Photosystem II is a unique enzyme which catalyzes light induced water oxidation. This process is driven by highly oxidizing ensemble of four Chl molecules, PD1, PD2, ChlD1 and ChlD2 called, P680. Excitation of one of the Chls in P680 leads to the primary charge separation, P680+Pheo-. Pheo- transfers electrons sequentially to the primary quinone acceptor QA and the secondary quinone acceptor QB. P680+ in turn extracts electrons from Mn4CaO5 cluster, a site for the water oxidation. There are two redox active tyrosines, TyrZ and TyrD, found in PSII. They are symmetrically located on the D1 and D2 central proteins. Only TyrZ acts as intermediate electron carrier between P680 and Mn4CaO5 cluster, while TyrD does not participate in the linear electron flow and stays oxidized under light conditions. Both tyrosines are involved in PCET. The reduced TyrD undergoes biphasic oxidation with the fast (msec-sec time range) and the slow (tens of seconds time range) kinetic phases. We assign these phases to two populations of PSII centers with proximal or distal water positions. We also suggest that the TyrD oxidation and stability is regulated by the new small lumenal protein subunit, PsbTn. The possible involvement of PsbTn protein in the proton translocation mechanism from TyrD is suggested. To assess the possible localization of primary cation in P680 the formation of the triplet state of P680 and the oxidation of TyrZ and TyrD were followed under visible and far-red light. We proposed that far-red light induces the cation formation on ChlD1. Transmembrane interaction between QB and TyrZ has been studied. The different oxidation yield of TyrZ, measured as a S1 split EPR signal was correlated to the conformational change of protein induced by the QB presence at the QB-site. The change is transferred via H-bonds to the corresponding His-residues via helix D of the D1 protein.

A partir de l'étude des effets de la chimie de surface des Nanodiamants (NDs) sur leurs propriétés électroniques, cette thèse a permis la mise en évidence d'un effet thérapeutique des NDs sur des cellules humaines. En particulier, il a été montré que les NDs de détonation peuvent générer des radicaux libres oxygénés sous radiation ionisante, ce qui pourrait améliorer l'efficacité de certains traitements de radiothérapie actuels. Les échanges électroniques entre le coeur des NDs et leur environnement sont en effet favorisés après des traitements de surface, notamment d'hydrogénation et de graphitisation de surface. Les conditions expérimentales permettant d'obtenir des NDs hydrogénées (NDs-H) sous plasma d'hydrogène ont été optimisées sous ultravide, puis ont été utilisées pour préparer de grandes quantités de NDs-H sous forme pulvérulente. La même procédure a été appliquée pour la graphitisation de surface des NDs, en utilisant des recuits sous vide à haute température. L'effet de ces traitements de surface sur les propriétés d'interactions électroniques des NDs a été étudié après exposition à l'air ambiant, puis en dispersion dans l'eau. Ces traitements de surface assurent notamment un potentiel Zeta positif aux NDs, dont l'origine a été discutée. Enfin, les interactions des NDs avec plusieurs lignées de cellules tumorales humaines ont été étudiées et l'efficacité des NDs pour radiosensibiliser des cellules radiorésistantes sous irradiation gamma a été montrée, ouvrant de nouvelles perspectives d'applications des NDs en nanomédecine. . / In this thesis, a therapeutic effect of nanodiamonds (NDs) has been evidenced by investigating the role of NDs surface chemistry on their electronic properties. More precisely, the generation of reactive oxygen species from detonation NDs under ionizing radiation, which could improve current radiotherapy treatments, has been demonstrated. To this end, surface treatments facilitating electron transfer from NDs to their environment, namely hydrogenation and surface graphitization, were developed. Experimental conditions ensuring an efficient hydrogenation by hydrogen plasma were determined under ultrahigh vacuum, before being used to prepare large quantities of NDs in powder phase. A similar procedure was applied to the surface graphitization of NDs, performed by annealing under vacuum at high temperature. The impact of such surface treatments on the electronic interaction properties of NDs has been investigated under ambient air and after dispersion in water. These surface treatments induce a positive Zeta potential to NDs in water, which origin has been discussed. Finally, their interactions with human tumor cells were observed. Radiosensitization of tumor cells using NDs under gamma irradiation was demonstrated, opening new perspectives for NDs in nanomedicine.

