Submitted by Maike Costa (maiksebas@gmail.com) on 2016-05-04T14:36:33Z No. of bitstreams: 1 arquivo total.pdf: 1858990 bytes, checksum: 3b9c1c92812cc3daa634b61430ba84d6 (MD5) / Made available in DSpace on 2016-05-04T14:36:33Z (GMT). No. of bitstreams: 1 arquivo total.pdf: 1858990 bytes, checksum: 3b9c1c92812cc3daa634b61430ba84d6 (MD5) Previous issue date: 2014-03-07 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Recently there have arisen new compounds of Schiff base type synthesized from the condensation of Meldrum's acid (or its derivatives) with a diamine (ethylenediamine or o-phenylenediamine) providing compounds classified as melens or melophens, which are structural analogues to the classical salens and salophens. The melophens have been used as ligands to form metal complexes analogous to salophens aiming its application in biomimetic catalysis. Herein, we describe the voltammetric electrochemical characterization to four ligands (H2melen, H2Cy2melen, H2melophen and H2Cy2melophen) and two complexes (MnII(Cy2melofen) and NiII(melophen)) on aprotic medium (DMF) using glassy carbon electrode work, and Ag|Ag+ (0,1 mol·L-1 TBAP, 10 mmol AgNO3) as reference electrode. The H2melen and H2Cy2melen behaved similarly showing an irreversible one electron reduction process (1e-). The proposed mechanism for those compounds involves a step dimerization. The H2melophen and H2Cy2melophen demonstrated similar behavior showing two reductions and two irreversible oxidations, where one of the processes is adsorption of reactant and product. The MnII(Cy2melophen) complex showed a single quasi-reversible redox process centered on the metal MnIII/MnII, which involves the transfer of one electron. The NiII(melophen) presented four cases, being a quasi-reversible (1e-) and the others irreversible processes involving a total of 5 electrons. All potentials were corrected across the redox couple of ferrocene (Fc/Fc+), and the effect of addition of acids and bases in the medium is discussed. / Recentemente, novos compostos do tipo base de Schiff, análogos estruturais aos clássicos salens e salofens, foram obtidos a partir da condensação do ácido de Meldrum (ou seus derivados) com uma diamina (etilenodiamina ou orto-fenilenodiamina), fornecendo compostos denominados melens ou melofens. Os melofens têm sido utilizados como ligantes a fim de formar complexos metálicos análogos aos salofens, visando sua aplicação em catálise biomimética. Neste trabalho é apresentada a caracterização eletroquímica de quatro ligantes (H2melen, H2Cy2melen, H2melofen e H2Cy2melofen) e dois complexos (MnII(Cy2melofen) e NiII(melofen)) em meio aprótico (DMF), empregando carbono vítreo como eletrodo de trabalho, mediante a aplicação de técnicas voltamétricas. O H2melen e o H2Cy2melen apresentaram comportamentos semelhantes exibindo uma redução irreversível envolvendo um elétron (1e-). O mecanismo proposto para esses compostos envolve uma etapa de dimerização. O H2melofen e o H2Cy2melofen apresentaram comportamentos semelhantes exibindo duas reduções e duas oxidações irreversíveis, onde em um dos processos ocorre adsorção do reagente e do produto. O complexo MnII(Cy2melofen) apresentou um único processo redox quase-reversível centrado no metal MnIII/MnII, o qual envolve 1e-. O NiII(melofen) apresentou quatro processos, sendo um quase-reversível (1e-) e os demais irreversíveis envolvendo um total de 5e-. Todos os potenciais foram corrigidos frente o par redox do ferroceno (Fc/Fc+), e o efeito da adição de ácidos e bases ao meio é discutido.

