The focus of the following research was to use the self-assembly process to create rotaxanes between several large bisphenylene crown ethers (> 22 atoms) with secondary ammonium salts. Also of great interest was to understand the complexation behavior of the crown ethers with the salts, with emphasis on determining the stoichiometries and association constants of the complexations in solution using NMR spectroscopy. The stoichiometry of the complexes was determined by the mole ratio method and the association constants were calculated graphically. Bis-(m-phenylene)-26-crown-8 did not form a complex in solution with several secondary ammonium salts even though the cavity size is large enough to allow the formation of pseudorotaxanes. However, the larger crown ether, bis-(m-phenylene)-32-crown-10 (BMP32C10), did form a complex. The complex stoichiometry varied between 1:1 (crown:salt) in solution and 1:2 in the solid state as evidenced by NMR and X-ray crystallography, respectively. The solid state complexes were pseudorotaxanes. Also, an interesting "exo" complex was formed in the solid state between BMP32C10 and a secondary diammonium salt. The major binding force for the complexes in the X-ray structures was hydrogen bonding. Weaker secondary stabilization was achieved via aryl-aryl aromatic interactions. The difference between the stoichiometries in the two phases and the observance of an "exo" complex demonstrates that one must be careful in describing the complexes in each phase. Also investigated was the complexation formed between dibenzo-24-crown-8 (DB24C8) and secondary diammonium salts. The association constants for the complexes were found to be relatively higher. Due to the weaker association constants and the different stoichiometries of complexation the meta-susbtituted bisphenylene crown ethers were not recommended for the formation of larger complexes, i.e. polyrotaxanes. However, it is suggested that the DB24C8 moiety be used in components of supramolecular assemblies. The functionalization of poly(propylene imine) dendrimers with two different crown ethers as peripheral moieties was attempted. The 1st, 3rd, and 5th generation poly(propylene imine) dendrimers were functionalized with 1,3-phenylene-16-crown-5 moieties by reacting the surface primary amines with the corresponding succinimide ester of the crown ether. The larger DB24C8 succinimide ester was not as reactive and full functionalization was not achieved. / Ph. D.

L'objectif de ce travail est l'analyse de la stabilité thermodynamique et de l'inertie chimique de complexes métalliques avec des ligands ou des nanoparticules conçus pour des applications en IRM. Deux types de ligands polyaminocarboxylates ont été étudiés, ligands pour lesquels les unités complexantes sont soit linéaires soit macrocycliques.Les ligands macrocycliques étudiés sont des ligands basés sur des squelettes DO3A, substitués par des entités benzimidazole (L1H4) ou p-nitrophenylbenzimidazole (L2H3). Les données thermodynamiques indiquent que les affinités de ces ligands vis-à-vis des ions de la première série de transition (Cu(II) et Zn(II)) ou vis-à-vis des lanthanides (Gd(III) et Eu(III)) sont plus élevées que celles des complexes correspondants avec le ligand DO3A. Ce renforcement d'affinité est corrélé avec la participation des groupements benzimidazole à la sphère de coordination de chacun des métaux. L'inertie chimique du complexe Gd(III)- L1H4 a ensuite été évaluée par relaxométrie en tampon phosphate, en présence d'une quantité équimolaire de Zn(II). Dans cette expérience, le Zn(II) joue le rôle d'un compétiteur du Gd(III) c'est-à-dire qu'il peut si le complexe Gd(III)-L1H4 n'est pas inerte chimiquement, induire une libération de l'ion gadolinium. Pour Gd(III)-L1H4, aucune