Understanding the behaviour of actinide species is of importance when removing and processing all nuclear waste. Examples include the safe clean-up of contaminated waste ponds and aspects of the TALSPEAK (Trivalent Actinide-Lanthanide Separation by Phosphorus Reagent Extraction from Aqueous Komplexes) process. The chemistry of the ponds and the TALSPEAK process has been studied by probing the aqueous solution behaviour of Ln(III), Am(III), Cm(III) and Th(IV) ions in the presence of organic (EDTA4- (ethylenediamine tetraacetate), DTPA5- (diethylenetriamine pentaacetate) and lactate) and inorganic (CO32- (carbonate) and OH- (hydroxide)) ligands by a variety of techniques including Nuclear Magnetic Resonance (NMR), Ultra Violet-Visible (UV-Vis) and luminescence spectroscopies, as well as potentiometry. Various ternary complexes have been shown to exist, including [M(EDTA)(CO3)]3-(aq), (where M = LnIII, AmIII or CmIII) and [Th(EDTA)(CO3)2]4-(aq), which form approximately over the pH range 8 to 11, and also [M(EDTA)(lactate)]2-(aq) (where M = Ln(III) or Am(III)) and [Th(EDTA)(lactate)]-(aq), which predominantly occur over the pH range 4 to 6. The nature of lactate interaction with [M(DTPA)]2-(aq) complexes (where M = Ln(III) or Am(III)) is unclear, as it may be possible that lactate can coordinate directly to the metal ion or to the acetate groups of DTPA5- (via a H-bonding interaction). The knowledge gained in this research has given a deeper insight into the nature of lanthanide and actinide coordination chemistry in mixed-ligand environments. For example, the increasing solubility of actinide metal ions in the contaminated waste ponds is probably due to the ability of organic ligands present in the ponds to solubilise metal ions at high pH, and also under TALSPEAK conditions of pH 3.5, there is likely to be minimal interaction of lactate with the [Ln(DTPA)]2-(aq) complexes. The determination of metal ion speciation using a combination of NMR, UV-Vis and luminescence spectroscopies, coupled with potentiometry, could be applied to new characterisation challenges faced in the future of the nuclear industry.

O objetivo do presente trabalho foi obter complexos binários e ternários de sinvastatina (SNV) e ciclodextrinas (CDs) utilizando diferentes tipos de CDs, métodos de secagem e polímeros para selecionar aquele que proporcionam um maior aumento da solubilidade aquosa do fármaco. Inicialmente complexos com diferentes CDs, a α, β, γ, e hidroxi-propil-β (HPβCD) foram obtidos através da secagem em estufa. Foram empregados os seguintes ensaios para sua caracterização: solubilidade, DSC, TG e difração de raios X. Adicionalmente, foi realizada a modelagem molecular com simulações de dinâmica molecular. O complexo com γCD parece ser o mais adequado para a complexação com a SNV, pois, foi o mais estável (menor energia) na modelagem molecular, além de ter apresentado uma nova fase sólida na difração de raios X. Complexos de SNV, γCD ou HPβCD foram obtidos por diferentes métodos de secagem (estufa com circulação forçada de ar, coevaporação, liofilização e estufa a vácuo) e a caracterização foi realizada através da solubilidade, DSC, TG e difração de raios X. Todos os complexos melhoraram a solubilidade da SNV, mas quando comparados às respectivas misturas físicas, o ganho foi baixo. As curvas DSC e a difração de raios X indicam que, no máximo, pode ter ocorrido uma complexação parcial em alguns casos. O que se verifica é que mesmo o complexo que apresentou maior ganho de solubilidade (HPβCD obtido pela coevaporação), a complexação do não foi total. Complexos ternários de SNV, βCD e diferentes polímeros (polietilenoglicol 1500, polietilenoglicol 4000, povidona, copovidona, crospovidona, maltodextrina e hidroxipropil-metilcelulose) foram preparados utilizando-se a coevaporação. A caracterização dos complexos foi realizada através da solubilidade, DSC e TG. Para todos os complexos houve ganho de solubilidade, mas apenas quando foi utilizado a crospovidona e a maltodextrina, existe diferença significativa entre a solubilidade observada para a mistura física e aquela registrada para o complexo. As curvas DSC indicam que ainda existe fármaco na forma livre até mesmo nos complexos que apresentaram maior solubilidade, dessa forma, nenhum dos polímeros utilizados foi capaz de promover um complexação total da SNV. / The purpose of this study was to obtain binary and ternary complexes of simvastatin (SV) and cyclodextrins (CDs) using different types of CDs, drying methods and polymers, to select those that offer greater increase in aqueous solubility of the drug. Initially, different complexes with CDs, α, β, γ, and hydroxy-propyl-β (HPβCD), were obtained using oven drying. The following tests were performed for complexes´s characterization: solubility, DSC, TG and X-ray diffraction. Additionally, molecular modeling was performed with molecular dynamics simulations. The complex with γCD seems to be the most suitable for complexation with the SV, since it has been the most stable (lowest energy) in molecular modeling, and has presented a new solid phase in X-ray diffraction. Complex of SV, γCD or HPβCD were obtained by different drying methods (forced air circulation oven, co-evaporation, freeze drying and vacuum oven) and the characterization was performed by solubility, DSC, TG and X-ray diffraction. All the complexes improved the solubility of SV, but when compared to their physical mixtures, the gain is low. The DSC curves and X-ray diffraction indicates that, at most, a partial complexation may have happened in some cases. It was verified that even the complex that had greater increase in solubility (HPβCD obtained by co-evaporation), the complexation was not total. Ternary complexes of SV, βCD and different polymers (polyethyleneglycol 1500, polyethyleneglycol 4000, povidone, copovidone, crospovidone, maltodextrin and hydroxypropyl-methyl-cellulose) were prepared using the co-evaporation. The characterization of the complexes was performed by solubility, DSC and TG. For all complexes there was a gain of solubility, but only when crospovidone and maltodextrin were used, there was a significant difference between the solubility observed for the physical mixture and the complex. The DSC curves indicate that non comlexed drug is still present, even in the complexes that had higher solubility. Thus, none of the polymers was able to promote a total complexation of SV.

[pt] Foram estudados os sistemas binários e ternários de cobalto (II) e de níquel(II) com os aminoácidos glicina, serina, ácido aspártico e ácido guanidoacético. Os aminoácidos glicina - Gly, serina - Ser, ácido aspártico - Asp e ácido guanidoacético - Gaa estão envolvidos em muitos processos bioquímicos. Esses aminoácidos fazem parte de muitas proteínas que, por sua vez, são bons agentes complexantes. O estudo das interações metal- aminoácido tem grande interesse, visto que estas representam modelos simplificados para a análise das mudanças provocadas nas propriedades das proteínas, quando estas se ligam aos íons metálicos. Neste estudo foram determinadas as constantes de formação e de interação das espécies pertencentes aos sistemas binários e ternários de cobalto(II) e de níquel(II), e também foram realizados estudos espectrofotométricos de UVVis de todos os sistemas estudados. A comparação dos espectros de UV-Vis em diferentes valores de pH com os gráficos de distribuição de espécies permitiu relacionar as bandas d-d com as respectivas espécies propostas. Analisando as constantes de formação dos complexos ternários ML1L2, constatou-se que os complexos de Ni(II) apresentam valores mais altos que os respectivos de Co(II), o que está de acordo com a série de Irving-Williams. Comparando-se os espectros de UV-Vis com os da literatura, pode-se concluir que as bandas encontradas, assim como os seus respectivos posicionamentos e absortividades molares referem-se a complexos octaédricos não regulares. Verificou-se que as maiores interações intramoleculares dos ligantes nos complexos estudados, ocorreram com as espécies contendo Gaa. A partir dos gráficos de distribuição de espécies em função do pH, pode-se verificar que, em pH biológico, para os três sistemas de Co(II), predominam as espécies ternárias protonadas. Para os sistemas de Ni(II), não é possível generalizar. No sistema Ni-Gly-Ser a espécie NiGlySer está em maior quantidade em pH em torno de 7; no sistema Ni-Asp- Gly, as espécies ternárias formam-se em menor quantidade em valores de pH mais baixos e em pH biológio, as espécies binárias de NiAsp hidrolizadas é que predominam; no sistema Ni-Ser-Gaa, as espécies ternárias protonadas é que estão em maior concentração. Em pH ~ 9, já encontramos espécies hidrolisadas (binárias e/ou ternárias) em todos os sistemas ternários. Em meio mais básico, as espécies ternárias fragmentam-se, gerando espécies binárias hidrolisadas dos tipos ML(OH)3 e ML(OH)4 que passam a ter maiores estabilidades. / [en] The binary and ternary systems of cobalt(II) and nickel (II) with the amino acids glycine, serine, aspartic acid and guanidinoacetic acid were studied. The amino acids glycine - Gly, serine - Ser, aspartic acid - Asp and guanidinoacetic acid - Gaa are all involved in several biochemical processes. These amino acids are constituents of many proteins, which are in turn, good complexing agents. The study of metal-amino acid interactions are of great interest, as they represent simplified models for the analysis of the changes caused in the proteins` properties, when these bond to metal ions. It was determined, in this work, the formation and interaction constants of species belonging to the binary and ternary systems of cobalt(II) and nickel(II). UV-Vis spectrophotometric analysis were also made for each of the systems studied. The comparison of the UV-Vis spectra in different pHs with the species` distribution graphs indicated a relationship between the d-d bands and the respective proposed specie. When analyzing the formation constants of the ternary complexes ML1L2, the Ni (II) complexes showed higher values than those of respective Co(II) complexes, a pattern which is in accordance with the Irving-Williams series. In conclusion to the comparison of the UV-Vis spectra with those in literature, we have that the bands found, as well as their respective position and molar absortivities, refer themselves to nonregular octahedral complexes. It was verified that the greatest intramolecular interactions beetween the ligands in the complexes studied were those of the species cointaining Gaa. From the graphs of species distribution in terms of pH, we were able to verify that in biological pH, for all three systems of Co(II), protonated ternary species were predominant. No generalizations were visible for the Ni(II) systems. In the Ni-Gly-Ser system, the specie NiGlySer is present in greater amounts in pH close to 7; in the Ni-Asp-Gly system, the ternary species are formed in lower quantities in lower pH values and in higher and biological pH values, binary species of hydrolyzed NiAsp are predominant; in Ni-Ser-Gaa systems, protonated ternary species are in higher concentration. In pH ~ 9, hydrolyzed (binary and/or ternary) species were found in all ternary systems. In more basic medium, the ternary species were fragmented, therefore generating ML(OH)3 and ML(OH)4 hydrolyzed binary species, which have in turn greater stability.

