Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Thirteen new dinuclear complexes of ligand 2,6-bis[(N-methylpiperazine-1- yl)methyl]-4-formyl phenol (L1) were prepared. Copper(II) and palladium(II) salts were used for the syntheses. Following compounds were prepared: [Cu2L1(CH3COO)2]ClO4, [Cu2L1(CF3COO)2(ClO4)][Cu2L1(CF3COO)2]ClO4, [Pd2L1(CH3COO)3], [Pd2L1(CF3COO)3], [Pd2L1(Cl)4]. These ones should act as anion receptors. The acetates were exchanged for phenylphosphinates in the case of the complex cation [Cu2L1(CH3COO)2]+ and the structure of [Cu2L1(phPO2H)2]ClO4 was obtained. Geometry of coordination shell of Cu2+ - ions in prepared complexes is tetragonal pyramid. The UV-VIS spectroscopy was used for study of interactions in system of the ligand - metal - anion. Interactions between the ligand and metals in oxidation state 2 were observed as well as interactions between the complex [Cu2L1(CH3COO)2]ClO4 and sodium salts.

Kanalrhodopsine (ChRs) sind lichtgesteuerte Ionenkanäle, welche nach Absorption eines Photons durch den Retinal-Cofaktor einen passiven Ionentransport über die Zellmembran katalysieren. Im Zuge von optogenetischen Anwendungen wird diese Reaktion für die Beeinflussung der Ionenhomöostase von verschiedenen Zelltypen und Geweben ausgenutzt. Zu Beginn dieser Arbeit wurden lichtinduzierte Strukturänderungen und Protontransferschritte in einem breiten Zeitbereich (Nanosekunden bis Minuten) in dem grün-absorbierenden ChR ReaChR mithilfe von stationärer und transienter UV-vis- und Fourier-Transform-Infrarot-Spektroskopie (FTIR) untersucht. Auf Basis der experimentellen Daten wurde ein komplexes Photozyklus-Modell konzipiert. Anschließend wurde die IR-aktive, nichtkanonische Aminosäure p-Azido-L-phenylalanin (azF) mittels Stopp-Codon-Suppression ortsspezifisch an mehreren Positionen innerhalb der vermuteten ionenleitenden Kanalpore in ReaChR inkorporiert und mit FTIR untersucht. azF ist sensitiv gegenüber Polaritätsänderungen und absorbiert in einem hochfrequenten Bereich (~2100 cm-1). Aufgrund der großen spektralen Separation zu endogenen Proteinschwingungen (< 1800 cm-1) können globale Konformations- und lokale Hydratisierungsänderungen simultan detektiert werden. Die erhobenen Daten leisten einen wichtigen Beitrag zum Verständnis der Bildung einer temporären Wasserpore in ChRs und demonstrieren zum ersten Mal den erfolgreichen in-vivo-Einbau einer artifiziellen Aminosäure in mikrobielle Rhodopsine und dessen schwingungsspektroskopische Analyse. Die Methode bietet aufgrund ihrer hohen Ortsauflösung ein großes Potential für die Studie von Mikroumgebungen innerhalb komplexer Proteinensemble. / Channelrhodopsins (ChRs) are light-gated ion channels. Upon absorption of a photon, the retinal chromophore isomerizes and drives conformational changes within the protein, which lead to a passive ion transport across the cell membrane. This capability is used for optogenetic applications to manipulate ionic homeostasis of different cell types and entire organisms. Within the work, light-induced structural changes and proton transfer steps were studied in the green-absorbing ChR ReaChR in great detail by steady-state and transient UV-vis and Fourier transform infrared spectroscopy (FTIR). The data were merged into a complex photocycle model. Next, the IR-active, unnatural amino acid p-azido-L-phenylalanine (azF) was site-specifically introduced at several sites of the putative ion pore of ReaChR by stop codon suppression. azF is sensitive to polarity changes and absorbs in a clear spectral window lacking endogenous protein vibrations. Thus, FTIR measurements of labeled mutants report for global conformational changes (< 1800 cm-1) and local hydration changes (~2100 cm-1) simultaneously. The presented findings reveal crucial insights regarding formation of a transient water pore in ChRs and demonstrate the first report of the successful in-vivo incorporation of an artificial amino acid into a microbial rhodopsin and its subsequent spectroscopic investigation. Additionally, the so far unprecedented spatial resolution renders this methodology superior over conventional FTIR methods to study microenvironments within complex protein ensembles.