réaction de ce type n'a été détectée, ce qui plaide en faveur de l'inertie chimique de ce complexe.Les ligands linéaires étudiés sont des dérivés dithiolés de ligands DTPA bisamide L@1H5. Ces ligands ont été conçus pour être greffés sur des nanoparticules d'or. La stabilité thermodynamique des complexes de Cu(II), Zn(II) et Gd(III) utilisant les ligands L@1H5 et L@1H5 greffé sur nanoparticule d'or (autrement appelé L@2H3) suit l'ordre de stabilité croissant Zn(II) < Cu(II) < Gd(III). Par ailleurs, les résultats montrent que le complexe Gd(III)-L@1H5 est moins stable d'au moins deux ordres de grandeur que le complexe Gd(III)-L@2H3. Ceci suggère qu'une fois greffé sur la nanoparticule, le complexe de gadolinium correspondant gagne en stabilité. Par ailleurs, des études comparatives d'inertie chimique montre que le complexe Gd(III)-L@1H5 greffé sur la nanoparticule a une inertie chimique comparable à celle de l'agent de contraste commercial Gd-DTPA. En revanche lorsque ce complexe est seul, sa vitesse de démétallation est rapide. Le greffage du ligand L@1H5 à la surface de la nanoparticule est donc au bénéfice de la stabilité et de l'inertie chimique de son complexe de Gd(III). Ce gain de stabilité peut être attribué à l''effet de ballast' de la nanoparticule qui rigidifie la structure du complexe et limite sa démétallation. / The aim of this work is to analyse the stability of metal complexes with ligands or nanoparticles of interest in MRI and to study their transmetallation mechanisms in the presence of endogenous cations near physiological pH. Two types of polyaminocarboxylate ligands were studied for which the binding unit was either linear or macrocyclic.Macrocyclic ligands are constituted of a DO3A backbone functionalized with a benzimidazole (L1H4) or a p-nitrophenylbenzimidazole unit (L2H3). Thermodynamic data indicated that the affinities of these ligands towards first row transition metal ions (Cu(II) and Zn(II) or lanthanide ions (Gd(III) and Eu(III)) are increased compared to the corresponding ones with DO3A. This enhancement is correlated to the involvement of the benzimidazole moiety to each metal coordination sphere. For gadolinium complex Gd(III)- L1H4, its kinetic inertness was evaluated in phosphate buffer by relaxometry, in the presence of equimolar quantities of Zn(II) as a competitor. In these conditions, if the complex is not chemically inert, it would be subjected to a transmetallation reaction, that is to say that at least, gadolinium would be released. For Gd(III)-L1H4, no such reaction was detected which is in favour of kinetic inertness of Gd(III)- L1H4.Linear ligand, dithiolated DTPA bisamide L@1H5 was designed with an aim of grafting it onto gold nanoparticles. L@1H5 and the ligand grafted into gold nanoparticle,namely L@2H3, were analysed for their thermodynamic stability towards mainly Cu(II), Zn(II) and Gd(III). Whatever the system, L@1H5 or L@2H3, the general trend of increasing complex stability was Zn(II) < Cu(II) < Gd(III). Furthermore, Gd(III)-L@1H5 complex was less stable than Gd(III)-L@2H3, this latter being 2 orders of magnitude more stable at physiological pH. This suggested that the gadolinium complex stability is enhanced when the ligand is grafted onto the nanoparticle. Moreover, comparative kinetic inertness studies showed that the gadolinium complex Gd(III)-L@1H5 is not chemically inert and demetallates rapidly while the gadolinium complex grafted onto the nanoparticle exhibit almost equal kinetic inertness as Gd-DTPA (Magnevist). The bulky nanoparticle probably rigidifies the structure of the complex and prevents Gd(III)-L@2H3 from an extensive demetallation, which was a good point for the possible use of these nanoparticles in living organisms for imaging applications.