O objetivo do presente trabalho foi obter complexos binários e ternários de sinvastatina (SNV) e ciclodextrinas (CDs) utilizando diferentes tipos de CDs, métodos de secagem e polímeros para selecionar aquele que proporcionam um maior aumento da solubilidade aquosa do fármaco. Inicialmente complexos com diferentes CDs, a α, β, γ, e hidroxi-propil-β (HPβCD) foram obtidos através da secagem em estufa. Foram empregados os seguintes ensaios para sua caracterização: solubilidade, DSC, TG e difração de raios X. Adicionalmente, foi realizada a modelagem molecular com simulações de dinâmica molecular. O complexo com γCD parece ser o mais adequado para a complexação com a SNV, pois, foi o mais estável (menor energia) na modelagem molecular, além de ter apresentado uma nova fase sólida na difração de raios X. Complexos de SNV, γCD ou HPβCD foram obtidos por diferentes métodos de secagem (estufa com circulação forçada de ar, coevaporação, liofilização e estufa a vácuo) e a caracterização foi realizada através da solubilidade, DSC, TG e difração de raios X. Todos os complexos melhoraram a solubilidade da SNV, mas quando comparados às respectivas misturas físicas, o ganho foi baixo. As curvas DSC e a difração de raios X indicam que, no máximo, pode ter ocorrido uma complexação parcial em alguns casos. O que se verifica é que mesmo o complexo que apresentou maior ganho de solubilidade (HPβCD obtido pela coevaporação), a complexação do não foi total. Complexos ternários de SNV, βCD e diferentes polímeros (polietilenoglicol 1500, polietilenoglicol 4000, povidona, copovidona, crospovidona, maltodextrina e hidroxipropil-metilcelulose) foram preparados utilizando-se a coevaporação. A caracterização dos complexos foi realizada através da solubilidade, DSC e TG. Para todos os complexos houve ganho de solubilidade, mas apenas quando foi utilizado a crospovidona e a maltodextrina, existe diferença significativa entre a solubilidade observada para a mistura física e aquela registrada para o complexo. As curvas DSC indicam que ainda existe fármaco na forma livre até mesmo nos complexos que apresentaram maior solubilidade, dessa forma, nenhum dos polímeros utilizados foi capaz de promover um complexação total da SNV. / The purpose of this study was to obtain binary and ternary complexes of simvastatin (SV) and cyclodextrins (CDs) using different types of CDs, drying methods and polymers, to select those that offer greater increase in aqueous solubility of the drug. Initially, different complexes with CDs, α, β, γ, and hydroxy-propyl-β (HPβCD), were obtained using oven drying. The following tests were performed for complexes´s characterization: solubility, DSC, TG and X-ray diffraction. Additionally, molecular modeling was performed with molecular dynamics simulations. The complex with γCD seems to be the most suitable for complexation with the SV, since it has been the most stable (lowest energy) in molecular modeling, and has presented a new solid phase in X-ray diffraction. Complex of SV, γCD or HPβCD were obtained by different drying methods (forced air circulation oven, co-evaporation, freeze drying and vacuum oven) and the characterization was performed by solubility, DSC, TG and X-ray diffraction. All the complexes improved the solubility of SV, but when compared to their physical mixtures, the gain is low. The DSC curves and X-ray diffraction indicates that, at most, a partial complexation may have happened in some cases. It was verified that even the complex that had greater increase in solubility (HPβCD obtained by co-evaporation), the complexation was not total. Ternary complexes of SV, βCD and different polymers (polyethyleneglycol 1500, polyethyleneglycol 4000, povidone, copovidone, crospovidone, maltodextrin and hydroxypropyl-methyl-cellulose) were prepared using the co-evaporation. The characterization of the complexes was performed by solubility, DSC and TG. For all complexes there was a gain of solubility, but only when crospovidone and maltodextrin were used, there was a significant difference between the solubility observed for the physical mixture and the complex. The DSC curves indicate that non comlexed drug is still present, even in the complexes that had higher solubility. Thus, none of the polymers was able to promote a total complexation of SV.

Le but de notre travail était d'étudier comment des interactions impliquant des acides nucléiques pouvaient réguler le cycle viral du virus de l'hépatite C (VHC). L'ARN génomique du VHC est très structuré au niveau de ses extrémités 5' et 3'. La tige-boucle 5BSL3.2 a été décrite comme interagissant avec la SLIIId, la Seq9110 et la SL2 par génétique inverse et expériences de complémentation de mutations. La résonance plasmonique de surface (SPR) a été utilisée afin de caractériser ces interactions. Cela nous a conduit à développer des méthodes permettant d’étendre l'utilisation de la SPR. Nous avons pu observer, in vitro, une interaction entre la 5BSL3.2 et miR-122, un microARN fortement exprimé dans les hépatocytes. Nos résultats ont également montré que la SL2 était une séquence ARN pouvant former au moins deux conformations. L'une étant capable d'interagir avec la 5BSL3.2 et l'autre pouvant s'auto-associer. L'étude de cette dimérisation sur modèle cellulaire a montré qu'elle était impliquée dans les mécanismes de la réplication virale. Le développement d'une méthode d'analyse des complexes ternaires a permis la caractérisation simultanée du complexe formé entre la boucle interne de la 5BSL3.2 et ses partenaires (Seq9110 et SLIIId) ainsi que du complexe formé entre la boucle apicale et ses partenaires (SL2 et miR-122). Ces résultats ont montré que les deux sites de liaison de la 5BSL3.2 étaient structurellement indépendants. Ces interactions pourraient donc coexister dans un contexte physiologique. Les résultats montrent que la SLIIId et la Seq9110 sont en compétition pour interagir avec la boucle interne de la 5BSL3.2 tandis que la tige-boucle SL2 et miR-122 sont en compétition pour interagir avec la boucle apicale de la 5BSL3.2. La 5BSL3.2 est donc un motif ARN structuré pouvant agir comme une plaque tournante, capable d'interagir avec d'autres régions de l'ARN génomique tandis que la SL2 a montré que les deux interactions qu'elle pouvait former, mutuellement exclusives, étaient importantes pour la prolifération virale. Les mécanismes de compétition observés pourraient être impliqués dans la commutation entre les différentes étapes du cycle viral. / We are interested in understanding how interactions involving nucleic acids regulate the life cycle of the Hepatitis C virus (HCV). The HCV genomic RNA is highly structured at the 5' and 3' ends. The stem-loop 5BSL3.2 was described to interact with the SLIIId, the Seq9110 and the SL2 by reverse genetics and complementation mutation experiments. Surface plasmon resonance (SPR) was used to characterize these interactions. This led us to develop methods to expand the use of this technique. We described in vitro evidences for an interaction between 5BSL3.2 and miR-122, a microRNA highly expressed in hepatocytes. As shown by our results, SL2 is a highly dynamic RNA motif that fluctuates between at least two conformations: one is able to hybridize with 5BSL3.2 and the other one is capable of self-associating. The study of this dimerization in living cells has shown an implication of this phenomenon in viral replication processes. The development of a ternary complex analysis method allowed the characterization of the Seq9110 (or SLIIId) and SL2 (or miR-122) interacting with 5BSL3.2. Our results shown that the two binding sites of 5BSL3.2, the apical and internal loops, are structurally independent, suggesting that these interactions may coexist in a physiological context. SLIIId and Seq9110 were shown to compete to interact with 5BSL3.2 internal loop while SL2 and miR-122 were shown to compete to interact with 5BSL3.2 apical loop. In conclusion, 5BSL3.2 is a structured RNA motif that could act as a molecular hub capable of interacting with other genomic RNA regions while the two interactions of the SL2, mutually exclusives, were shown to be crucial for viral proliferation. The competition mechanisms observed could be involved in the commutation between viral cycle steps.

