das reações testadas. Também foi estudada a reatividade de n-butilteluretos vinílicos e arílicos com reagentes organometálicos. Ou seja, foi estudada a reação de troca telúrio/metal com compostos organoilzinco e organoilmanganês. As reações com compostos de organoilzinco apresentaram resultados insatisfatórios, devido à baixa seletividade de transferência de grupos ligados ao zinco. As reações com compostos de manganês apresentaram bons resultados, com seletividade na transferência de ligantes e bons rendimentos dos produtos de captura dos compostos de organoilmanganês com eletrófilos. Foi estudada também a reação de acoplamento cruzado entre compostos de aril Grignard e teluretos de butil-vinila na presença de cloreto de manganês e iodeto de cobre (MnCl2/CuI). A reação ocorreu com elevada estereosseletividade e com rendimentos de moderados a bons. / In this PhD thesis synthetic methodologies for the preparation of organic compounds of tellurium employing organometallic reagents were developed. Initially, the SN2 type opening reaction of lactones by means of lithium or magnesium organotellurolates leading to the corresponding carboxylic acids was studied. The metal organotellurolates were prepared by reacting elemental tellurium with organolithium or Grignard reagents, avoiding the manipulation of bad smelling dialkylditellurides. The opening reactions occured easily, leading to the products in good yields (60 - 88 %). The tellurocarboxylic acids were transformed into alcohols by in situ reduction or into acyl derivatives, by a Steglich esterification. The obtained alcohols are precursors of the corresponding dilithium species by reaction with n-butyllithium. Additionally, functionalized arylbutyltellurides were prepared by reacting lithium alkyltellurolates with functionalized aryl iodides in the presence of CuI (5 mol %). The influence of ligands was also explored, leading to improved yields. It was also investigated the reactivity of vinyl butyltellurides with organometallic reagents. The tellurium/metal exchange reaction with organozinc and organomanganese compounds was studied. The reactions with organozinc compounds presented unsatisfactory results, in view of the low selectivity transfer of the groups linked to zinc. The reaction with organomanganese compounds presented better results in view of the fast Te/Mn exchange reaction, selectivity in the ligand transfer and good yields of the organomanganese capture products with electrophiles. It was also studied the cross-coupling reaction between aryl Grignard reagents and vinyl butyl tellurides in the presence of manganese chloride and copper iodide (MnCl2/CuI). The reaction occuried with high stereosselectivity and in moderate to good yields.
163

Etude du transport de l'iode par chémogénomique / A chemogenomics study of iodide transport