Foram estudados os equilíbrios dos complexos de Mn (II) com íons azoteto, em meio aquoso, por método potenciométrico indireto, através de medidas de pH, em meio de azoteto 0 a 1,8 M, e a 25,0 ºC, utilizando força iônica 2,00 M mantida com perclorato de sódio. Nas diferentes concentrações de íon metálico empregadas, 20, 40, 60, 80 e 100 mM, obteve-se uma mesma curva de formação de número médio de ligantes vs. concentração de ligante livre, o que configura a inexistência de complexos polinucleares nessas condições experimentais. Os valores de número médio de ligantes n&#175;, e de concentração de ligante livre, [L], foram utilizados para a integração de função de Bjerrum, obtendo-se a função de Fronaeus, F0(L), a partir da qual calcularam-se, por métodos gráficos e matemáticos, as quatro sucessivas constantes globais de equilíbrio: &#946;1 = 4,15 &#177; 0,02 M-1 , &#946;2 = 6,61 &#177; 0,04 M-2 , &#946;3 = 3,33 &#177; 0,02 M-3 , &#946;4 = 0,63 &#177; 0,01 M-4 . Avaliando os valores das constantes, observa-se que os complexos formados são fracos e, em obediência à regra de Irving e Williams, são menos estáveis que os complexos de cobalto (II) e de níquel (II). Em concentrações de ligante superiores a 1M há condições para lenta oxidação espontânea dos complexos de manganês(II) a manganês(III) com significativas mudanças espectrais. / The equilibria of complex formation between manganese(II) cations and azide anions were studied in aqueous medium by an indirect potentiometric method, at 25°C and ionic strengh 2.0 M (NaClO4). The equilibrium data were based on pH measurements of Mn(II) in N3&#175;/HN3 buffers. Metal ion concentration changing from 20 to 100 mM have defined one single formation curve of n_ (Bjerrum function) vs. [N 3 &#175; ] which is an evidence that only mononuclear species ara present in the working solutions. Integration of the formation curve from the best n&#175;vs. [N3&#175;] data leads to Fronaeus function data. They were properly treated to obtain the formation by a variety of methods (graphic and mathematical). The best set formed is: &#946;1 = 4,15 &#177; 0,02 M-1 , &#946;2 = 6,61 &#177; 0,04 M-2 , &#946;3 = 3,33 &#177; 0,02 M-3 , &#946;4 = 0,63 &#177; 0,01 M-4 . The complex are weaks and are is agreement with the Irving and Williams rule, i. e., less stable than the corresponding complexes of Ni(II) and Co(II). At ligand concentration higher t than 1,0 M there were conditions for a slow spontaneous oxidation of manganese(II) complexes to manganese to manganese(III), with remarkable spectral changes.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Parenteral solutions are used for patients with complexes diseases, for pre-term infants and surgical patients. The administration of solutions contaminated by aluminium for a long period of time can lead to severe intoxication, with consequent bone and neurological diseases. Considering that, the FDA (Food and Drug Administration) has been investigating the consume of aluminium through solutions for parenteral nutrition and established a maximum limit of 5 μg Al/kg weight of the patient per day. It has been found elevated aluminium concentration in solutions of phosphates (28 000 μg/L) and calcium gluconate (12 000 μg/L). In this work, the interaction between aluminium and the anion gluconate was evaluated by means of spectrophotometry, ion-exchange experiments and potentiometric titration. By spectrophotometry, the reaction with Morin allowed to calculate the amount of aluminium that reacted with the anion gluconate in solutions of calcium and sodium gluconate and also gluconic acid. Ion-exchange experiments included other ligands with affinity for aluminium and a resin in the Al3+-form. The ability of the ligands citrate, oxalate, EDTA, NTA, and gluconate in the form of gluconic acid, calcium gluconate, and sodium gluconate to withdraw it from the Al3+-form resin was evaluated at different concentrations and periods of time. Aluminium quantification was carried out by atomic absorption spectrometry either by