[pt] Foram estudados alguns sistemas binários de Cu(II) e Zn(II) formados com as poliaminas (PA= En, Tn, Put, Spd e Spm) e os complexos ternários (MLPA), onde L foi a PCr ou o ATP e PA uma das cinco poliaminas. O estudo foi realizado em solução aquosa por potenciometria, espectroscopia de ultravioleta-visível, Raman, RMN e RPE e cálculos de menor energia de estabilização e modelagem molecular. As constantes de estabilidade foram determinadas pela potenciometria. Os valores das constantes dos complexos com as poliaminas apresentam um comportamento bastante diferenciado entre os sistemas formados com o Cu(II) e Zn(II). A ordem dos valores das constantes de estabilidade dos sistemas com o Cu(II) é:CuPut<CuTn<CuEn<CuSpd<CuSpm, e dos sistemas com Zn(II) é: ZnPut<ZnEn<ZnTn<ZnSpm<ZnSpd. Esse comportamento diferenciado se deve a estrutura formada nos complexos. Enquanto o anel de 5 membros formado pelo complexo CuEn é mais estável do que o anel de 6 e 7 membros formados pelos complexos CuTn e CuPut, respectivamente, nos sistemas com o Zn(II) o complexo que forma anel de 6 membros (ZnTn) é mais estável do que o complexo que forma anel de 5 membros (ZnEn). Já o complexo ZnPut é o menos estável pela coordenação monodentada da poliamina ao Zn(II). Os complexos formados com Cu(II) e Zn(II) com a Spd e Spm também apresentam comportamento diferenciado. Com o Cu(II) as poliaminas Spd e Spm formam complexos se coordenando com três e quatro grupamentos amino, respectivamente. Com o Zn(II) a coordenação deve ser por três grupamentos amino nos dois complexos formados. Interações entre as poliaminas protonadas e os dois ligantes são observadas de um modo geral exceto no sistema Zn:ATP:Spd, e isso se deve a conformação que a molécula formada sofre que desfavorece a interação entre os ligantes. Interações entre as triamina (Spd) e tetramina (Spm) e a PCr, são observadas nos complexos ternários, para ambos os íons, mesmo quando estas não estão protonadas. Esta interação deve ser pelo átomo de nitrogênio não coordenado da poliamina e o átomo de oxigênio não coordenado da PCr. Neste trabalho foi possível esclarecer o modo de coordenação do Cu(II) com a PCr em solução, que é pelos grupamentos guanidino e fosfato do ligante, tanto no complexo binário como nos complexos ternários. Também para o Zn(II) a PCr se complexa do mesmo modo. O modo de coordenação do ATP ao Zn(II) tanto nos complexos binários como ternários, deve ser através dos grupamentos fosfatos PB e Py . / [en] Some binary systems of Cu(II) and Zn(II) with polyamines (PA=En, Tn, Put, Spd and Spm), and ternary complexes (MLPA) of Cu(II) and Zn(II), where L is PCr or ATP, and PA is one of the five polyamines, were studied. The study was performed in aqueous solution using potentiometry, ultraviolet-visible, Raman, NMR and EPR spectroscopies, and, calculations of the lowest stabilization energy for formed complexes and molecular modeling. The stability constants were determined by potentiometry. The order of the values of stability constants of the systems with Cu(II) is: CuPut<CuTn<CuEn<CuSpd<CuSpm. For systems with Zn(II) it is: ZnPut<ZnEn< ZnTn<ZnSpm<ZnSpd. This different behavior is due to the structures formed by the complexes. While the 5-membered ring formed by CuEn complex is more stable than the 6- and 7-membered ring complexes formed by CuTn and CuPut, respectively, in systems with Zn(II) the complex that forms the 6-membered ring (ZnTn) is more stable than 5-membered ring (ZnEn). The complex ZnPut is less stable than systems formed with other diamines, suggesting a monodentate coordination of this polyamine with Zn(II). The complexes formed by Cu(II) and Zn(II) with Spd and Spm also have a peculiar behavior. With Cu(II) the polyamines Spd and Spm form complexes by coordinating with three and four amino groups, respectively. With Zn(II) coordination should be through three amino groups in both complexes. Interactions between protonated polyamines and the two ligands are generally observed, except in the system Zn:ATP:Spd. This can be because of the conformation suffered by the molecule, hindering the interaction between the ligands. Interactions between the tridentate (Spd) and tetradentate (Spm) polyamines and PCr are observed in the ternary complexes for both ions, even when the PA´s are not protonated. This interaction should be between the non-coordinated nitrogen atom from the PA and the non-coordinated oxygen atom from PCr. It was possible to clarify the coordination mode of Cu(II) with PCr in solution, which occurs through the guanidine and phosphate groups of PCr, both in the binary and ternary complexes. The ion Zn(II) also coordinates in the same way. The coordination mode of ATP with Zn(II) in the binary and ternary complexes probably takes place through the PB and PY phosphates groups.

Na presente tese investigou-se a adsorção induzida de um cátion metálico (cádmio(II)) na presença simultânea de dois ligantes (um pseudo-haleto e uma amina ou haleto) na interface eletrodo de mercúrio/solução aquosa, com vistas a uma melhor compreensão desse processo. Os estudos de adsorção foram precedidos por estudos de equilíbrio dos compostos de coordenação formados em solução aquosa. Medidas experimentais foram feitas por potenciometria com eletrodo de amálgama, em força iônica 1,00 M, ajustada com NaCl04. Análise dos dados por programas computacionais adequados levou à quantificação das constantes de estabilidade de 7 espécies binárias e 9 espécies mistas para o sistema Cd(II)/ SCN-/C6H12N4 e de 8 espécies binárias e 6 mistas para o sistema Cd(II)/I-/SCN-, sendo todas estas espécies mononucleares. Para possibilitar um maior grau de automação das medidas cronocoulométricas de adsorção, o eletrodo de gota pendente de mercúrio, anteriormente desenvolvido no IQ-USP, teve seu sistema mecânico aperfeiçoado e passou a ser controlado por computador. O \"software\" se incumbe de calcular e comandar o tempo de abertura da micro-válvula do eletrodo para gerar gotas com a área solicitada. Aproveitando a possibilidade de realizar aquisição (de dados de carga durante e após a formação das gotas de mercúrio, introduziu-se um novo método para corrigir a componente faradaica que interfere nos experimentos de determinação da carga absoluta do eletrodo por extrusão. Após provar o bom funcionamento do método, conseguiu-se a combinação inédita do método de extrusão de gotas com acronocoulometria num único experimento automatizado feito com a mesma gota de mercúrio. Com as informações assim geradas, torna-se possível conhecer e optar entre o potencial e a carga absoluta como parâmetro que define o estado elétrico da interface eletrodo/solução. Com esta combinação de técnicas, foi investigada a adsorção de cádmio induzida por tiocianato e hexametilenotetramina. Este sistema apresentou um interessante comportamento: a hexametilenotetramina, ao contrário do tiocianato, não induz a adsorção de ions cádmio, mas na presença desse pseudo-haleto provoca um intenso reforço na adsorção induzida que pode alcançar um fator de 50 vezes. Também foi possível realizar estimativas sobre as espécies que adsorvem preferencialmente, e da área média ocupada pelos complexos na condição de máxima adsorção. A energia livre de adsorção pode ser estimada pela isoterma de Henry, para baixas concentrações de ligantes. A adsorção de cádmio induzida por iodeto e tiocianato foi investigada de maneira preliminar. Nos estudos deste sistema ficou bem evidenciada a importância da utilização da carga como variável independente, ao invés do potencial. / The induced adsorption of a metallic cation (cadmium (II)) in the presence of two ligands, simultaneously (a pseudo-halide and an amine or halide), has been investigated at the mercury electrode/aqueous solution interface with the purpose of gaining a better understanding about such kind of process. The adsorption studies have been preceded by studies of the equilibria of the coordination compounds formed in aqueous solutions. Experimental measurements have been made by potentiometry with an amalgam electrode with 1,00 M ionic strength adjusted with NaClO4. Analysis of the data with adequated software allowed the quantification of the stability constants of 7 binary and 8 mixed species for the system Cd(II)/ SCN-/C6H12N4</sub and 8 binary and 6 mixed species for the system Cd(II)/I-/SCN-, all species being mononuclear. To provide a greater degree of automation of the chronocoulometric measurements of adsorption, the hanging drop mercury electrode, formely developed at the Chemistry Institute-USP, has had its mechanical parts perfectioned and wasput under computer control. A software was written to calculate and control the opening and closure of the micro-solenoid valve of the electrode to generate drops with the required area. A new method for the correction of the faradaic component that interferes with the absolute electrode charge during extrusion experiments was introduced and applied to charge measurements obtained making data aquisition during and shortly after the drop formation. Once proved that the method works, efforts were directed to combine the extrusion with the chronocoulometric measurements in one automated experiment dane with the same mercury drop. As a result, it is now a simple matter to make a choice between potential or charge on the electrode to define the electric state of the electrode/solution interface. With this combination of techniques, the adsorption of cadmium(II) induced by thiocyanate and hexamethylenetetramine has been investigated. An interesting behavior whas observed: the hexamethylenetetramine alone, doesn\'t induce adsorption of cadmium (II) as does the thiocyanate but provides a strong reinforcement (up to a factor of 50) of the induced adsorption when it is present simultaneously with the pseudo-halide. Some estimatives about the species that can adsorb preferentially has been made, as well as an evaluation of the mean area ocupied by the complexes at the maximum adsorption condition. The free energy of adsorption has been calculated, considering an Henry isotherm for the lowest concentration range. Preliminary studies of the induced adsorption of the Cd(II)/I-/SCN- system revealed a slight reinforcement of the adsorption, when both ligands are presente. The iodide always controls the process. The advantage of using the charge in place of potential as the independent variable is evident for this system.

