Submitted by Maike Costa (maiksebas@gmail.com) on 2017-06-28T12:38:08Z No. of bitstreams: 1 arquivototal.pdf: 2848315 bytes, checksum: 889dad8fe5cef6b4c28b622bd45da5cb (MD5) / Made available in DSpace on 2017-06-28T12:38:08Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2848315 bytes, checksum: 889dad8fe5cef6b4c28b622bd45da5cb (MD5) Previous issue date: 2016-02-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Homonuclear complexes LnCitnH2O (Ln3+ = Eu3+, Tb3+ and Gd3+) were synthesized by stoichiometric addition of the respective aqueous solutions of the Ln3+ ions under the form nitrate and sodium citrate solution (Na3Cit) at a ratio of 1:1. A complex of formula Bi6O4(OH)4Cit2.2H2O, (M1), was synthesized similarly to the homonuclear complexes Ln3+, wherein the composition obtained was not compatible with the stoichiometry of the starting reactants, i.e., the stoichiometric bismuth/citrate ratio of 1:1. Other bismuth complex, with minima formula BiCit2H2O, (M2), was synthesized by reaction of Na3Cit with Bi(NO3)3 and phen, from the stoichiometric ratio 1:1:1, i.e., citrate, Bi3+ and phen. The complex EuCit.1/2(phen).2H2O (phen = 1,10-phenanthroline) was obtained by reaction between Na3Cit, Eu(NO3)3 and phen with a stoichiometry of the starting reactants in the ratio 1:1:1. Complexes bismuth and lanthanide, heteronucleares, were also synthesized in the ratio 1:1:2, from their respective nitrate salts of Bi3+ and Ln3+ and of the Na3Cit salt. All of these materials were characterized using: atomic graphite furnace absorption spectrophotometry, elemental analysis (CHN), (except for complexes M1 and M2), infrared (IR) spectroscopy and thermal analysis (TG-DTA-DTG). For the EuCit.1/2(phen).2H2O complex, luminescence spectroscopy was also used, which showed high luminescent intensity when irradiated with light of wavelength 350 nm. From the quantitative data of the graphite furnace, elemental analysis (CHN) and thermal analysis techniques, the chemical composition of each complex was suggested and by infrared, coordination forms of the ligands Cit and phen to ions metallics were found. For the heteronuclear complexes, the results of all these techniques indicate structures of the types [LnBi2Cit2.3H2O](H2O)3 ( Ln = Eu3+ and Gd3+ ) and [BiTbCit.2H2O](H2O)3. / Complexos homonucleares LnCit.nH2O (Ln3+ = Eu3+, Tb3+ e de Gd3+ ( n= 1 - 3)) foram sintetizados por adição estequiométrica das respectivas soluções aquosas dos íons de Ln3+, sob a forma nitrato, e da solução de citrato de sódio (Na3Cit), sendo a proporção usada referente às soluções dos reagentes de 1:1. Complexos de bismuto e lantanídeo, heteronucleares, também foram sintetizados a partir dos respectivos sais de nitrato de Bi3+ e Ln3+ e do sal de Na3Cit agora na proporção 1:1:2. Um complexo de fórmula Bi6O4(OH)4Cit2.2H2O, (M1), foi sintetizado de modo semelhante aos dos complexos homonucleares Ln3+, porém, a composição obtida não foi compatível com a estequiometria dos reagentes de partida, ou seja, estequiométrica de 1:1, bismuto / citrato. Outro complexo de bismuto, com fórmula mínima de BiCit.2H2O, (M2), foi sintetizado pela reação de Na3Cit com Bi(NO3)3 e fen, a partir da razão molar 1:1:1, isto é, citrato, ion de bismuto e fen. Também um complexo de európio com composição EuCit.1/2(fen).2H2O (fen = 1,10-fenantrolina) foi obtido pela reação entre Na3Cit, Eu(NO3)3 e fen com uma estequiometria dos reagentes de partida também na proporção de 1:1:1. Todos estes materiais foram caracterizados por: espectrofotometria de absorção utilizando forno de grafite, análise elementar (CHN), (com exceção dos complexos M1 e M2), espectroscopia vibracional na região do infravermelho (FTIR) e análise térmica (TG-DTA-DTG). Para o complexo EuCit.1/2(fen).2H2O espectroscopia de luminescência foi também usada, tendo o mesmo mostrado alta intensidade luminescente quando irradiado com luz de comprimento de onda de 350 nm. A partir dos dados quantitativos de forno de grafite, análise elementar (CHN) e técnicas de análise térmica, a composição química de cada complexo foi sugerida e pelos espectros de infravermelho, as formas de coordenação dos ligantes Cit e fen aos íons metálicos foram também indicadas. Para os complexos heteronucleares, os resultados das três primeiras técnicas indicam estruturas dos tipos [LnBi2Cit2.3H2O](H2O)3 ( Ln = Eu3+ e Gd3+) e [BiTbCit.2H2O](H2O)3.