Sistemas de análises químicas em fluxo com multi-impulsão empregam bombas solenoide como unidade propulsora de fluidos, as quais proporcionam fluxos pulsados. Estes provêm um eficiente transporte radial de massas, o que garante boa homogeneização das soluções envolvidas, mesmo em situações de dispersão limitada. O objetivo principal deste trabalho foi então comparar o desempenho de metodologias envolvendo reagentes imobilizados em sistemas de análises em fluxo com fluxos constantes ou pulsados. Para isto, foram selecionadas as determinações espectrofotométricas de ácido ascórbico em produtos farmacêuticos, utilizando reator tubular de polietileno (50 cm) com MnO2(s) imobilizado, e reação com formaldoxima (0,25 mol L-1); e de carbaril em águas naturais, explorando extração líquido-líquido com xileno imobilizado em membrana de PVDF, e solução de NaOH a 0,1 mol L-1 como fluxo aceptor. Adicionalmente, compararam-se os dois tipos de fluxo em uma nova titulação em fluxo, a titulação monitorada por traçador; a determinação de acidez total em vinagres foi selecionada e utilizaram-se as titulações por injeção em fluxo e programada em triângulo, ambas empregando solução de NaOH a 0,01 mol L-1 como titulante e fenolftaleína como indicador ácido-base, com monitoramento por traçador empregando azul brilhante FCF (ca. 6 mg L-1). Na determinação de ácido ascórbico, o desempenho do sistema com fluxos pulsados foi superior àquele com fluxos constantes quanto ao limite de detecção: 0,33 contra 0,60 mg L-1 (critério 3,3 ?), e à repetibilidade: d.p.r. estimado como 2,5 contra 5,6% (n = 20); quanto à exatidão, não foi encontrada diferença estatisticamente significativa entre o método proposto e o da Farmacopeia Britânica ao nível de confiança de 95%. Na determinação de carbaril, o uso de fluxos pulsados favoreceu a extração do analito, obtendo-se uma sensibilidade 9,3% maior relativamente ao emprego de fluxos constantes, além de uma melhor linearidade da curva analítica; entretanto, o método mostrou-se susceptível a interferência de outros metilcarbamatos, o que comprometeu sua aplicação à análise de águas naturais. Na determinação de acidez total, a exploração de fluxos pulsados proporcionou menores variações da razão dos valores de absorbância relativos ao monitoramento do traçador e do indicador; não foi encontrada diferença estatística entre as titulações em fluxo propostas e o método titulométrico de referência ao nível de confiança de 95% / Multi-pumping flow systems use solenoid pumps as fluid propelling devices, which deliver pulsed flows. These flows provide an efficient radial mass transport, thus good mixing conditions even in limited sample dispersion situations. The main objective of this work was then to compare the performance of methodologies involving immobilized reagents in flow systems with constant or pulsed flows. To this end, the spectrophotometric determinations of ascorbic acid in pharmaceutical products using a 50-cm polyethylene tubular reactor with immobilized MnO2(s) with further colour-forming reaction with 0.25 mol L-1 formaldoxime; and carbaryl in natural waters exploiting liquid-liquid extraction with xylene immobilized in a PVDF membrane and a 0.1 mol L-1 ¬¬NaOH solution as acceptor stream, were selected. Moreover, constant and pulsed flows were compared in relation to a novel strategy for flow titration, named tracer-monitored titration; the determination of total acidity in vinegars was selected and flow injection and triangle-programmed titrations were applied, both using a 0.01 mol L-1 NaOH solution as titrant, phenolphtalein as acid-base indicator and ca. 6 mg L-1 brilliant blue FCF as tracer. Regarding ascorbic acid determination, the pulsed flow system was superior in relation to the constant flow system for detection limit: 0.33 against 0.60 mg L-1 (3.3 ? criterion), and for repeatability: r.s.d. estimated as 2.5 against 5.6% (n = 20); in relation to accuracy, no significant differences between the proposed method and that of the British Pharmacopoeia were found at the 95% confidence level. Regarding carbaryl determination, use of pulsed flows favored the analyte extraction, leading to a 9.3% sensitivity improvement in relation to use of constant flows; besides the attainment of better linearity of the analytical curve. The method was however susceptible to interference of other methylcarbamates, thus the application to natural water analyses was impaired. Regarding total acidity determination, pulsed flows exploitation provided lower variations in the ratio of absorbance values related to the monitoring of tracer and indicator; no significant differences between the proposed titrations and the reference method were found at the 95% confidence level

Das aus dem Apoprotein Opsin und dem kovalent gebundenen Liganden bestehende Rhodopsin dient als Modellsystem für den Aktivierungsmechanismus der größten Klasse von G-Protein-gekoppelten Rezeptoren (GPCR). Infolge einer photochemischen Reaktion vollführt Rhodopsin eine Bewegungsabfolge von Sekundärstrukturelementen, wodurch es aktiviert wird, das G-Protein bindet und den Stimulus auf zellinterne Signalwege überträgt. Mithilfe der ortsspezifischen Mutagenese wurden Mutanten des bovinen Rhodopsins erzeugt, in eine künstliche Lipidumgebung eingelagert und hauptsächlich mittels FTIR-Spektroskopie untersucht. Anhand der Y191F- und Y192F-Mutanten konnte die Translokation des transienten Gegenions der Schiffschen Base Glu181 während der Aktivierung bestimmt werden. Die Interaktionen des Tyr206 sind für die gekoppelte Bewegung von EL2 und TM5 mitbestimmend, was mittels Y206F-Mutante gezeigt wurde. Eine Anhäufung von Methioninen auf der cytoplasmatischen Seite des Rezeptors ist u.a. für das Ausklappen der TM6 zuständig. Diese Bewegung ist wichtige Determinante der Rezeptoraktivierung. Hierfür wurden insgesamt fünf Mutanten verwendet. Im zweiten, hauptsächlichen Teil der Arbeit wird das bislang kaum untersuchte humane Rhodopsin mit dem bovinen Rezeptor verglichen. Ausgehend von verschiedenen Dunkelzuständen, konnte gezeigt werden, dass die Aktivierungsmechanismen beider Rezeptoren voneinander divergieren, um letztlich bei der Bildung der aktiven Spezies wieder zu konvergieren. Über die Analyse der Aminosäuresequenzen der Mammalia-Rhodopsine wurden zwei Bereiche hoher Variabilität identifiziert, die u.a. die molekulare Ursache für diese Diskrepanzen liefern. Diese Feststellung wurde mit human-bovinen-Rhodopsinchimären bewiesen. Ergänzend zu dieser Studie wurde Schafsrhodopsin einem Vergleich sowohl mit bovinem als auch mit humanem Rezeptor unterzogen. Es zeigte, als eine weitere natürlich vorkommende Variante des Lichtrezeptors, einen eigenständigen Weg der Aktivierung. / Rhodopsin, which consists of the apoprotein opsin and its covalently bound ligand, is used as a model system to understand the activation mechanism of the large family of G protein coupled receptors (GPCRs). As a result of a photochemical reaction, rhodopsin undergoes activating structural changes, enabling it to bind the G protein and transmitting the stimulus to intracellular signaling pathways. In the first part of this work, site-directed mutants of bovine rhodopsin were produced, incorporated into an artificial lipid environment, and studied mainly by FTIR spectroscopy. The translocation of the transient Schiff base counterion (Glu181) during the activation process was determined using the Y191F- and Y192F-mutants. The interactions of Tyr206 contributed to the coupled movement of EL2 and TM5, which was shown by Y206F-mutant. A striking accumulation of methionines on the cytoplasmic side of the receptor was observed to be a key-player for the activating outward motion of TM6. In the second and primary part of this work, human rhodopsin, which has been rarely studied, was compared with the bovine receptor. Starting from various dark states, it was shown that the activation mechanisms of both receptors diverge from each other and yet ultimately converge in the formation of the active species. By analyzing the amino acid sequences of mammalian rhodopsins, two regions of high variability were identified, which provide the molecular basis for these discrepancies. This finding was verified by the investigation of human/bovine rhodopsin chimeras. In addition to this study, ovine rhodopsin was compared with both the bovine and human forms. It showed, as another naturally occurring variant of the light receptor, an independent pathway of activation.