graphite furnace or flame. The results showed that the exchange was bigger in the calcium gluconate solution followed by sodium gluconate and gluconic acid. Comparing with the other complexing agents, gluconic acid showed the lower extraction ability. These results are in agreement with the stability constants found in the literature for the aluminium complexes with these ligands. Potentiometric titration was carried out to evaluate the stability constants of the possible complexes build between aluminium and the ion gluconate in aqueous solution. The results showed that the predominant species in solution have a proportion metalligand 1:1. Stability constants obtained showed a good agreement with the stability constants of the complexes collected from the literature. / Soluções parenterais são utilizadas em pacientes que sofrem de doenças complexas, em pacientes pediátricos e cirúrgicos. A administração de soluções parenterais contaminadas por alumínio por períodos longos de tempo, pode fazer com que os pacientes sofram intoxicação, causando enfermidades graves, como problemas cerebrais e doenças nos ossos. Em vista disto, a FDA (Food and Drug Administration) tem investigado o consumo de alumínio através de soluções de nutrição parenteral, e estabeleceu um limite máximo de 5 μg Al/kg de peso do paciente por dia. Foi constatado em vários trabalhos publicados, que altas concentrações de alumínio foram encontradas em aditivos utilizados em NP. Entre os aditivos, destacam-se os de pequenos volumes, tais como as soluções de fosfato (28 000 μg/L de Al) e soluções de gluconato de cálcio (12 000 μg/L de Al). Neste trabalho, investigou-se a interação do gluconato de cálcio, que compõe as soluções de nutrição parenteral disponíveis comercialmente, com alumínio, avaliando a forma como o alumínio se encontra associado ao ânion gluconato. O método espectrofotométrico foi usado como um método direto para a quantificação do alumínio. Este método permitiu através da reação entre o alumínio e o Morin, obter a concentração de alumínio que reagiu com o ácido glucônico, gluconato de cálcio e gluconato de sódio em soluções destas substâncias em diferentes concentrações. Não somente o método espectrofotométrico mas também o estudo da extração de alumínio de uma resina catiônica na forma Al3+ pelas soluções de ácido glucônico, gluconato de cálcio e gluconato de sódio foi realizado a fim de comprovar que realmente o íon gluconato atua como um ligante para o alumínio. E esta interação é crescente na seguinte ordem: gluconato de cálcio > gluconato de sódio > ácido glucônico. Para fins comparativos realizou-se a extração do alumínio da resina catiônica na forma Al3+ por agentes complexantes. Os agentes complexantes analisados foram EDTA, NTA, ácido cítrico, ácido oxálico e ácido glucônico. Foi verificado que as soluções de EDTA, NTA, ácido cítrico e ácido oxálico extraíram maiores quantidades de alumínio do que a solução de ácido glucônico. Isto confirma os altos valores encontrados na literatura para as constantes de estabilidade desses complexantes com alumínio, ao passo que complexos de ácido glucônico com alumínio apresentam valores menores para as constantes de estabilidade. Para concluir o estudo de interação entre o ânion gluconato e o íon alumínio, foi utilizado o método potenciométrico para determinar as possíveis constantes de estabilidade dos complexos formados em solução aquosa. Os resultados obtidos confirmam a interação e a estabilidade dos complexos formados entre o alumínio e ânion gluconato. Neste experimento, acredita-se que as porcentagens de 100, 64,2 e 52% obtidas para o deslocamento sofrido nas curvas de titulação das soluções nas razões molares 1:1, 2:1 e 3:1, L:M, indicam que houve predominância da formação de complexos 1:1. Já com excesso do ligante, ou seja para a razão molar estudada de 10:1, L:M, a proporção encontrada para as espécies formadas é de 2:1. Assim, as espécies 1:1 e 2:1 possivelmente podem estar presentes nas soluções comerciais de gluconato de cálcio, comprovando assim a alta contaminação por alumínio que existe nestas soluções.