Submitted by Maria Aparecida (cidazen@gmail.com) on 2017-11-16T13:16:54Z No. of bitstreams: 1 JOSÉ RIBAMAR NASCIMENTO DOS SANTOS.pdf: 1283725 bytes, checksum: 4c5d6eba4cec82d8cb883aa89b0a81f6 (MD5) / Made available in DSpace on 2017-11-16T13:16:54Z (GMT). No. of bitstreams: 1 JOSÉ RIBAMAR NASCIMENTO DOS SANTOS.pdf: 1283725 bytes, checksum: 4c5d6eba4cec82d8cb883aa89b0a81f6 (MD5) Previous issue date: 2017-09-19 / CAPES / The electro-oxidation of ethanol was evaluated on a pyrolytic graphite electrode (PGE) chemically modified with the nickel(II)-bis(1,10-phenanthroline) complex (Ni(II)(Phen)2) supported on reduced graphene oxide (RGO) (rGO/Ni(II)(Phen)2/PGE). The Ni(II)(Phen)2 complex, reduced graphene oxide (rGO) and the rGO/Ni(II)(Phen)2 composite were prepared and characterized by the techniques of Spectroscopy in the UV-Vis, Fourier Transform Infrared Spectroscopy and Diffraction of X-rays. The electrocatalytic activity of the material was evaluated by cyclic voltammetry and chronoamperometry. In alkaline solution, the voltamograms obtained for rGO/Ni(II)(Phen)2/PGE showed the formation of well defined redox peaks associated with the Ni(II)/Ni(III) redox couple. The results showed that the RGO/Ni(II)(Phen)2 composite significantly increases the electrocatalytic activity for ethanol oxidation compared to the electrode modified only with the Ni(II)(Phen)2 complex. Using the Laviron theory, the charge transfer rate constant (ks) and the electron transfer coefficient (α) of the electrode reaction were calculated to be 0.56 s-1 and 0.61, respectively. A investigation of the electro-oxidation of ethanol was performed by evaluating the effect of different parameters such as potential scan rate, OH- concentration and alcohol concentration. The chronoamperometric experiments were used to determine the diffusion coefficient of ethanol (D = 4.7 Χ 10-6 cm2 s-1) and the catalytic rate constant (kcat = 1.26 Χ 107 cm3 mol-1 s-1). The results obtained in this study clearly indicate the viability of rGO/Ni(II)(Phen)2/PGE as an electrocatalyst for ethanol oxidation. / A eletro-oxidação do etanol foi avaliada em um eletrodo de grafite pirolítico (PGE) quimicamente modificado com o complexo de níquel(II)-bis(1,10-fenantrolina) (Ni(II)(Phen)2) suportado em óxido de grafeno reduzido (rGO) (rGO/Ni(II)(Phen)2/PGE). O complexo Ni(II)(Phen)2, o óxido de grafeno reduzido (rGO), e o compósito rGO/Ni(II)(Phen)2 foram preparados e caracterizados pelas técnicas de Espectroscopia na região do UV-Vis, Espectroscopia de Infravermelho com Transformada de Fourier e Difração de Raios X. A atividade eletrocatalítica do material foi avaliada por voltametria cíclica e cronoamperometria. Em solução alcalina, os voltamogramas obtidos para rGO/Ni(II)(Phen)2/PGE mostraram processos redox bem definidos associados ao par redox Ni(II)/Ni(III). Os resultados mostraram que o compósito rGO/Ni(II)(Phen)2 aumenta significativamente a atividade eletrocatalítica para a oxidação do etanol em comparação com o eletrodo modificado apenas com o complexo Ni(II)(Phen)2 adsorvido na superfície do eletrodo. Usando a teoria de Laviron, a constante de velocidade de transferência de carga (ks) e o coeficiente de transferência de elétrons (α) da reação do eletrodo foram calculados sendo 0,56 s-1 e 0,61, respectivamente. Uma investigação da eletro-oxidação do etanol foi realizada avaliando o efeito de diferentes parâmetros, como a velocidade de varredura do potencial, a concentração de OH- e a concentração de álcool. Os experimentos cronoamperométricos foram utilizados para determinar o coeficiente de difusão do etanol (D = 4,7 Χ 10-6 cm2 s-1) e a constante de velocidade catalítica (kcat = 1,26 Χ 107 cm3 mol-1 s-1). Os resultados obtidos neste estudo indicam, claramente, a viabilidade do rGO/Ni(II)(Phen)2/PGE como eletrocatalisador da oxidação de etanol.