Doctor of Philosophy / Department of Chemistry / Jun Li / Reduction in electrode size down to nanometers dramatically enhances the detection sensitivity and temporal resolution. Here we explore nanoelectrode arrays (NEAs) and nanoparticles in building high performance biosensors. Vertically aligned carbon nanofibers (VACNFs) of diameter ~100 nm were grown on a Si substrate using plasma enhanced chemical vapor deposition. SiO[subscript]2 embedded CNF NEAs were then fabricated using techniques like chemical vapor deposition, mechanical polishing, and reactive ion etching, with CNF tips exposed at the final step. The effect of the interior structure of CNFs on electron transfer rate (ETR) was investigated by covalently attaching ferrocene molecules to the exposed end of CNFs. Anomalous differences in the ETR were observed between DC voltammetry (DCV) and AC voltammetry (ACV). The findings from this study are currently being extended to develop an electrochemical biosensor for the detection of cancerous protease (legumain). Preliminary results with standard macro glassy carbon electrodes show a significant decrease in ACV signal, which is encouraging. In another study, NEA was employed to capture and detect pathogenic bacteria using AC dielectrophoresis (DEP) and electrochemical impedance spectroscopy (EIS). A nano-DEP device was fabricated using photolithography processes to define a micro patterned exposed active region on NEA and a microfluidic channel on macro-indium tin oxide electrode. Enhanced electric field gradient at the exposed CNF tips was achieved due to the nanometer size of the electrodes, because of which each individual exposed tip can act as a potential DEP trap to capture the pathogen. Significant decrease in the absolute impedance at the NEA was also observed by EIS experiments. In a final study, we modified gold nanoparticles (GNPs) with luminol to develop chemiluminescence (CL) based blood biosensor. Modified GNPs were characterized by UV-Vis, IR spectroscopy and TEM. We have applied this CL method for the detection of highly diluted blood samples, in both intact and lysed forms, which releases Fe[superscipt]3[superscript]+ containing hemoglobin to catalyze the luminol CL. Particularly, the lysed blood sample can be detected even after 10[superscript]8 dilution (corresponding to ~0.18 cells/well). This method can be readily developed as a portable biosensing technique for rapid and ultrasensitive point-of-care applications.

Indigo N,N’-diarylimine (Nindigo) and indigo N-arylimine (Mindigo) are redox-active ligands which exhibit near-infrared absorption and can accommodate up to five ligand charge states. This dissertation explores the coordination chemistry of these ligands to further understand the role that metal-ligand combinations play on ligand-centered properties, which include electrochemical potentials, UV-Vis-NIR absorption, pKa values, hydricities, and NH bond strengths at different ligand charge states. A series of cis-Nindigo palladium complexes containing acetylacetonate (acac) and hexafluoroacetylacetonate (hfac) ligands were synthesized. The acac complexes were easier to oxidize by 0.11 to 0.16 V and absorbed at lower wavelengths compared to their hfac analogues. Complexes using indigo bis(4-methylphenylimine) were more easily reduced than complexes of indigo bis(2,6-dimethylphenylimine). Cis- and trans-Mindigo complexes of palladium acac and hfac were synthesized as the first coordination complexes of Mindigo. Trans-Mindigo complexes were more difficult to reduce by 0.33 to 0.37 V and absorbed at lower wavelengths than their cis-Mindigo counterparts. Cis-Mindigo complexes were easier to reduce and harder to oxidize than the corresponding cis-Nindigo complexes. The NH bond strengths of cis-Nindigo complexes containing Pd(acac) and Ru(bipy)2 (bipy = 2,2’-bipyridyl) fragments were determined through a potential-pKa diagram in tetrahydrofuran and acetonitrile, respectively. The NH bond strength and hydricity values of the