This thesis describes the preparation and characterisation of a number of homochiral coordination and metallosupramolecular assemblies. These species were formed from the reaction of chiral pyridine and quinoline containing ligands and metal ions. The combination of traditional coordination chemistry and supramolecular interactions led to a range of polymeric and network structures being formed. The ligands used in this thesis can be divided into two broad categories: alkaloids and ligands derived from them, and amino acid-based ligands. In the first category three new ligands were synthesized, and a variety of routes towards alkaloid-based homochiral ligands were investigated. The second category focused on three ligand motifs, and resulted in the preparation of 16 ligands. These two categories of ligands were reacted with a range of metal salts to investigate their coordination and supramolecular chemistry. The structure of twenty complexes was determined by single crystal X-ray crystallography. The complexes had a range of structures, with discrete and polymeric species being formed. Hydrogen bonding was an important feature in the supramolecular chemistry of the complexes, playing a different role in different series of complexes. Two chiral coordination polymers and one chiral coordination network were synthesized. All three of these structures possessed directionality to some degree: in the coordination network and one of the polymers the directionality is counterbalanced by the opposite directionality being present in the crystal, while the second coordination polymer is generated by the screw axis present and has a high degree of overall directionality.

Thesis (Ph.D.)--Mississippi State University. Department of Chemistry. / Title from title screen. Includes bibliographical references.

Chiral perturbation theory is a useful tool in the study of low energy reactions involving light particles. However the inclusion of heavy particles in chiral perturbation theory results in large contributions from loop diagrams which violate the standard power counting scheme. We review two methods, referred to as heavy baryon chiral perturbation theory and infrared regularization, which remove the high energy effects of the heavy particles and which therefore do not violate the power counting scheme. We then use these two methods to calculate the amplitude for pion photoproduction to fourth order and prove that the two amplitudes are equivalent.

Thesis (Ph.D.)--Baylor University, 2009. / Includes bibliographical references (p. 184-195).

Made available in DSpace on 2014-06-11T19:35:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-03-19Bitstream added on 2014-06-13T19:05:20Z : No. of bitstreams: 1 rinaldo_d_dr_araiq.pdf: 1188120 bytes, checksum: 1e4f3603501a8b454e918390b4c81bce (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Este trabalho abordou a determinação quali e quantitativa de enantiômeros de catequinas em extratos e infusões das folhas de espécies do gênero Byrsonima (Malpighiaceae), tais como: B.basiloba, B. cocolobifolia, B. crassa, B. intermedia e B. verbascifolia. O trabalho descreve a determinação rápida e eficiente de catequina, ent- catequina, epicatequina e ent-epicatequina por cromatografia líquida de alta eficiência acoplada a detector de arranjo de fotodiodos e dicrísmo circular, usando coluna de fase estaconária quiral. O método possui alta seletividade e permite identificar inequivocadamente diastereômeros de catequinas em matrizes complexas como extratos vegetais, com limites de detecção (0,42 a 0,77 μg mL-1 ) e quantificação (1,27 a 2,32 μg mL-1 ) satisfatórios para as condições analisadas, e valores de precisão (0,3 to 4,8%) e exatidão (70,0 a 110,2%) recomendados pela ANVISA. Com exceção da espécie B. intermedia, quatro espécies do gênero apresentaram em seus extratos e infusões os diastereômeros catequina, epicatequina e ent-epicatequina. Experimentos para avaliar a epimerização da catequina indicaram que a incomum ent-epicatequina não é um artefato, podendo ser um produto do metabolismo de espécies do gênero Byrsonima. Enantiômeros da catequina apresentam diferentes atividades farmacológicas, o que pode causar a ocorrência de efeitos colaterais diversos, danosos à saúde humana. Portanto, esses resultados podem alertar quanto ao consumo indiscriminado de plantas medicinais pela população e contribuir para criação de políticas mais rigorosas no controle de qualidade de fitoterápicos no Brasil / This work deals with the qualitative and quantitative determination of catechin and epicatechin enantiomers both in extracts and infusions from the leaves of the Byrsonima (Malpighiaceae) species (B.basiloba, B. cocolobifolia, B. crassa, B. intermedia and B. verbascifolia). This work describes a simple and reliable analytical high performance liquid chromatographic (HPLC) method coupled with photodiode array detector and circular dichroism for simultaneous determination of catechin, ent-catechin, epicatechin and ent-epicatechin. The direct separation was obtained in normal phase by HPLC using chiral stationary phase. The method has high selectivity. Regardless of variations in retention time, it was possible to identify unequivocally the enantiomers of catechin and epicatechin in complex matrices like plant extracts with satisfactory limit of detection (0.42 to 0.77 μg mL-1 ) and limite of quantification (1.27 to 2.32 μg mL-1 ). Under the conditions used, precision values were 0.3 to 4.8%, whereas accuracy values were 75.0 to 110.2%, recommended by ANVISA. Aside from B. intermedia specie, the other four Byrsonima species presented catechin, epicatechin and ent-epicatechin diastereomers both in methanolic extract and infusions. Experiments were carried out for verification the possibility of catechin epimerization. It was observed that the unusual ent- epicatechin was not an artifact, but product of Byrsonima species metabolism. Enantiomers of catechin present dissimilar pharmacological activities, which may cause the occurrence of various side effects, harmful to human health. Therefore, these results may warn about the indiscriminate use of medicinal plants by the population and contribute to the quality control of Brazilian herbal medicines

