In molecular magnetism, rational design and serendipity have played complementary roles in the synthesis of complexes which display a breadth of interesting physical characteristics. These range from the basic understanding of magneto‐structural correlations, to more complicated phenomena such as slow relaxation of the magnetisation, spin frustration effects, and tuning magnetic interactions with a view to spintronics. The inherent physical properties of these complexes has already afforded molecules which can behave as single‐molecule magnets, singlechain magnets, single‐ion magnets, magnetic metal‐organic frameworks, magnetic refrigerants, and molecular qubits. Even when the building blocks are well known, the rational design of magnetic clusters can be extremely difficult, with the shape and nuclearity often dominated by several internal and external factors. Metallosupramolecular processes proffer an attractive strategy to the rational design of these clusters by making use of structurally‐rigid precursors which, when combined in the correct stoichiometric ratio, can be used to construct various predefined discrete two‐ and three‐dimensional polygons and polyhedra. In particular, the use of metalloligands as structurally‐rigid precursors is appealing, not only because of their often‐straightforward synthesis, but because of their ability to be easily modified in order to create comparable building blocks with different chemical and physical properties. It is therefore surprising that there are limited examples of magnetic architectures built through this approach. Each chapter of this thesis aims to exploit the use of acetylacetonate‐based paramagnetic metalloligands for the synthesis of structurally analogous magnetic coordination capsules, with inherently different magnetic properties. Chapter 2 describes the structural and magnetic studies of fourteen tetradecanuclear coordination cubes, synthesised using the paramagnetic metalloligand [MIIIL3] (MIII = Cr, Fe; HL = 1‐(4‐pyridyl)butane‐1,3‐dione). The heterometallic [MIII8MII6L24]n+ (MII = Co, Ni, Cu, and Pd; n = 0‐ 12) cubes formed from the reaction of [MIIIL3] and a “naked” MII salt are all topologically similar, with the MIII ions occupying the corners of the cubes and the MII ions occupying the faces. Excluding the PdII‐based cube, all of the complexes display magnetic exchange interactions at low temperatures. Due to the enormous size of these clusters and their resulting matrices, the magnetic fitting was done using the process of statistical spectroscopy. Chapter 3 describes the structural and magnetic studies of five [MIII2MII3L6]n+ (MIII = Cr, Fe, and Al; MII = Co, Zn, and Pd; HL = 1‐(4‐pyridyl)butane‐1,3‐dione; n = 0‐6) trigonal bipyramids, built using the diamagnetic and paramagnetic metalloligands [MIIIL3]. [FeIII2CoII3L6Cl6] represents the first magnetic trigonal bipyramid synthesised through the pyridyl‐based metalloligand approach. SQUID magnetometry studies show a weak antiferromagnetic exchange interactions between the FeIII and CoII ions, while EPR spectroscopy measurements demonstrate a small increase in the zero‐field splitting parameter of the FeIII ion upon coordination of [FeIIIL3] to a MII ion. Complete active space self‐consistent field (CASSCF) calculations show the axial zero‐field splitting parameter of CoII to be ≈‐14 cm‐1, which is consistent with the magnetothermal and spectroscopic data. Chapter 4 describes the synthesis and characterisation of six magnetic trigonal bipyramids, synthesised through dynamic covalent reactions of the metalloligand [FeIIILNH23] (HLNH2 = 1‐(4‐ aminophenyl)butane‐1,3‐dione) with either a dialdehyde or diacyl dichloride. The three [FeIII2MII3Lim3]n+ (MII = Co, Ni; n = 0‐6) imine‐based cages are formed from the reaction of the metalloligand with 2,6‐pyridinedicarboxaldehyde in the presence of a templating MII salt and a catalytic amount of acid, whereas the three [FeIII2Lam3] amide‐based cages are formed from the reaction of the metalloligand with isophthaloyl chloride in the presence of a base. The [FeIII2NiII3Lim3]n+ trigonal bipyramid displays weak antiferromagnetic interactions between FeIII and NiII ions, with JFe‐Ni = ‐0.12 cm‐1 and DNi = 8.93 cm‐1, while the [FeIII2Lam3] amide‐based cages display interesting configurational features dominated by the enthalpic gain from a series of intermolecular interactions.

Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-07-09T11:07:13Z No. of bitstreams: 1 MICHELE DAYANE RODRIGUES LEITE - DISSERTAÇÃO - (PPGCEMat) 2016.pdf: 2339827 bytes, checksum: 65a0c0a732eb5fa82f5548cfc96484f6 (MD5) / Made available in DSpace on 2018-07-09T11:07:13Z (GMT). No. of bitstreams: 1 MICHELE DAYANE RODRIGUES LEITE - DISSERTAÇÃO - (PPGCEMat) 2016.pdf: 2339827 bytes, checksum: 65a0c0a732eb5fa82f5548cfc96484f6 (MD5) Previous issue date: 2016-03-08 / CNPq / O campo da engenharia de tecidos envolve a utilização de estruturas tridimensionais capazes de simular o ambiente ideal para a acomodação, fixação, proliferação, diferenciação e orientação das células, a fim de permitir o crescimento e a regeneração, de forma organizada, do novo tecido. O sistema BioExtruder, que relaciona baixo custo e alta reprodutibilidade e é capaz de controlar a porosidade das estruturas, tem sido uma das técnicas de manufatura aditiva mais utilizadas para produzir tais estruturas tridimensionais. Assim, biomateriais biodegradáveis são as alternativas mais eficazes para o desenvolvimento desses materiais, como a Policaprolactona, um polímero sintético que vem sendo bastante utilizado na engenharia de tecidos. O mel apresenta propriedades físico-químicas que contribuem diretamente em sua atividade antibacteriana, antibiótica, anti-inflamatória e cicatrizante. Portanto, este trabalho teve como objetivo produzir estruturas tridimensionais de Policaprolactona e Policaprolactona/Mel a partir do sistema Bioextruder, avaliando a influência do mel na matriz polimérica. As estruturas obtidas foram caracterizadas pelas técnicas de microscopia Eletrônica de Varredura (MEV), Espectroscopia na Região do Infravermelho com Transformada de Fourier (FTIR), Termogravimetria (TG), Calorimetria Exploratória Diferencial (DSC), Ensaio de Porosidade, Ensaio Mecânico de Compressão, citotoxicidade e Adesão Celular. As análises morfológicas por MEV mostraram estruturas com tamanhos de poros definidos, interconectados e uma geometria interna regular, com porosidade em torno de 54%. Através dos resultados por FTIR foi possível identificar as bandas de absorção características de cada material, indicando que a técnica utilizada para a obtenção das estruturas tridimensionais não provocou alterações químicas nos materiais após o seu processamento. Pelas técnicas de TG e DSC observou-se que as estruturas apresentaram comportamento térmico estável e, pela análise da curva tensão-deformação obtida no ensaio mecânico de compressão, apresentaram comportamento característico de materiais porosos. Os testes de Citotoxicidade para as estruturas de PCL puro e PCL/Mel 5% apresentaram viabilidade celular em torno de 90%, caracterizando-as como não tóxicas quando em contato com as células, viabilizando sua utilização como biomaterial. / The field of tissue engineering encompasses the use of three-dimensional structures able to simulate the ideal environment for accommodating, fixing, proliferation, differentiation and cell orientation, to enable the growth and regeneration, in an organized manner, of the new tissue. The Bioextruder system, relates low cost and high reproducibility, and is capable of controlling the porosity of the structures, this additive manufacturing technique has been commonly used to produce such three dimensional structures. Thus, biodegradable biomaterials are the most efficient alternatives for the development of these materials, such as polycaprolactone, a synthetic polymer which has been widely used in tissue engineering. Honey has physicochemical properties that directly contribute to its antibacterial, antibiotic, antiinflammatory and healing activities. Therefore, this study aimed to produce threedimensional structures of Polycaprolactone and Polycaprolactone/Honey by means of the Bioextruder system, assessing the influence of honey in the polymer matrix. The obtained structures were characterized by the following techniques: Scanning Electron Microscopy (SEM), Fourier Transform Infrared spectroscopy (FTIR), Thermogravimetry (TG), Differential Scanning Calorimetry (DSC), Porosity, Compression Strength, Cytotoxicity and Cell Adhesion. Morphological analysis by SEM showed structures with defined and interconnected pore sizes, and a regular internal geometry, with porosity around 54%. By the FTIR results it was possible to identify the characteristic absorption bands of each material, indicating that the technique used for obtaining the three-dimensional structures did not cause chemical changes in the material after processing. TG and DSC techniques showed that the structures presented a stable thermal behavior, and analyzing the stress-strain curve by the mechanical compression test, the characteristic behavior of porous materials was observed. Cytotoxicity test for pure PCL structures and PCL / Honey 5% showed cell viability around 90%, characterizing them as non-toxic when in contact with the cells, enabling its use as a biomaterial.