Foram estudados os equilíbrios dos complexos de Mn (II) com íons azoteto, em meio aquoso, por método potenciométrico indireto, através de medidas de pH, em meio de azoteto 0 a 1,8 M, e a 25,0 ºC, utilizando força iônica 2,00 M mantida com perclorato de sódio. Nas diferentes concentrações de íon metálico empregadas, 20, 40, 60, 80 e 100 mM, obteve-se uma mesma curva de formação de número médio de ligantes vs. concentração de ligante livre, o que configura a inexistência de complexos polinucleares nessas condições experimentais. Os valores de número médio de ligantes n&#175;, e de concentração de ligante livre, [L], foram utilizados para a integração de função de Bjerrum, obtendo-se a função de Fronaeus, F0(L), a partir da qual calcularam-se, por métodos gráficos e matemáticos, as quatro sucessivas constantes globais de equilíbrio: &#946;1 = 4,15 &#177; 0,02 M-1 , &#946;2 = 6,61 &#177; 0,04 M-2 , &#946;3 = 3,33 &#177; 0,02 M-3 , &#946;4 = 0,63 &#177; 0,01 M-4 . Avaliando os valores das constantes, observa-se que os complexos formados são fracos e, em obediência à regra de Irving e Williams, são menos estáveis que os complexos de cobalto (II) e de níquel (II). Em concentrações de ligante superiores a 1M há condições para lenta oxidação espontânea dos complexos de manganês(II) a manganês(III) com significativas mudanças espectrais. / The equilibria of complex formation between manganese(II) cations and azide anions were studied in aqueous medium by an indirect potentiometric method, at 25°C and ionic strengh 2.0 M (NaClO4). The equilibrium data were based on pH measurements of Mn(II) in N3&#175;/HN3 buffers. Metal ion concentration changing from 20 to 100 mM have defined one single formation curve of n_ (Bjerrum function) vs. [N 3 &#175; ] which is an evidence that only mononuclear species ara present in the working solutions. Integration of the formation curve from the best n&#175;vs. [N3&#175;] data leads to Fronaeus function data. They were properly treated to obtain the formation by a variety of methods (graphic and mathematical). The best set formed is: &#946;1 = 4,15 &#177; 0,02 M-1 , &#946;2 = 6,61 &#177; 0,04 M-2 , &#946;3 = 3,33 &#177; 0,02 M-3 , &#946;4 = 0,63 &#177; 0,01 M-4 . The complex are weaks and are is agreement with the Irving and Williams rule, i. e., less stable than the corresponding complexes of Ni(II) and Co(II). At ligand concentration higher t than 1,0 M there were conditions for a slow spontaneous oxidation of manganese(II) complexes to manganese to manganese(III), with remarkable spectral changes.

Polydentate ligands are useful in many industries, mainly because of their ability to form complexes. The aim of this thesis is to study acid-base and coordination properties of polydentate ligands from the group of polyaminopolyphosphonates DTPMP and HMDTMP. The protonation constants of ligands as well as stability constants of complexes with biologically relevant ions Cu2+ , Zn2+ , Ni2+ , Mg2+ , Ca2+ , Co2+ , K+ and Na+ were determined by potentiometric titration. 31 P-NMR titration was used to determine pKa on nitrogen atoms, which could not be measured by potenciometric titration. Seven pKa for HMDTMP ligand and nine for DTPMP were obtained. The stability constants show that the HMDTMP ligand forms less stable complexes than the DTPMP ligand.

[pt] Tiossemicarbazonas e seus complexos metálicos apresentam um amplo espectro de atividades biológicas. As tiossemicarbazonas α(N)-heterocíclicas tem sido muito estudadas em razão de sua comprovada ação antitumoral. O mecanismo de ação antitumoral dessas drogas se dá pela inibição da enzima ribonucleotídeo difosfato redutase (RDR), que catalisa o ciclo de reações redox envolvido na conversão de ribonucleotídeos a desoxirribonucleotídeos durante a síntese do ADN. A forma ativa dessas drogas é o complexo de ferro. Desse modo, a obtenção de novos complexos de Fe de tiossemicarbazonas α(N)-heterocíclicas constitui uma importante estratégia para a obtenção