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Ao longo dos últimos anos, Sr2+ tem sido aplicado em estudos in vitro e in vivo como um importante agente para o estímulo de osteogênese. Dessa forma, a criação de matrizes bioativas contendo Sr2+ é uma tendência na área de modificações de superfícies metálicas para aplicações em implantes de substituição óssea. Nesta dissertação, desenvolvemos sistemas bioinspirados que possam atuar como carreadores de Sr2+ em biomateriais. Na primeira parte, superfícies de Ti foram modificadas com filmes híbridos contendo SrCO3 e ou CaCO3. A formação dos filmes híbridos foi mediada pela deposição de filmes Langmuir-Blodgett sobre superfícies de Ti. Essas matrizes altamente organizadas atuaram como molde para a deposição de filmes híbridos contínuos e homogêneos sobre as superfícies. A resposta biológica desses materiais foi avaliada por cultura de osteoblastos in vitro, indicando que os materiais não são tóxicos e, em especial, que a associação entre SrCO3 e CaCO3 dá origem a recobrimentos com composição e propriedades superficiais otimizadas que induzem melhores respostas osteogênicas. Na segunda parte, foi sintetizado um novo complexo entre morina e Sr2+. A estrutura desse complexo foi inspirada no fármaco ranelato de estrôncio, um dos compostos mais utilizados para o tratamento da osteoporose. Dessa forma, aliamos a propriedade antioxidante da morina, um flavonóide natural, e a atividade osteogênica do Sr2+ para desenvolver um novo composto bioativo. A estrutura do complexo morina-Sr2+ foi caracterizada por diferentes técnicas espectroscópicas, onde determinamos que a complexação ocorre com a estequiometria 1:1. Visando o desenvolvimento de recobrimentos bioativos para superfícies metálicas, estudamos também a complexação entre morina e Sr2+ em monocamadas de Langmuir. Através da caracterização físico-química das monocamadas contendo morina na presença de Sr2+, observamos que é possível formar multicamadas auto-organizadas contendo o complexo morina-Sr2+ sobre superfícies sólidas. Essas matrizes mostram-se promissoras para uso em modificações de superfícies com propriedades osteogênicas. Por fim, o último sistema apresentado nessa dissertação é a criação de matrizes auto-organizadas de colágeno tipo I, mimetizando a organização hierárquica dessa proteína no tecido ósseo. Para isso, a auto-organização das fibrilas de colágeno sobre superfícies sólidas foi mediada por um processo onde o substrato é lentamente emerso de uma solução contendo moléculas de colágeno. Essa emersão faz com que forças competitivas (fricção e tensão superficial) atuem na interface sólido-líquido-ar e promovam o alinhamento das fibrilas de colágeno auto-organizadas no menisco da solução/substrato. A estrutura dos filmes finos assim formados foi caracterizada e mostrou-se ser dependente da concentração, pH e força iônica da solução de colágeno. Filmes de colágeno altamente orientados formados por essa metodologia poderão ser utilizados como sistemas carregadores de Sr2+ através da biomineralização de hidroxiapatita. Por fim, nessa dissertação foram apresentados três sistemas distintos com um ponto comum: a atuação como matrizes carreadoras de Sr2+. Por meio da densa caracterização da composição e das propriedades superficiais, mostramos que esses sistemas são promissores para o uso como recobrimentos bioativos sobre superfícies de Ti / In the past few years, Sr2+ has been described to play a fundamental role on the bone osteogenesis, as demonstrated by in vitro and in vivo studies. Therefore, the design of bioactive coatings containing Sr2+ is an interesting approach to modify metallic implants for bone regeneration. Herein, we described the development of bio-inspired systems to act as carriers of Sr2+ in biomaterials. In the first section, Ti surfaces were modified by hybrid films containing SrCO3 and or CaCO3. The formation of hybrid films was mediated by the deposition of Langmuir-Blodgett films on the Ti surfaces. Those matrices act as a template for the organized nucleation and growth of biominerals. By this methodology, continuous and homogeneous thin films were formed on the Ti surfaces. The biological response was accessed by in vitro osteoblasts culture. The hybrid films were nontoxic to the osteoblasts and we observed that the association of SrCO3 and CaCO3 resulted in a coating displaying a synergic composition and surface properties that induced better metabolic responses on the cultured osteoblasts. In the second section, we described the synthesis of a new Sr2+-morin complex. The