Die Kopplung von akustischer Levitation mit optischer Spektroskopie ermöglicht die Untersuchung von Reaktionen und intermolekularen Wechselwirkungen unter besonderen Bedingungen. Mit akustischer Levitation können Proben im µL-Bereich kontaktfrei gehaltert und Verunreinigungen durch Oberflächenkontaminationen ausgeschlossen werden. Durch die Verwendung verschiedener Methoden der optischen Spektroskopie wie Raman-Streuung, UV/Vis-Absorptions- und Fluoreszenz-Spektroskopie konnten die levitierten Proben untersucht werden. Die durchgeführten Untersuchungen zeigen, dass die Ultraschallfalle aufgrund der Wandlosigkeit sowie des Kontakts der levitierten Probe mit der Atmosphäre und der daraus resultierenden möglichen Aufkonzentrierung eine interessante Möglichkeit zur Probenhandhabung in der Mikrofluidik darstellt. Anhand zweier sonochemischer Reaktionen wurde mit Absorptionsspektroskopie gezeigt, dass das Ultraschallfeld des Levitators nur einen sehr geringen Einfluss auf die levitierte Probe ausübt. Mittels Absorptions- und Fluoreszenzspektroskopie wurde die durch die Verdampfung induzierte Aggregation eines Farbstoffes untersucht. Zudem wurde die relative Quantenausbeute des Farbstoffes im levitierten Tropfen bestimmt. Der Kontakt des levitierten Tropfens mit der umgebenden Atmosphäre kann auch zur Aufnahme von Substanzen aus der Atmosphäre führen. Dieser Effekt wurde anhand von levitierten ionischen Flüssigkeiten volumetrisch und schwingungsspektroskopisch bei verschiedenen Luftfeuchten untersucht und die Wechselwirkungen mit dem absorbierten Wasser detailliert charakterisiert. Die Kopplung und simultane Messung von Raman-Streuung und UV/Vis-Spektroskopie ermöglichte die Untersuchung der Bildung und Aggregation von Silber-Nanopartikeln und deren Auswirkungen auf die oberflächenverstärkte Raman-Streuung. Zudem wurde die Stabilisierung von Silber-Nanopartikeln in ionischen Flüssigkeiten und die Wechselwirkungen der Partikel mit den ionischen Flüssigkeiten untersucht. / Acoustic levitation in combination with optical spectroscopy allows for investigations of reactions and intermolecular interactions under specific conditions. Samples with microliter volumes can be handled without contact to solid surfaces resulting in the absence of impurities from surface contamination. Using different optical spectroscopy methods such as Raman, UV/vis, and fluorescence spectroscopy, different levitated samples were characterized in detail within this work. The investigations show that the acoustic levitator is an interesting tool for sample handling due to the wall-less fixture and because of the interaction of the levitated sample with the surrounding atmosphere. This interaction leads to an increase of a solved analyte upon the evaporation of the solvent. The ultrasonic field inside the trap was characterized by investigations of sonochemical reactions, which show a negligible influence of the ultrasonic field on the levitated sample. Absorption as well as fluorescence spectroscopy was used to study the aggregation of a dye due to an increasing concentration upon evaporation of the solvent. Furthermore, the relative quantum efficiency of the dye was determined from levitated droplet experiments. The interaction of the levitated droplet with the surrounding atmosphere can also lead to absorption of airborne substances. This effect was investigated for different levitated ionic liquids. Volumetric and vibrational studies were performed on levitated ionic liquids under different atmospheric humidity conditions to characterize the interaction of ionic liquids with water. Hyphenation of Raman scattering and UV/vis absorption spectroscopy enabled the investigation of the formation and aggregation of silver nanoparticles and the correlation of this information with the recorded surface-enhanced Raman spectra. In addition, the stability of silver nanoparticles in ionic liquids and the interactions of the particles with the ionic liquids were examined.