Waltz, Fanny 17 October 2011 (has links)
Une importante avancée dans la compréhension des mécanismes gouvernant le processus de transport des ions iodures à l’intérieur des cellules thyroïdiennes a été le clonage en 1996 de la protéine responsable de ce transport : le symporteur Na/I (ou NIS). De nombreuses recherches ont été conduites depuis afin de caractériser cette protéine ainsi que les mécanismes qui régulent son expression et son activité. Les mécanismes cellulaires de régulation du transport et les protéines impliquées dans la régulation post-traductionnelle du symporteur restent toutefois largement inconnus. La compréhension de l’ensemble de ces mécanismes permettrait pourtant d’améliorer le traitement d’un grand nombre de patients. Le transport d’iode est en effet non seulement impliqué dans différentes pathologies de la thyroïde, mais aussi dans les contaminations à l’iode radioactif consécutives aux accidents nucléaires et dans de prometteuses stratégies de thérapie génique anticancéreuses. La chémogénomique, aussi appelée génétique chimique, est une approche multidisciplinaire dont le but est d’explorer les systèmes vivants au moyen de petites molécules organiques. Afin de mieux comprendre les mécanismes qui gouvernent le transport d’iode, notre laboratoire a mis en place une stratégie de génétique chimique qui a permis dans un premier temps de découvrir 10 molécules capables d’inhiber le transport d’iode. L’objectif de cette thèse était d’identifier les cibles protéiques de deux de ces molécules : ITB5 et ITB2. Des études d’électrophysiologie et de flux isotopique ayant montré que ces deux molécules ont un mode d’action différent, leur étude devait permettre d’identifier au moins deux protéines impliquées dans le transport des ions iodures.Afin d’identifier les protéines cibles d’ITB5 et d’ITB2, des sondes ont été synthétisées. Ces sondes sont constituées du composé d’intérêt, d’un groupement photoactivable permettant de créer, sous irradiation lumineuse, une liaison covalente avec la ou les protéine(s) cible(s) et d’une molécule de Biotine ou de Desthiobiotine afin d’extraire les protéines marquées des lysats cellulaires. Une fois marquées et capturées sur des billes d’agarose Streptavidine, les protéines d’intérêt ont été séparées sur des gels SDS-PAGE colorés au nitrate d’argent ou au bleu de Coomassie. Les bandes correspondantes ont été excisées, digérées à la trypsine et les peptides obtenus analysés par spectrométrie de masse. L’interrogation de la base de données Swissprot avec les données issues des expériences menées avec la sonde ITB5-P2 a permis d’identifier 3 protéines interagissant visiblement avec ce composé. Les expériences basées sur le composé ITB2 ont du être suspendues par manque de temps mais des résultats encourageants ont déjà été obtenus. Une bande pouvant correspondre à une protéine marquée spécifiquement par la sonde ITB2-P1 a en effet pu être observée en Western-blot suite à une première expérience de capture sur billes. Elle n’a toutefois pas pu être visualisée sur gel du fait d’une présence trop importante de protéines captées non spécifiquement par les billes. Les conditions expérimentales de capture ayant été optimisées avec le composé ITB5, leur application au composé ITB2 devrait maintenant permettre d’obtenir des gels plus propres à partir desquels la bande d’intérêt pourra être excisée pour être, elle aussi, analysée par spectrométrie de masse. / An important breakthrough in the understanding of the mechanisms governing the process of iodide transport inside thyroid cells has been the cloning in 1996 of the protein responsible for this transport : the Na/I symporter (NIS). Different studies have been conducted ever since in order characterize this protein as well as the mechanisms which regulate its expression and its activity. Nevertheless, the cellular mechanisms of transport regulation and the proteins implied in the posttranslational regulation of the symporter remain largely unknown. The full understanding of these mechanisms would allow the treatment improvement of a lot of patients. Iodide transport is indeed involved not only in different thyroid pathologies, but also in radioactive iodide contaminations following nuclear accidents and in promising anticancer strategies by gene transfer. Chemogenomics, also called chemical genetics, is a multidisciplinary approach which goal is to explore the living systems thanks to small organic molecules. To better understand the mechanisms which govern iodide transport, our laboratory has set up a direct chemical genetic strategy which allowed us first to discover 10 molecules able to inhibit iodide transport. The objective of this thesis was to identify the protein targets of two molecules : ITB5 and ITB2. Electrophysiological and isotopic flux studies showed that these two molecules have a different mechanism of action. Their study should then allow the identification of at least two proteins involved in iodide transport.To identify the protein targets of ITB5 and ITB2, different probes were synthesized. These probes are made from the compound of interest, a photoactivable group allowing the creation, under light irradiation, of a covalent bound with the protein target(s) and a Biotin or Desthiobiotine molecule to extract the labeled proteins from cellular lysates. Once labeled and captured on agarose-Streptavidin beads, the proteins of interest were separated on SDS-PAGE gels stained either with silver nitrate or Coomassie blue. The corresponding bands were excised, digested by trypsin and the obtained peptides analyzed by mass spectrometry. A query made in the data bank Swissprot with the data obtained after the experiments conducted with the probe ITB5-P2 allowed us to identify 3 proteins apparently interacting with the compound ITB5. The experiments based on ITB2 had to be suspended because of a lack of time but encouraging results have been obtained. A band which may correspond to a protein specifically labeled by the probe ITB2-P1 has indeed been observed on a Western-blot after a first on-bead capture experiment. However, we couldn’t visualize it on a gel because of the important presence of proteins captured non specifically by the beads. The capture experimental conditions were optimized with the compound ITB5. These conditions will now be applied to the compound ITB2 and this should allow us to obtain cleaner gels on which the band of interest will be excised for an analyze by mass spectrometry.
164