Orientador: Manoel Roberto Robilotta / Banca: José de Sá Borges Filho / Banca: Manuel M. B. Malheiro de Oliveira / Banca: Lauro Tomio / Banca: Alfredo Pio Noronha Rodrigues Galeão / Resumo: Utilizando a simetria quiral, calculamos a contribuição dominante ao potencial nucleon-nucleon (NN) devido à troca de três píons não correlacionados. Esta contribuição é isovetorial com as componentes pseudoescalar e axial. A pseudoescalar é dominante, tem um alcance de 1.0 fm e contribui no canal de píon. No mesmo contexto, estudamos a produção de um píon na interação nucleon-nucleon devida à troca de dois píons. O termo dominante do Kernel da produção é construído a partir da mesma interação básica usada no potencial NN devido à troca de três píons. Relacionamos este termo à componente central do potencial NN devido à troca de dois píons e mostramos que esta, por sua vez, é dominada pelo fator de forma escalar píon-nucleon. O Kernel obtido foi aplicado para o limiar da produção e na construção de um potencial de três nucleons. Os resultados foram generalizados para um potencial NN central qualquer e comparados ao potencial de Argonne e àquele devido à troca de um méson escalar ...ctício / Abstracts: Using the chiral symmetry, we calculated the dominant contribution to the nucleon-nucleon (NN) potential due to the exchange of three non-correlated pions (3o). This contribution is isovetor with pseudoscalar and axial components. The pseudoscalar component is dominant, it has a range of 1.0 fm and it contributes in the pion channel. In the same context, we studied the pion production in the nucleon-nucleon interaction due to the exchange of two pions (2o). The dominant term of the production Kernel is built from the same basic interaction used in the 3o-exchange NN potential. We related this term to the central component of the 2o-exchange NN potential and we showed that the latter, on its turn, is dominated by the pion-nucleon scalar form factor. The obtained Kernel was applied at the threshold and in the constructioin of a three-nucleon potential. The results were generalized foa a central NN potential of any kind and compared to the potentials of Argonne and to that due to the exchange of one ...ctitious scalar meson / Doutor