Análise cinética diferencial explora diferenças em taxas reacionais entre os analitos e um sistema reacional comum; etapas de separação prévia dos analitos podem então ser prescindidas. Sistemas de análise por injeção em fluxo (FIA) se afiguram como uma ferramenta importante para métodos envolvendo essa estratégia, pois permitem um controle preciso da dispersão de reagentes / amostras e da temporização. O objetivo deste trabalho foi então explorar estes dois aspectos favoráveis visando a determinação simultânea de cobre e de níquel, a partir de suas reações com o reagente cromogênico 5-Br-PADAP. Três alíquotas de amostra eram simultaneamente inseridas, por meio de um injetor proporcional, no fluxo transportador reagente (5-Br-PADAP 75 mg L-1 + sistema tampão 0,5 mol L-1 em ácido acético / acetato, pH 4,7) de um sistema FIA em linha única. Durante o transporte em direção ao detector, as zonas estabelecidas se coalesciam, originando uma zona complexa que era monitorada a 562 nm. Os valores locais máximos e mínimos da função concentração / tempo obtida eram considerados para calibração multivariada utilizando a ferramenta quimiométrica PLS-2 (partial least squares - 2). A concentração do reagente, a capacidade tampão, a temperatura, a vazão, os comprimentos do percurso analítico e das alças de amostragem, bem como a distância inicial entre as zonas de amostra estabelecidas foram avaliados para construção dos modelos matemáticos. Estes foram criados a partir de 24 soluções-padrão mistas de Cu2+ e Ni2+ (0,00-1,60 mg L-1 em HNO3 a 0,1% v/v). Duas variáveis latentes foram suficientes para capturar > 98 % das variâncias inerentes ao conjunto de dados e erros médios das previsões (RMSEP) foram estimados em 0,025 e 0,071 mg L-1 para Cu e Ni, salientando a boa precisão do modelo de calibração. O sistema proposto apresenta boas figuras de mérito: fisicamente estável, quando mantido em operação por quatro horas ininterruptas, consumo de 314 \'mü\'g 5-Br-PADAP por amostra, frequência analítica de 33 amostras por hora (165 dados, 66 determinações) e erros nas leituras em sinais de absorbância tipicamente < 5%. Entretanto, verificou-se a inexatidão das previsões efetuadas pelo modelo proposto, quando comparadas aos resultados obtidos por ICP OES. A partir deste fato, tornam-se necessários maiores estudos referentes a este tipo de matriz, bem como de técnicas de mascaramento dos possíveis interferentes presentes / Differential kinetic analysis exploits the differences in reaction rates between the analytes and a common reactant system; prior steps of analyte separation can then be waived. Flow-injection systems (FIA) are considered as an important tool for methods involving such a strategy because they allow precise control of sample / reagent dispersion and timing. The aim of this work was then to exploit these two favorable aspects for the simultaneous determination of copper and nickel using the 5-Br-PADAP chromogenic reagent. Three sample aliquots were simultaneously inserted by means of a proportional injector into reagent carrier stream (75 mg L-1 5-Br-PADAP + 0.5 mol L-1 acetic acid / acetate, pH 4.7) of a single-line FIA system. During transport towards detection, the established zones coalesce themselves, resulting in a complex zone that was monitored at 562 nm. The local maximum and minimum values of the concentration / time obtained function were considered for multivariate calibration using the PLS-2 (partial least squares - 2) chemometric tool. The reagent concentration, buffering capacity, temperature, flow rate and lengths of the analytical path, sampling loops and initial distance between plugs were established and evaluated for the construction of mathematical models. To this end, 24 Cu2+ and Ni2+ (0.00 - 1.60 mg L-1, also 0.1% v/v HNO3) mixed standard solutions were used. Two latent variables were enough to capture > 98% of the variance inherent in the data set and average prediction errors (RMSEP) were estimated as 0.025 and 0.071 mg L-1 for Cu and Ni, emphasizing the good precision the calibration model. The proposed system presents good figures of merit: physical stability when kept in operation for four uninterrupted hours, consumption of 314 \'mü\'g 5-Br-PADAP per sample, sample throughput of 33 h-1 (165 data, 66 determinations) and error readings in absorbance signals typically <5%. However, inaccuracy of the predictions made by the proposed model when compared to results obtained by ICP OES was noted. Thus, further studies involving this type of matrix, as well as masking techniques of potential interferences present, are recommended

Análise cinética diferencial explora diferenças em taxas reacionais entre os analitos e um sistema reacional comum; etapas de separação prévia dos analitos podem então ser prescindidas. Sistemas de análise por injeção em fluxo (FIA) se afiguram como uma ferramenta importante para métodos envolvendo essa estratégia, pois permitem um controle preciso da dispersão de reagentes / amostras e da temporização. O objetivo deste trabalho foi então explorar estes dois aspectos favoráveis visando a determinação simultânea de cobre e de níquel, a partir de suas reações com o reagente cromogênico 5-Br-PADAP. Três alíquotas de amostra eram simultaneamente inseridas, por meio de um injetor proporcional, no fluxo transportador reagente (5-Br-PADAP 75 mg L-1 + sistema tampão 0,5 mol L-1 em ácido acético / acetato, pH 4,7) de um sistema FIA em linha única. Durante o transporte em direção ao detector, as zonas estabelecidas se coalesciam, originando uma zona complexa que era monitorada a 562 nm. Os valores locais máximos e mínimos da função concentração / tempo obtida eram considerados para calibração multivariada utilizando a ferramenta quimiométrica PLS-2 (partial least squares - 2). A concentração do reagente, a capacidade tampão, a temperatura, a vazão, os comprimentos do percurso analítico e das alças de amostragem, bem como a distância inicial entre as zonas de amostra estabelecidas foram avaliados para construção dos modelos matemáticos. Estes foram criados a partir de 24 soluções-padrão mistas de Cu2+ e Ni2+ (0,00-1,60 mg L-1 em HNO3 a 0,1% v/v). Duas variáveis latentes foram suficientes para capturar > 98 % das variâncias inerentes ao conjunto de dados e erros médios das previsões (RMSEP) foram estimados em 0,025 e 0,071 mg L-1 para Cu e Ni, salientando a boa precisão do modelo de calibração. O sistema proposto apresenta boas figuras de mérito: fisicamente estável, quando mantido em operação por quatro horas ininterruptas, consumo de 314 \'mü\'g 5-Br-PADAP por amostra, frequência analítica de 33 amostras por hora (165 dados, 66 determinações) e erros nas leituras em sinais de absorbância tipicamente < 5%. Entretanto, verificou-se a inexatidão das previsões efetuadas pelo modelo proposto, quando