PhD / SYNOPSIS OF THIS THESIS The aim of this thesis is to more fully understand and explain the binding mechanism of organic molecules to the Au(111) surface and to explore the conduction of such molecules. It consists of five discreet chapters connected to each other by the central theme of “The Single Molecule Device: Conductance and Binding”. There is a deliberate concentration on azine linkers, in particular those with a 1,10-phenanthroline-type bidentate configuration at each end. This linker unit is called a “molecular alligator clip” and is investigated as an alternative to the thiol linker unit more commonly used. Chapter 1 places the work in the broad context of Molecular Electronics and establishes the need for this research. In Chapter 2 the multiple break-junction technique (using a Scanning Tunnelling Microscope or similar device) was used to investigate the conductance of various molecules with azine linkers. A major finding of those experiments is that solvent interactions are a key factor in the conductance signal of particular molecules. Some solvents interfere with the molecule’s interaction with and attachment to the gold electrodes. One indicator of the degree of this interference is the extent of the enhancement or otherwise of the gold quantized conduction peak at 1.0 G0. Below 1.0 G0 a broad range for which the molecule enhances conduction indicates that solvent interactions contribute to a variety of structures which could bridge the electrodes, each with their own specific conductance value. The use of histograms with a Log10 scale for conductance proved useful for observing broad range features. vi Another factor which affects the conductance signal is the geometric alignment of the molecule (or the molecule-solvent structure) to the gold electrode, and the molecular alignment is explored in Chapters 3 for 1,10-phenanthroline (PHEN) and Chapter 4 for thiols. In Chapter 3 STM images, electrochemistry, and Density Functional Theory (DFT) are used to determine 1,10-phenanthroline (PHEN) structures on the Au(111) surface. It is established that PHEN binds in two modes, a physisorbed state and a chemisorbed state. The chemisorbed state is more stable and involves the extraction of gold from the bulk to form adatom-PHEN entities which are highly mobile on the gold surface. Surface pitting is viewed as evidential of the formation of the adatom-molecule entities. DFT calculations in this chapter were performed by Ante Bilic and Jeffery Reimers. The conclusions to Chapter 3 implicate the adatom as a binding mode of thiols to gold and this is explored in Chapter 4 by a timely review of nascent research in the field. The adatom motif is identified as the major binding structure for thiol terminated molecules to gold, using the explanation of surface pitting in Chapter 3 as major evidence and substantiated by emergent literature, both experimental and theoretical. Furthermore, the effect of this binding mode on conductance is explored and structures relevant to the break-junction experiment of Chapter 2 are identified and their conductance values compared. Finally, as a result of researching extensive reports of molecular conductance values, and having attempted the same, a simple method for predicting the conductance of single molecules is presented based upon the tunneling conductance formula.