de candidatos a antitumorais. Nesse trabalho investimos no estudo, em solução aquosa, da interação entre 2- piridinoformamida tiossemicarbazona (H2Am4DH) e seus derivados N(4)-metil (H2Am4M), N(4)-etil (H2Am4E) e N(4)- fenil (H2Am4Ph) e os íons Cu(II) e Fe(III). Esse estudo foi monitorado por espectroscopia de absorção na região do UV-vis. Para o cálculo das constantes de formação dos complexos foram levados em consideração os valores das constantes cumulativas calculadas inicialmente para as tiossemicarbazonas livres ( β HL e β H2L+). Quatro novos complexos de Fe(III) foram isolados e caracterizados: [Fe(2Am4DH)2]Cl, [Fe(2Am4Me)2]Cl, [Fe(2Am4Et)2]Cl e [Fe (2Am4Ph)Cl3]. Os valores de susceptibilidade magnética para os complexos estão na faixa de 1,36-1,66 MB. Esses valores são próximos do calculado (1,73 MB) para complexos de Fe(III), octaédricos, spin baixo. Os dados de infravermelho indicam que as tiossemicarbazonas estão coordenadas ao ferro através do sistema quelante Npy-N-S. O comportamento eletroquímico dos complexos é bastante similar, sugerindo que suas estruturas em solução são igualmente similares. A toxicidade das tiossemicarbazonas e de seus complexos de ferro frente à Artemia salina foi estudada como um pré-screening para sua ação antitumoral. Os valores de LD50 obtidos indicam que esses compostos têm atividade citotóxica, sugerindo que poderiam igualmente apresentar ação antitumoral. Além disso, os potenciais de redução FeIII/FeII observados para os complexos estão dentro da faixa ideal dos redutores celulares. Assim, se confirmada a atividade antitumoral o mecanismo de ação poderia envolver a redução FeIII/FeII por tiois celulares, como sugerido para outros complexos de ferro de tiossemicarbazonas. / [en] Thiosemicarbazones and their metal complexes present a wide range of bioactivities. It has been shown that the antitumoral action of á(N)-heterocyclic thiosemicarbazones occurs through the inhibition of ribonucleotide diphosphate reductase (RDR), a key enzyme involved in the conversion of ribonucleotides into deoxyribonucleotides during DNA syntheses. The active form of the drugs are their iron complexes. Hence the preparation of new iron complexes with á(N)- heterocyclic thiosemicarbazones constitutes an interesting strategy in designing antitumoral drug candidates. In the present work the interactions of 2- pyridineformamide thiosemicarbazone (H2Am4DH) and its N(4)- methyl (H2Am4Me), N(4)-ethyl (H2Am4Et) and N(4)-phenyl (H2Am4Ph) derivatives with Cu(II) as well as Fe(III) ions in aqueous solution were studied, monitored in the visible region by the variations of the absorption spectrum. The cumulative protonation constants â HL and â H2L+ were determined for the ligands by a potentiometric method and were used in the calculation of the complex formation constants. The iron(III) complexes [Fe(2Am4DH)2]Cl, [Fe (2Am4Me)2]Cl, [Fe(2Am4Et)2]Cl and [Fe(2Am4Ph)Cl3] were obtained and characterized. The values of magnetic moments in the 1.59-1.66 BM range are close to the calculated value of 1.73 BM, characteristic of the presence of one unpaired electron as in low spin iron(III) complexes. The infrared data for the complexes indicate coordination of the thiosemicarbazones through the Npy-N-S chelating system. The resemblance of electrochemical behaviors suggests that the structures of the complexes in solution are also very similar. The toxicity of the thiosemicarbazones and their metal complexes against Artemia salina was assayed as a prescreening of antitumoral action. The low values of LD50 obtained for the studied compounds in this assay indicate that they could present antineoplastic properties. Moreover, the determined values of FeIII/FeII redox potentials for the complexes fall in the range of cellular reductants. Therefore, if the complexes present antitumoral activity, their biochemical pathway could involve FeIII/FeII reduction by cellular thiols, as suggested previously for iron complexes of other thiosemicarbazones.