[pt] Foram estudados os sistemas binários de complexos de Cu(II) e Al(III) formados com a fosfocreatina (PCr), o adenosina 5 trifosfato (ATP), a glicina (Gli), a serina (Ser), a tirosina (Tir) e a treonina (Tre) e os sistemas ternários (MLaLb) onde La foi o ATP ou a PCr e o Lb foi um dos quatro aminoácidos. O estudo foi realizado em solução aquosa através da técnica potenciométrica e das técnicas espectroscópicas ultravioleta-visível, Raman, RMN e RPE. As constantes de estabilidade foram determinadas pela potenciometria. Considerando L como um dos aminoácidos, foi observado que todos os complexos CuL são mais estáveis que os complexos AlL correspondentes. Este fato pode ser explicado pela grande afinidade entre o Cu(II) e o grupo amino. Por outro lado, os complexos binários formados com os fosfatos (ATP ou PCr) e o Al(III) apresentaram valores maiores de log b, do que os complexos de Cu(II) correspondentes. Este fato pode ser justificado pela grande afinidade do Al(III) com os átomos de oxigênio dos fosfatos. Pela mesma razão, todos os complexos ternários de Al(III) apresentaram-se mais estáveis do que os de Cu(II) correlacionados. Os valores das constantes de estabilidade dos complexos poderiam ser divididos em dois grupos: o dos complexos binários e o dos complexos ternários, com valores mais altos. Para os complexos de cobre, este comportamento foi confirmado pelo decréscimo dos valores dos comprimentos de onda máximos no espectro de absorção e no aumento no parâmetro Ao à medida que as constantes de estabilidade aumentaram. Os comprimentos de onda máximos dos complexos CuATPLb foram maiores que os dos complexos CuPCrLb, o que indica que o ATP deve coordenar com o Cu(II) através de dois átomos de oxigênio dos fosfatos e a PCr deve coordenar, nos complexos CuPCrLb, através de um átomo de oxigênio e um átomo de nitrogênio. O valor de D log K [log bCuLaLb) - (log bCuLa + log bCuLb)] mostrou que, quando La foi o ATP, os complexos ternários de Cu(II) e de Al(III) foram menos estáveis do que os seus binários respectivos, sugerindo não existir qualquer tipo de interação entre os ligantes. Aplicando o mesmo cálculo para os sistemas de Cu(II) onde La foi a PCr e Lb a serina ou a tirosina, o valor de D log K foi maior do que zero, indicando que estes ligantes favoreceram a formação de complexos ternários mais estáveis, o que pode ser justificado pela interação do grupo OH destes aminoácidos com o grupo livre (carboxilato ou fosfato) da PCr. Para todos os complexos AlPCrLb, onde Lb foi um dos quatro aminoácidos em estudo, os valores das constantes de estabilidade dos ternários foram maiores do que a soma das constantes dos seus binários. Este fato, não pode ser justificado pela interação do grupo OH dos aminoácidos com a PCr, já que a glicina não apresenta este grupo. Provavelmente, a interação ocorre através do oxigênio não coordenado do fosfato da PCr e do hidrogênio do grupo amino do aminoácido. O estudo do sistema Al(III):Ser pela espectroscopia Raman, mostrou que o complexo [Al(Ser)(H2O)4] 2+ é a espécie predominante e a serina atua como ligante bidentado (átomo de N do grupo amino e átomo de oxigênio do carboxilato). Este deve ser o comportamento de todos os complexos de Al(III) com os aminoácidos. / [en] The binary systems of Cu(II) and Al(III) complexes with adenosine triphosphate (ATP), phosphocreatine (PCr), glycine (gly), serine (Ser), tyrosine (Tyr) and threonine (Thr) and the ternary systems where La was ATP or PCr and Lb was one of the four amino acids, were investigated. The study was performed in aqueous solution using potentiometry, ultraviolet visible, Raman, NMR and EPR spectroscopies. The stability constants of the complexes were determined by potentiometry. When L is one of the amino acids, it can be observed that all the CuL complexes are more stable than the correspondent AlL complexes. This can be explained by the greater affinity between the Cu(II) and the amino group. On the other hand, the binary complexes formed by one of the phosphates (ATP or PCr) and Al(III) have greater values of log b than the correspondent complexes of Cu(II). This can be explained by the greater affinity of Al(III) ion to the oxygen atoms of the phosphates. For this same reason, all the ternary complexes of Al(III) are more stable than the Cu(II) ones. The values of the stability constants of the complexes could be divided in two groups: one of the binary complexes and the second of the ternary complexes, with higher values. For the Cu(II) complexes this behavior was confirmed by the decreasing of the maximum wavelength in the absorption spectra and the increasing of the A0 parameter as the stability constants increase. The maximum wavelength of the CuATPLb complexes were greater than those of the CuPCrLb complexes and this means that ATP must be bound to Cu(II) ion through two oxygen atoms of the phosphates, whereas in CuPCrLb complexes, PCr is bound through one oxygen atom and one nitrogen atom and the amino acid is the same. Values of DlogK (logbCuLaLb - (logbCuLa+ logbCuLb) showed that when La was ATP, the ternary complexes of Cu(II) and Al(III) were less stable than the binary ones suggesting that it does not occur any interaction between the ligands in the ternary complexes. When La was PCr, the stability constants of the Cu(II) complexes where Lb was Ser or Tyr were greater. This showed that these ligands favored more stable ternary complexes and this must be due to the interaction of the OH group of these amino acids and the phosphate or carboxylate of PCr. For the AlPCrLb complexes, when Lb was one of the four amino acids, the stability constants of the complexes were greater. This shows that in this case, the interaction cannot be between the OH groups of the amino acid since glycine does not have any OH group. Probably the interaction occur through the non coordinated oxygen of the phosphate of PCr and the hydrogen of the amino group of the aminoacid. The study of the sistem Al(III):Ser by Raman spectroscopy, showed that [Al(Ser)(H2O)4]2+is the predominant species and that Ser acts as bidentate ligand (N atom of the amino group and O atom of the carboxylate). This must be the behavior of all the complexes of Al(III) and the amino acids.