Les propriétés biologiques intéressantes des biaryles à chiralité axiale ainsi que le défi lié à la construction de la liaison Csp2-Csp2 du motif biarylique ont suscité un vif intérêt des chimistes organiciens de synthèse. Les biaryles à chiralité axiale sont des structures privilégiées en chimie médicinale ainsi qu’en catalyse asymétrique. L’objectif de notre recherche était le contrôle de la chiralité axiale de la (-)-stéganacine en utilisant deux approches atropo-sélectives distinctes: couplage croisé de Suzuki-Miyaura (en présence de métaux de transition), couplage ARYNE (sans métaux de transition). Le couplage croisé de Suzuki-Miyauraatropo-diastéréosélectif a été réalisé en utilisant des β-hydroxysulfoxydes énantiopurs comme auxiliaires de chiralité. Le biaryle diastéréopur issu de ce couplage croisé a été transformé en un intermédiaire rapporté dans la littérature sans épimerisation de la chiralité axiale. La seconde approche était le couplage ARYNE atropo-diastéréosélectif, et fut testée dans un premier temps avec le p-tolylsulfoxyde énantiopur. Cependant nous avions rencontré un problème de manque de réactivité de l’arylsulfoxyde lithié. En revanche la chiralité axiale de la (-)-stéganacine a été contrôlée en utilisant des oxazolines comme auxiliaires de chiralité. / The interesting biological properties of axially chiral biaryls and the challenge of Csp2-Csp2 bond formation ofthe biaryl motif have aroused keen interest among synthetic organic chemists. The axially chiral biaryls areprivileged structures in medicinal chemistry and in asymmetric catalysis. The goal of our research is based onthe control of the axial chirality of (-)-steganacin using two differents atropo-selective approaches: Suzuki-Miyaura cross-coupling (in presence of transition metals), and ARYNE coupling (without any transitionmetals). The atropo-diastereoselective Suzuki-Miyaura cross-coupling was carried out using enantiopure β-hydroxysulfoxydes as chiral auxiliary. The resulting diastereopure biaryl was converted into an intermediatereported in the literature without any epimerization of axial chirality. The second approach was the atropodiastereoselectiveARYNE coupling which was tested for the first time with the enantiopure p-tolylsulfoxyde.However, we encountered a problem due to lack of reactivity of lithiated arylsulfoxide. Finally, the axialchirality of (-)-steganacin was controlled using oxazolines as chiral auxiliary.

A teoria de perturba ca o quiral (ChPT) e aceita, atualmente, como a teoria efetiva da cromodinamica quantica (QCD) para baixas energias. Ela foi colocada na sua versa o moderna com os artigos de Gasser e Leutwyler, na primeira metade da d ecada de 80 e, durante os 25 anos que se seguiram, ocorreu um aumento considera vel da variedade de fenomenos por ela descritos, sempre acompanhando a precisa o cres- cente dos resultados experimentais. Os trabalhos que apresentamos nesta tese de doutorado se inserem neste contexto e envolvem duas partes, ambas relacionadas a` determina c ao de alguns dos parametros que compo em a lagrangiana da ChPT. Por ser uma teoria efetiva, tais constantes s o podem ser fixadas por experimentos, modelos ou por c alculos da QCD na rede. Em um dos trabalhos, discutimos a cons- tante de decaimento do p on, F, e os efeitos decorrentes do acr escimo de intera co es eletromagn eticas a` ChPT. N os argumentamos que as incertezas estimadas para o valor mais aceito de F podem estar subestimadas. Mostramos, tamb em, que na o se pode determinar esta constante na presen ca das intera co es eletromagn eticas, pois a grandeza de onde ela e extra da adquire uma dependencia no calibre utilizado no ca lculo e tem suas propriedades alteradas drasticamente. No outro trabalho, abor- damos os fatores de forma escalares dos m esons pseudoescalares em tres sabores. A partir dos resultados obtidos com a ChPT e do uso de um modelo que trata dos fatores de forma no espa co das posi co es, conseguimos escreve-los em termos ape- nas das constantes presentes na lagrangiana em ordem dominante da ChPT, F e as massas dos m esons pseudoescalares. No s determinamos, tamb em, os respectivos raios quadra ticos m edios e, comparando-os com os calculados com a ChPT, obtive- mos as LECs L4(mu) = -0,26 · 10^-3 e L5(mu) = 0,85 · 10^-3, para mu = 770 MeV. Esses valores sa o compat veis com as principais estimativas vindas da ChPT. / At present, chiral perturbation theory (ChPT) is considered the effective theory of quantum chromodynamics (QCD) at low energies. It was established in its modern version by the papers of Gasser and Leutwyler written in the first half of the 80s. For the last 25 years, there has been considerable increase in the number of phe- nomena described by ChPT, always following the growing precision of experiments. The two works we present in this Ph.D. thesis are related to ChPT and discuss the determination of some of the parameters that appear in the ChPT lagrangian. As ChPT is an effective theory, such constants can only be fixed by experiments, models or calculations in the lattice. In the first presented work, we discuss the pion decay constant, F, and how it is changed by the inclusion of electromagne- tic interactions. We argue that the uncertainty of the most accepted value of F might be underestimated. We also show that we cannot determine this constant in the presence of electromagnetic interactions because the function from which it is extracted acquires a gauge dependence and the functions properties drastically change. In the other work, we deal with pseudoscalar meson scalar form factor in three flavors. We manage to write the form factors only in terms of constants present in ChPT lagrangian at leading order, F and masses of pseudoscalar mesons, using ChPT results and the model that deals with form factors in coordinate space. We also determine the respective square radii and, comparing these to those calculated using ChPT, we have obtained L4(mu) = -0.26 · 10^-3 and L5(mu) = 0.85 · 10^-3, for mu = 770 MeV. These values are compatible with the main estimates evaluated with ChPT.