Multi-capteurs chimiques de chloramines et de chloroforme à transduction optique. Application à la surveillance de la qualité de l’air dans les piscines / Multi-chemical sensor for the optical detection of chloramines and chloroform. Application for monitoring the air quality in pools

Nguyen, Trung Hieu 04 February 2014 (has links)
Le chlore est largement utilisé pour ses propriétés bactéricides dans les piscines. Dans les eaux de piscine, le chlore réagit avec les matières azotées et carbonées générées par l’activité humaine (sueur, salive, urine, peau) pour former divers composés toxiques tels que la monochloramine (NH2Cl), la dichloramine (NHCl2), le trichlorure d'azote (NCl3), le chloroforme (CHCl3), etc… qui se retrouvent dans l’atmosphère. La détection et la quantification de ces composés volatils à des teneurs ppb (partie par milliard) est un réel besoin afin de contrôler la qualité de l’air des piscines. Cependant il n’existe pas à ce jour des appareils à la fois sensibles et peu coûteux.L’objectif de ce travail de thèse est d’élaborer des capteurs chimiques colorimétriques, sensibles, sélectifs et peu coûteux de la monochloramine, du trichlorure d’azote et du chloroforme. Dans ce but, nous avons mis au point des capteurs chimiques réalisés à partir de matrices nanoporeuses de silicate dopée des réactifs. Ainsi le capteur de NCl3 dopé de NaI et d’amylose permet de mesurer de faibles teneurs de NCl3 (5 ppb à 180 ppb) dans les atmosphères humides (50-80% HR) des piscines. Grâce au changement rapide de couleur, de transparent à rose-violet, visible à l’œil nu, le capteur de NCl3 permet de surveiller la qualité de l’air dans les piscines. Le capteur sélectif de NH2Cl est basé sur la réaction de Berthelot. La matrice de silicate nanoporeuse dopée de nitroprussiate de sodium et de phénol en milieu alcalin, initialement transparente, devient bleue lors d’une exposition à NH2Cl gazeux. Ce capteur permet de détecter NH2Cl dans la gamme de 60 à 250 ppb dans une atmosphère très humide (≈ 80%). Utilisé pour la sonder la qualité des eaux de piscine, il permet de mesurer NH2Cl dans l’eau avec une limite de détection de 0,1 µmol•L-1. Une étude préliminaire de la détection de CHCl3 a également été entreprise pour déterminer les molécules-sonde aptes à réagir avec le chloroforme en formant des produits colorés. Les réactifs de la réaction de Fujiwara ont été sélectionnés. L’étude de la réactivité de la 2,2’-bipyridine en solution en présence d’une base forte a permis de mettre en évidence la formation simultanée de deux composés colorés, dont la formation dépend de la nature de l’environnement réactionnel. / In swimming-pools, chlorine is used as a disinfectant to minimize the risk to users from microbial contaminants. In water, chlorine reacts with nitrogen compounds generated by human activity like saliva, sweat, urine and skin, leading to the formation of toxic compounds, such as monochloramine (NH2Cl), dichloramine (NHCl2), nitrogen trichloride (NCl3), chloroform (CHCl3), etc… The detection and the quantification of these volatile compounds at ppb level (part per billion) is an important and significant challenge to be able to monitor the air quality in swimming pool. Or, there is currently no commercially available and low-cost system which can instantaneously measure at ppb concentrations.The aim of this research is to develop a cheap, sensitive and selective chemical and colorimetric sensors of monochloramine, nitrogen trichloride and chloroform. For this purpose, we developed chemical sensors based on the use of nanoporous silicate matrices doped with probe-molecules. The NCl3 sensor doped with NaI and amylose can detect NCl3 at ppb level (5 ppb – 180 ppb) in humid atmospheres (from 50% to 80% relative humidity) at ambient pool temperatures. Due to the fast change of color, visible with naked eyes, these sensors can be used to detect peaks of pollution and to monitor the air quality of indoor pools. The NH2Cl selective sensor is based on the Berthelot reaction. The nanoporous silicate matrices doped with sodium nitroprusside and phenol in an alkaline medium, turn from transparent to blue upon exposure to gaseous NH2Cl. This sensor can detect NH2Cl in the range from 60 to 250 ppb in a very humid atmosphere (≈ 80%). Used to probe the quality of pool water, this sensor can detect NH2Cl in water with a detection limit of 0,1 µmol•L-1. A preliminary study of the CHCl3 detection was also conducted to identify probe-molecules capable of reacting with chloroform to form colored products. The reagents of the Fujiwara reaction were selected. The study of the 2,2’-bipyridine reactivity in solution in the presence of a strong base allowed highlighting the simultaneous formation of two colored compounds, whose formation depends on the nature of the reaction environment.
165