Na presente tese investigou-se a adsorção induzida de um cátion metálico (cádmio(II)) na presença simultânea de dois ligantes (um pseudo-haleto e uma amina ou haleto) na interface eletrodo de mercúrio/solução aquosa, com vistas a uma melhor compreensão desse processo. Os estudos de adsorção foram precedidos por estudos de equilíbrio dos compostos de coordenação formados em solução aquosa. Medidas experimentais foram feitas por potenciometria com eletrodo de amálgama, em força iônica 1,00 M, ajustada com NaCl04. Análise dos dados por programas computacionais adequados levou à quantificação das constantes de estabilidade de 7 espécies binárias e 9 espécies mistas para o sistema Cd(II)/ SCN-/C6H12N4 e de 8 espécies binárias e 6 mistas para o sistema Cd(II)/I-/SCN-, sendo todas estas espécies mononucleares. Para possibilitar um maior grau de automação das medidas cronocoulométricas de adsorção, o eletrodo de gota pendente de mercúrio, anteriormente desenvolvido no IQ-USP, teve seu sistema mecânico aperfeiçoado e passou a ser controlado por computador. O \"software\" se incumbe de calcular e comandar o tempo de abertura da micro-válvula do eletrodo para gerar gotas com a área solicitada. Aproveitando a possibilidade de realizar aquisição (de dados de carga durante e após a formação das gotas de mercúrio, introduziu-se um novo método para corrigir a componente faradaica que interfere nos experimentos de determinação da carga absoluta do eletrodo por extrusão. Após provar o bom funcionamento do método, conseguiu-se a combinação inédita do método de extrusão de gotas com acronocoulometria num único experimento automatizado feito com a mesma gota de mercúrio. Com as informações assim geradas, torna-se possível conhecer e optar entre o potencial e a carga absoluta como parâmetro que define o estado elétrico da interface eletrodo/solução. Com esta combinação de técnicas, foi investigada a adsorção de cádmio induzida por tiocianato e hexametilenotetramina. Este sistema apresentou um interessante comportamento: a hexametilenotetramina, ao contrário do tiocianato, não induz a adsorção de ions cádmio, mas na presença desse pseudo-haleto provoca um intenso reforço na adsorção induzida que pode alcançar um fator de 50 vezes. Também foi possível realizar estimativas sobre as espécies que adsorvem preferencialmente, e da área média ocupada pelos complexos na condição de máxima adsorção. A energia livre de adsorção pode ser estimada pela isoterma de Henry, para baixas concentrações de ligantes. A adsorção de cádmio induzida por iodeto e tiocianato foi investigada de maneira preliminar. Nos estudos deste sistema ficou bem evidenciada a importância da utilização da carga como variável independente, ao invés do potencial. / The induced adsorption of a metallic cation (cadmium (II)) in the presence of two ligands, simultaneously (a pseudo-halide and an amine or halide), has been investigated at the mercury electrode/aqueous solution interface with the purpose of gaining a better understanding about such kind of process. The adsorption studies have been preceded by studies of the equilibria of the coordination compounds formed in aqueous solutions. Experimental measurements have been made by potentiometry with an amalgam electrode with 1,00 M ionic strength adjusted with NaClO4. Analysis of the data with adequated software allowed the quantification of the stability constants of 7 binary and 8 mixed species for the system Cd(II)/ SCN-/C6H12N4</sub and 8 binary and 6 mixed species for the system Cd(II)/I-/SCN-, all species being mononuclear. To provide a greater degree of automation of the chronocoulometric measurements of adsorption, the hanging drop mercury electrode, formely developed at the Chemistry Institute-USP, has had its mechanical parts perfectioned and wasput under computer control. A software was written to calculate and control the opening and closure of the micro-solenoid valve of the electrode to generate drops with the required area. A new method for the correction of the faradaic component that interferes with the absolute electrode charge during extrusion experiments was introduced and applied to charge measurements obtained making data aquisition during and shortly after the drop formation. Once proved that the method works, efforts were directed to combine the extrusion with the chronocoulometric measurements in one automated experiment dane with the same mercury drop. As a result, it is now a simple matter to make a choice between potential or charge on the electrode to define the electric state of the electrode/solution interface. With this combination of techniques, the adsorption of cadmium(II) induced by thiocyanate and hexamethylenetetramine has been investigated. An interesting behavior whas observed: the hexamethylenetetramine alone, doesn\'t induce adsorption of cadmium (II) as does the thiocyanate but provides a strong reinforcement (up to a factor of 50) of the induced adsorption when it is present simultaneously with the pseudo-halide. Some estimatives about the species that can adsorb preferentially has been made, as well as an evaluation of the mean area ocupied by the complexes at the maximum adsorption condition. The free energy of adsorption has been calculated, considering an Henry isotherm for the lowest concentration range. Preliminary studies of the induced adsorption of the Cd(II)/I-/SCN- system revealed a slight reinforcement of the adsorption, when both ligands are presente. The iodide always controls the process. The advantage of using the charge in place of potential as the independent variable is evident for this system.

The thesis is divided into four chapters Chapter 1 provides a brief introduction to the metal-nucleic acid interactions, the role of synthetic models to understand them with both solution (potentiometric) and solid state (Crystallographic) studies. Further the work done in the area of nucleobase [purines and pyrimidines] metal complexes and nucleotide metal complexes are briefly reviewed. Chapter 2 contains an account of synthesis and characterizations of metal [Cu/Co] purine [adenine] complexes and is divided into two sections Viz., Section I and Section II. Section I Five crystals structures of copper adenine dimeric complexes are synthesized and characterized with 1, 10-phenanthroline as coligand. The first ternary [Cu2(phen)2(µ-ade)2Cl2].3H2O complex (2a) crystallizes in the orthorhombic space group Pna21. In the crystal structure of 2a it has been observed that the five and six membered rings of adenine are arranged in such a way that the five membered ring nitrogen atoms N9 and N9A are coordinated to Cu1 while the nitrogen atoms N3 and N3A are coordinated with Cu2 center. This is the first time such co-ordination is observed for the copper-adenine dimeric complexes, while the earlier report shows an alternate coordination. In the complex adenine-adenine dimer formation is observed, mediated via N-H···N hydrogen bond interactions which give rise to a corrugated sheet like pattern along the bc plane. The 1,10-phenanthroline rings and water molecules are packed in the grooves of these corrugated sheets via non covalent interactions. The second ternary [Cu2(phen)2 (µ-ade)(µ-Cl)Cl2].5H2O complex (2b) obtained under same reactant conditions, as 2a, by changing the ratio of the reactants, is the unique example of a dimeric copper complex with one adenine acting as a bridging ligand. The complex 2b crystallizes in the monoclinic centric space group P21/c. Interestingly, the crystal packing of complex 2b does not show any direct adenine-adenine hydrogen bond interactions as was seen for 2a, but adenine moieties of neighboring molecules interact indirectly, mediated via N-H···O and O-H···N hydrogen bonds through solvent water molecules forming a zig-zag pattern. It is interesting to note that two hydrogen bond networks are running across the body diagonal like “X” mediated by the nitrogen atoms of the adenine base and the chlorine atom, axially coordinated to copper centre. Similarly the water molecule O4 and N7 are involved in forming a four membered ring at the body center through the non covalent interactions. As seen for the complex 2a, complex 2b also depicts the presence of slipped π-π stacking intra and intermolecular interactions for the 1,10-phenanthroline rings. The third complex [Cu2(phen)2(µ-ade)2(H2O)2](ClO4)2 complex (2c), obtained by post synthetic modification of 2a, crystallizes in the monoclinic space group Cc. The adenine moieties forms a dimer mediated via N-H···N hydrogen bonds at the pseudo two fold and are connected to the neighboring dimers through the possible hydrogen bond between the nitrogen atom N1 and the axially coordinated oxygen atom O1 of the water molecule. The perchlorate anions are trapped in the pockets surrounded by the adenine and 1,10-phenanthroline moieties. The Nitrogen atom N6, N6A of the adenine bases forms hydrogen bond with N7, N7A of the five membered rings of adenine bases and the oxygen atom O4, O7 of both perchlorate ions, the other oxygen atoms O3, O5 from Cl1 and O8 of Cl2 are involved in C-H···O hydrogen bonds but the remaining oxygen atoms O6, O9 and O10 of the perchlorate ions are not involved