Pd(acac) complex were comparable to the values of diaryl amines. The NH bond strength and hydricity of the Ru(bipy)2 complex were substantially smaller due to the lower oxidation potentials of this complex. In both cases, the ligand’s NH bond strengths were not affected greatly by the ligand’s charge state. Ru(acac)2 complexes of neutral, aprotic cis-Nindigo and cis-Mindigo ligands were synthesized. The Nindigo/Mindigo ligand could be protonated, and the resulting complexes demonstrated substantial temperature dependence of some of their 1H NMR chemical shifts. The NH bond strengths and hydricities of the Ru(acac)2 complexes were determined using cyclic voltammetry and pKa measurements. The NH bond strengths and hydricities of these complexes are substantially smaller than the Pd(acac) and Ru(bipy)2 complexes. Collectively, these results show that Nindigo and Mindigo can act as both a proton and electron reservoirs, and the thermodynamics of proton and electron transfer can be tuned through the choice of metal and ligand combinations. / Graduate / 2020-07-17

Foi sintetizada e caracterizada a spiro-ciclopentil-1,2-dioxetanona, um derivado de 1,2-dioxetanona inédito, de forma a se contribuir com informações acerca da quimiluminescência de peróxidos orgânicos. Estudos mecanísticos da decomposição quimiluminescente de 1,2-dioxetanonas são escassos, principalmente quando comparados à enorme quantidade de resultados existentes sobre a formação de estados excitados na decomposição de 1,2-dioxetanos. A spiro-ciclopentil-1,2-dioxetanona foi preparada pela ciclização do 1-carbóxi-1- hidroperóxiciclopentano com N,N-diciclohexilcarbodiimida, com rendimento de 1,2%, e caracterizada por RMN de 1H e 13C a baixa temperatura e pelo comportamento cromatográfico da solução peroxídica. Evidências para a ocorrência do mecanismo de Luminescência Iniciada Quimicamente por Troca de Elétron (CIEEL) na formação de estados excitados, na sua variante intermolecular, foram obtidas por estudos cinéticos da decomposição quimiluminescente dessa 1,2-dioxetanona por diferentes ativadores (ACTs). Entretanto, a decomposição desse peróxido ocorre com rendimentos de formação de estados excitados singlete baixos (ΦS≈ 10-4 E mol-1), indicando que essa 1,2-dioxetanona também possui baixa eficiência de formação de estados excitados, conforme constatado recentemente para outros derivados. Foram encontradas evidências para a ocorrência de uma transferência de elétron na etapa limitante de velocidade, onde o ACT é formado no estado excitado, com um coeficiente de transferência de elétron de α = 0,19. Ainda, foi observada uma correlação entre a energia livre liberada para a formação de estados excitados e os rendimentos quânticos, nos moldes do mecanismo CIEEL. De acordo com os resultados obtidos nesse trabalho e em trabalhos anteriores, postula-se que o tamanho do substituinte alquílico no anel da 1,2-dioxetanona causa um efeito drástico na eficiência da decomposição catalisada do peróxido na seqüência CIEEL, diminuindo o valor da constante de equilíbrio para a formação inicial do complexo de transferência de carga Em uma segunda parte do trabalho, foi averiguado o mecanismo da reação peróxi-oxalato em meios aquosos, uma vez que a maioria dos trabalhos sobre esta transformação nestes meios possui ênfase na aplicação analítica. Foi observado que as reações dos oxalatos de bis(2,4,6-triclorofenila) (TCPO), moderadamente reativo, e bis(2,4-dinitrofenila) (DNPO), altamente reativo, com H2O2 e catálise por imidazol, ocorrem pelo mesmo mecanismo, em 1,2-dimetoxietano e em misturas aquosas desse solvente. Para TCPO, observou-se que há a formação de um intermediário de catálise nucleofílica, previamente ao ataque nucleofílico do H2O2. Para DNPO, há uma adição nucleofílica direta do H2O2 ao éster, com e sem catálise básica por imidazol. Em meios aquosos, a hidrólise do éster oxálico ocorre paralelamente à peridrólise, que leva à emissão de luz. Entretanto, as constantes de velocidade para a peridrólise do éster são