structure of the complex was inspired by the strontium ranelate, one of the most used drugs for osteoporosis treatment. This way, we aimed to ally the antioxidant properties of morin, a natural flavonoid compound, and the osteogenic behavior of Sr2+ to design a new bioactive compound. The chemical structure of the complex was determined by spectroscopic techniques and we observed that the complexation happens at the stoichiometry 1:1. To design bioactive coatings on Ti surfaces, we also performed the complexation between the strontium and morin directly on Langmuir monolayers. By physicochemical characterization, we identified that multilayers containing the Sr2+-morin complex can be built on solid supports. These results show that Sr2+-morin can be a promising approach to design biofunctional coatings on metallic surfaces. In the last section, we described the creation of hierarchical collagen thin films, mimetizing the structure found on bone tissue. To this, solid supports were pulled out from collagen solution at a controlled rate. In this approach, the self-templating is mediated by competing forces (i.e. surface tension and friction) that act in the meniscus placed between the solution and the support. This process allows the deposition of self-aligned collagen fibers on surfaces. The film\'s structure was characterized and is dependent on pH, pulling rate, ionic and collagen concentration of the solution. In the future, these films will be applied to create mineralized functional coatings containing Sr2+. In conclusion, the materials developed herein has an important point in common: they are different matrices to carry Sr2+ ions. By the composition and surface characterization performed herein, we believe that these materials can be applied in the design of biofunctional coatings for metallic implant surfaces

Observações diretas das propriedades do interior da Terra são muito restritas. A maior parte das informações advém de estudos indiretos ligados à geofísica, os quais necessitam ser relacionados a estudos de materiais em laboratório para serem corretamente interpretados. Experimentos de laboratório, no entanto, precisam ser realizados em condições extremas de pressão e temperatura, o que constitui uma tarefa muito difícil de ser alcançada. Nesse contexto, estudos teóricos são fundamentais no suporte à elaboração de modelos sobre a estrutura e a composição interna da Terra. O objetivo de nosso trabalho é utilizar métodos de primeiros princípios para ajudar a elucidar o comportamento dos silicatos (MgSiO3 e CaSiO3) e dos carbonatos (MgCO3 e CaCO3) de magnésio e cálcio nas condições termodinâmicas extremas do manto. O estudo da estabilidade energética desses silicatos e carbonatos, bem como o de outros minerais que compõem o manto, fornece novas evidências sobre a melhor forma de o cálcio ser incorporado nessa região profunda, além de determinar qual carbonato é o principal hospedeiro de carbono nas profundezas da Terra. As propriedades dos sistemas foram obtidas através da teoria do funcional da densidade, considerando diversas aproximações para a energia de troca e correlação, e o método PAW (Projector Augmented Wave). As propriedades termodinâmicas foram investigadas usando a aproximação quase harmônica e a teoria de perturbação do funcional da densidade. As simulações computacionais foram efetuadas utilizando o código Quantum ESPRESSO. Observamos que a decomposição dos silicatos em seus respectivos óxidos alcalinos terrosos, MgO e CaO, mais SiO2 não é favorável. Além disso, a coexistência dos silicatos MgSiO3 e CaSiO 3 é mais estável do que a formação de ligas do tipo Mg1xCaxSiO3. Dessa forma, concluímos que o cálcio, no manto, existe numa fase independente, fazendo parte de um silicato (CaSiO3). Nossos resultados mostraram que a decomposição dos carbonatos em seus respectivos óxidos alcalinos terrosos, MgO e CaO, mais CO2 também é desfavorável, indicando que deve existir uma baixa concentração de CO 2 livre no manto, e que o carbonato de magnésio é mais estável do que o carbonato de cálcio. Portanto, nossa investigação propõe que o MgCO3 é o principal hospedeiro de carbono, na forma oxidada, no manto. Por fim, notamos que as propriedades estruturais e termodinâmicas são melhores descritas quando a energia de van der Walls é adicionada à energia de troca e correlação, indicando que esses cálculos mais precisos constituem um passo importante para melhorar a construção de modelos teóricos sobre as propriedades e a composição do manto. / Direct observations of the Earths interior properties are