in hydrogen bond network. Thus the dimerization involves axial oxygen atoms and the five and six membered nitrogen atoms N7 and N1. The 1,10-phenanthroline rings show both intra as well as intermolecular slipped π-π stacking interactions. The fourth complex [Cu2(phen)2(µ-ade)2(H2O)2](BF4)2 complex (2c), obtained by post synthetic modification of 2a, crystallizes in the monoclinic space group Cc. The adenine moiety forms intermolecular N-H···N hydrogen bonds with the neighboring adenine moieties at the pseudo two fold and is connected to the neighboring dimers through the N-H···O hydrogen bond via axial water molecule. The dimerization of the neighboring adenine moieties is favored through the hydrogen bond between the oxygen atom O2 of Cu2 and N1 of the six membered ring, in return the oxygen atom O1 of second molecule is hydrogen bonded to the nitrogen N7 of the five membered ring of the first molecule. Interestingly the three fluorine atoms F1, F2 and F3 are involved in hydrogen bond and in the second BF4 ion only two fluorine atoms F6 and F7 are involved where F1 and F6 acts as a bifurcated hydrogen bond acceptor while the remaining fluorine atoms are not taking part. Here too, as in the previous case of 2c 1,10-phenanthroline rings show both intra as well as intermolecular slipped π-π stacking interactions. The fifth complex [Cu2(phen)2(µ-ade)2(H2O)2](PF6)2 complex (2c), obtained by post synthetic modification of 2a, crystallizes in the monoclinic space group Cc. The adenine moiety forms intermolecular N-H···N hydrogen bonds with the neighboring adenine moieties at the pseudo two fold and is connected to the neighboring dimers through the N-H···O hydrogen bond via axial water molecule. As observed in the previous structure of 2c and 2d the dimerization of the neighboring molecule is favored through the hydrogen bond between the oxygen atom O2 of Cu2 and N1 of the six membered ring, in return the oxygen atom O1 of second molecule is hydrogen bonded to the nitrogen N7 of the five membered ring of the first molecule. Interestingly the nitrogen atom N6 of the six membered ring is involved in four hydrogen bonds, Where one H is hydrogen bonded to N1 of the neighboring base while the second hydrogen atom is being shared by three fluorine atoms belonging to the second PF6 ion and in turn all these three fluorine atoms acts as bifurcated acceptor of the hydrogen bond with the carbon atoms of 1,10-phenanthroline. It is noteworthy that the fluorine atoms F3, F4, F5 and F6 are involved in single hydrogen bonds with the 1,10-phenanthroline carbon atoms. At the same time the rest of the fluorine atoms are not involved in any non covalent interactions. Here too, as in the previous cases of 2c and 2d 1,10-phenanthroline rings show both intra as well as intermolecular slipped π-π stacking interactions. The complexes 2c, 2d and 2e are isostructural. All the three complexes crystallized in the noncentric space group Cc as the precursor complex 2a [Pna21] with the difference being the nature of the complex, 2a being neutral whereas 2c, 2d and 2e are complex salts. All the three complexes have similar bond lengths between the coordinating atoms and the central copper metal but they differ in the angles subtended by the ligands at the copper centres which are also reflected in the dihedral angle between the planes of the coordinating ligands. Though the molecular structure of the three complexes differs only in the nature of the counter ion, the crystal packing analysis reveals the finer differences. The interaction of adenine with neighboring adenine is same for the three complexes 2c, 2d and 2e but differs from the precursor complex 2a. Section II covers the synthesis and characterization of cobalt adenine binary and ternary complexes with 1,10-phenanthroline and 2,2’-bipyridyl as coligands for the ternary complexes. The first binary [Co2(µ-Hade)2(µ-H2O)2(H2O)4](NO3)4·2H2O complex (2f) crystallizes in the centric space group P21/c. Though there were four water molecules, coordinated to the metal Co centres, available for intra molecular hydrogen bond interactions with the base nitrogen atoms the orientation of the coordinated bases is not favorable to enable the C-H···O hydrogen bond formation, but intermolecular hydrogen bonds were observed. The structure is stabilized mainly through the O-H···O and N-H···O hydrogen bond interactions between the neighboring molecules via nitrate ions. Interestingly there is an absence of any direct adenine-adenine interactions. The terminally coordinated water molecule O2 forms hydrogen bond with nitrate anion on both sides, which in turn the nitrates hold the bases of two different molecules as the network is running -N6-O10-O9-O2-O5-N6-. Both the nitrate anion oxygen atoms are involved in hydrogen bond where all the oxygen atoms are bifurcated acceptor. The nitrate ions with nitrogen atoms N10 and N11 are making a nine and eight membered ring through hydrogen bond with adenine nitrogen atoms [N6 and N7] and coordinated water molecules [O2 and O3] respectively. The second binary [Co(Hade)2(H2O)4]SO4·5H2O complex (2g) crystallizes in the centric space group P21/n. Interestingly, only one adenine [N3A] is involved in forming the O-H···N intramolecular hydrogen bond with the water molecule while the adenine on other side is not in favorable orientation. All the water molecules coordinated to the metal center are involved in forming hydrogen bonds where O1, O2 and O4 form two hydrogen bonds while, O3 forms three hydrogen bonds. The water molecule and sulphate ions are trapped in between the adenine bases and forming an interesting network of hydrogen bond running in opposite directions. In general the sulphate and the water molecule are holding the symmetry related molecules connecting the nitrogen atoms N6 and N7 of the adenine. The crystal structure of 2g shows the presence of intermolecular π-π stacking interaction between the six membered rings of the neighboring adenine molecules along a axis. These stacked adenine moieties looks like a zig- zag pattern when viewed down a axis. Here too as in previous case of 2f there are no adenine-adenine interactions present. It is noteworthy that both of these complexes[differing only in the nature of salts i.e. CoNO3 and CoSO4] differ in the adenine coordination to the cobalt centre [N9 and N3 co-ordination in 2f; N9 coordination in 2g]. The third ternary [Co2(µ-ade)2(µ-OH)2(phen)2](NO3)2·6H2O complex (2h) was synthesized by a one pot reaction and crystallizes in the triclinic space group P-1. Though there are two hydroxyl ions coordinated to the metal centre there is no favorable intramolecular hydrogen bond formation. The adenine moieties of 2h interact with each other forming a dimer at the inversion centre, which looks like a zig -zag sheet pattern, via N-H···N hydrogen bond. In addition to this the hydroxyl O1 forms hydrogen bond with water oxygen and the oxygen atom of the disordered nitrate anion. These chains are further linked to neighboring chains by N-H···O hydrogen bond and a slipped π-π interaction between the 1,10-phenanthroline rings forming a sheet like pattern. The fourth ternary [Co2(µ-ade)2(µ-OH)2(phen)2](OTs)2·6H2O complex (2i) , was also synthesized by a one pot reaction and crystallizes in the triclinic space group P-1. Similar to previous case though there are two hydroxyl groups bridging the metal centres as dimers, no intramolecular hydrogen bonds were observed. The adenine moieties interact with each other forming a zig-zag pattern via N-H···N hydrogen bond like in the previous structure 2h. Interestingly, contrary to the previous case where two such zig- zag sheets interacted with each other through slipped π-π stacking between the 1,10-phenanthroline rings, no such interaction was found among the neighboring sheets. Instead, the 1,10-phenanthroline rings interact with tosylate counter ion through C-H···O hydrogen bonds. Down the c axis projection, at the inversion centre tosylate ion and the water molecules form an eight membered ring where the water oxygen O1W acts as a donor in the two hydrogen bonds and the oxygen atom O2 of the tosylate acts as bifurcated acceptor. On the other side, the tosylate oxygens form a twelve membered ring with the water oxygen atom O2W. Thus, eight membered and twelve membered rings are formed alternately and both are subtending an angle of 113°. It is noteworthy that the tosylate ion is parallel to the adenine base while perpendicular to the 1,10-phenanthroline rings favoring the π-π and C-H···π stacking interactions between the neighboring zig zag chains. The fifth ternary [Co2(µ-ade)2(µ-OH)2(bpy)2](NO3)2·6H2O complex (2j) synthesized via one pot reaction and crystallizes in the triclinic space group P21/n. Similar to previous two cases there are two hydroxyl groups bridging the metal centres as dimers, no intramolecular hydrogen bonds were observed in the present case. The adenine moieties interact with each other forming a zig-zag pattern via N-H···N hydrogen bond as observed in the previous two structures 2h and 2i. The adenine also interacts with nitrate ion through N-H···O hydrogen bond. The nitrate groups are oriented parallel to the adenine base. The adenine base