No presente trabalho construímos o potencial nucleon-nucleon devido à troca de dois píons dentro do contexto relativístico da teoria de perturbação quiral, formulada por Becher e Leutwyler. No estudo do espalhamento píon-nucleon, eles desenvolveram um método que exibe a regra de contagem de potências, mantendo a invariância relativística. Os autores também chamam a atenção para um problema presente na formulação de bário pesado, de que sua série quiral não converge na região de baixa energia em torno de t=4µ2, onde µ é a massa do píon. Nós mostramos que este problema é bastante relevante para o potencial nucleon-nucleon, principalmente pelo fato dessa região de energia determinar suas características assintóticas. A dinâmica da troca de dois píons na interação nucleon-nucleon é determinada pelas sub-amplitudes píon-nucleon. Partindo da sub-amplitude de Becher e Leutwyler, obtemos diagramas classificados em três famílias, de acordo com sua topologia e constantes de acoplamento envolvidas. Na definição do potencial subtraímos, da amplitude relativéstica, a iteração da troca de um píon, seguindo a prescrição de Blankenbecler e Sugar. O nosso potencial até a ordem q4 é expresso em termos de seis funções básicas, associadas a integrais de loop, calculadas relativisticamente. Ele mantém as propriedades assintóticas corretas, desde que as integrais básicas não sejam expandidas. Forçando tal expansão, com o objetivo de comparar com os resultados de Entem e Machleidt, observamos concordância na maioria dos termos. Algumas diferenças estão associadas à discrepância na relação de Goldberger-Treiman, indicadas por GT, e dois termos, a contribuições de dois loops. As demais, muito provavelmente estão relacionadas à iteração da troca de um píon. No espaço de configuração, comparamos os nossos resultados com a parte de médio alcance de duas versões do potencial de Argonne, AV14 e AV18. Observamso uma boa concordância apenas para o potencial central isoescalar, o canal mais importante para a fenomenologia. Para as demais componentes, temos discrepâncias inclusive entre as versões AV14 e Av18. Com base na classificação da dinâmica em três famílias e analisando suas contribuições para cada componente, apresentamos uma proposta de como evitar ambiguidades desse tipo na construção de potenciais fenomenológicos. / This work is devoted to the construction of a two-pion Exchange nucleon-nucleon potential in the framework of the relativist chiral perturbation theory, formulated by Becher and Leutwyler. In their study of pion-nucleon scattering they developed a method to regain the Power counting rules while keeping Lorentz invariance. These authors also Drew attention to a problem present in the heavy baryon formulation, that is chiral serie does not converge in the low-energy region around t=4µ2, where µ is the pions mass. We have shown that this problem is rather relevant to nucleon-nucleon potential, mainly due to the fact that this range of energy determines its asymptotic properties. The dynamics of the two-pion Exchange nucleon-nucleon interaction is determined by pion-nucleon sub-amplitudes. Starting from Becher and Letwylers sub-amplitude, we obtain diagrams classified in three families, according to their topology and the coupling constants involved. In the definition of the potential we substract, from the relativist amplitude, the iteration o fone-pion Exchange, following the prescription of Blankenbecler and Sugar. Our potential up to order q4 is expressed in terms of six basic functions associated to relativistic loop integrals. It keeps the correct asymptotic properties, as long as we do not expand the basic integrals. Forcing such na expansio, in order to compare it with the results from Entem and Machleidt, we observe na agreement in the majority o terms. Some differrences are associated to the Goldberg-Treiman discrepancy, indicated by GT, and two terms come from two loop calculations. The remaining ones are probably related to the prescription adopted for the iteration o fone-pion exchange. In configuration space we compare our results with the médium-range component of two versions of the Argonne potential, AV14 and AV18. We obtain agreement only for the central isoscalar potential, the most important to phenomenology. Regarding other channels, we observe discrepancies even between AV14 and AV18. Based on the classification of the dynamics in three families and analysing their contributions to each component, we propose a way to overcome such ambiguities in the construction of phenomenological potentials.