very restricted. Most of the information comes from indirect studies related to geophysics, which need to be related to materials studies in the laboratory to be correctly interpreted. Laboratory experiments, however, need to be performed under extreme pressure and temperature conditions, which is a very difficult task to achieve. In this context, theoretical studies are fundamental in supporting the elaboration of models on the structure and internal composition of the Earth. The purpose of our work is to use first principles methods to help elucidate the behavior of magnesium and calcium silicates (MgSiO3 and CaSiO3) and carbonates (MgCO3 and CaCO3) under the extreme thermodynamic conditions of the lower mantle. The study of the energy stability of these carbonates and silicates, as well as of other mantle minerals, provides new evidence on how calcium can best be incorporated into the mantle and to determine which carbonate is the main carbon host in the Earths deep mantle. The properties of the systems were obtained within the density functional theory, using several approximations for the exchange and correlation energy, and the PAW (Projector Augmented Wave) method. The thermodynamic properties were investigated using the quasi-harmonic approximation and the density functional perturbation theory. The computational simulations were performed using the Quantum ESPRESSO code. We observe that the decomposition of the silicates in their respective alkali earth oxides, MgO and CaO, plus SiO2 is not favorable. In addition, the coexistence of silicates MgSiO3 and CaSiO3 is more stable than the formation of alloys like Mg1xCaxSiO3. Thus, we conclude that the calcium in the lower mantle exists in an independent phase, being part of a silicate (CaSiO3). Our results also indicate that the decomposition of the carbonates into their respective alkali earth oxides, MgO and CaO plus CO2 is unfavorable, showing that there should be a low concentration of free CO2 in the mantle and that the magnesium carbonate is more stable than calcium carbonate. Therefore, our investigation proposes that MgCO3 is the main oxidized carbon host in the lower mantle. Finally, we note that the structural and thermodynamic properties are best described when the van der Walls interactions are taken into account in the exchange and correlation energy, indicating that these more accurate calculations constitute an important step to improve the construction of theoretical models on the properties and composition of the mantle.

Os carbonatos continentais vêm sendo bastante estudados nos últimos anos, devido ao seu potencial como arquivo paleoclimáticoe, mais recentemente, como rocha reservatório de hidrocarbonetos. Carbonatos continentais quaternários são registrados na serra da Bodoquena e no platô Corumbá/Ladário, adjacências da Bacia do Pantanal, no Estado de Mato Grosso do Sul,bem como na serra das Araras, Mato Grosso. O estudo desses depósitos é deinteresse científico, uma vez que eles podem contribuir como análogos para ocorrências de carbonatos continentais mais antigos, bem como servir como objeto de análises específicas relacionadas com os fatores que teriam contribuído para sua formação. O objetivo deste trabalho foi investigar carbonatos continentais quaternários expostos nas adjacências do Pantanal Matogrossense, analisando ograu de influência do clima e de atividades tectônicas em sua gênese e evolução. Para isso procedeu-se com seu mapeamento, bem como com seu estudo sedimentológico, petrográfico, isotópico e cronológico. Os depósitos estudados foram depositados nos últimos 525 mil anos, sendo a deposição ainda ativa em algumas áreas. Suagênese ocorreu em ambientes deposicionais lacustres, localmente sujeito à entrada significativa de fluxos de detritos, além de ambientes de canal fluvial, e de nascentes. Os depósitos produzidos por fluxos de detritos são representadospor conglomerados com matriz de lama carbonática, sendo restritos às escarpas doplatô Corumbá/Ladário. Depósitos lacustres consistem em carbonatos finos e/ou fossilíferos, que estão presentes em todas as áreas estudadas; Canais fluviais, caracterizados por tufas maciças e laminadas, presentes nas serras das Araras e Bodoquena; e carbonatos de nascente, que consistem em tufas laminadas em forma de pendentes, presentes na serra das Araras. Os carbonatos das áreas de estudo formam duas sucessões sedimentares, sendo a sucessão 1, basal, caracterizada por depósitos lacustres, inclusive com fluxos de detritos, e em parte, fluviais. Seu topo é uma superfície erosiva