comparadas aos resultados obtidos por ICP OES. A partir deste fato, tornam-se necessários maiores estudos referentes a este tipo de matriz, bem como de técnicas de mascaramento dos possíveis interferentes presentes / Differential kinetic analysis exploits the differences in reaction rates between the analytes and a common reactant system; prior steps of analyte separation can then be waived. Flow-injection systems (FIA) are considered as an important tool for methods involving such a strategy because they allow precise control of sample / reagent dispersion and timing. The aim of this work was then to exploit these two favorable aspects for the simultaneous determination of copper and nickel using the 5-Br-PADAP chromogenic reagent. Three sample aliquots were simultaneously inserted by means of a proportional injector into reagent carrier stream (75 mg L-1 5-Br-PADAP + 0.5 mol L-1 acetic acid / acetate, pH 4.7) of a single-line FIA system. During transport towards detection, the established zones coalesce themselves, resulting in a complex zone that was monitored at 562 nm. The local maximum and minimum values of the concentration / time obtained function were considered for multivariate calibration using the PLS-2 (partial least squares - 2) chemometric tool. The reagent concentration, buffering capacity, temperature, flow rate and lengths of the analytical path, sampling loops and initial distance between plugs were established and evaluated for the construction of mathematical models. To this end, 24 Cu2+ and Ni2+ (0.00 - 1.60 mg L-1, also 0.1% v/v HNO3) mixed standard solutions were used. Two latent variables were enough to capture > 98% of the variance inherent in the data set and average prediction errors (RMSEP) were estimated as 0.025 and 0.071 mg L-1 for Cu and Ni, emphasizing the good precision the calibration model. The proposed system presents good figures of merit: physical stability when kept in operation for four uninterrupted hours, consumption of 314 \'mü\'g 5-Br-PADAP per sample, sample throughput of 33 h-1 (165 data, 66 determinations) and error readings in absorbance signals typically <5%. However, inaccuracy of the predictions made by the proposed model when compared to results obtained by ICP OES was noted. Thus, further studies involving this type of matrix, as well as masking techniques of potential interferences present, are recommended

Submitted by Erika Demachki (erikademachki@gmail.com) on 2014-10-13T21:33:03Z No. of bitstreams: 2 Dissertação - Adriana Pereira Mundim Guedes - 2013.pdf: 2999561 bytes, checksum: 755cb864a8446e6ff5c334be00ea5367 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Jaqueline Silva (jtas29@gmail.com) on 2014-10-16T18:47:44Z (GMT) No. of bitstreams: 2 Dissertação - Adriana Pereira Mundim Guedes - 2013.pdf: 2999561 bytes, checksum: 755cb864a8446e6ff5c334be00ea5367 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2014-10-16T18:47:44Z (GMT). No. of bitstreams: 2 Dissertação - Adriana Pereira Mundim Guedes - 2013.pdf: 2999561 bytes, checksum: 755cb864a8446e6ff5c334be00ea5367 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2013-09-13 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Motivated by the perspective of ruthenium complexes to be used in cancer treatment, our research group has tested the hipotesis that some complexes of Ru (III) are able to interact with serum proteins, particularly albumin and transferrin. The Complex cis- [RuCl2(NH3)4]Cl (CTRu(III)) have been tested against different kind of tumor cells, obtaining good results. Starting from promising results obtained with this compound, subsequent studies are required to understanding the mechanism by which it exerts specificity for tumor cells. In this article, we report the first application of absorption UV-Vis, Fluorescence and Electron Paramagnetic Resonance (EPR) spectroscopy, to study the complex CTRu(III) interaction with human serum albumin (hsA) and bovine serum albumin (bsA). Fluorescence measurements revealed strong proteinsbound complex with Ksv of 1.32 x 105 and 3.71 x 105 for hsA and bsA, respectively. EPR spectra from mono-nuclear Ru(III) complexes in buffer, showed a significant decrease in the overall signal intensity following the first aquation step, is consistent with the formation of oxo-bridged Ru(III) dimers. EPR spectra revealed that the BSA very rapid binding to the protein via covalent binding through ligand-exchange with protein side chains, likely with histidine imidazoles. On the other hand, the complex binds non-covalently in hsA, probably as a product of the oligomerization of the complex in hemin-biding pocket. Furthermore, two species are slowly formed by covalent binding of the complex with the histidine residues, producing a species of axial symmetry and the other rhombic symmetry. These bonds seem to arise from the interaction of the complex with the histidine residue located in the binding Sudlow’s site II. / Motivado pela perspectiva de complexos de rutênio podem ser utilizados no tratamento do câncer, o nosso grupo de pesquisa testou a Hipótese que alguns complexos de Ru (III) são capazes de interagir com as proteínas do soro, particularmente albumina e transferrina. O complexo de cis-[RuCl2(NH3)4]Cl (CTRu(III)) foi testado contra diferentes tipos de células tumorais, obtendo bons resultados. A partir de resultados promissores obtidos com este composto, estudos subsequentes são necessários para a compreensão do mecanismo pelo qual ele exerce sua especificidade para células de tumor. Neste artigo, apresentamos a aplicação de espectroscopia de absorção UV-vis, fluorescência e ressonância paramagnética eletrônica (RPE), para estudar a interação do complexo CTRu(III) com albumina sérica humano (hsA) e a albumina sérica bovina (bsA). Medidas de fluorescência revelaram uma forte ligação do complexo com as proteínas com Ksv de 1,32 x 105 e 3,71 x 105 para hsA e bsA, respectivamente. Espectros de RPE de complexos de Ru (III) mono-nucleares em tampão mostraram um decréscimo significativo na intensidade do sinal global após a primeira passo de aquação, que é consistente com a formação de dímeros de oxo complexos de Ru (III). Os espectros de RPE revelaram que a ligação à bsA é muito rápida, a ligação covalente à proteína ocorre através de troca dos ligantes com cadeias laterais de proteínas, provavelmente com o imidazol da histidina. Por outro lado, o complexo se liga não covalentemente na hsA, provalente como produto da oligomerização do complexo no bolso de ligação hemin. Além disso, duas espécies são formadas lentamente por ligação covalente do complexo com os resíduos histidina, produzindo uma espécie de simetria axial e a outra de simetria rômbica. Essas ligações parecem surgir pela interação do complexo com o resíduo histidina localizado no sítio de ligação Sudlow II.

