Neste trabalho, foi desenvolvido equipamento portátil e procedimentos analíticos automáticos para determinação de cátions e anions em águas usadas para consumo humano e suprimento. Os procedimentos foram baseados no processo de multicomutação em fluxo e detecção fotométrica empregando fotômetro feito no laboratório. Os sistemas de fluxo foram construídos empregando válvulas solenóide, com interface independente de comutação acionadas por computador usando apenas um canal de bombeamento. O sistema proposto foi controlado por um computador rodando um software escrito em QuickBasic 4.5. Os dói fotômetros baseados em LED foram desenvolvidos usando como detectores de radiação foto-transistores e foto-diodos. Nos dois casos a fonte de radiação (LED) e o foto-detector foram acoplados a cela de fluxo obtendo assim, uma unidade compacta. O fotômetro foi projetado para usar um foto-transistor para determinações seqüenciais de nitrato, nitrito, ferro(II), ferro(III) em águas de rios.O fotômetro proposto usa um foto-diodo para determinação de cloreto por turbidimetria, fosfato e amonium por fotometria. A sistema de fluxo foi desenhado associando-se os processos de multicomutação e multisite garantindo redução de reagente e de efluente. O sistema sistema foi empregado para determinação de cloreto, fosfato e amônio em águas de rios. Os dois sistemas propostos apresentaram excelente performance incluindo boa precisão, freqüência analítica e baixo consumo de reagente. Além disso, o sistema baseado em multisite apresentou baixo volume de efluente gerado. As dimensões reduzidas de ambos os fotômetros e do modulo de analise em fluxo, permitiram a portabilidade, o que possibilita sua aplicação em condições de campo. / In this work it was developed a portable apparatus and automatic analytical procedures for the determination of cations and anions in waters used for human consumption and industrial provisioning. The procedures were based on the multicommutation process in flow analysis and detection was performed using a homemade photometer. The flow systems were designed employing a set of solenoid valves, which were assembled to work as independent commutation units, thus under computer control several solutions were handled using a single pumping channel. The proposed system was controlled by computer running a software wrote in QuickBasic 4.5. The two LED based photometers were developed using as light detection a phototransistor and a photodiode. In both cases, the radiation source (LED) and the photodector were coupled to the flow cell in order to obtain compact unit. The photometer designed using a phototransistor was employed for the sequential determination of nitrate, nitrite, iron(II) and iron(III) in river water. The photometer designed using a photodiode was employed in the system used for the determination of chloride by turbidimetry, phosphate and ammonium by photometry. The flow system was designed associating the multisite and multicommutation process intending reduction of the reagent consumption and waste generation. The useful of the system was proved performing the determination of chloride, ammonium and phosphate in river water. The two proposed systems presented very overall performance including precision and accuracy, analytical frequency and low reagent consumption. Furthermore, the system based on multisite approach presented a very low volume of waster generation. The reduced dimensions of both photometer and flow system module allow their portability, thus we can suggest that the proposed systems are reliable for work in field condition.

Ce mémoire est consacré à la conception de matériaux moléculaires pour la détection et le dosage in situ d'espèces cationiques par deux approches électrochimiques d'analyse : la reconnaissance électrochimique cationique et la redissolution anodique.<br />La première partie de ce travail concerne l'étude de deux récepteurs complexants possédant plusieurs centres rédox. Ces récepteurs présentent des propriétés de reconnaissance électrochimique, en milieux aqueux ou organique, et cette reconnaissance est basée soit sur le phénomène de communication électronique intramoléculaire entre les centres rédox multiples, soit sur les modes de coordination mis en jeu dans les complexes formés. Ces ligands ont été mis à profit pour la détection, la quantification et la différenciation électrochimique de cations métalliques et lanthanides.<br />Dans une seconde partie, deux matériaux d'électrodes constitués par des films de polymères complexants permettant la détection et le dosage électrochimique de cations métalliques ont été élaborés et optimisés dans le but de développer de nouveaux dispositifs électroanalytiques sensibles et sélectifs pour l'analyse de traces de métaux.