Transition Metal Mediated Transformations of Carboranes

Eriksson, Ludvig January 2003 (has links)
<p>This thesis describes the use of copper and palladium to mediate transformations of carboranes, especially <i>p</i>-carborane.</p><p>1-(1-<i>p</i>-carboranyl)-<i>N</i>-methyl-<i>N</i>-(2-butyl)-3-isoquinolinecarboxamide, a carborane containing analogue of the peripheral benzodiazepine receptor (PBR) ligand PK11195, has been synthesised. A key step in the reaction is the copper (I) mediated coupling of p-carborane with ethyl 1-bromo-isoquinoline-3-carboxylate. </p><p><i>p</i>-Carborane has been arylated on the 2-<i>B</i>-atom in high yields, using the Suzuki–Miyaura reaction. Thus the reaction between 2-I-<i>p</i>-carborane and various arylboronic acids [1-naphthyl-, phenyl-, 4-MeO-C<sub>6</sub>H<sub>4</sub>-, 3-CH<sub>3</sub>CONH-C<sub>6</sub>H<sub>4</sub>-, 4-NC-C<sub>6</sub>H<sub>4</sub>-, 3-NO<sub>2</sub>-C<sub>6</sub>H<sub>4</sub>-], gave the corresponding 2-aryl-<i>p</i>-carboranes in DME solution when reacted in the presence of cesium fluoride and the catalytic Pd<sub>2</sub>(dba)<sub>3</sub>–dppb system. Under the same conditions, the boron-boron bond forming reaction of two <i>p</i>-carboranylboronic esters (2-[(pinacolato)boron]-<i>p</i>-carborane and 2-[(neopentyl glycolato)boron]-p-carborane) was also shown feasible.</p><p><i>p</i>-Carborane has been vinylated on the 2-<i>B</i>-atom in high yields by use of the Heck reaction. The coupling between 2-I-<i>p</i>-carborane and various styrenes [4-H-, 4-C<sub>6</sub>H<sub>4</sub>-, 4-Cl , 4-Br-, 4-NO<sub>2</sub>-, 4-CH3O- and 4 CH<sub>3</sub> ] resulted in the formation of the corresponding<i>trans</i>-β-(2-<i>B</i>-<i>p</i>-carboranyl) styrene in DMF solution when reacted in the presence of silver phosphate and the palladacycle Herrmann´s catalyst. The reaction was shown to proceed at higher rate with electron rich than with electron deficient olefins.</p><p>The feasibility of palladium-catalysed isotopic exchange of an iodinated closo-carborane with a radioisotope of iodine has been studied. 2-I-<i>p</i>-carborane was selected as a model compound. It was shown, that such isotopic exchange is possible and provides a high yield (83 ± 4.2 %) during 40 min long reaction. The reaction conditions were optimised, and it was demonstrated that presence of the tetra n-butylammonium hydrogensulphate is important in order to stabilise catalyst and provide reproducibility of labelling. In this work we have modified the methodology and extended the application to a wider range of iodinated carboranes. By the use of Herrmann’s catalyst in toluene at 100 °C this [<sup>125</sup>I]-iodide labelling could be improved and extended. 2-I-<i>p</i>- 9-I-<i>m</i>-, 9-I-<i>o</i>-, 3-I-<i>o</i>-carborane, 1-phenyl-3-I-<i>o</i>-carborane and 1,2-diphenyl-3-I-<i>o</i>-carborane could be [<sup>125</sup>I]-iodide labelled in high to excellent yields within 5 minutes.This reported palladium catalyzed radio-iodination of the uncharged closo-carboranes might find use in pharmacokinetic studies of carborane derivatives.</p>
166