Im Mittelpunkt der in dieser Arbeit durchgeführten Untersuchungen steht die Aufklärung der Strukturen der Komplexe von Uran mit aliphatischen (Hydroxy-)Carbonsäuren als Liganden sowie die Strukturen, die bei Sorption von Uran an dem Eisenmineral Hämatit in An- und Abwesenheit organischer Säuren gebildet werden. Das ternäre System aus Hämatit, Uran(VI) und organischem Ligand ist sehr komplex. Daher ist es notwendig eine Aufspaltung in einfachere binäre Systeme vorzunehmen und die Ergebnisse dieser Teilsysteme heranzuziehen, um das komplexere ternäre System zu verstehen. Anhand der umfangreichen durchgeführten Arbeiten zu den wässrigen Uran(VI)-Komplexen können nun Rückschlüsse von der Struktur einer Carbonsäure auf die Struktur der gebildeten Uran(VI)-Komplexe in Abhängigkeit vom pH getroffen werden. Zuerst sollte festgehalten werden, dass Uran(VI) üblicherweise pentagonal-bipyramidale Komplexe ergibt. Das Pentaaquauranylion zeigt beispielsweise zwei axiale Sauerstoffatome (Oax) bei einem Abstand von 1,76 Å und fünf äquatoriale Sauerstoffatome (Oeq) bei einem Abstand von 2,40 Å, die von koordinierten Wassermolekülen stammen. Im Zuge der Komplexierung mit organischen Liganden werden die Wassermoleküle durch organische Liganden ersetzt, was zu messbaren Veränderungen der Bindungsabstände führt. Monocarbonsäuren bilden mit Ausnahme der Ameisensäure nacheinander mit steigendem pH 1:1-, 1:2- und 1:3-Komplexe. Die teilweise in der Literatur postulierten 1:4-Komplexe beschränken sich wahrscheinlich auf extrem hohe Ligandkonzentration (>>1 M) oder nicht-wässrige Lösungen (z. B. 1:4-U-ac-Komplex [Ryan 1967]). Anhand der Verringerung der spektralen Aufspaltung Δν der symmetrischen und antisymmetrischen Valenzschwingung der Carboxygruppe konnte für diese Komplexe eine bidentate Koordination nachgewiesen werden. Mittels EXAFS konnte die bidentate Struktur anhand einer Verlängerung des Oeq-Abstandes auf 2,47 Å im Falle der 1:3-Komplexe in den Systemen U-ac und U-prop bestätigt werden. Die Ameisensäure hingegen bildet monodentate Komplexe. Dies konnte durch eine Erhöhung von Δν und eine Verkürzung des Oeq-Abstandes gezeigt werden. Ursache für dieses Verhalten ist der fehlende +I-Effekt durch den organischen Rest, der unter anderem eine deutliche Erhöhung der Säurestärke im Falle der Ameisensäure nach sich zieht. Bei Bi- und Tricarbonsäuren bestimmt der Abstand der Carboxygruppen zueinander, welche Art der Koordinierung auftritt. Werden die Carboxygruppen durch maximal ein Kohlenstoffatom voneinander getrennt (Oxal- und Malonsäure) oder wird durch eine cis-Doppelbindung eine cis-Konfiguration der Carboxygruppen zueinander erzwungen (Maleinsäure), treten 1:1- und 1:2 , sowie für Oxalsäure auch 1:3-Komplexe mit chelatartiger Koordinierung auf. Dies wird durch eine Erhöhung von Δν und eine Verringerung von r(U-Oeq) auf 2,36 Å (1:2-Komplexe) untermauert. Liegen mindestens zwei Kohlenstoffatome zwischen den Carboxygruppen (Bernsteinsäure, Tricarballylsäure), so bilden sich überwiegend bidentate Komplexe aus. Der 1:3-Komplex im System U-suc ist allerdings gemischt bidentat/monodentat und erreicht deshalb auch einen gegenüber dem 1:3 U-ac Komplex etwas verkürzten Oeq-Abstand von 2,45 Å. Eine weitere wichtige Gruppe von Liganden sind die α- und β-Hydroxycarbonsäuren. Die α-Hydroxycarbonsäuren bilden 1:1-, 1:2-, 2:2- und 3:3-Komplexe aus. Der Ligand koordiniert dabei als 5-Ring-Chelat an Uran(VI). Die Bildung polynuklearer Spezies wird belegt mit einem stufenweisen und sehr starken Ansteigen der Absorption im UV/VIS-Bereich, der durch eine Deformation der linearen O=U=O-Bindung hervorgerufen wird. Außerdem zeigt die EXAFS-Spektroskopie, dass bei pH ~ 2–4 eine U-U-Wechselwirkung bei r(U-U) ~ 3,92 Å auftritt, wodurch die Bildung eines µ2-O verbrückten Dimers nachgewiesen ist. Im nahneutralen pH-Bereich (pH 6–7) ist eine sehr starke U-U-Wechselwirkung bei r(U-U) ~ 3,83 Å er-kennbar. Diese kann durch Ausbildung einer µ3-O verbrückten dreikernigen Struktur erklärt werden. Zwischen den α-Hydroxymonocarbonsäuren und den α-Hydroxydi- und -tricarbon-säuren, die als substituierte Äpfelsäure aufgefasst werden können, besteht der wesentliche Unterschied, dass die Homologen der Äpfelsäure das Dimer im oben genannten pH-Bereich als dominierende Spezies aufweisen, während es bei den Monocarbonsäuren erst bei höheren pH-Werten (pH ~ 4–5) und lediglich zu ~50 % (lac) auftritt. Die β-Hydroxycarbonsäuren bilden hingegen bidentat koordinierende 1:1-, 1:2- und 1:3-Komplexe. Die 1:3-Komplexe sind isostrukturell zum 1:3-U-ac-Komplex. Die Hydroxygruppe in β-Position beteiligt sich folglich nicht an der Komplexierung. Bei der Sorption von Uran(VI) an Hämatit in An- und Abwesenheit organischer Liganden ergibt sich ein breit gefächertes Spektrum an Möglichkeiten. Allgemein lässt sich feststellen, dass