Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-07-12T17:47:09Z No. of bitstreams: 1 lucasfagundesesteves.pdf: 3341806 bytes, checksum: 01a9ea92db8351da3b0d30ea2a019200 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-07-13T16:53:28Z (GMT) No. of bitstreams: 1 lucasfagundesesteves.pdf: 3341806 bytes, checksum: 01a9ea92db8351da3b0d30ea2a019200 (MD5) / Made available in DSpace on 2016-07-13T16:53:28Z (GMT). No. of bitstreams: 1 lucasfagundesesteves.pdf: 3341806 bytes, checksum: 01a9ea92db8351da3b0d30ea2a019200 (MD5) Previous issue date: 2012-02-29 / FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais / Neste trabalho foram utilizadas metodologias teóricas para a descrição do mecanismo de ação de complexos binucleares de platina(II) do tipo 1,1/c,c e 1,1/t,t. Inicialmente foi elucidada a influência do arranjo conformacional da cadeia espaçadora na estabilidade de complexos binucleares, através da construção de um parâmetro topológico chamado grau de distorção (λ). Para a construção do parâmetro λ, foi realizada uma busca conformacional no nível PM3 utilizando o método de Monte Carlo (MC) para o ligante desses complexos binucleares, a molécula de 1,6-hexanodiamina. O parâmetro λ, correlaciona-se linearmente com a energia PM3 dos confôrmeros obtidos, aumentando o seu valor à medida que a energia total diminui. O parâmetro λ correlaciona-se fortemente com as energias relativas em fase gás ( ) e em fase aquosa ( ) após a inclusão das esferas de coordenação metálica dos complexos 1,1/c,c e 1,1/t,t em determinadas conformações e posterior otimização no nível DFT com o funcional B3LYP e o conjunto de funções de base 6-31+G(d,p) para todos os átomos, exceto para a platina, a qual foi tratada com o pseudopotencial LANL2DZ. As reações de hidrólise dos complexos 1,1/c,c e 1,1/t,t foram estudadas em fase gás no nível B3LYP/6-31+G(d,p)/LANL2DZ e em fase aquosa com os modelos PCM/UAHF e PCM/Bondi. As constantes de velocidade calculadas para a reação direta em fase aquosa resultaram em valores muito próximos daqueles determinados experimentalmente, os quais são da ordem de 10-5s-1, para os complexos 1,1/c,c e 1,1/t,t. Durante esta dissertação também foi avaliada a influência da conformação na primeira barreira de hidrólise de complexos 1,1/c,c, mostrando que algumas conformações, que em um primeiro momento são instáveis, podem gerar barreiras de reação menores do que as conformações mais estáveis. Foram estudados os mecanismos de coordenação de complexos 1,1/c,c com a guanina em fase gás e fase aquosa no mesmo nível de teoria utilizado durante a etapa de hidrólise. / In this work, theoretical methods were used to describe the action mechanism of binuclear platinum(II) complexes named 1,1/c,c and 1,1/t,t. Initially, the influence of the conformational arrangement of the diamine chain on the stability of binuclear complex was elucidated, through the construction of a new topological parameter called distortion degree λ. In order to create the λ parameter, were performed a conformational search at PM3 level of theory using Monte Carlo (MC) method only for the ligand of these binuclear complexes, the 1,6-hexanediamine molecule. The λ parameter linearly correlates with the PM3 energy of the conformers, increasing its value, as the total energy decreases. The λ parameter has a strong correlation with the relative energies in gas phase ( ) and aqueous phase ( ) after the inclusion of the metallic coordination sphere of the 1,1/c,c and 1,1/t,t complexes in some specific conformations. Subsequent optimization has been carried out at DFT approach with the B3LYP functional and the 6-31+G(d,p) Pople’s basis set for all atoms, except for platinum, which was treated with LANL2DZ pseudopotential. The hydrolysis reaction of 1,1/c,c and 1,1/t,t complexes were studied in gas phase at B3LYP/6-31+G(d,p)/LANL2DZ level and in aqueous phase with the PCM/UAHF and PCM/Bondi model. The calculated rate constants for the forward reaction in aqueous phase lead to values very close to those experimentally resolute, which are about 10-5s-1 for the 1,1/c,c and 1,1/t,t complexes. During this study the influence of conformation on the first hydrolysis barrier of 1,1/c,c complex were also evaluated, showing that some conformations, which at the first moment were considerable unstable, can generate lower reaction barriers than the most stable conformations. The coordination mechanism of 1,1/c,c complex with guanine in gas and aqueous phase at the same level of theory used during the hydrolysis step were also studied and compared with literature.