Neste trabalho estudamos aspecto estruturais de modelos onde os bárions são tratados como sólitons quirais, tais como o proposto pó Skyrme e variantes, contendo um termo estabilizador de sexta ordem, proporcional à corrente bariônica. Modelos deste tipo têm sido bastante estudados na literatura e suas predições para as propriedades estásticas do núcleon, sistematicamente, se mantêm por volta de 2/3 dos respectivos valores experimentais. Em geral, uma dada versão do modelo envolve apenas dois ou três parâmetros, mas pode dar origem a mais de uma dezena de previsões, e esta proliferação de números torna difícil a sua avaliação. Por isso, neste trabalho investigamos os vínculos estruturais ou numéricos entre as previsões do modelo, de modo a tornar mais objetiva a sua comparação com a experimentação. Todos os modelos considerados têm a mesma parte de longo alcance. Assim, a busca de padrões é feita considerando-se tanto versões diferentes das lagrangianas de curto alcance, vários valores para os parâmetros, e campos do píon que se transformam segundo representações não usuais de SU(2) X SU(2). Dessas várias possibilidades emerge um número muito grande de resultados numéricos que, depois de organizados, mostram regularidade. Dessas regularidades decorre uma proposta para a análise dos dados experimentais. Finalmente, este trabalho também inclui um cálculo alternativo do fator de forma píon-núcleon, a partir da interação NN do modelo de Skyrme. / In this work we study structural features of models where baryons are treated as chiral solitons, such as that proposed by Skyrme and variants, containing a sixth order stabilizing term, proportional to the baryonic current. Models of this kind have been widely considered in the literature and their predictions for nucleon static properties are systematically around 2/3 of the corresponding experimental values. In general a given version of the model contains only two or three parameters, but may hield more than ten observable predictions. This makes its assessment rather difficult. Therefore in this work we investigate structural and numerical constraints between the predictions of the model, so as to render the comparision with experimental more objective. All the models considered here contain the same long range parl. Hence the search of patterns is clone by considering different versions for the short range lagrangian. Various values for the free parameters and pion fields which transform according to unusual representations of SU(2) x SU(2) . A rather large amount of numerical results emerge form these various possibilities, which display regularities after being organized. These patterns motivate a proposal for the analysis of experimental information. Finally, this work also includes an altenative calculation for the pion-nucleon form factor, starting from the NN interaction in the Skyrme model.