significativamente maiores do que as para a sua hidrólise. Observou-se que a reação de TCPO com H2O2 em meios orgânico e aquoso, catalisada por 2,6-lutidina (2,6-dimetilpiridina), ocorre com essa base agindo como um catalisador não-nucleofílico. Por último, estudou-se a reação de TCPO com H2O2 em tampão carbonato de potássio, um meio essencialmente aquoso, onde a espécie reativa é a base conjugada do H2O2; entretanto, a constante de velocidade da peridrólise se mostrou similar à de hidrólise do éster oxálico. Nessa última parte do trabalho, foi demonstrado que a reação peróxi-oxalato também pode ser conduzida em meios aquosos. / Spiro-cyclopentyl-1,2-dioxetanone, a new 1,2-dioxetanone derivate, was synthesized and characterized, in order to contribute to the present mechanistic knowledge on organic peroxide chemiluminescence. Mechanistic studies on the chemiluminescent 1,2-dioxetanone decomposition are highly limited, especially when compared to the huge amount of data available for 1,2-dioxetanes. The spiro-cyclopentyl-1,2-dioxetanone was prepared by 1-carboxy-1-hydroperoxycyclopentane cyclization with N,N-dicyclohexylcarbodiimide, in a 1.2% yield and characterized by low temperature 1H and 13C NMR and the chromatographic behavior of the peroxide solution. Evidence for the occurrence of the Chemically Initiated Electron Exchange Luminescence (CIEEL) mechanism for excited states formation, in its intermolecular version, was obtained from kinetic studies of the chemiluminescent decomposition of this 1,2-dioxetanone with different activators (ACTs). However, the decomposition of this peroxide occurs with low yields of singlet excited state formation (ΦS≈ 10-4 E mol-1), showing that also this 1,2-dioxetanone possesses low excitation efficiency, as recently found for other derivatives. Evidence was found for the occurrence of an electron transfer in the rate limiting step, where the ACT is formed in its electronically excited state, with an electron transfer coefficient α= 0.19. Moreover, a correlation between the free energy released upon excited states formation and the quantum yields is observed, in agreement with the CIEEL mechanism. The results obtained in the present work together with previous data, allow to postulate that the size of the alkyl substituent on the 1,2-dioxetanone ring plays a crucial role for the efficiency of the catalyzed peroxide decomposition in the CIEEL sequence, by lowering the equilibrium constant for initial charge transfer complex formation. In a second part of this work, the mechanism of the peroxyoxalate reaction in aqueous media was studied, due to the fact that most of recent work on this system is mainly concerned only to analytical application aspects. The reaction of the moderately reactive bis(2,4,6-trichlorophenyl) (TCPO) and the highly reactive bis(2,4- dinitrophenyl) oxalate (DNPO) with H2O2 and imidazol catalysis, showed to occur by the same mechanism, in 1,2-dimethoxyethane as well as in its aqueous mixtures. For TCPO, the formation of an intermediate due to nucleophilic catalysis by imidazole was observed, preceding the H2O2 nucleophilic attack. For DNPO, direct nucleophilic addition of H2O2 to the ester occurs, with and without imidazole catalysis. In aqueous media, oxalic ester hydrolysis also occurs concomitantly to its perhydrolysis, which leads to light emission. However, the rate constants for perhydrolysis are significantly higher than the hydrolysis rate constants. For the reaction of TCPO with H2O2 in organic and aqueous medium, catalyzed by 2,6-lutidine (2,6-dimethylpyridine), it was shown that this base acts as a nonnucleophilic catalyst. Finally, the reaction of TCPO with H2O2 in potassium carbonate buffer, an essentially aqueous media, was studied, where the reactive species is the H2O2 conjugate base; however, the oxalic ester perhydrolysis rate constant proofed to be similar to its hydrolysis rate constant. In this last part it is also shown that the peroxyoxalate reaction can be carried out in aqueous media.