O presente trabalho procura dar continuidade a uma das linhas de pesquisa desenvolvida pelo Grupo de Química Analítica do Instituto de Química da Universidade de são Paulo: o estudo da formação de complexos. O sistema Hg(II) / S2O2-3 foi analisado potenciometricamente, com a finalidade de identificar o número de complexos formados, assim como estimar as constantes de estabilidade envolvidas no fenônemo de complexação. Tal equilíbrio foi levado a termo a 25,0 &#177; 0,1&#176;C, e força iônica 2,00M, sendo detectados quatro espécies complexas. O modelo matemático que melhor se ajustou aos dados experimentais fornecidos pelo sistema, conta com os seguintes valores para as constantes globais de formação: &#946;1 1 = x 1024 M-1 (valor atribuído) &#946;2 = (8,0 &#177; 2,8) x 1027 M-2 &#946;3 = (1,71 &#177; 0,03) x 1030 M-3 &#946;4 = (3,07 &#177; 0,77) x 1030 M-4. Na região de baixa concentração analítica de ligante, 5mM, o acesso experimental foi limitado pela precipitação de sulfeto mercúrico sendo impossível obter informaçôes sobre a primeira espécie. O comportamento do mercúrio no sistema Hg(II) / S2O2-3 foi estudado de uma forma mais abrangente, sendo estendido ao meio não complexante, onde o equilíbrio de dismutação do cátion mercuroso governa. Nas mesmas condições de temperatura e força iônica anteriores, foram obtidos alguns parâmetros desse equilibrio, a saber: - potenciais formais de eletrodo: Eo\'Hg(I) / Hg(O) = ( 0,456 &#177; 0,014 ) V Eo\'Hg(II) / Hg(O) = ( 0,559 &#177; 0,0016) V Eo\'Hg(III) / Hg(I) = ( 0, 6625 &#177; 0,0023 ) V - constante do equilibrio heterogêneo: Qp (potenciométrica) = (3 &#177; 1) x 103 Adicionalmente, foram realizados estudos eletrogravimétricos sobre o mecanismo de oxidação coulométrica do mercúrio metálico, em diversos eletrólitos suporte, merecendo destaque a estabilização do Hg(I) por cloreto, e do Hg (II) por tiossulfato, mostrando que a transferência eletrônica é um processo por etapas. Complementando o estudo do sistema, a potencialidade análitica do tiossulfato na determinação dos cátions do mercúrio foi confirmada em titulações potenciométricas. / The present work belongs to one of the topics developed by the Analytical Chemistry Group in the Chemistry Institute of the são Paulo University: the study of complex formation equilibrium. The Hg(II)/S2O2-3 system was potentiometrically analysed with the purpose of identifying the number of formed complexes as well as computing their stability constants. Such equilibria study was performed at a 25.0 &#177; 0.1ºC temperature and 2.00 M ionic strengh, mantained with NaClO4. Four stepwise complexes have been detected by a calculus procedure based on non-linear regression. The best formation constants set is: &#946;1 1 = x 1024 M-1 (arbitrary value) &#946; 2 = (8,0 &#177; 2,8) x 1027 M-2 &#946;3 = (1,71 &#177; 0,03) x 1030 M-3 &#946;4 = (3,07 &#177; 0,77) x 1030 M-3. At lower ligand concentration, nearly 5mM, the experimental access was limited by the mercuric sulphide precipitation, being impossible to achieve data on the first specie. The mercury performance in the Hg(II)/S2O2-3 system was more widely studied with concern to the non-complexing media, where the disrnutation of mercurous cation leads. With the same previous temperature and ionic stengh conditions, some equilibria parameters have been determined: - electrode potentials: Eo\'Hg(I) / Hg(O) = ( 0,456 &#177; 0,014 ) V Eo\'Hg(II) / Hg(O) = ( 0,559 &#177; 0,0016) V Eo\'Hg(III) / Hg(I) = ( 0, 6625 &#177; 0,0023) V - heterogeneous equilibria constant: Qp = (3 &#177; 1) x 103. Electrogravimetric studies about the coulometric oxidation mecanism of metallic mercury have also been executed. The oxidation was carried out at several suporting electrolites, regarding the Hg(II) stabilization by the tiossulphate anion, and the Hg(I) by chloride, showing that the electrochemical transfer occurs in a step by step process. In addition to system study, the analytical potentiality of the tiossulphate on the determination of mercury cationic species was confirmed by potentiometric titulations.