Développement d'électrodes sélectives pour l'analyse de composés d'intérêt pharmaceutique : Antipaludéens et halogénures

Kimbeni Malongo, Trésor 25 June 2008 (has links)
RESUME Le travail de thèse porte sur le développement d’électrodes sélectives originales et performantes pour l’analyse de composés d’intérêt pharmaceutique. La partie introductive traite des notions relatives à l’électrochimie mais également de notions sur les molécules médicamenteuses étudiées, en l’occurrence les principes antipaludéens et l’iode. La partie expérimentale se subdivise en deux parties distinctes selon le type d’électrodes sélectives auxquelles font appel les techniques électrochimiques. La première partie concerne l’élaboration, la caractérisation et l’application des électrodes potentiométriques à membrane polymérique incluant une paire d’ions et sélectives à diverses molécules organiques pharmacologiquement actives (antipaludéens). Leur application aussi bien en analyse pharmaceutique qu’en cinétique de dissolution est décrite. La deuxième partie est consacrée à l’élaboration d’un type de senseur ampérométrique original à pâte de carbone à base d’argent micronisé ou colloïdal et à la comparaison de ses performances avec l’électrode d’argent métallique. L’intérêt analytique est mis en évidence par la détermination quantitative des iodures. Les différents aspects susceptibles d’influencer leur comportement, dont la nature des agents précipitants (tétraphénylborate de sodium et le tétrakis (4-chlorophényl) borate de potassium) et de plastifiants ont été investigués. Les bonnes performances des ces électrodes en analyse quantitative ont permis d’explorer les possibilités de leur utilisation à l’étude de la cinétique de dissolution. L’ampérométrie à électrode à pâte de carbone modifiée à base d’argent à l’échelle micronisée (35% m/m) couplée à la chromatographie liquide ionique s’est avérée très sensible vis-à-vis des iodures en particulier et des halogénures en général. Les facteurs susceptibles d’influencer les grandeurs de séparation et la réponse de l’électrode ont été investigués et l’exploitation du signal ampérométrique permet le dosage sélectif et rapide de faibles concentrations en iodures. Les informations fournies par les mesures réalisées en voltampérométrie cyclique à l’aide des mêmes électrodes permettent une bonne compréhension mécanistique quant au mode de détection ampérométrique évitant ainsi toute confusion à ce sujet et permettant l’optimisation du processus de détection. ------------------------------------------------ ABSTRACT This thesis describes the development of original and high performance selective electrodes for the analysis of several pharmaceutical compounds. The introduction describes the pharmaceutical compounds of interest (antimalarial drugs and iodine) and provides an overall understanding of the electrochemical groundwork pertaining to their analysis. The experimental aspect of the thesis is divided into two parts, each according to the type of electrode and electrochemical technique used for the analysis. The first part describes the design, characterization, and application of polymer membrane based ion selective potentiometric electrodes. Selectivity was provided by including ion pairs of several antimalarial drugs into the membrane. The feasibility of use of these electrodes in pharmaceutical analysis as well as in dissolution trials is also described in this part. The second part describes the design of an original silver-modified carbon paste amperometric sensor and compares its performances to those of a plain metallic silver electrode. The electrode has been modified by silver microparticles or by silver nanoparticles. Quantitative iodine determination serves to prove the usefulness of this new sensor in analytical chemistry. Different aspects, such as the nature of the counter ions (sodium tetraphenylborate and potassium tetrakis (4-chlorophenyl) borate) and the plastifying agents that are likely to influence electrode behaviour have been investigated. Since the electrodes have been shown to perform well in quantitative analysis, the possibility of use in dissolution trials was explored. Micronized silver-modified carbon paste electrode (35% Ag m/m) coupled to anionic-exchange liquid chromatography with amperometric detection was shown to be very sensitive with regards to the assay of halogenides in general and iodide in particular. After having investigated the various factors likely to influence chromatographic separation and electrode response, it was shown that the sensor could be used to rapidly and selectively determine low iodide concentrations in complex samples. Cyclic voltammetric analysis provided information concerning the mechanisms allowing amperometric detection, thus allowing an optimisation of the detection procedures.
167