A espectroscopia fotoacústica e de fluorescência foram empregadas no estudo de reação da transferência de elétrons entre um doador (Octaetil-porfirina) dois tipos de aceitadores [Diclorodiciano-benzoquinona (DDQ) e Duroquinona (DQ)] em um meio rígido [poli (metil-metacrilato)] . Foram preparados filmes nos quais a concentração de doador foi mantida constante e a de aceitador foi variada. Observou-se um aumento exponencial da amplitude do sinal fotoacústico do doador em 620 nm, com o aumento da concentração de aceitadores nos filmes. O modelo de Perrin para a supressão de fluorescência foi aplicado aos dados de fotoacústica e o raio da esfera de ação, que representa a distância crítica para a ocorrência da transferência de elétrons, foi determinado. Os resultados obtidos foram: para DDQ37 angstron e para aDQ 32 a 34angstron. Era esperado um raio maior para a DDQ devido a sua maior elétron afinidade. Também foi aplicado a estes dados o modelo de Kaneko, desenvolvido para a supressão de fluorescência. Dele se obtém a distribuição de moléculas aceitadoras incorporadas na esfera de ação. Para uma mesma concentração de aceitadores (2,8mmoldm-3) , a probabilidade de encontrar uma molécula de DDQ na esfera de ação foi 27%, enquanto que a probabilidade de encontrar uma molécula de DQ na esferade ação foi de 20%. Este resultado é, na verdade, equivalente ao encontrado no modelo de Perrin pois a probabilidade maior encontrada para a DDQ vem do fato do raio da sua esfera de ação ser maior. O valor encontrado para o raio crítico com os dados de fluorescência foi de 34 A para a DQ. Isto demonstra que as duas técnicas são complementares e que a espectroscopia fotoacústica pode ser usada para monitorar o processo de transferência de elétrons / Steady-state photoacoustic and fluorescence spectroscopy were employed to study the electron-transfer reaction from donor molecules (Octaethyl-porphirin) to two types of acceptor molecules [Dichloro-dicyano-benzoquinone (DDQ) and Duroquinone (DQ)I in a rigid medium [poly (methyl -metacrylate)] . Films were prepared with a fixed donor concentration and severa1 acceptor concentrations. It was observed an exponential growth in the donor photoacoustic signal amplitude at 620 nm, with the increase in the acceptor concentration. Perrin model, used in fluorescence quenching, was applied to the photoacoustic data and the radius o£ an action sphere, which represents a critica1 distance for the electron transfer process, was determined. The results obtained were: for DDQ 37 angstron and for DQ from 32 to 34 angstron. It was expected a larger radius for DDQ than for DQ due to its stronger electron affinity. Kaneko\'s model, was also applied to these data. It provides the distribution o£ incorporated acceptor molecules in the action sphere. For the same acceptor concentration (2.8 mmol , the probability of finding one DDQ molecule in the action sphere was 27%, while for the DQ molecule this value was 20%. Actually, this result is equivalent to that found using Perrin model, because the larger probability obtained for DDQ comes frm the fact that its critical radius is bigger . The value obtained for the critica1 radius from the fluorescence data was 34 angstron for DQ. This shows that these two techniques are complementary and that photoacoustic spectroscopy can be used to monitor the electron transfer process

Sem resumo / Sem abstract

A transferência de elétrons tem sido objeto de um estudo intenso nos últimos anos, por causa da importância deste tipo de reação em processos naturais como a fotossíntese. Com isto, um progresso considerável foi conseguido na proposição de modelos para o centro de reação fotossintético, em particular utilizando o sistema-modelo porfirina-quinona. Nosso intuito e estudar o processo de transferência de elétrons da porfirina para a quinona, aleatoriamente distribuídas em uma matriz polimérica, utilizando a técnica de espectroscopia fotoacústica. A utilização de um filme de polímero como meio tem duas vantagens. A primeira e aproximar nosso sistema-modelo do processo fotossintético natural, no qual os doadores e os aceitadores de elétrons estão