die Sorption etwa bei pH 3–4 einsetzt und im nahneutralen pH-Bereich (pH 6–7) maximal wird. Die Anwesenheit organischer Liganden bewirkt im Allgemeinen eine Verschiebung der Sorptionskante zu höheren pH-Werten, wobei folgende Reihenfolge der pH-Werte bei 50 %iger Sorption zu beobachten war: ohne Ligand ~ Protocatechusäure < Essigsäure < Bernsteinsäure < Weinsäure. Weiterhin kann festgestellt werden, dass die Sorptionskomplexe in der Nähe der Sorptionskante monomer sind und in oligomere Urankomplexe im nahneutralen pH-Bereich übergehen. Ohne Zugabe eines Liganden bildet sich mit steigendem pH zuerst ein über Kante verknüpfter, monomerer Sorptionskomplex (ES-Monomer) aus, der sich durch einen Fe-Abstand von ~3,45 Å und einen Oeq-Abstand von ~2,40 Å auszeichnet. Im neutralen pH-Bereich sorbiert Uran als oligomerer (wahrscheinlich dreikerniger) Sorptionskomplex (ES-Trimer) mit r(U-U) = 3,82–3,88 Å und r(U-Oeq) = 2,33–2,37 Å. Im Übergangsbereich kann sich zu geringen Teilen ein einfach oder doppelt über Ecke verknüpfter Sorptionskomplex (SCS- oder DCS-Monomer), wobei das SCS-Monomer einen Fe-Abstand von ~3,70–3,75 Å und einen Oeq-Abstand von ~2,40 Å aufweist, bilden. In Gegenwart von Essigsäure ändern sich lediglich die Strukturparameter minimal. In Gegenwart von Bernstein- und Weinsäure bilden sich im Gegensatz dazu über den Liganden verknüpfte Sorptionskomplexe aus, die also keine U-Fe-Wechselwirkung zeigen und sich besonders durch ihren sehr niedrigen DW(Oeq) von den anderen Sorptionskomplexen unter-scheiden. Im neutralen pH-Bereich liegen wiederum dreikernige Sorptionskomplexe vor, wo-bei es im Falle der Weinsäure auch möglich wäre, dass das aus dem aquatischen System be-kannte Trimer über die Weinsäure an die Oberfläche bindet. Im Unterschied dazu sorbiert Uran(VI) in Gegenwart der Protocatechusäure nahe der Sorptionskante als Gemisch eines monomeren ES- und DCS-Komplexes. Bei weiterer Erhöhung des pH dominiert der DCS-Komplex, der eine starke U-Fe-Wechselwirkung bei r(U-Fe) = 4,19 Å zeigt. Eine Oligomerisierung bleibt in diesem Falle aus. Die im Rahmen dieser Arbeit gewonnenen Ergebnisse tragen zu einem besseren Verständnis der Wechselwirkung von Uran(VI) mit organischen Säuren, sowie von Uran(VI) mit Hämatit in Gegenwart organischer Säuren, bei und liefern die Strukturen für die gebildeten wässrigen Komplexe und die Sorptionskomplexe. Damit unterstützen sie den Aufklärungsprozess des Transports radioaktiver Stoffe und können somit zuverlässigere Risikobewertungen für Endlager nuklearer Abfälle und für Rückstände des Uranerzbergbaus ermöglichen. / This study is focussed on throwing light on the structures of uranium(VI) complexes with aliphatic (hydroxy-) carboxylic acids and on the structures of the sorption complexes on the iron mineral hematite in presence and absence of organic acids. The ternary system of hematite, uranium(VI), and organic ligand is very complicated, thus it is necessary to decompose it in binary systems. The results within these binary systems are used to better understand the complicated ternary system. Based on the comprehensive investigations on the aqueous uranium(VI) complexes, it is now possible to draw inferences from the structure of the carboxylic acid about the structure of the formed uranium(VI) complex in dependence of the pH. At first it has to be mentioned that uranium(VI) commonly gives pentagonal bipyramidal complexes. The pentaaquauranylion is formed by two axial oxygen atoms (Oax) at a distance of 1.76 Å and five equatorial oxygen atoms (Oeq) at 2.40 Å stemming from coordinated water molecules. Due to complexation with organic ligands water is replaced by the ligand, thus the interatomic distances change. Monocarboxylic acids, except for formic acid, form with rising pH 1:1, 1:2, and 1:3 complex-es, successively. 1:4-complexes that were sometimes postulated in literature are probably restricted to very high ligand concentrations (>>1 M) or to non-aqueous solutions. On the basis of the decrease of the spectral splitting Δν of the symmetric and antisymmetric vibration mode of the carboxylic group bidentate coordination is verified. By using EXAFS spectros-copy the structure of the 1:3 complexes with acetic and propionic acid shows an elongation of the U-Oeq distance (r(U-Oeq)) to 2.47 Å and a six fold coordination in the equatorial plane. This distance is characteristic for bidentate coordination of the carboxylic group. In contrast, formic acid gives monodentate complexes. This is proved by an increase of Δν and a shortening of r(U-Oeq). The reason for this behaviour is the missing +I effect from the organic chain that accounts for a dramatically stronger acidity of formic acid. Among the bi- and tricarboxylic acids, the distance between the carboxylic groups is decisive for the prevailing mode of