marcada por horizonte profundo de calcrete.A sucessão 2 apresenta depósitos lacustres, fluviais e de nascentes, que são pouco alterados em relação à sucessão 1. A presença de calcretes sobre depósitospleistocênicos sugere que após este período pode ter havido incidência de clima semi-árido/árido, que foi seguido por climas relativamente mais úmidos a partir do Holoceno médio. Apesar da possível influência climática, as estruturas pré-cambrianas e a neotectônica regional, condicionaram diretamente a formação desses carbonatos, quanto a localização de lagos alongados paralelamente a planos de falha, e na formação de carbonatos pendentes de nascentes favorecidos por desníveis topográficos e escarpas produzidas por falhamento. / Continental carbonates has been highly studied in the last years due its potential as climatic archive and, recently, as hydrocarbons reservoir. Quaternary continental carbonates are registered at sierra of Bodoquena, Corumbá/Ladário plateau, Pantanal basin surroundings, at Mato Grosso do Sul State, as well at sierra of Araras, Mato Grosso do Sul State. The study of these deposits has scientific interest, because they can be analogues to ancient continental carbonates, as well to be studied in specific ways to understand the factors that contributed to its genesis. The objective of this study was to investigate quaternary continental carbonates exposed at Pantanal Matogrossense surroundings, analyzing the climatic influence and tectonics related to its genesis. To achieve this goal, mapping, sedimentological, petrographical, isotopical and chronological studies were carried out. The studied deposits were formed in the last 525 thousand years, and it\'s still active in some areas. Their genesis occurred in lacustrine depositional systems, locally mixed with debris flows, as well in fluvial channels and spring settings. The debris flows were represented by conglomerates with carbonatic mud matrix, restricted to the borders of Corumbá/Ladário plateau. The lacustrine depositsare composed by fine and/or fossiliferous carbonates, outcropping in all studied regions; Fluvial channels, characterized by massive and laminated tufas, occurring in sierra of Araras and Bodoquena; and spring carbonates, represented by pendant laminated tufas, occurring mainly in sierra of Araras. The carbonates described in the studied area were divided into two sedimentar successions. The succession 1, basal, is characterized by lacustrine deposits, includind presence of debris flows sediments, and in some places, fluvial deposits. Its top is a erosion surface marked by a deep calcrete horizon. The succession 2 presents lacustrine, fluvial and spring deposits, not so changed as succession 1. The occurrence of calcretes over pleistocenic deposits suggests a period of aridity, followed by more humid climates from middle Holocene. Despite the climatic influence, the Precambrian structures and regional tectonics, influenced directly the genesis of thesecarbonates, with lakes elongated according faults and pendants tufas, favored by topographic discontinuity and fault scarps.

Dados de geoquímica isotópica e elementar foram obtidos em rochas carbonáticas da Fm. Sete Lagoas, Grupo Bambuí, visando contribuir para o entendimento da evolução sedimentar da bacia do São Francisco, assim como decifrar as variações ambientais da água do mar durante o Neoproterozoico. Esta unidade é composta de rochas carbonáticas sobrepostas aos diamictitos da Fm. Carrancas na parte sul do Cráton do São Francisco. As seções Inhaúma (IN), Linha Verde (LV) e Funilândia (FN) são constituídas por carbonatos impuros de cor cinza clara e dolomitos de cor bege, pobres em matéria orgânica, com altos teores de sedimentos detríticos e depositados num ambiente marinho raso com influência de correntes de maré. Os valores de \'\'delta\'\' POT.3\' C mais representativos do ambiente deposicional variam entre -1,0 e 0%o e permitem posicionar estas três seções na primeira sequência deposicional da Formação Sete Lagoas, acima da capa carbonática criogeniana. No entanto, os carbonatos destas seções apresentam baixos teores de Sr, resultando em razões \'ANTPOT.87 Sr\'/\'ANTPOT.86 Sr\' muito radiogênicas entre 0,7111 e 0,7114. As anomalias isotópicas podem estar relacionadas com processos de dolomitização tectônica que ocorreu em uma escala regional na área de influência tectônica da Faixa Araçuaí, na fronteira oriental do cráton. As seções Sete Lagoas (SL) e Haras Veredas (HV) são constituídas por carbonatos puros de cor cinza escuro a preto, ricos em matéria