Un des principaux défis du domaine de la biologie structurale est l'obtention d'informations à haute résolution sur les grandes macromolécules biologiques. En raison de leurs tailles et de leurs flexibilités, les techniques traditionnelles de biologie structurales sont souvent impuissantes. Une des techniques prometteuses est la microscopie à force atomique (AFM). Contrairement à la microscopie optique, l'AFM utilise une sonde mécanique de très faible taille (<10 nm) pour obtenir des informations topographiques sur du matériel biologique isolé et déposé sur des surfaces ultras plates. L'objectif du travail de thèse est de développer les outils informatiques pour permettre la modélisation de grandes macromolécules au niveau atomique tout en intégrant des contraintes topologiques obtenues par l'imagerie AFM. À partir d'images AFM de hauteur, à haute résolution, un protocole d'assemblage de domaines protéiques a été mis au point. Il utilise une recherche exhaustive dans l'espace tridimensionnel réel de toutes les orientations possibles des domaines de la macromolécule à modéliser qui respectent les contours imposés par l'image AFM. Un jeu de contraintes de distance entre chacun des domaines permet un premier tri des modèles candidats. Un classement final est attribué à chaque modèle selon un score appelé EFactor, estimateur de la ressemblance entre la surface topographique expérimentale et celle du modèle. Le protocole a été validé sur le système modèle que sont les anticorps. Il a été également utilisé pour reconstruire une particule virale (virus de la mosaïque du tabac) et assembler la structure tétramérique de la protéine membranaire l'aquaporine Z. / A major challenge in the field of structural biology is to obtain high-resolution information on the major biological macromolecules. Because of their size and their flexibility, the traditional techniques of structural biology are often powerless. One of the promising techniques is atomic force microscopy (AFM). Unlike optical microscopy, AFM uses a mechanical probe of very small size (<10 nm) to obtain topographical information on isolated biological material deposited on ultra flat surfaces. The aim of the thesis was to develop tools to enable the modeling of large macromolecules at the atomic level while incorporating topological constraints obtained by AFM imaging. Using high resolution AFM height images, a protocol for assembling protein domains has been developed. It uses an exhaustive search in real three-dimensional space of all possible orientations of the macromolecule's domains respecting the boundaries imposed by the AFM topographical image. A set of distance constraints between each of the domains allows an initial screening of candidate models. A final ranking is assigned to each model according to a score called EFactor, estimator of the similarity between the experimental topography and the model. The protocol was validated on model systems that are antibodies. It was also used to reconstruct a virus particle (tobacco mosaic virus) and assemble the tetrameric structure of the membrane protein aquaporin Z.

Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-06-15T19:48:16Z No. of bitstreams: 1 MARIA JUCÉLIA LIMA DANTAS – DISSERTAÇÃO (PPG-CEMat) 2016.pdf: 3511044 bytes, checksum: c308b22312ce9f189d694fc843ba74af (MD5) / Made available in DSpace on 2018-06-15T19:48:16Z (GMT). No. of bitstreams: 1 MARIA JUCÉLIA LIMA DANTAS – DISSERTAÇÃO (PPG-CEMat) 2016.pdf: 3511044 bytes, checksum: c308b22312ce9f189d694fc843ba74af (MD5) Previous issue date: 2016-02-29 / Capes / Estruturas tridimensionais são ferramentas bastante atrativas para a engenharia de tecidos, mimetizado fisicamente a matrix extracelular natural que atuam como suportes para o desenvolvimento celular. O objetivo do trabalho foi produzir estruturas tridimensionais biodegradáveis de quitosana-hidroxiapatitagelatina (CS/HA/G) com diferentes quantidades de HA e avaliar suas propriedades e comportamento in vitro. As estruturas tridimensionais foram produzidas em duas etapas. Numa primeira etapa foram obtidas esferas de CS contendo diferentes quantidades de HA de baixa cristalinidade (20, 50 e 70 % m/m). A HA de baixa cristalinidade foi gerada in situ no interior das esferas de CS. Para isso foi precipitado CaHPO4 em uma dissolução de CS e a suspensão resultante foi conformada na forma de esferas mediante gotejamento em dissolução de Na5P3O10 (TPP) com pH 8-9. As esferas precipitadas foram mantidas sob agitação nesta solução para conseguir a reticulação da CS e a transformação do CaHPO4 em HA, e finalmente liofilizadas. Para a obtenção das estruturas tridimensionais, as esferas