Ce travail se propose de corréler les propriétés de transport électronique souvent très remarquables des oxydes de structure dérivée de la perovskite à leurs propriétés structurales. D'un point de vue expérimentale, l'intercalation électrochimique d'espèces oxygénées dans ces réseaux a permis d'obtenir des matériaux de cations de valences élevées où les phénomènes de transfert de charges sont exacerbés...

Le cuivre est un élément essentiel à tout être vivant, il intervient en tant que cofacteur dans de nombreux processus biologiques. Cependant, en excès, il est toxique pour l'organisme et peut impliquer des réactions de type Fenton. Sa concentration dans les cellules est donc régulée par des protéines qui permettent son transport et son élimination. La maladie de Wilson est due à une anomalie au niveau d'une de ces protéines (l'ATP7B). C'est une maladie génétique, dont les deux parents sont porteurs sains. Elle entraîne une accumulation du cuivre dans le foie, le cerveau et les yeux. Cette maladie orpheline (1/30 000 à 1/100000) présente des symptômes nombreux et souvent peu spécifiques à la maladie de Wilson. Les traitements actuels visent à diminuer l'absorption intestinale ou à augmenter l'excrétion urinaire du cuivre et doivent être suivis à vie. Ils ne visent absolument pas le foie qui est le premier organe touché et sont peu sélectifs du cuivre. Actuellement, il n'existe pas de traitement capable d'éliminer le cuivre directement au niveau du foie qui est le premier organe touché. Une molécule capable d'éliminer le cuivre en excès contenu dans les cellules du foie (hépatocytes) serait donc très utile pour soulager les malades. Pour cela, nous avons conçu des vecteurs comportant une partie ciblante pour pouvoir cibler le foie et une partie chélatante pour complexer le cuivre(I). Cette partie chélatante présente une forte affinité pour le cuivre(I) et une forte sélectivité Cu+/Zn2+. Ainsi, deux modèles de parties chélatantes basés sur deux et trois cystéines ont été synthétisés et des études de complexation du cuivre(I) mais aussi d'autres métaux divalents de configuration d10 ont été réalisés. Enfin, la vectorisation de ces modèles a été réalisée et des tests cellulaires ont été faits afin d'évaluer la complexation des ces vecteurs pour le cuivre(I) intracellulaire.

La chimie des formes moléculaires électro et photo-actives de chalcogénures à clusters octaédriques de Re(III) est un domaine frontière au carrefour des matériaux hybrides organiques/inorganiques et de la chimie du solide. La première partie de ce travail de thèse concerne l'utilisation du cluster [Re6Se8(CN)6]4- comme noeud octaédrique pour orienter l'organisation de la structure étendue de sels de radicaux cations de dérivés du tétrathiafulvalène (TTF). Les groupements cyano sont connus en ingénierie cristalline pour leur aptitude à diriger les structures cristallines par le biais de liaisons halogène directionnelles CN-...I. Ces liaisons faibles ont été mises en oeuvre dans un sel de radical cation ternaire, où une molécule organique neutre di-halogénée joue le rôle d'espaceur entre deux clusters. L'organisation de la structure anionique du sel peut modifier les propriétés électroniques du matériau. Ce résultat a conduit à synthétiser d'autres espaceurs polyhalogénés et à les engager dans des expériences d'électrocristallisation. La seconde partie de ce travail est, pour une part, consacrée à l'exploration de la réactivité des formes moléculaires [Re6Se8(CH3CN)6](SbF6)2 vis-à-vis de ligands acétylénures. Cette approche est motivée par le débat actuel sur la nature de la structure électronique de ces formes moléculaires. D'autre part, la réactivité établie de ce cluster avec des dérivés de la pyridine nous a conduits à développer de nouveaux ligands fonctionnels basés sur ce motif. La fonctionnalisation des ligands confère au cluster de nouvelles propriétés qui dépendent de la nature du groupement terminal.

Structure elucidation of charge delocalised carotenoid mono- and dications by NMR and VIS/NIR spectroscopy. Studies of the nucleophilic reactions of these cations. Studies of the β,β-carotene-iodine complex. Isolation and anmalysis of new carotenoid glucoside esters from extremophilic bacteria.