orgânica, com baixos teores de sedimentos detríticos e depositados num ambiente relativamente profundo, com pouca influência de correntes de maré. Os valores de \'\'delta\'\' POT.3\' C destas seções são bastante positivos, entre 8,5 e 12,6%o, interpretados como valores primários, o que permite posicionar estas duas seções na segunda sequência deposicional da Formação Sete Lagoas. Os altos valores de \'\'delta\'\' POT.3\' C podem representar alta bioprodutividade com altas taxas de soterramento de matéria orgânica no ambiente marinho, assim como alta produtividade de carbonato autigênico. A deposição dos carbonatos ocorreu em um mar epicontinental restrito com conexões intermitentes com os oceanos contemporâneos, dificultando a homogeneização isotópica do Sr, como demonstrado pela grande variação das razões \'ANTPOT.87 Sr\'/\'ANTPOT.86 Sr\' obtidas nas seções SL e HV, entre 0,7073 e 0,7085. Este cenário é reforçado pela configuração tectônica da bacia, limitada pelas faixas orogênicas Brasília (W) e Araçuaí (E) no final do período Ediacarano. Correlação global por meio de isótopos de Sr não é confiável neste caso. As datações U-Pb obtidas em grãos de zircão detrítico de duas amostras de diamictitos da Formação Carrancas sugerem o Cráton do São Francisco como principal fonte dos sedimentos representados pelas idades de ca. 2800 Ma. Um grão de ca. 1200 Ma, define a idade máxima de deposição desta unidade e a área fonte pode ser rochas do Supergrupo Espinhaço. / Isotope and elemental geochemistry data were obtained on carbonate rocks of the Sete Lagoas Formation in order to contribute to the understanding of the sedimentary evolution of the São Francisco basin in the basal part of the Bambuí Group, as well as to decipher the environmental variations of seawater during the Neoproterozoic. This unit consists of carbonate rocks overlying the diamictites of the Carrancas Formation in southern São Francisco Craton. The Inhaúma (IN), Linha Verde (LV) and Funilândia (FN) sections consist of light gray impure carbonates and beige dolomites, poor in organic matter, with high contents of detrital sediments and deposited in a shallow marine environment with influence of tidal currents. The most representative \'\'delta\'\' POT.3\' C values of the depositional setting range between -1.0 and 0%o, and allow us to correlate these sections with the basal depositional sequence of the Sete Lagoas Formation, above the Cryogenian cap carbonate. However, the carbonates of these sections have low Sr concentrations, resulting in highly radiogenic \'ANTPOT.87 Sr\'/\'ANTPOT.86 Sr\' ratios between 0.7111 and 0.7114. The isotopic anomalies may be related to tectonic dolomitization processes that occurred on a regional scale in the tectonic influenced areas of Araçuaí Belt, on the eastern border of the São Francisco Craton. The Sete Lagoas (SL) and Haras Veredas (HV) sections are composed mainly of dark gray to black pure carbonates, rich in organic matter, with low contents of detrital sediments and deposited in a relatively deep environment with little influence of tidal currents. The \'\'delta\'\' POT.3\' C values of these sections are consistent and very positive, between 8.5 and 12.6%o, being interpreted as representative of the isotopic composition of seawater in the depositional environment, which allow us to correlate these two sections with the second depositional sequence of Sete Lagoas Formation. The very positive \'\'delta\'\' POT.3\' C values may represent high bio-productivity with high burial rates of organic matter in the marine environment, as well as high productivity of authigenic carbonate. The deposition of these carbonates occurred in a restricted epicontinental sea with intermittent connections with contemporary oceans, making difficult the Sr isotopic homogenization with seawater. This explains the large variation on the \'ANTPOT.87 Sr\'/\'ANTPOT.86 Sr\' ratios obtained on carbonates from the SL and HV sections, ranging between 0.7073 and 0.7085. The tectonic setting of the São Francisco Craton, limited by orogenic belts of Brasilia (W) and Araçuaí (E) during the late Ediacaran period, supports this scenario. Global correlation by means of Sr isotope is not reliable in this case. The U- ages of detrital zircon grains from diamictites of the Carrancas Formation are mainly discordant, but ages of ca. 2800 Ma suggest the São Francisco Craton as the main source of sediments. One grain dated at ca. 1200 Ma sets the maximum depositional age for the units, and the source area could be the rocks from the Espinhaço Supergroup.