de CS HA foram aglutinadas mediante impregnação com dissolução aquecida (40°C) de 5 % de G, arrefecimento até -18°C e liofilização. As esferas foram caracterizadas mediante microscopia ótica (MO), microscopia eletrônica de varredura (MEV), difração de raios X (DRX), análises termogravimétricas (TG) e espectroscopia de infravermelho (IV). E as estruturas tridimensionais por Porosidade, Grau de Intumescimento (GI), propriedade mecânica de resistência à comrpressão via seco e úmido. O diâmetro médio das esferas segundo os resultados de MO foi de 2,6 ± 0,22mm e 2,8± 0,28mm para CS-HA 20% e CS-HA50%,respectivamente. Já as partículas de CS-HA70% apresentaram diâmetro médio de 3,9± 0,37mm tendo sua morfologia e porosidade superficial variou com o conteúdo de HA. A presença de HA de baixa cristalinidade no interior das esferas foi confirmada pelos resultados DRX e IV. Nas imagens de MEV foi possível observar que os cristais de HA estão homogeneamente dispersos no interior das esferas. Os resultados de TG revelaram boa concordância entre as quantidades de HA projetadas e as realmente obtidas nas esferas. Os resultados das estruturas tridimensionais indicam influência pelas diferentes concentrações de hidroxiapatita. Com o aumento na fração cerâmica observa-se a densificação da superfície, uma pequena diminuição da porosidade e no grau de intumescimento, como também um aumento no modulo de elasticidade via seca e uma pequena diminuição nas propriedades mecânicas via úmido, causado pelo intumescimento da estrutura. O compósito que apresentou resultados mais satisfatórios foi CS-HA20%, exibindo um melhor perfil à porosidade, grau de intumescimento e prorpriedades mecânicas. O estudo sugere que as estruturas tridimensionais necessitam de reajustes para serem aplicadas em regeneração óssea, entretanto podem ser indicadas para aplicações em engenharia de tecidos, em situações preferencialmente ex-vivo, como suportes temporários de células. / Three-dimensional structures are very attractive tools for tissue engineering, physically mimicked the natural extracellular matrix, these structures act as supports for cell development. The goal was to produce biodegradable threedimensional structures of chitosan-hydroxyapatite-gelatin (CS / HA / L) with different HA contents and evaluate their properties and behavior in vitro. The three-dimensional structures were produced in two steps. In a first step CS were obtained spheres containing different amounts of HA low crystallinity (20, 50 and 70% w / w). The poorly crystalline HA was generated in situ within the CS spheres. To this precipitate was dissolved in CS CaHPO4 and the resulting suspension was shaped in the form of spheres by dripping in dissolution Na5P3O10 (TPP) at pH 8-9. The precipitated spheres were kept in this solution under stirring to obtain the halftone processing and the CS HA CaHPO4 , and finally lyophilized. To obtain the three-dimensional structures, CS-HA spheres were bonded by impregnation with warm solution (40 ° C) 5% C, cooling to -18 °C and lyophilization. The spheres were characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TG) and infrared spectroscopy (IR). And the three dimensional structures by porosity, Degree of Swelling (GI), mechanical property of resistance comrpressão via dry and wet. The average diameter of the spheres according to the results of MO was 2.6 ± 0.22 mm and 2.8 ± 0,28mm CS-20% CSHA50% respectively. Already the particles of CS-HA70% had a mean diameter of 3.9 ± 0,37mm having their morphology and surface porosity varied with the HA content. The presence of low crystallinity with in the HA spheres was confirmed by the XRD results and IV. In the SEM images was observed that HA crystals are homogeneously dispersed within the sphere. The TG data showed good agreement between the HA and the amounts actually projected on the spheres obtained. The results indicate influences of threedimensional structures for various concentrations of hydroxyapatite. With the increase in the ceramic fraction is observed densification of the surface, a slight reduction of the porosity and the degree of swelling, as well as an increase in the modulus of elasticity via a small decrease in the mechanical properties wet route, caused by swelling of the structure. The composite that presented better results was CS-HA20%, showing a better profile to the porosity, degree of swelling and mechanical prorpriedades. The study suggests that threedimensional structures require adjustments to be applied in bone regeneration, but can be suitable for applications in tissue engineering, in situations preferably ex vivo, as temporary supports cells.