The correlation between NMR chemical shifts of interstitial atoms and electronic structures of boron- and carbon-centered hexazirconium halide clusters was investigated by density functional theory (DFT) calculation. The influences of bridging halide and terminal ligand variations on electronic structure were examined respectively. Inverse proportionality was found between the chemical shifts and the calculated energy gaps between two Kohn-Sham orbitals of t1u symmetry, which arose from the bonding and antibonding interaction between the zirconium cage bonding orbitals and the interstitial 2p orbitals. Chemical shielding properties of the interstitial atoms were calculated with Gauge Including Atomic Orbital (GIAO) method. Stepwise ligand substitution of terminal chlorides on [(Zr6CCl12)Cl6]4-cluster by tri(n-butyl)-phosphine oxide (Bu3PO) was conducted with the aid of TlPF6. Composition of the reaction mixtures was analyzed by use of both 13C and 31P NMR. A preliminary scheme for synthesis and separation of [(Zr6CCl12)Cl6-x(Bu3PO)x]x-4 (x = 3 ?? 5) mixture based on solubility difference was reevaluated. Three 1,10-phenanthroline based bidentate ligands, namely, 2,9-Bis(diphenyl-phosphinyl)-1,10-phenanthroline, 2,9-Bis(diethoxyphosphoryl)-1,10-phenanthroline, and 2,9-Bis(di-n-butoxyphosphoryl)-1,10-phenantholine, were synthesized for bridge-chelating the hexazirconium clusters. Coordination chemistry of these ligands with the [Zr6BCl12] and [Zr6CCl12] clusters was subject to preliminary investigation.

The correlation between NMR chemical shifts of interstitial atoms and electronic structures of boron- and carbon-centered hexazirconium halide clusters was investigated by density functional theory (DFT) calculation. The influences of bridging halide and terminal ligand variations on electronic structure were examined respectively. Inverse proportionality was found between the chemical shifts and the calculated energy gaps between two Kohn-Sham orbitals of t1u symmetry, which arose from the bonding and antibonding interaction between the zirconium cage bonding orbitals and the interstitial 2p orbitals. Chemical shielding properties of the interstitial atoms were calculated with Gauge Including Atomic Orbital (GIAO) method. Stepwise ligand substitution of terminal chlorides on [(Zr6CCl12)Cl6]4-cluster by tri(n-butyl)-phosphine oxide (Bu3PO) was conducted with the aid of TlPF6. Composition of the reaction mixtures was analyzed by use of both 13C and 31P NMR. A preliminary scheme for synthesis and separation of [(Zr6CCl12)Cl6-x(Bu3PO)x]x-4 (x = 3 ?? 5) mixture based on solubility difference was reevaluated. Three 1,10-phenanthroline based bidentate ligands, namely, 2,9-Bis(diphenyl-phosphinyl)-1,10-phenanthroline, 2,9-Bis(diethoxyphosphoryl)-1,10-phenanthroline, and 2,9-Bis(di-n-butoxyphosphoryl)-1,10-phenantholine, were synthesized for bridge-chelating the hexazirconium clusters. Coordination chemistry of these ligands with the [Zr6BCl12] and [Zr6CCl12] clusters was subject to preliminary investigation.

Rotaxanes and porphyrins are two particularly active fields of research in chemistry. However,molecules that combine the interesting properties of these types of structures are not so common. In this thesis we describe new porphyrin-based multi-rotaxanes, whose syntheses constitute interesting challenges.Porphyrins linked to two or four coordinating macrocycles were synthesised. The "gathering-andthreading" effect of copper(I) was used to thread molecular rods through the rings; the subsequent introduction of stoppers led to the formation of rotaxanes. In the case of the porphyrinic bis-macrocycle a [4]rotaxane was obtained. Host/guest complexation studies with rigid nitrogen ligands showed that the rotaxane behaves as a distensible molecular receptor that can adopt an "inflated" or "deflated" conformation and adjust its shape to the size of the guest. In the case of the porphyrinic tetra-macrocycle the formation of a [3]rotaxane of novel architecture was observed.The synthesis of a new, more rigid bis-macrocycle is in progress. This compound will be used for the construction of a [4]rotaxane that could act as a molecular press able to change the conformation of a guest substrate by compression.