nitrogen atom N6 is involved in holding the neighboring adenine nitrogen atom N7 in addition to the nitrate oxygen atoms O3 and from the same nitrate the other oxygen atoms O4 is involved in hydrogen bond with the carbon atom C8 thus forming a nine membered ring. These chains interact with the parallel chains by slipped π-π stacking interaction similar to that observed in complex 2h. Chapter 3 describes the syntheses and characterizations of copper pyrimidine [uracil, cytosine and thymine] ternary complexes with 1,10-phenanthroline as coligand. The first polymeric [Cu(phen)(µ-ura)(H2O)]n·H2O complex (3a) crystallizes in the monoclinic space group P21/c. The protons of the water oxygen O1W is oriented towards the uracil rings enabling O-H···O intramolecular hydrogen bonds with O2 as a bifurcated bond acceptor of the uracil on either sides and the chain extends to infinity along the c axis. The structure is stabilized by slipped π-π stacking interactions between the 1,10-phenanthroline rings of neighboring polymeric chains. Each polymeric chain also interacts through C-H···O hydrogen bond between the neighboring chains. The second polymeric [Cu(phen)(µ-ura)(H2O)]n·MeOH complex (3b) is isostructural to (3a) and crystallizes in the monoclinic space group P21/c. Similar to 3a the coordinated water oxygen O1w is oriented towards the uracil rings enabling O-H···O intramolecular hydrogen bonds with O2, as a bifurcated hydrogen bond acceptor, of the uracil on either sides and the chain extends to infinity along the c axis. The structure is stabilized by slipped π-π stacking interactions between the 1,10-phenanthroline rings of neighboring polymeric chains. Each polymeric chain also interacts through C-H···O hydrogen bond between the neighboring chains. Both these complexes differ only in the lattice solvent molecule i.e. water for 3a and methanol for 3b. These complexes are the first example of direct uracil to metal coordination structurally characterized. Also, both the ring nitrogen atoms N1 and N3 are involved in coordination to the metal. The third polymeric [Cu4(cytosine)3Cl3(OH)2]n·14H2O complex 3c is the first polymeric complex known with cytosine and 1,10-phenanthroline as coligands. It crystallizes in the orthorhombic centric space group Pbca. Out of the four, three copper centres adopts square pyramidal [4+1] geometry {τ = 0.17 [Cu1], 0.028 [Cu3] and 0.053 [Cu4]}, whereas the fourth copper centre exhibits distorted trigonal bypyramidal [3+2] geometry. {[τ = 0.66 [Cu2]}. Two copper centres Cu1 and Cu3 have same co-ordination environment viz., the basal plane of the square pyramid is formed by cytosine [N1and N1A], 1,10-phenanthroline [N7, N8 and N11, N12] and chlorine ligands [Cl1, Cl3] while the axial site is occupied by other chlorine atom [Cl2] which act as a bridge between Cu1 and Cu3 in the polymeric chain. The cytosine ring attached to Cu1 and Cu3 act as tridentate ligand co-ordinating to two other copper centres [Cu2, Cu4] via O2, O2A and N3, N3A respectively. Thus remaining three sites of Cu2 are occupied by 1,10-phenanthroline [N9, N10] and a bridged hydroxyl [O1D] moiety. The hydroxyl moiety [O1D] acts as a bridging ligand between Cu2 and Cu4. Thus the basal plane of the trigonal bipyramid for Cu2 is formed by N9, O2 and O2A while axial sites are occupied by N10 and O1D. The basal plane for Cu4 is formed by N3, N3A, O1D and N3C [from third cytosine ligand] while the axial site is occupied by a hydroxyl ion [O1]. The structure is stabilized by slipped π-π intra molecular stacking interactions between the 1,10-phenanthroline rings. The cytosine moieties interact with each other through bifurcated N-H···O hydrogen bond where the proton of N6c is involved with O2 and O2A of the other two cytosine moieties coordinated to the same copper centre. The neighboring chains of the polymer are linked by inter molecular slipped π-π stacking interactions between the cytosine ring attached to Cu4 and the 1,10-phenanthroline rings. The chains are also connected through C-H···Cl hydrogen bonds where the chlorine atom Cl4 is involved in the bifurcated hydrogen bond one as intramolecular and the second as intermolecular. Both the Nitrogen atoms [N6, N6A] of different cytosine are involved in the noncovalent interactions, with the water [O41, O10W] as intermolecular hydrogen bond as well as intramolecular hydrogen bond with chlorine atoms [Cl4, Cl4* (* symmetry generated)] respectively. The water molecules pack between the polymeric chains via noncovalent interactions. Thus this complex is the first example of its kind where all the possible binding modes of cytosine are utilized. The fourth [Cu2(Phen)2(thy) (µ-OH)2(H2O)].HCO3·4.5H2O complex (3d) obtained as the minor product along with 3e crystallizes in the triclinic space group P1 with two molecules in the asymmetric unit. The structure displays the presence of a pseudo centre of inversion between the two molecules. But careful analysis of the structure reveals that the two different tautomeric forms of thymine are coordinated to the two copper centres in each molecule, thus making it a cocrystal. The molecule shows the presence of O-H···O intramolecular hydrogen bond between the thymine oxygen and the bridged hydroxyl ion. The structure is stabilized by slipped π-π stacking and C-H···π interactions between the 1,10-phenanthroline rings of neighboring molecules. The molecules also interact with solvent molecules and counter ions through non covalent C-H···O interactions. The fifth [Cu2(Phen)2(thy)(µ-OH)2(H2O)]Cl·3H2O complex (3e) which was the major product along with 3d also crystallizes in the triclinic space group P1 with two molecules in the asymmetric unit. The difference between 3d and 3e is the change in the nature of counter ion i.e. HCO3- for 3d and Cl- for 3e. Similar to 3d the two different tautomeric forms of thymine are coordinated to the two copper centres in each molecule, thus making it a cocrystal. The molecule shows the presence of O-H···O intramolecular hydrogen bond between the thymine oxygen and bridged hydroxyl ion. The structure is stabilized by slipped π-π stacking and C-H···π interactions between the 1,10-phenanthroline rings of neighboring molecules. The molecules also interact with solvent molecules and counter ions through non covalent C-H···O and C-H···Cl interactions. The sixth Cu(phen)(thy)2 complex (3e) was obtained just by changing the pH in the reaction condition for 3d and 3e and crystallizes in the monoclinic centric space group C2/c. Here a different tautomer of thymine other than that observed for 3d and 3e was coordinated to the central copper metal. The structure is mainly stabilized by slipped π-π stacking between the 1,10-phenanthroline rings of neighboring molecules as well as between the thymine rings. The thymine molecules also interact with neighboring thymine molecules through non covalent N-H···O interactions. These thymine thymine interactions were absent in 3d and 3e. Chapter 4 presents the synthesis and characterization of ternary copper 5’-Adenosine monophosphoric acid (5’-AMP)/ 5’-cytidine monophosphoric acid (5’-CMP) complexes with 2,2’-bipyridine/1,10-1,10-phenanthroline as coligands. The first Cu(bpy)(5’-AMP)2·2H2O complex (4a), obtained at pH = 3.0, crystallizes in the triclinic space group P1 with two molecules in the asymmetric unit Viz., complex A and Complex B. The phosphate group of 5’-AMP which has two protons in the uncoordinated state gets monodeprotonated at one hydroxyl group during the complex formation and is co-ordinated to the copper centre. Thus in each complex the charge on the central copper atom is balanced by 5’-AMP monodeprotonated ligand. The environment around both copper centres is same, Cu1 and Cu2 exhibits square planar geometry. The least square plane analysis reveals that the ribose sugar moieties adopt envelope conformation. The ΦCN angle, which is the torsion angle of the base with respect to sugar, are 84(2)°, 41(2) ° for complex A and - 43(2)°, 47(2) ° for complex B suggesting a anti conformation about the glycosyl bond for all the four 5’-AMP ligands. All the four ribose ring are puckered with one carbon atom of the ring,[C4’ and C3’A for complex A, C4’B and C3’C for complex B], displaced from the best four atom plane of furanose ring on the same side as C5’. [C4’ = -0.539(2) Å, C3’A = - 0.539(2) Å for complex A; C4’B = 0.509(17) Å, C3’C = 0.535(20) Å for complex B], suggesting in each complex, the confirmation of the ribose sugar of two 5’-AMP ligands are different. [C4’ endo and C3’A endo for complex A; C4’B endo and C3’C endo for complex B] Both the complexes A and B are stabilized by C-H···O intramolecular interaction between the adenine base and the phosphate oxygen atom. The structure is stabilized through a complicated network of C-H···O and N-H···O hydrogen bond interactions between the neighboring molecules where the oxygen atoms of the water molecules are involved in forming the network of bifurcated hydrogen bond. The adenine rings interact with each other through the N-H···N hydrogen bonds forming a dimer between the N6-N7 and N7-N6 similar to the base pairing observed in the DNA molecule, in addition to this the atom N6 is involved in forming