The purpose of this study was to investigate the fundamental characteristics of a chelating surfactant in terms of solution behaviour, chelation of divalent metal ions, and interaction in mixtures with different foaming agents and divalent metal ion, as well as examining its prospects in some practical applications. Chelating surfactants are functional molecules, with both surface active and chelating properties, which are water soluble and therefore suitable for chelation in many aqueous environments. The dual functionality offers the possibility to recover the chelating surfactant as well as the metals. The DTPA (diethylenetriaminepentaacetic acid)-based chelating surfactant 4-C12-DTPA (2-dodecyldiethylenetriaminepentaacetic acid) was synthesized at Mid Sweden University. In the absence of metal ions, all eight donor atoms in the headgroup of 4-C12-DTPA are titrating and the headgroup charge can be tuned from +3 to -5 by altering the pH. The solution properties, studied by surface tension measurements and NMR diffusometry, were consequently found strongly pH dependent. pH measurements of chelating surfactant solutions as a function of concentration was used to extract information regarding the interaction between surfactants in the aggregation process. Small differences in the conditional stability constants (log K) between coordination complexes of DTPA and 4-C12-DTPA, determined by competition measurements utilizing electrospray ionization mass spectrometry (ESI-MS), indicated that the hydrocarbon tail only affected the chelating ability of the headgroup to a limited extent. This was further confirmed in hydrogen peroxide bleaching of thermomechanical pulp (TMP) treated with 4-C12-DTPA. Interaction parameters for mixed systems of 4-C12-DTPA and different foaming agents were calculated following the approach of Rubingh’s regular solution theory. The mixtures were also examined with addition of divalent metal ions in equimolar ratio to the chelating surfactant. Strong correlation was found between the interaction parameter and the phase transfer efficiency of Ni2+ ions during flotations. Furthermore, a significant difference in log K between different metal complexes with 4-C12-DTPA enabled selective recovery of the metal ion with the highest log K. The findings in this study contribute to the understanding of the fundamental characteristics of chelating surfactants, which can be further utilized in practical applications.

The interaction between the amino acid glutathione (GSH) and zinc (II) and cadmium (II) ions was investigated using data obtained by potentiometric and voltammetric measurements. Solutions with ionic strength 0.1 M KCl with different metal-ligand ratios were titrated with standard solution of KOH and the pH profiles obtained were used to propose models of chemical equilibrium between the species. The potentiometric data treatment was performed using the Hyperquad software, which enabled that the formation constants of the differents pecies could be refined. The program HySS,belonging to the Hyperquad computer package, was used to obtain the species distribution curves. The best fit models of equilibrium was reached suggesting the existence of species in which the metal ions were coordinated by one and two molecules of the ligand, and the highest values were found for log β complex type MH2L, MHL2 and ML2. For the voltammetric data, multivariate curve resolution with alternating least squares (MCR-ALS) was applied. Several voltammograms recorded at different metal-ligand ratios generated a series of overlapping peaks, from which it was possible to recover the pure voltammograms and their concentration profiles applying non-negativity, unimodality and "closure" as constraints. For both systems studied (GSH-Zn and GSH-Cd), voltammograms were resolved to three components, the free metal and two complexes. The potentiometric and voltammetric data treated with MCR-ALS were capable to complement one another, constituting a important tool in the investigation of chemical equilibria between metal ions and ligands. / A interação entre o aminoácido glutationa (GSH) e os íons zinco (II) e cádmio (II) foi investigada a partir de dados obtidos por medidas potenciométricas e voltamétricas. Soluções com força iônica 0,1 M de KCl de diferentes proporções metal-ligante foram tituladas com solução padrão de KOH e os perfis de pH assim obtidos foram usados para propor os modelos de equilíbrio químico entre as espécies. Para tratar os dados potenciométricos foi utilizado o programa Hyperquad, possibilitando que as constantes de formação das diferentes espécies pudessem ser refinadas. O programa HySS, pertencente ao pacote computacional do Hyperquad, foi utilizado para obtenção as curvas de distribuição das espécies. O melhor ajuste dos modelos de equilíbrio foi alcançado propondo a existência de espécies em que os íons metálicos foram coordenados por uma e duas moléculas do ligante, sendo que os maiores valores de log β foram encontrados para os complexos do tipo MH2L, MHL2 e ML2. Para os dados voltamétricos, foi aplicado o método de resolução multivariada de curvas com mínimos quadrados alternantes (MCR-ALS). Vários voltamogramas registrados a diferentes proporções metal-ligante geraram uma série de picos sobrepostos, a partir dos quais foi possível recuperar os voltamogramas puros e respectivos perfis de concentração aplicando não negatividade, unimodalidade e closure como restrições. Para ambos os sistemas estudados (GSH-Zn e GSH-Cd) os voltamogramas foram resolvidos para três componentes, o metal livre e dois complexos. A potenciometria e a voltametria submetida a MCR-ALS mostraram-se capazes de se complementarem, constituindo-se em grandes ferramentas na investigação de equilíbrios químicos entre íons metálicos e ligantes.