Transition Metal Mediated Transformations of Carboranes

Eriksson, Ludvig January 2003 (has links)
This thesis describes the use of copper and palladium to mediate transformations of carboranes, especially p-carborane. 1-(1-p-carboranyl)-N-methyl-N-(2-butyl)-3-isoquinolinecarboxamide, a carborane containing analogue of the peripheral benzodiazepine receptor (PBR) ligand PK11195, has been synthesised. A key step in the reaction is the copper (I) mediated coupling of p-carborane with ethyl 1-bromo-isoquinoline-3-carboxylate. p-Carborane has been arylated on the 2-B-atom in high yields, using the Suzuki–Miyaura reaction. Thus the reaction between 2-I-p-carborane and various arylboronic acids [1-naphthyl-, phenyl-, 4-MeO-C6H4-, 3-CH3CONH-C6H4-, 4-NC-C6H4-, 3-NO2-C6H4-], gave the corresponding 2-aryl-p-carboranes in DME solution when reacted in the presence of cesium fluoride and the catalytic Pd2(dba)3–dppb system. Under the same conditions, the boron-boron bond forming reaction of two p-carboranylboronic esters (2-[(pinacolato)boron]-p-carborane and 2-[(neopentyl glycolato)boron]-p-carborane) was also shown feasible. p-Carborane has been vinylated on the 2-B-atom in high yields by use of the Heck reaction. The coupling between 2-I-p-carborane and various styrenes [4-H-, 4-C6H4-, 4-Cl , 4-Br-, 4-NO2-, 4-CH3O- and 4 CH3 ] resulted in the formation of the correspondingtrans-β-(2-B-p-carboranyl) styrene in DMF solution when reacted in the presence of silver phosphate and the palladacycle Herrmann´s catalyst. The reaction was shown to proceed at higher rate with electron rich than with electron deficient olefins. The feasibility of palladium-catalysed isotopic exchange of an iodinated closo-carborane with a radioisotope of iodine has been studied. 2-I-p-carborane was selected as a model compound. It was shown, that such isotopic exchange is possible and provides a high yield (83 ± 4.2 %) during 40 min long reaction. The reaction conditions were optimised, and it was demonstrated that presence of the tetra n-butylammonium hydrogensulphate is important in order to stabilise catalyst and provide reproducibility of labelling. In this work we have modified the methodology and extended the application to a wider range of iodinated carboranes. By the use of Herrmann’s catalyst in toluene at 100 °C this [125I]-iodide labelling could be improved and extended. 2-I-p- 9-I-m-, 9-I-o-, 3-I-o-carborane, 1-phenyl-3-I-o-carborane and 1,2-diphenyl-3-I-o-carborane could be [125I]-iodide labelled in high to excellent yields within 5 minutes.This reported palladium catalyzed radio-iodination of the uncharged closo-carboranes might find use in pharmacokinetic studies of carborane derivatives.
168

Chemical Derivatization in Combination with Liquid Chromatography Tandem Mass Spectrometry for Detection and Structural Investigation of Glucuronides