A síntese e caracterização de sistemas hetero-híbridos gerados a partir da 3,6-bi-2-piridil-1,2,4,5-tetrazina (bptz) e interações com ouro nanoparticulado são abordados nesta tese. O bptz foi estudado por meio de métodos espectroscópicos e teóricos, focalizando principalmente o efeito SERS associado à adsorção em nanopartículas de ouro. O mecanismo de transferência de carga para metais macroscópicos foi transposto para a condição nanoparticulada, envolvendo ligações químicas entre bptz e as nanopartículas. Os complexos estudados possuem fórmula geral [LmRu(µ-bptz)RuLm]Xn, com “L” indicando os ligantes periféricos 5-cloro-1,10-fenantrolina (Clphen) ou 4’-(fenil)-2,2&#8217:6&#8217,2&#8221-terpirdina (ptpy) e “X” os contra-íons. Foram investigadas suas espectroeletroquímicas eletrônica e SERS, e as mudanças de perfil vibracional foram modeladas, incorporando o mecanismo de transferências de carga entre complexo e o ouro, além dos mecanismos ressonantes e eletromagnéticos / The synthesis and investigation of heterohybrid systems encompassing 3,6-bi-2-pyridyl-1,2,4,5-tetrazine (bptz) and its ruthenium complexes associated with gold nanoparticles are dealt with in this thesis. Bptz was characterized by spectroscopic and theoretical techniques, focusing on its SERS spectra after the adsorption onto nanoparticles. The charge transfer mechanism in the SERS spectra of macroscopic metals was transposed to the nanoparticle condition, assuming the formation of chemical bonds between bptz and the nanoparticles. Complexes of general formula [LmRu(µ--bptz)RuLm]Xn, “L” the peripheric ligants 5-chlorine-1,10-phenantroline or 4’-(phenyl)-2,2&#8217:6&#8217,2&#8221-terpyrdine (ptpy), and “X” counter-ions were also investigated, with special emphasis on their electronic and SERS spectroelectrochemistry. The changes in the vibrational profiles were successfully explained by the occurrence of charge transfer between the adsorbed complex and gold, in addition to the electromagnetic and resonance mechanisms.

A síntese e caracterização de sistemas hetero-híbridos gerados a partir da 3,6-bi-2-piridil-1,2,4,5-tetrazina (bptz) e interações com ouro nanoparticulado são abordados nesta tese. O bptz foi estudado por meio de métodos espectroscópicos e teóricos, focalizando principalmente o efeito SERS associado à adsorção em nanopartículas de ouro. O mecanismo de transferência de carga para metais macroscópicos foi transposto para a condição nanoparticulada, envolvendo ligações químicas entre bptz e as nanopartículas. Os complexos estudados possuem fórmula geral [LmRu(µ-bptz)RuLm]Xn, com “L” indicando os ligantes periféricos 5-cloro-1,10-fenantrolina (Clphen) ou 4’-(fenil)-2,2&#8217:6&#8217,2&#8221-terpirdina (ptpy) e “X” os contra-íons. Foram investigadas suas espectroeletroquímicas eletrônica e SERS, e as mudanças de perfil vibracional foram modeladas, incorporando o mecanismo de transferências de carga entre complexo e o ouro, além dos mecanismos ressonantes e eletromagnéticos / The synthesis and investigation of heterohybrid systems encompassing 3,6-bi-2-pyridyl-1,2,4,5-tetrazine (bptz) and its ruthenium complexes associated with gold nanoparticles are dealt with in this thesis. Bptz was characterized by spectroscopic and theoretical techniques, focusing on its SERS spectra after the adsorption onto nanoparticles. The charge transfer mechanism in the SERS spectra of macroscopic metals was transposed to the nanoparticle condition, assuming the formation of chemical bonds between bptz and the nanoparticles. Complexes of general formula [LmRu(µ--bptz)RuLm]Xn, “L” the peripheric ligants 5-chlorine-1,10-phenantroline or 4’-(phenyl)-2,2&#8217:6&#8217,2&#8221-terpyrdine (ptpy), and “X” counter-ions were also investigated, with special emphasis on their electronic and SERS spectroelectrochemistry. The changes in the vibrational profiles were successfully explained by the occurrence of charge transfer between the adsorbed complex and gold, in addition to the electromagnetic and resonance mechanisms.

This thesis describes the design, synthesis and reactivity of bimetallic complexes of doubly-pillared Schiff-base calixpyrrole ligands. Chapter One introduces the oxygen reduction reaction in light of the global energy scenario at present and in the future. Compounds and materials known to catalyse this reaction are discussed, with particular focus on transition metal complexes of pyrrole-containing macrocycles and the ability of these compounds to act as catalysts in redox reactions. Chapter Two describes the design and synthesis of several of the macrocyclic ligands developed during this project. The wide range of metals and geometries supported by one of the ligands, H4L, are outlined and include complexes of alkali-metals (Li, K), a rare earth metal (Mg), transition metals (Pd, Fe) and an actinide (UO2 2+). Chapter Three presents the use of [Co2(L)] for the reduction of dioxygen to water. The redox behaviour of the complex and its ability to reversibly bind oxygen were evaluated. The catalytic activity of [Co2(L)] was investigated in solution by UV-Vis spectrophotometry and electrochemically by rotating ring-disk electrochemistry. In Chapter Four, the ability of [Zn2(L)] to bind anions is described. Isothermal microcalorimetry, NMR, UV-Visible spectrophotometry, and fluorophotometry were used to study the de-aggregation of the anion free complex and the subsequent anion binding event. The stability of the complexes was estimated by DFT calculations. Chapter Five outlines the synthesis of complexes of L for other transition metals relevant to small molecule activation. Chapter Six contains a conclusion and suggestions on further investigations to carry out. Chapter Seven presents the full experimental details and analytical data for this work.