PhD / SYNOPSIS OF THIS THESIS The aim of this thesis is to more fully understand and explain the binding mechanism of organic molecules to the Au(111) surface and to explore the conduction of such molecules. It consists of five discreet chapters connected to each other by the central theme of “The Single Molecule Device: Conductance and Binding”. There is a deliberate concentration on azine linkers, in particular those with a 1,10-phenanthroline-type bidentate configuration at each end. This linker unit is called a “molecular alligator clip” and is investigated as an alternative to the thiol linker unit more commonly used. Chapter 1 places the work in the broad context of Molecular Electronics and establishes the need for this research. In Chapter 2 the multiple break-junction technique (using a Scanning Tunnelling Microscope or similar device) was used to investigate the conductance of various molecules with azine linkers. A major finding of those experiments is that solvent interactions are a key factor in the conductance signal of particular molecules. Some solvents interfere with the molecule’s interaction with and attachment to the gold electrodes. One indicator of the degree of this interference is the extent of the enhancement or otherwise of the gold quantized conduction peak at 1.0 G0. Below 1.0 G0 a broad range for which the molecule enhances conduction indicates that solvent interactions contribute to a variety of structures which could bridge the electrodes, each with their own specific conductance value. The use of histograms with a Log10 scale for conductance proved useful for observing broad range features. vi Another factor which affects the conductance signal is the geometric alignment of the molecule (or the molecule-solvent structure) to the gold electrode, and the molecular alignment is explored in Chapters 3 for 1,10-phenanthroline (PHEN) and Chapter 4 for thiols. In Chapter 3 STM images, electrochemistry, and Density Functional Theory (DFT) are used to determine 1,10-phenanthroline (PHEN) structures on the Au(111) surface. It is established that PHEN binds in two modes, a physisorbed state and a chemisorbed state. The chemisorbed state is more stable and involves the extraction of gold from the bulk to form adatom-PHEN entities which are highly mobile on the gold surface. Surface pitting is viewed as evidential of the formation of the adatom-molecule entities. DFT calculations in this chapter were performed by Ante Bilic and Jeffery Reimers. The conclusions to Chapter 3 implicate the adatom as a binding mode of thiols to gold and this is explored in Chapter 4 by a timely review of nascent research in the field. The adatom motif is identified as the major binding structure for thiol terminated molecules to gold, using the explanation of surface pitting in Chapter 3 as major evidence and substantiated by emergent literature, both experimental and theoretical. Furthermore, the effect of this binding mode on conductance is explored and structures relevant to the break-junction experiment of Chapter 2 are identified and their conductance values compared. Finally, as a result of researching extensive reports of molecular conductance values, and having attempted the same, a simple method for predicting the conductance of single molecules is presented based upon the tunneling conductance formula.

Les papiers récupérés sont de plus en plus utilisés pour fabriquer du papier recyclé de haute blancheur. La ligne de recyclage inclut entre autres les opérations de désencrage et de blanchiment, le peroxyde d’hydrogène (H2O2) étant le réactif blanchissant le plus utilisé en milieu alcalin (stade P). Son efficacité est toutefois limitée car il est peu ou moyennement réactif sur les fonctions azoïques des colorants papetiers. L’objectif de cette étude était donc d’améliorer l’élimination des colorants azoïques lors d’un stade P.L'amélioration du stade P utilisé en délignification des pâtes chimiques a fait l’objet de nombreuses études. En particulier, l’activation ou la catalyse de H2O2 par des complexes cuivre(II)-phénanthroline (Cu-Phen) présentant des résultats très intéressants, des essais de blanchiment de pâtes désencrées et colorées ont été entrepris. Le système H2O2/Cu-Phen s’est également révélé efficace en décoloration, mais le mécanisme n’avait alors pas été étudié.L’objectif de ce travail était donc de déterminer dans quel cas et pourquoi le complexe cuivre(II)-phénanthroline était capable