Le CO2 est un gaz à effet de serre qui peut être valorisé par réduction électrochimique en CO dans les carbonates alcalins fondus. Les objectifs principaux de ma thèse sont la détermination théorique des conditions favorables à cette réduction électrochimique dans les carbonates alcalins fondus et l'étude de la faisabilité de cette réduction électrochimique dans des eutectiques binaires et ternaire en conditions expérimentales. La solubilité du CO2 dans Li2CO3-K2CO3 a été déterminée par mesure manométrique et augmente avec la température. La faisabilité expérimentale de la réduction électrochimique du CO2 en CO dans les eutectiques sur électrode d'or et de carbone graphite a été prouvée expérimentalement à des températures supérieures à 550 °C par voltampérométrie cyclique (système quasi-rapide à lent), à la fois sans prétraitement de l'électrode d'or et à l'aide d'un traitement de l'électrode d'or par pré-électrolyse à un potentiel légèrement plus négatif que celui dû à la réduction de CO2. Une approche globale des mécanismes réactionnels impliqués dans la réduction de CO2 a été proposée. / Carbon Dioxide is a greenhouse which can be valorised by means of electrochemical valorisation into carbon monoxide. The main goals of the thesis consist in the theoretical determination of the conductive conditions leading to this electrochemical valorisation in alkali molten carbonates along with the study of the feasability of this electrochemical reduction in binary and ternary eutectics under experimental condition. CO2 solubility has been determined by manometric measure and increase along with the temperature. CO2 electrochemical experimental feasibility into CO in eutectics on gold plate electrode and graphite carbon has been prooved by cyclic voltamperometry for temperatures exceeding 550°C , without gold plate electrode preatreatement and with gold plate preatreatement by an pre-electrolysis at potential sligthly negative as the CO2 reduction potential. A global approach of reactional mecanisms implied in CO2 reduction is proposed.

The Great Australian Bight (GAB) is an extensive W-E striking continental margin basin that drifted northwards during the Cenozoic following rifting and separation from Antarctica in the mid/late Cretaceous. Seafloor spreading accelerated in the mid-Eocene and was associated with local volcanism. The mid-Eocene succession of the GAB is conspicuously mounded and separates a dominantly siliciclastic succession below from a fully marine carbonate succession above. The mounded succession was penecontemporaneous with major changes in global climate, oceanographic conditions and tectonic re-organization in the region, and thus may hold important clues as to the palaeo-environmental changes associated with these changes. The mid Eocene has so far only been described locally or in passing, usually by studies focused on either the siliciclastics below or the carbonates above. It was therefore chosen as a major focus point for the research project reported herein. Exploration activity in the GAB has been limited despite the presence of a working petroleum system and large target structures, but industry interest has increased over the past few years leading to 3D seismic surveys being acquired in the GAB. The focus for exploration is the Cretaceous succession beneath the relatively thin Cenozoic cover, which however, is still important in terms of shallow hazards and as overburden to the anticipated productive sections. As is often the case, the new 3D seismic data shows many overburden features in great detail and thus affords new insights to be gained that improve our understanding of the post-rift evolution of the marginThis thesis expands upon and reinterprets a pre-existing sequence framework in the Cenozoic GAB based from ODP Leg 182 results. A vast database of 2D and 3D seismic surveys has been integrated with exploration wells and borehole data and several surfaces have been calibrated to borehole and well constraints, then mapped to the maximum lateral extent across the available dataset. Surface mapping provided new insight into sequence deposition and palaeoenvironmental settings. Structure maps and thickness maps highlight key depocentre locations and trends over the Cenozoic GAB as well as stacked mass debris aprons. The newly discovered sequences raise new questions regarding trigger mechanisms in a-seismic areas and feed into industry geohazard perception models. The base surface of the Cenozoic framework hosts a plethora of mounded features across shelf and basinal section. All mounds within the dataset have been mapped. A set a bryozoan reef mounds have been interpreted lying parallel to the margin as linear complexes over 500 km. They coincide with the underlying siliciclastic delta clinoform breakpoints and provide insight into the changing palaeoenvironment at the 43 Ma mark, cessation of siliciclastics and regional marine transgression. Further mound mapping aided by 3D attribute extractions along the base Cenozoic unconformity led to the interpretation of a series of enigmatic igneous-based mounded features. The discoveries have been included in a comparative study, comparing all mounded features (igneous or carbonate) and contrasting their individual characteristics of geometry, seismic facies, dimension in order to understand mound origin and emplacement. A new grouping of mounds in the GAB has been established, the origin and emplacement mechanisms of which contribute to the global knowledge base.