envoltos nas proteínas do centro de reação e, portanto, em um meio polimérico. A segunda e possibilitar a utilização desses filmes como possíveis componentes eletrônicos moleculares. Identificamos os estados eletrônicos da porfirina e da quinona e tentamos determinar o estado de cargas separadas, P+ e Q-. A partir dos espectros obtidos, determinamos a eficiência quântica de fluorescência da porfirina utilizada nos filmes. Estudamos, também, a degradação da porfirina nos filmes preparados. Por fim, verificamos o efeito da concentração crescente da quinona nos filmes preparados com a porfirina / The electron transfer phenomenon has been the subject of intense study for the last years, due to the importance of this kind of reaction in natural processes as photosynthesis. A great improvement has been achieved in the proposition of models for the photosynthetic reaction center, in particular using the porphyrin-quinone model system. Our intention is to study the electron transfer process of the porphyrin to the quinone randomly distributed in a polymeric matrix, using the photo acoustic spectroscopy. The utilization of a polymeric film as an environment has two advantages. The first is to approximate our model system to the natural photosynthetic process, in which the electron donors and acceptors are surrounded by, the proteins of the reaction center, and thus in a polymeric environment. The second is to allow the utilization of these films as possible molecular electronic components. We identified the electronic states of the porphyrin and the quinone, and we attempted to determine the charge separated electronic state. We determined the fluorescence quantum efficiency of the porphyrin films, by their photo acoustic and absorption spectra. Also, we studied the degradation of the porphyrin in the prepared films. Finally, we checked the effect of the increasing concentration of the quinone in the films prepared with the porphyrin

Este trabalho teve como objetivo estudar a transferência de elétrons em um meio rígido através de técnicas espectroscópicas convencionais, tais como a fluorescência e a fotoacústica, e verificar a possibilidade de se determinar a taxa de transferência através destas técnicas. Foram utilizados como doador de elétrons a tetrafenilporfirina (TPP), como aceitador de elétrons a duroquinona (DQ), e como meio rígido o polimetilmetacrilato (PMMA) e o poliestireno (PS). As amostras foram estudadas na forma de filmes, com uma distribuição aleatória de doadores e aceitadores de elétrons. Com a espectroscopia de fotoacústica não foi possível se detectar a ocorrência da transferência de elétrons. Com a fluorescência, usando o modelo de Perrin, foi possível determinar o raio crítico de transferência, 72k para o par TPP/DQ em poliestireno. No entanto, verificou-se a impossibilidade de se determinar univocamente a taxa de transferência de elétrons. Nos filmes preparados com polimetilmetacrilato foi observada uma fotodegradação irreversível, o que inviabilizou seus estudos / The objective of this work was to study the electron transfer process in a rigid medium using conventional spectroscopic techniques, such as fluorescence and photoacoustic, and verify the possibility of determining the electron transfer rate through these techniques. The molecules used were: tetraphenylporphyrin (TPP) as electron donor, duroquinone (DQ) as the electron acceptor, and polystyrene (PS) and polymethylmetacrilate (PMMA) as the rigid medium. The samples were studied in the form of films, with a random distribution of electron donor and acceptor molecules. With the photoacoustic spectroscopy it was not possible to detect the occurrence of the electron transfer process. With the fluorescence technique, using Perrin model, it was possible to determine the criticai radius for electron transfer, 7 À, for the par TPP/DQ in polystyrene. However, it was verified the impossibility of determining univocally the electron transfer rate. In the films made with polymethylmetacrilate, an irreversible photodegradation was observed, what made the study of these films non viable