d’améliorer la décoloration de fibres cellulosiques colorées. Trois questions intermédiaires se sont posées : (1) quel effet Cu-Phen a-t-il sur le colorant isolé? (2) la décoloration d’une pâte de fibres colorées par H2O2 est-elle améliorée par Cu-Phen? (3) par quel mécanisme la décoloration est-elle rendue plus efficace?Le travail a donc été organisé en trois études : (1) caractérisation des colorants sélectionnés et du complexe en l’absence d’oxydant et examen des interactions entre les deux, (2) étude et optimisation paramétrique de H2O2/Cu-Phen pour la décoloration de pâtes colorées, (3) étude du mécanisme d’oxydation en milieu aqueux, en l’absence et en présence de cellulose.Ce travail s’est appuyé sur de nombreuses techniques analytiques (spectroscopies RMN, FTIR, UV-vis et RPE ; ESI-MS) et des calculs de spéciation. Il a prouvé que le complexe Cu-Phen en présence de H2O2 améliorait la décoloration de colorants azoïques, avec ou sans fibres cellulosiques. Il a été mis en évidence que la phénanthroline agissait comme un stabilisant permettant d’ajuster la solubilité, la stabilité et le potentiel d’oxydo-réduction du cuivre(II), mais qu’elle n’était pas indispensable. De plus, le pH du milieu est également un paramètre clé, jouant à la fois sur l’activité du complexe et sur ses interactions avec le substrat. Le substrat (colorant mais aussi cellulose) s’est trouvé fortement dégradé par ce système H2O2/Cu-Phen. Les résultats corroborent l’hypothèse de l’oxydation du substrat par les radicaux hydroxyles issus de la décomposition de H2O2, plutôt que par H2O2 lui-même, ce mécanisme étant l’une des étapes d’un cycle catalytique.La recherche menée et les résultats obtenus sont applicables non seulement à l’amélioration du blanchiment des pâtes désencrées, mais aussi au traitement d’effluents colorés dans les industries du papier et du textile. / Today, recovered papers are reused for the manufacture of bright paper after deinking and fiber bleaching, which generally starts with an alkaline hydrogen peroxide stage (H2O2). However, the efficiency of H2O2 is often limited due to its low reactivity on the azo groups of paper dyes contained in recovered papers. The goal of this study was to improve the removal of these azo dyes by H2O2.The improvement of H2O2 bleaching has been studied thoroughly in the context of chemical pulp delignification. In particular, the activation or catalysis of H2O2 by copper(II)-phenanthroline complexes (Cu-Phen) was found to be very effective. This inspired a preliminary bleaching study on deinked pulp and dyed pulp, and resulted in significant improvement of dye removal, which gave birth to our project.The purpose of this work was to determine to what extent copper(II)-phenanthroline could improve the hydrogen peroxide color-stripping of dyed cellulosic fibers, and how. To answer this question, three intermediate issues were addressed: (1) does Cu-Phen alone have an effect on the dye? (2) does Cu-Phen improve the color-stripping of a dyed pulp by H2O2? (3) how does the H2O2/Cu-Phen system enhance the dye-color-stripping efficiency?This work was thus divided into three studies: (1) the selected dyes and the complex were characterized in the absence of any oxidant and the interactions between the two were examined, (2) the H2O2/Cu-Phen system was applied on two dyed pulps to assess their color-stripping potential and to attempt to optimize it, and (3) the oxidation mechanism was investigated via trials in aqueous solution, with and without cellulose.Using several analytical techniques (NMR, FTIR, UV-vis and EPR spectroscopy; ESI-MS) and speciation calculations, this work proved that the Cu-Phen complex enhanced H2O2 for the color-stripping of azo dyes, with and without fibers. It also provided evidence that phenanthroline acted as a stabilizer to adjust the solubility, stability and redox potential of copper(II), but may not be indispensable. The substrate (dyes but also cellulose) was strongly degraded by the H2O2/Cu-Phen system. The results of the mechanistic study supported the hypothesis of substrate oxidation by radicals produced via decomposition of H2O2 rather than by hydrogen peroxide itself. This mechanism, strongly dependent on the pH, is probably part of a catalytic cycle.Finally, along with further research proposed based on our conclusions, this thesis should contribute to the improvement of deinked pulp bleaching as well as wastewater treatment in the pulp and textile industries.