a bifurcated hydrogen bond with the O7 atom of the phosphate group. Additionally, there is a presence of slipped π···π stacking interaction, between the bipyridine rings and adenine rings in a -B-A:A-B- fashion [B= 2,2’-bipyridine and A:A= adenine adenine adduct]. The second {Cu2(bpy)2(µ-5’-AMP)2(H2O)2·2[Cu(bpy)(5’-AMP)(H2O)2]·10H2O} complex (4b) is a cocrystal obtained at pH = 6.0, crystallizes in the monoclinic space group C2. The crystal structure of 4b can be described as a cocrystal made up of one dimeric [complex D] and two monomeric [complex M] copper (II) complexes. Both the complexes are ternary with 5‘-AMP and 2,2’- bipyridine as co ligands. These complexes are neutral in nature with the charge on the copper centres balanced by the 5’-AMP ligands. The asymmetric unit consists of half of this two component cocrystal system. The basal plane for the monomeric complex M is formed by two nitrogen atoms [N10A, N11A] from the 2, 2’-bipyridine , one water molecule [O1A] and a phosphate oxygen atom [O9A] from one of the 5’-AMP ligand, while the axial site is occupied by the other water molecule, O1W. The basal plane for the dimeric complex D is formed by two nitrogen atoms [N10, N11] from the 2, 2’- bipyridine , and two phosphate oxygen atom [O9 andO7] from two bridging 5’-AMP ligand, while the axial site is occupied by the other water molecule O2A. The 5’-AMP ligand bridges the two copper centres to form the dimeric complex. It is noteworthy that both the axial water molecules of complex D are on the same side. The least square plane reveals that the ribose sugar moieties adopt envelope conformation. The ΦCN angle, which is the torsion angle of the base with respect to sugar, 72(1)° for complex D and 77(1)° for complex M, suggest an anti conformation for both the complexes about the glycosyl bonds. The ribose rings are puckered in both complex D and M, with C3’ and C3’A displaced from the best four atom plane of furanose ring. C3’ deviates from the sugar plane by 0.604(13) Å which is opposite to C5’, imply C3’ exo conformation for the ribose ring. While for the ribose moiety in complex M, C3’A deviates from the sugar plane by 0.585(11)Å which is on the same side of C5’, confirm C3’A endo conformation for the ribose ring. The conformation around the C4’-C5’ bond described by the angles ΦOO [O1’-C4’-C5’-O5’= -60(1)°] and ΦOC [C3’-C4’-C5’-O5’= -179.8(9)°] is gauche trans, a rare conformation, for the complex D while around the C4’A-C5’A bond the angles ΦOO [O1’A- C4’A-C5’A-O5’A= -59(1)°] and ΦOC [C3’A-C4’A-C5’A-O5’A = 57(1)°] suggest the commonly observed gauche gauche conformation. The structure is stabilized through the extensive network of C-H···O and N-H···O hydrogen bond interactions between the neighboring molecules. The adenine rings interact with each other through the N-H···N hydrogen bonds forming a dimer between N6-N7 and N7- N6, mimicking the base pair observed in the DNA molecule, in addition to this N6 is involved in the formation of a bifurcated hydrogen bond with the O8 atom of the phosphate group. Additionally, there is a presence of slipped π···π stacking interaction, between the bipyridine rings and adenine rings in a -B-B-A:A-B-B- fashion [B= bipyridine and A:A= adenine adenine adduct]. The third [Cu2(bpy)2(µ-5’-AMP)2]·14H2O complex 4c crystallizes in the triclinic space group P1 with one molecule in the asymmetric unit. The complex is neutral in nature with the charge on the copper centres being balanced by the 5’-AMP ligands. It is noteworthy that both the axial water molecules of complex are on the opposite side to each other which is in contradiction to the orientation of the water molecule in dimeric complex D of the molecule 4b. The least square plane analysis of the ribose sugar moiety reveals that the sugar moiety adopts envelope conformation. The ΦCN angle, which is the torsion angle of the base with respect to sugar, is 2(4)° for one 5’-AMP ligand and 69(4)° for other 5’-AMP ligand, suggesting an anti conformation for both the complexes about the glycosyl bonds. The ribose rings are puckered in both the ligands, with C3’ and C2’A displaced from the best four atom plane of furanose ring. C3’ deviates from the sugar plane by -0.624(3)Å which is on the same side of C5’, reveals C3’ endo conformation for the ribose ring. While for the other ribose moiety, C2’A deviates from the sugar plane by 0.509(3)Å which is on the same side of C5’, confirms C2’A endo conformation for the ribose ring. The conformation around the C4’-C5’ bond described by the angles ΦOO [O1’-C4’-C5’-O5’= - 76(3)°] and ΦOC [C3’-C4’-C5’-O5’= 41(3)°] is gauche gauche for one of the 5’-AMP ligand. Also around the C4’A-C5’A bond the torsion angles ΦOO [O1’A-C4’A-C5’A-O5’A= -59(2)°] and ΦOC [C3’A-C4’A-C5’A-O5’A = 59(3)°] suggest the commonly observed gauche gauche conformation for the other 5’-AMP ligand. The complex is stabilized by C-H···O and N-H···O intramolecular interactions between the adenine base and the phosphate oxygen atom. The phosphate oxygen atoms O8 and O8A become bifurcated by hydrogen bonding to O1W and O4W. In turn by symmetry relation it forms a sheet like structure extending to infinity. The adenine also interacts with the bipyridine ring with slipped π···π stacking interaction. The structure is stabilized by extensive net work of C-H···O and N-H···O hydrogen bond interactions between the neighboring molecules. The adenine rings interact with each other through the N-H···N hydrogen bonds forming a dimer between N6-N7 and N7- N6, mimicking the base pair observed in the DNA molecules, in addition to this N6 is involved in the formation of a hydrogen bond with the O8 atom of the phosphate group. Very interestingly, the axially coordinated water molecules O1A, O2A along with the phosphate oxygen atoms O8, O8A and water molecules O1W, O4W form a six membered ring in the chair conformation of a cyclohexane ring through hydrogen bonds mediated by the water molecules. Additionally, there is a presence of slipped π···π stacking interaction, between the bipyridine rings and adenine rings in a –B-B-A:A-B-B- fashion [B= bipyridine and A:A= adenine adenine adduct]. This is similar to previous two structures. All the three structures show the presence of different coordinating nature of phosphate groups obtained just by varying the pH conditions. The presence of cocrystal suggests that more than one type of coordination can exists at the same time. The fourth [Cu2(bpy)2(µ-5'CMP)(µ3-5'CMP)(Cl)]n·3H2O polymeric complex (4d) crystallizes in the Orthorhombic space group P212121. The polymer can be described as follows. There are two 5’-CMP ligand in the asymmetric unit viz., I and II. I acts as bidentate bridging ligand co-ordinating through base [N3] and phosphate oxygen [O9] to Cu1 and Cu2 respectively. II acts as a tridentate ligand co-ordinating to Cu1 through phosphate oxygen [O7A] while to Cu2 through the base [N3A] and phosphate oxygen [O9A]. Thus ligand I connects Cu1 and Cu2 forming a chain along the a axis while this chain is extended in b axis direction via ligand II. The least square plane analysis of the ribose sugar moiety reveals that both sugar moieties adopt envelope conformation. The ΦCN angle, which is the torsion angle of the base with respect to sugar, are 40.0(8)° [for ligand I] and 19.2(8)° [For ligand II] suggesting an anti conformation for both sugar moieties about the glycosyl bond. Both the ribose ring adopt a puckered confirmation with C2’ and C3’A displaced from the best four atom plane of furanose ring by 0.511(7) Å and 0.461(7) Å for ligand I and II respectively. Both the atoms C2’ and C3’A are on the same side as C5’, hence the conformation is C2’ endo [for ligand I] and C3’A endo [for ligand II] respectively. The conformation around the C4’-C5’ bond described by the angles ΦOO [O1’-C4’-C5’-O5’= -86.0(6)°{for I} and O1’A-C4’A-C5’A-O5’A= -72.8(2)°{for II}] and ΦOC [C3’-C4’-C5’-O5’= 33.9(8)°{for I} and C3’A-C4’A-C5’A-O5’A = 45.6(6)°{for II}] is gauche gauche for both the ribose rings in the polymeric complex. The polymeric strand is stabilized by N-H···O intramolecular interaction between the cytosine base and the phosphate oxygen atom. The cytosine base also interacts with the axial Chlorine atom to form N-H···Cl hydrogen bond. The structure is stabilized through the extensive network of N-H···O, C-H···O and O-H···O hydrogen bond interactions between the water molecules and polymerizing, making the sheets to run in third direction. The chlorine atom Cl1 at the same time along with the water molecule O1W and O8W of the phosphate group forms an envelope shape five membered ring [Cl1-O2W-O8-O1W-O3W-Cl1] via hydrogen bond. Thus the water molecules, the phosphate oxygen atoms, the chlorine atoms and the nitrogen atoms of the base make the network of hydrogen bonds in three dimension. In the three dimensional network the copper atoms, the base and the sugar with the phosphate are running anti parallel direction pushing the bipyridyl ring on the outer side, thus remaining as the back bone of the sheet. Additionally, there is a presence of slipped π···π stacking interaction, both intra and inter strand, between the 2, 2’-bipyridine rings. Thus the bipyridine rings, stacked