The thesis entitled ‘Studies on the Chemistry of Carbonates and Carbamates’ comprises of seven chapters. Chapter 1 The reactivity of propargyloxycarbonyl (Poc) derivatives of amines and alcohols with various sulphur nucleophiles is addressed in this chapter. The chapter is divided into three different parts. Part 1: The difference in reactivity of propargyloxycarbonyl (Poc) derivatives of amines and alcohols with benzyltriethylammonium tetrathiomolybdate [(PhCH2NEt3)2MoS4, 1] is studied in detail and the results are discussed. It has been shown that amino alcohols can be protected as their diPoc derivatives using 2 equiv of propargyloxycarbonyl chloride (2). The selective deprotection of the O-Poc group using 1 equiv of 1 without affecting the N-Poc group is achieved (Scheme 1). Scheme 1 Part 2: The reactivity of propargyloxycarbonyl derivatives of various alcohols, phenols and primary and secondary amines with benzyltriethylammonium tetrathiomolybdate (1) is compared with the reactivity of these Poc derivatives with other sulphur nucleophiles such as sodium thiophenoxide, lithium sulphide, hydrogen sulphide and ammonium sulphide. The study reveals that tetrathiomolybdate (1) is the best sulphur nucleophile for the deprotection of Poc group. Poc derivatives of primary amines cyclized to the corresponding 4-methylene-2-oxazolidinones when treated with other sulphur nucleophiles (Scheme 2). Scheme 2 Part 3: The reaction between different propargyloxycarbonyl derivatives of alcohols and benzyltriethylammonium tetrathiomolybdate (1) is studied. It is found that propargyloxycarbonyl derivatives can be made more reactive towards tetrathiomolybdate by substituting the propargyl system with electron withdrawing substituents. Chapter 2 The application of propargyloxycarbonyl group for the protection of the side chain hydroxyl groups of serine, threonine and tyrosine is discussed. The O-Poc derivatives are shown to be stable to a variety of acidic and basic conditions and the applications of these derivatives in solution phase peptide synthesis is addressed. The easy and effective deprotection of the O-Poc group provides a new strategy for the synthesis of peptides bearing the hydroxy amino acid residues: serine, threonine and tyrosine. Scheme 3 Chapter 3 Development of a novel C2-symmetric protecting group for amines and amino acids is described in this chapter. But-2-ynyl-1,4-bisoxycarbonyl chloride (BbcCl, 3) is synthesized from 1,4-dihydroxybut-2-yne and used as a reagent for protecting amines as biscarbamates (Scheme 4). These biscarbamates (Bbc derivatives) are deblocked using benzyltriethylammonium tetrathiomolybdate (1) to get the amines back. Scheme 4 The orthogonal stability of the Bbc group with Boc, Cbz and Fmoc groups is established. It is also shown that Bbc group can be deblocked to the corresponding amines using resin-bound tetrathiomolybdate. The application of Bbc protected amino acids in solution phase peptide synthesis is demonstrated (Scheme 5). Scheme 5 Chapter 4 The simultaneous protection and activation of amino acids using various pentafluorophenyl carbonates is described in two parts. Part 1: A very efficient and high yielding method for the simultaneous protection of the amino group and activation of carboxylic acid group using propargyl pentafluorophenyl carbonate (PocOPfp, 4) is discussed. Treating amino acids with 2 equiv of 4 protects the amino group as a propargyl carbamate and activates the carboxylic acid group as a pentafluorophenyl ester (Scheme 6). Scheme 6 Part 2: The generality of the methodology developed for the simultaneous protection and activation of amino acids using PocOPfp (4) is studied with five different pentafluorophenyl carbonates viz. AlocOPfp, CbzOPfp, BocOPfp, EocOPfp and TrocOPfp. The studies reveal that the effectiveness of the methodology depends on the nature of the pentafluorophenyl carbonates and on the nature of the amino acids. Sterically bulky pentafluorophenyl carbonates such as BocOPfp reacted slowly with amino acids while electron deficient pentafluorophenyl carbonates such as TrocOPfp reacted faster and gave the N-protected active esters in very good yields. Amino acids bearing longer aliphatic side chains reacted better than the other amino acids. Chapter 5 The chapter describes results of the detailed studies on the base catalyzed cyclization of N-alkyl and N-aryl-O-propargyl carbamates to the corresponding 4-alkylidene-2-oxazolidinones. The effect of various bases and solvents on these cyclization reactions is studied systematically to design the most suitable conditions. The best results were obtained using catalytic amount of LiOH in DMF. The cyclization reactions of N-aryl-O-propargyl carbamates were faster than the cyclization of N-alkyl-O-propargyl