L’utilisation de dioxygène lors de la délignification des pâtes à papier permet une réduction considérable des coûts de production et de l’impact environnemental du procédé de blanchiment. Seulement, le taux de délignification est limité par le fait qu’une partie de la lignine résiduelle n’est pas réactive vis-à-vis du dioxygène et que la cellulose est partiellement dépolymérisée au cours du procédé. L’utilisation de catalyseur pourrait permettre d’améliorer l’efficacité et la sélectivité de la délignification au dioxygène comme le suggèrent certaines études. Le complexe cuivre(II)-phénanthroline présente des résultats prometteurs en termes d’efficacité, mais entraîne une dégradation importante de la cellulose. Différents ligands polypyridiniques ont été étudiés dans ces travaux, afin de trouver un complexe du cuivre(II) présentant une affinité forte vis-à-vis de la lignine et faible vis-à-vis de la cellulose. Les complexes formés ont été caractérisés par spectroscopie UV/Vis et voltammétrie cyclique et étudiés comme catalyseurs de l’oxydation de différents substrats : un composé modèle de lignine non phénolique et des substrats lignocellulosiques (un modèle de cellulose, un modèle de lignine native et une pâte kraft industrielle). Les résultats ont montré que la nature même du ligand a un effet important sur l’activité catalytique du complexe de Cuivre (II) lors de l’oxydation du composé modèle de lignine. En revanche, les complexes actifs présentent une activité faible lors de la délignification d’une pâte kraft et oxydent fortement les hydrates de carbone. Ce manque de sélectivité ne permet pas une application pour la production de pâte à papier mais oriente l’utilisation de ce type de catalyseur dans de nouvelles applications n’ayant pas les mêmes contraintes sur le degré de polymérisation de la cellulose. / Dioxygen delignification considerably reduces the operating cost of the bleaching process and decreases the environmental impact of the bleaching effluent. Unfortunately the performance of dioxygen delignification is limited since part of the residual lignin is not reactive toward dioxygen while cellulose depolymerisation occurs. Studies suggested that dioxygen delignification could be improved thanks to the use of catalysts such as copper(II)–phenanthroline type complexes which have shown promising results on delignification efficiency. However cellulose was also more degraded. Different polypyridinyl ligands have been studied in this work, in an attempt to find copper(II) complexes that have more affinity toward lignin and less toward cellulose. Complexes have been characterised by UV/Vis spectroscopy, cyclic volammetry, and they were studied for the catalysed oxidation of various substrates: a non phenolic lignin model compound and lignocellulosic substrates (a model of cellulose, a model of native lignin and an industrial kraft pulp). It has been shown that the nature of the ligand had a significant effect on the catalytic activity of Cu(II) complexes in the oxygen oxidation of the lignin model compound. However, the active complexes only show a limited activity during the delignification of a kraft pulp and oxidize carbohydrates. This lack of selectivity prevents from an industrial application for paper pulp production but may be useful for the design of products with fewer constraints on cellulose polymerization degree.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Leishmanioses são um grupo de doenças com um largo espectro de manifestações clínicas, as quais variam desde lesões cutâneas até o envolvimento visceral severo, podendo levar ao óbito. A leishmaniose é, ainda hoje, uma doença negligenciada, estando entre os agravos prioritários do programa de pesquisa sobre doenças da pobreza da Organização Mundial da Saúde (OMS). Além de não haver vacinas disponíveis, a terapia é baseada em medicamentos injetáveis que causam sérios efeitos colaterais, tornando o tratamento inviável para muitos países endêmicos. Drogas derivadas de metal representam um novo arsenal terapêutico antimicrobiano e anti-câncer. Os inibidores de peptidase/agentes quelantes tais como 1,10-fenantrolina e seus derivados, no estado livre de metal ou como ligantes com metais de transição, interferem com a função de vários sistemas biológicos. Em trabalhos anteriores, nosso grupo descreveu que o parasito L. braziliensis produziu moléculas gp63 sensíveis a 1,10-fenantrolina. No presente trabalho, demonstramos a distribuição celular da molécula gp63 em uma cepa virulenta de L. braziliensis por meio de análises bioquímicas e imuno-histoquímica. Depois disso, relatamos os efeitos inibitórios de três compostos derivados da 1,10-fenantrolina, 1,10-fenantrolina-5,6-diona (phendio), [Cu(phendio)2] e [Ag(phendio)2], nas atividades metalopeptidases celulares e extracelulares produzidas por promastigotas de L. braziliensis, bem como as suas ações sobre a viabilidade do parasita