G-quadruplex structures are found in important regions of the eukaryotic genome, such as telomeres and regulatory sequences of genes, and are likely to play important roles in regulation of biological events. The significant structural differences with duplex DNA make quadruplex DNA a very attractive target for anticancer drug design. The purpose of this study is to explore conformational space in a series of heterocyclic cations to discover novel structural motifs that can selectively bind and stabilize specific G-quadruplex arrangements. A variety of biophysical techniques such as thermal melting experiments, biosensor surface plasmon resonance, circular dichroism, fluorescence displacement assay and mass spectrometry were employed to evaluate the affinity of the compounds and their recognition properties. The screening of the molecules allowed the identification of not only selective G-quadruplex ligands but also potential quadruplex groove binders. These results can be useful for the development of new efficient telomerase inhibitors which are endowed with pharmacological activity.

The goal of this work was to better understand how molybdate and trivalent cations can be used as additives to pH neutral electrolytes to activate the Hydrogen Evolution Reaction (HER). Special emphasis was laid on the chlorate process and therefore also to some of the other effects that the additives may have in that particular process. Cathode films formed from the molybdate and trivalent cations have been investigated with electrochemical and surface analytical methods such as polarization curves, potential sweep, Electrochemical Impedance Spectroscopy (EIS), current efficiency measurements, Scanning Electron Microscope (SEM), Energy-Dispersive X-ray Spectroscopy (EDS), X-ray Photoelectron Spectroscopy (XPS), X-Ray Fluorescence (XRF) and Inductively Coupled Plasma (ICP) analysis. Trivalent cations and molybdate both activate the HER, although in different ways. Ligand water bound to the trivalent cations replaces water as reactant in the HER. Since the ligand water has a lower pKa than free water, it is more easily electrochemically deprotonated than free water and thus catalyzes the HER. Sodium molybdate, on the other hand, is electrochemically reduced on the cathode and form films which catalyze the HER (on cathode materials with poor activity for HER). Molybdate forms films of molybdenum oxides on the electrode surface, while trivalent cation additions form hydroxide films. There is a risk for both types of films that their ohmic resistance increases and the activity of the HER decreases during their growth. Lab-scale experiments show that for films formed from molybdate, these negative effects become less pronounced when the molybdate concentration is reduced. Both types of films can also increase the selectivity of the HER by hindering unwanted side reactions, but none of them as efficiently as the toxic additive Cr(VI) used today in the chlorate process. Trivalent cations are not soluble in chlorate electrolyte and thus not suitable for the chlorate process, whereas molybdate, over a wide pH range, can activate the HER on catalytically poor cathode materials such as titanium. / Målsättningen med detta doktorsarbete har varit att bättre förstå hur trivalenta katjoner och molybdat lösta i elektrolyten kan effektivisera elektrokemisk vätgasproduktion. Tillämpningen av dessa tillsatser i kloratprocessen och eventuella sidoeffekter har undersökts. De filmer som bildas på katoden av tillsatserna har undersökts med både elektrokemiska och fysikaliska ytanalysmetoder: polarisationskurvor, potentialsvep, elektrokemisk impedansspektroskopi (EIS), strömutbytesmätningar, svepelektronmikroskopi (SEM), energidispersiv röntgenspektroskopi (EDS), röntgenfotoelektronspektroskopi (XPS), röntgenfluorensens (XRF) och induktivt kopplat plasma (ICP). Både trivalenta katjoner och molybdat kan aktivera elektrokemisk vätgasutveckling, men på olika sätt. Vatten bundet till trivalenta katjoner ersätter fritt vatten som reaktant vid vätgasutveckling. Eftersom vatten bundet till trivalenta katjoner har lägre pKa-värde, går det lättare att producera vätgas från dessa komplex än från fritt vatten. Natriummolybdat däremot reduceras på katoden och bildar filmer som kan katalysera vätgasutvecklingen på substratmaterial som har låg katalytisk aktivitet för reaktionen. Molybdat bildar molybdenoxider på ytan medan trivalenta katjoner bildar metallhydroxider. Båda typerna av film riskerar att bilda filmer som är resistiva och deaktiverar vätgasutvecklingen. Laboratorieexperiment visar att problemen minskar med minskad molybdathalt. Båda filmerna kan öka selektiviteten för vätgasutveckling genom att hindra sidoreaktioner. Filmerna är dock inte lika effektiva som de filmer som bildas från den ohälsosamma tillsatsen Cr(VI), vilken används i kloratprocessen idag. Trivalenta katjoner är inte lösliga i kloratelektrolyt och är därför inte en lämplig tillsats i kloratprocessen. Molybdat har god löslighet och kan aktivera vätgasutveckling i ett stort pH‑intervall på titan och andra substratmaterial som själva har betydlig sämre aktivitet för vätgasutveckling. / <p>QC 20120530</p> / c6839