[pt] O presente trabalho representa um estudo espectroscópico vibracional de complexos metálicos com aminoácidos. Foram analisados complexos ternários com os íons metálicos Zn(II), Cd(II) e Ni(II), com os seguintes aminoácidos: glicina, serina, metionina, cisteína, ácido aspártico e ácido guanidoacético, e somente um complexo binário do íon Ni(II) com o ácido guanidoacético. A análise vibracional rigorosa, aliada às caracterizações dos complexos e à utilização de cálculos teóricos foram recursos fundamentais e preciosos neste trabalho científico. Os trabalhos existentes em espectroscopia vibracional realizados para complexos metálicos com aminoácidos como ligantes são incompletos no que diz respeito à caracterização vibracional e à análise estrutural completa desses compostos. Aliado a isso, a escassez de informação na literatura científica sobre espectros vibracionais de complexos de metais, tendo aminoácidos como ligantes contribuiu significativamente na escolha do tema. Para a caracterização dos compostos foram utilizadas as seguintes técnicas: espectroscopia no infravermelho, análise termogravimétrica, análise elementar e espectroscopia Raman. Os cálculos mecânico-quânticos utilizados fundamentaram-se basicamente na utilização da Teoria do Funcional de Densidade (DFT) com o método B3LYP e o conjunto de base 6-311G (d,p). Foi determinado também por procedimento mecânicoquântico a Análise dos Orbitais Naturais de Ligação (NBO), para dois complexos de níquel (II), com o intuito de conhecer a real hibridização do cátion metálico na formação do complexo, assim como a hibridização dos átomos que formam parte da esfera de coordenação do complexo. Paralelamente à utilização desses recursos, foi realizada a interpretação da segunda derivada espectral tanto do espectro infravermelho quanto do espectro Raman, além da Análise de Deconvolução de Bandas que nos permitiu evidenciar as bandas recobertas e/ou sobrepostas de forma a elucidar corretamente o espectro vibracional estudado. O trabalho apresenta ainda uma nova proposta de atribuição vibracional, baseada na geometria distorcida dos diferentes modos normais, ou geometrias de não equilíbrio, ou perturbadas da molécula, concluindo com a atribuição teórica experimental dos diferentes espectros vibracionais. Por fim, as conclusões nos levam a perceber quão complexa e importante se faz a atribuição dos espectros vibracionais de complexos de compostos de coordenação bioinorgânicos, com o intuito de elucidar essencialmente a região de baixa energia, onde os modos vibracionais metal-ligante acontecem. O procedimento de integração das metodologias empregadas resultam em uma análise espectroscópica precisa e bem fundamentada. / [en] This work represents a spectroscopic vibrational study of metal complexes having amino acids as ligands. Here, were analyzed ternary complexes having Zn(II), Cd(II) and Ni(II) as central metallic ions with the following amino acids: cysteine, methionine, aspartic acid, serine, and with guanido acetic acid. The study was extended to one binary complex of Ni(II) with the guanidoacetic acid acting as ligand. The rigorous vibrational analyses allied to the complexes characterizations and to the theoretical calculations, were the fundamental and precious recourses in this research work. The infrared and/or vibrational spectroscopic information of metal – amino acids complexes are incomplete related to the vibrational characterization of all the normal modes, also we find lack of information referred to characterization and structural analysis. Allied to this fact, the lack of information or references in scientific literature on vibrational spectra of metal complex having amino acids as ligands, had a great contribution to elect the subject of this research. For the complexes characterization were used the following techniques: infrared analysis, thermo gravimetric analysis, elementary analysis and Raman spectroscopy. The quantum mechanical procedures were basically substantiated on the Density Functional Theory (DFT) with the B3LYP method and with the basis set 6-311G (d, p). The Natural Bond Orbital (NBO) was also determinate for two Ni(II) complexes. The intention here was to know the real hybridization of the metallic cation in the complex formation as well as the hybridization of the atoms which are inside of the coordination sphere of the central metallic ion. Joint to the utilization of these research sources, concerning the vibrational spectra, we carried out the second derivative interpretation for the infrared and Raman spectra, and using this information we extended the interpretation study of the normal modes to the deconvolution band analysis. This technique allowed us to put in evidence the overlapped bands, in such a way we are able to obtain almost all the fundamental bands in the vibrational spectrum. The research work present also a new way to assign the normal modes based on the characterization of the distorted geometry of the different normal modes, concluding with the theoretical and experimental assignment of the different vibrational spectra of these complexes. The conclusions point out to the consideration of the great importance which has the correct interpretation or assignment of the fundamental bands in the vibrational spectra of bioinorganic coordination compounds, essentially with the purpose to elucidate the low energy region where the metal – ligand vibrational modes are localized. The procedure of the integrated methodologies used here result in a precise and well substantiated vibrational analysis.

The co-ordination of Ni in hyperaccumulator plants was investigated using a number of mass spectrometry (MS)-based analytical techniques. Initial field studies on nickeliferous (lateritic) soils in Western Australia failed to identify plants containing elevated metal concentrations. For this reason, Ni-hyperaccumulators were collected from known ultramafic sites in New Caledonia, as well as grown under controlled conditions. Using electrospray ionization MS a Ni-nicotianamine (Ni-NA) complex [NiII(C12H20N3O6)]+ was identified in the South African Ni-hyperaccumulator Berkheya coddii. The association between Ni and NA was examined further in a range of Thlaspi species which accumulate different concentrations of Ni and Zn in their foliar tissues. In order to quantitate the concentration of NA a new liquid chromatography-MS (LC-MS) based analytical protocol was developed which allowed the quantification of NA and free amino acids. From the analysis of the leaf tissue in Thlaspi a strong correlation emerged between Ni and NA but not Zn. This suggested that NA plays a role in the transport of Ni in Ni-hyperaccumulating Thlaspi plants. An inverse proportionality was found between Fe and Ni. Higher NA production could be related to maintenance of Fe homeostasis. A correlation was also found between Zn and asparagine. These results are consistent with the operation of separate transport mechanisms for Ni and Zn. Further extreme examples of Ni-hyperaccumulation were also examined using LC-MS and metabolite profiling based on gas chromatography-MS (GC-MS). (For complete abstract open document)