e na interação com as células de macrófagos murinos. As moléculas gp63 foram detectadas em compartimentos de parasitos, incluindo membrana citoplasmatica e bolsa flagelar. O tratamento de promastigotas de L. braziliensis durante 1 hora com 1,10-fenantrolina e seus derivados resultou numa inibição significativa da viabilidade celular e mostrou um mecanismo de ação irreversível. Estes inibidores de metalopeptidases induziram apoptose em promastigotas de L. braziliensis, demonstrada através da marcação com anexina/iodeto de propídio e ensaio TUNEL. O pré-tratamento de promastigotas com os inibidores de metalopeptidases induziram uma diminuição na expressão de moléculas de superfície gp63, assim como uma redução significativa no índice de associação com macrófagos. Em paralelo, macrófagos infectados com L. braziliensis e tratados com 1,10-fenantrolina e seus derivados promoveram uma potente redução sobre o número de amastigotas intracelulares. O tratamento de macrófagos com 1,10-fenantrolina e seus derivados não induziram o aumento de óxido nítrico. A ação combinatória sobre a capacidade de crescimento entre os compostos derivados da 1,10-fenantrolina e Glucantime, quando ambos foram utilizados em concentracões sub-inibidoras, também foi observada. In vivo os compostos derivados da 1,10-fenantrolina e seus drivados foram capazes de controlar o tamanho das lesões a partir da terceira semana de tratamento em relação ao controle não tratado em hamsters infectados quando administrado por via intraperitoneal. Os animais tratados com os compostos apresentaram maior resposta intradérmica (DTH) aos antígenos de L. braziliensis. Coletivamente, a 1,10-fenantrolina e seus derivados metálicos apresentam uma nova perspectiva de estudos para o desenvolvimento de novos fármacos anti-L. braziliensis / Leishmaniasis is a group of diseases with a wide spectrum of clinical manifestations, which range from self-limited skin lesions to severe visceral involvement that can lead to death. Leishmaniasis is still a neglected disease, and it is among the priorities of the research program on diseases of poverty of World Health Organization (TDR/WHO). There is no available vaccine and the treatment is based on drugs that cause serious side effects, and are unaffordable in several endemic countries. Metal-based drugs represent a novel antimicrobial and anti-cancer therapeutics arsenal. Peptidase inhibitors/chelating agents such as 1,10-phenanthroline and its substituted derivatives, either the metal-free state or as ligands coordinated to transition metals, interfere with crucial functions of several biological systems. In previous works, our group described that L. braziliensis produced gp63 molecules sensible to 1,10-phenanthroline. Herein, we initially studied the cellular distribution of gp63 in a virulent strain of L. braziliensis by biochemical and immunocytochemical analyses. After that, we reported the inhibitory effects of three 1,10-phenanthroline derivative compounds, 1,10-phenanthroline-5,6-dione (phendio), [Cu(phendio)2]and [Ag(phendio)2], on both cellular and extracellular metallopeptidase activities produced by L. braziliensis promastigotes as well as their actions on the parasite viability and on the interaction with murine macrophage cells. The gp63 molecules were detected in several parasite compartments, including cytoplasm, membrane lining the cell body and flagellum, and flagellar pocket. The treatment of L. braziliensis promastigotes for 1 hour with 1,10-phenanthroline and its derivatives resulted in a significant inhibition of cell viability and showed an irreversible mechanism of action. These metallopeptidase inhibitors induced apoptosis in L. braziliensis promastigotes as judged by annexin/propidium iodide staining and TUNEL assays. The pre-treatment of promastigotes with metallopeptidase inhibitors induced a reduction on the expression of surface gp63 as well as a significant reduction on the association index with macrophages. In parallel, the treatment of L. braziliensis-infected macrophages with the 1,10-phenanthroline and its derivatives promoted a powerful reduction on the number of intracellular amastigotes. The treatment of macrophage cells with 1,10-phenantroline and its derivatives did not induce nitric oxide production. A synergistic inhibition on the growth ability was observed when 1,10-phenanthroline derivative compounds and Glucantime were used at sub-inhibitory concentrations. In vivos the compounds 1,10-phenanthroline derivatives and its were able to control the lesions size from the third week of treatment on, when compared to untreated control infected hamsters. The animals treated with the compounds showed greater response to the intradermal antigens of L. braziliensis. Collectively, the 1,10-phenanthroline and its metal-based drugs present a good perspective for prospective studies to the development of new anti-L. braziliensis drugs