Long-distance radical cation transport was studied in DNA condensates where linearized pUC19 plasmid was ligated to an oligomer and transformed into DNA condensates with spermidine. DNA condensates were detected by Dynamic Light Scattering and observed by Transmission Electron Microscopy. Introduction of charge into the condensates causes long-distance charge migration, which is detected by reaction at the remote guanines. The efficiency of charge migration in the condensate is significantly less than it is for the corresponding oligomer in solution. This result is attributed to a lower mobility for the migrating radical cation in the condensate, caused by inhibited formation of charge-transfer-effective states. Radical cation transport was also studied in DNA condensates made from an oligomer sandwiched between two linearized plasmids by double ligation. Unlike the single ligated plasmid condensates, the efficiency of charge migration in the double ligated plasmid-condensates is high, indicative of local structural and conformational transformation of the DNA duplexes. Organic monomer units having extended ð-conjugation as part of a long conducting polymer was synthesized and characterized. The monomer units were covalently attached to particular positions in DNA oligonucleotides by either the convertible nucleotide approach or by phosphoramidite chemistry. Successful attachment of the monomer units to DNA were confirmed by mass spectral analysis. The DNA-conjoined monomer units can self assemble in the presence of complementary sequences which act as templates that can control polymer formation and structure. By this method the para-direction of the polymer formation can be enforced and may be used to generate materials having nonrecurring, irregular structures.

Crystallization of proteins in the human body can lead to the development of diseases such as sickle cell anemia and cataract. Understanding protein crystallization can give insight into such diseases. Furthermore, protein crystallization is necessary for protein structure resolution. This is important since resolution of protein structure is the first step towards establishing structure/function relations, and possibly towards performing specific structural modifications that may change the function in desirable directions. Another important application of protein crystallization is in downstream processing in the pharmaceutical industry where it is used for separation and as a final purification step. The present study increases knowledge of interactions between protein molecules during crystallization and hence the crystallization process. Crystallization of proteins in the human body can lead to the development of diseases such as sickle cell anemia and cataract. Understanding the processes involved in protein crystallization can help us gain a better understanding of such diseases. Crystallization of human gamma D-crystallin (HGD) and apoferritin, two proteins found in the lens, was studied in relation to cataract formation. Crystallization of both proteins was studied in the presence of divalent cations which are found at elevated concentrations in cataractous lenses. Results indicate that the divalent cations studied enhance crystallization of these proteins. A thermodynamic property, the osmotic second virial coefficient, was measured in protein solutions and its value was correlated with the occurrence of crystallization. It was found that the second virial coefficient successfully predicted crystallization of both proteins. A new method was developed for indirect measurement of the second virial coefficient using dynamic light scattering. This new method is more robust and efficient than the traditional static light scattering method. Finally the ability of solubilizers to prevent crystallization in HGD solutions was studied. A commercial solubilizer, NDSB-201, was found to increase the energy barrier to nucleation. Although this did not prevent crystallization, it resulted in fewer and smaller crystals being obtained. The naturally occurring alpha A-crystallin was a superior solubilizer to NDSB-201, as it suppressed aggregation and prevented crystallization of HGD under conditions for which NDSB-201 did not. The findings in the present study provide insight into the processes by which protein crystallization occurs and hence into diseases associated with protein crystallization. The findings in the present study provide insight into the processes by which protein crystallization occurs. Using the second virial coefficient to assess whether a protein will crystallize out of solution, approaches for retardation and prevention of protein crystallization, and implications for future research, are discussed.