Lampinen Salomonsson, Matilda January 2008 (has links)
This thesis presents novel approaches for structural investigation of glucuronides using chemical derivatization in combination with liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MSn). Today, LC-ESI-MSn is the dominant technique for quantitative as well as qualitative analyses of metabolites, due to its high sensitivity and selectivity. However, for compounds without an easily ionizable group, e.g., steroids, the sensitivity is limited. In the work presented in this thesis, a derivatization procedure forming a basic oxime significantly increased the detection sensitivity for the altrenogest glucuronide. Furthermore, in structural evaluations of glucuronides, the limitation of LC-MSn becomes evident due to the initial neutral loss of 176 u, i.e. monodehydrated glucuronic acid, which often makes it impossible to elucidate the structures of the conjugates. To solve this problem, the main part of the work described in this thesis was devoted to chemical derivatization as a means of facilitating the determination of the site of conjugation. For the first time, the isomeric estriol glucuronides were evaluated using a combination of three reagents 2-chloro-1-methylpyridinium iodide (CMPI), 1-ethyl-3-(3-dimethyl- aminopropyl)-carbodiimide (EDC), and 2-picolylamine (PA). Interestingly, the derivatization gave a selective fragmentation pattern leading to differentiation of the isomers. Another derivatization reagent, 1,2-dimethylimidazole-4-sulfonyl chloride (DMISC), was also tested for the first time in structural investigations. The isomeric glucuronides of morphine, formoterol, and hydroxypropranolol were evaluated. They can all be conjugated in aliphatic as well as aromatic positions. DMISC was proven to be useful in two ways. Firstly, the morphine and formoterol glucuronides that contained a free phenol could be differentiated from those that were conjugated in the aromatic position based on different reactivity. Secondly, for the aromatic O-glucuronide of 4’-hydroxypropranolol, DMISC was proven to react with the amine. This product gave a different fragmentation pattern compared to the corresponding derivative of the aliphatic glucuronide.
169

Biochemical and Biophysical Studies of Human SUR1 NBD1, Rat SUR2A NBD2 and the Role of the C-terminal Extension in Rat SUR2A NBD1

Alvarez, Claudia Paola 18 March 2013 (has links)
SUR2A-mediated regulation of KATP channels is affected by residues belonging to the C terminus of the first nucleotide binding domain (NBD1). We studied the C-terminal region of NBD1 by comparing experiments using NBD1 S615-D914 and NBD1 S615-K972 constructs to studies of NBD1 S615-L933 also performed in our laboratory. Our NMR data suggests that the C-terminal region of NBD1 from residues Q915 to L933 is disordered and transiently contacts the NBD1 core, which may affect NBD1 phosphorylation. Tryptophan quenching fluorescence experiments corroborate that the Q915-L933 C-terminal tail contacts the NBD1 core. Fluorescence thermal denaturation experiments suggest that NBD1 S615-D914 has a higher affinity for MgATP compared with NBD1 S615-L933, implying that the C-terminal tail varies MgATP binding. Additional experiments were performed to identify soluble constructs of hSUR1 NBD1 and rSUR2A NBD2 that would allow detailed biophysical studies of these domains. Some of the constructs studied showed improved solubility and stability.
170

Biochemical and Biophysical Studies of Human SUR1 NBD1, Rat SUR2A NBD2 and the Role of the C-terminal Extension in Rat SUR2A NBD1

Alvarez, Claudia Paola 18 March 2013 (has links)
SUR2A-mediated regulation of KATP channels is affected by residues belonging to the C terminus of the first nucleotide binding domain (NBD1). We studied the C-terminal region of NBD1 by comparing experiments using NBD1 S615-D914 and NBD1 S615-K972 constructs to studies of NBD1 S615-L933 also performed in our laboratory. Our NMR data suggests that the C-terminal region of NBD1 from residues Q915 to L933 is disordered and transiently contacts the NBD1 core, which may affect NBD1 phosphorylation. Tryptophan quenching fluorescence experiments corroborate that the Q915-L933 C-terminal tail contacts the NBD1 core. Fluorescence thermal denaturation experiments suggest that NBD1 S615-D914 has a higher affinity for MgATP compared with NBD1 S615-L933, implying that the C-terminal tail varies MgATP binding. Additional experiments were performed to identify soluble constructs of hSUR1 NBD1 and rSUR2A NBD2 that would allow detailed biophysical studies of these domains. Some of the constructs studied showed improved solubility and stability.

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