coordination. If the carboxylic groups are only separated by no more than one carbon atom (oxalic and malonic acid) or if the cis-configuration of the carboxylic groups is enforced by a cis-configuration of the ligand (maleic acid), 1:1 and 1:2 complexes with chelating coordination will be formed. This is evidenced by an increase of Δν and a decrease of r(U-Oeq) to 2.36 Å (1:2-complexes). If at least two carbon atoms separate the carboxylic groups from each other (succinic acid), the coordination will be mainly bidentate. However, the 1:3 complex in the U-suc system gives a mixed bidentate/monodentate coordination, thus r(U-Oeq) is only increased to 2.45 Å. Another important group of ligands are the α- and β-Hydroxy acids. α-Hydroxy acids form 1:1, 1:2, 2:2, and 3:3 complexes with rising pH. In all cases the ligand gives 5-membered ring chelates. The formation of polynuclear species is evidenced by a stepwise and very strong increase of the absorption in the UV-Vis range that is caused by a deformation of the linear O=U=O moiety. Moreover, EXAFS spectroscopy shows a uranium-uranium interaction at r(U-U) ~ 3.92 Å in the pH range of 2–4. This distance gives evidence for the formation of a µ2-O bridged dimer. In the near neutral pH range (pH 6–7) a very strong U-U interaction is visible at r(U-U) ~ 3,83 Å. This feature can be explained by the formation of a µ3-O bridged trimeric structure. The main difference between the α-Hydroxy diacids that can be understood as homologues of malic acid and the α-Hydroxy monoacids (glycolic acid, lactic acid, etc.) is the strength of the dimeric complex. Among the homologues of malic acid the complex sta-bility constant of the dimer is so high that the formation of a 1:2 complex is suppressed and the relative concentration of the dimer is at least 90 % in the pH range of 2–4. Among the α-Hydroxy monoacids the occurrence of the dimer is shifted to higher pH values and the relative concentration is limited (e.g. ~50 % in the U-lac system). On the contrary, β-Hydroxy acids form bidentate coordinated 1:1, 1:2, and 1:3 complexes. The 1:3 complexes are isostructural to the 1:3 complex in the U-ac system. Hence, the β-Hydoxy group does not participate in the coordination. For the sorption of uranium(VI) on hematite in absence and presence of organic ligands a widespread array of opportunities exists. In general, sorption starts at pH 3–4 and reaches its maximum in the near neutral pH range (pH 6–7). The presence of organic ligands leads to a shift of the sorption edge to higher pH. The following sequence of the pH where 50 % sorp-tion is reached were found: without ligand ~ protocatechuic acid < acetic acid < succinic acid < tartaric acid. Moreover, it can be stated that the complexes near to the sorption edge are monomeric and merge into oligomeric uranium(VI) complexes in the near neutral pH range. In the absence of organic ligands a monomeric edge-sharing complex (ES monomer) is formed at low pH which is characterized by an U-Fe distance of ~3.45 Å and an Oeq distance of ~2.40 Å. In the near neutral pH range an oligomeric edge-sharing complex (ES trimer) is formed with r(U-U) = 3.82–3.88 Å and r(U-Oeq) = 2.33–2.37 Å. It is possible that in the intermediate pH range a small fraction of single or double corner-sharing (SCS or DCS) complexes occur. The SCS monomer is characterized by r(U-Fe) ~3,70–3,75 Å and r(U-Oeq) ~2,40 Å. The presence of acetic acid has only small effects on the structural parameters. In presence of succinic and tartaric acid and at low pH the sorption complexes are of the type hematite-ligand-uranium, thus no uranium-iron interaction can be found and the DW(Oeq) is very small in contrast to all the other investigated sorption complexes. In the neutral pH range trimeric sorption complexes are formed again. In case of tartaric acid it is conceivable that the trimeric complex known from the aqueous U-tar system is sorbed to the hematite surface. In contrast, the presence of protocatechuic acid results in the formation of a mixture of ES and DCS monomeric complexes at low pH. With ongoing increase of pH the fraction of the DCS monomer rises. This DCS complex shows a strong uranium-iron interaction at r(U-Fe) = 4,19 Å. A formation of oligomeric complexes at neutral pH does not appear. The results gained during all these investigations can help to better understand the interaction of uranium(VI) and carboxylic acids, and beyond that the sorption of uranium(VI) on hematite in the presence of carboxylic acids. Structures of the aqueous and sorption complexes are proposed. All these findings support the ongoing research on the transport behaviour of radioactive matter and may lead to more reliable risk assessment in connection with the permanent disposal of nuclear waste and the residues of uranium mining.