carbamates. The effect of substitutions on the propargyl group in these reactions is studied by preparing various substituted propargyl carbamate derivatives from the corresponding amines and propargyl chloroformates (Scheme 7). Scheme 7 Chapter 6 An efficient procedure for the synthesis of dehydroalanine and dehydroamino butyric acid derivatives from the preformed carbonate derivatives of serine and threonine respectively, by treating with K2CO3 in DMF is discussed in this chapter. The reaction proceeds stereoselectively through a trans E2-elimination pathway to give only the Z-isomer of dehydroamino butyric acid derivatives from the carbonate derivatives of threonine. The methodology offers an easy access to dehydropeptides and proceeds without racemization of other stereogenic centers present in the peptide (Scheme 8). Scheme 8 Chapter 7 This chapter describes the use of propargyloxycarbonyl derivatives of lysine as an efficient tool for the synthesis of peptide conjugates using a click chemistry approach. The Cu(I) catalyzed cycloaddition reaction between azides and alkynes is employed in the synthesis of conjugates of lysine. Peptides bearing an Nε-Poc Lysine residue can be synthesized using traditional strategies and these peptides can be easily conjugated with azide derivatives of sugars and amino acids (Scheme 9). Scheme 9 The efficiency of the method is demonstrated by carrying out more than one click reaction in one pot using di and tri-propargyl derivatives of lysine. A dendritic core (6) is prepared from a tri-propargyl derivative (5) of lysine and an azide derived from leucine (Scheme 10). Scheme 10 The abbreviations used in the thesis are consistent with those reported in J. Org. Chem. 2007, 71, 23A. Less common abbreviations are defined, the first time they are mentioned in the thesis.

Orientador: Alexandre Campane Vidal / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-24T11:53:39Z (GMT). No. of bitstreams: 1 Belila_AlineMariaPocas_M.pdf: 4962104 bytes, checksum: f61b885a8c2ed37b65751400d6efc90b (MD5) Previous issue date: 2014 / Resumo: A caracterização de reservatórios carbonáticos é um trabalho complexo devido a alta heterogeneidade dessas rochas. Com as recentes descobertas dos reservatórios barremianos/aptianos pertencentes a fase rifte da Bacia de Santos, observa-se a importância de novos estudos que auxiliem a interpretação e caracterização destes reservatórios. Com este propósito, foram estudadas sucessões carbonáticas aflorantes da Formação Morro do Chaves, Bacia de Sergipe-Alagoas, análogas aos reservatórios da Bacia de Santos. A caracterização destas rochas foi realizada através do estudo de afloramentos para avaliar aspectos de escala mais ampla e descrição petrográfica para identificação de características em micro-escala, visando a identificação das potenciais fácies reservatório com base nos dados petrofísicos. O espaço poroso foi caracterizado utilizando imagens de tomografia computadorizada de raios-x, determinando a heterogeneidade, anisotropia e volume elementar representativo das amostras. Para a utilização dos dados de tomografia, é proposto um novo método de segmentação de imagens tridimensionais baseado na rede neural de Self-Organizing Maps. A partir dos resultados, foram determinados o valor da porosidade absoluta e conectividade do espaço poroso, validando o método como uma ferramenta consistente para a análise quantitativa e qualitativa do espaço poroso em rochas heterogêneas / Abstract: The carbonate reservoir characterization is a complex activity due to the high heterogeneity of these rocks. The recent Barremian/Aptian reservoirs discoveries belonging to the rift phase of the Santos Basin, shows the importance of further studies to assist the reservoirs interpretation and characterization. For this purpose, outcropping carbonate successions of Morro do Chaves Formation in Sergipe-Alagoas Basin were studied, analogous to Santos Basin reservoirs. The rock characterization was developed through the study of outcrops to evaluate aspects of larger scale and petrographic description to assess micro-scale characteristics in order to identify of potential reservoir facies based on petrophysical data. The pore space was characterized using x-ray computed tomography images, determining the heterogeneity, anisotropy and representative elementary volume of the samples. For the tomography data, a new method is proposed for three-dimensional image segmentation based on neural network Self-Organizing Maps. From the results, we determined the absolute value of porosity and pore space connectivity, validating the method as a consistent tool for quantitative and qualitative analysis of the pore space in heterogeneous rocks / Mestrado / Geologia e Recursos Naturais / Mestra em Geociências