O óxido nítrico (NO) é um versátil agente biológico, atuando em diversas partes do organismo, tais como cérebro, artérias, sistema imunológico, fígado e pulmões. Alterações nos níveis basais de NO são relacionadas a causas de diversas doenças como hipertenção, câncer, doença de Raymond´s e agregação plaquetária. Visando suprir tal deficiência, mostrou-se de grande valia a obtenção de fármacos capazes de liberar quantidades significativas de NO e de maneira controlada. Uma das possibilidades é o uso de compostos de coordenação, com centro metálico rutênio coordenado ao ligante nitrosil, os quais possuem como característica liberação de NO por estímulo externo. Neste trabalho foram estudados as propriedades químicas, fotoquímicas, farmacológicas e tumoricidas do complexo trans-[RuC(MAC)NO]2+, onde MAC é 1,4,8,11-tetraazaciclotetradecano (cyclam) ou 1,4,8,12-tetraazaciclopentadecano ([15]aneN4), na presença do fotossensibilizador [Ru(NH3)5pz]2+. Os estudos fotoquímicos mostraram que o fotossensibilizador utilizado, [Ru(NH3)5pz]2+, possui tempo de vida no estado excitado de 113 ps, e apresenta processos de transferências eletrônicas e de energia fotoinduzida com o oxigênio molecular, gerando espécies reativas de oxigênio (EROS) como oxigênio singlete e ânion superóxido. Na presença do complexo macrocíclico trans-[RuC(MAC)NO]2+ a irradiação luminosa de [Ru(NH3)5pz]2+ na região do visível proporciona trasferência eletrônica fotoinduzida entre o fotosenssibilizador e o complexo nitrosilo com concomitante formação de NO. O rendimento quântico de NO (NO) é dependente do meio e é de cerca de 10-4 Einstein.mol.cm-1 em meio aquoso sob argônio e 10-2 Einstein.mol.cm-1 em meio oxigenado. Os estudos farmacológicos mostraram que a mistura proposta, em tampão fosfato pH 7,4, promoveu 75% de dilatação em musculatura de aorta pré-contraída com KC enquanto que, quando incorporados em sistemas carreadores de fármacos como emulsão óleo-em-água, HEG gel e membrana sol-gel, promoveram 40%, 35% e 35% de dilatação, respectivamente. A via vasodilatadora foi detectada como sendo pela ativação da GMPc (guanosina monofosfato cíclica), através da quantificação da concentração de cálcio citosólico. Os estudos das atividades anti-tumorais com os complexos doadores de NO foram realizados com linhagens celulares do tipo B16F10, Melan A, HL-60 WMs e Jurkat. Estes experimentos mostraram redução da viabilidade celular dos melanomas entre 50% e 75%, não apresentou ação em células normais (MelanA), mostrando-se seletivos ás células neoplasicas; e 95% de redução da viabilidade celular das células leucêmica (HL-60). Os resultados obtidos e descritos neste trabalho permitem vislumbrar que o uso de espécies doadoras de NO e oxigênio singlete possam ser utilizados no futuro em terapia clínica. / Nitric oxide (NO) is a multipurpose biological agent that shows important role in brain, arteries, immunological system, liver and lungs. The NO basal level alterations have correlation with several diseases as hypertension, cancer, Raymonds disease and platelet aggregation. Aiming supply this deficient NO level, it was necessary propose new compounds that can release NO at controlled manner. One of the possibilities is utilize nitrosyl ruthenium complexes that have ability to release NO under external stimulus. In this work we have studied, the chemical, photochemical, pharmacological and anti-tumoral properties of the trans-[RuC(MAC)NO]2+ complex, were MAC is 1,4,8,11-tetraazacyclotetradecane (cyclam) or 1,4,8,12-tetraazacyclopentadecane ([15]aneN4), in the presence of the sensitizer [Ru(NH3)5pz]2+. The photochemical studies of [Ru(NH3)5pz]2+ complex showed excited state lifetime of 113 ps and presented photoinduced electron and energy transfer with oxygen resulting in reactive oxygen species (ROS) generation as singlet oxygen and superoxide anion. In the presence of trans-[RuC(MAC)NO]2+ complex, the visible light irradiation of [Ru(NH3)5pz]2+ causes photoinduced electron transfer between the photosensitizer and the nitrosyl ruthenium complex resulting NO generation. The quantum yield (NO) is milieu dependent and showed 10-4 Einstein.mol.cm-1 in inert atmosphere and 10-2 Einstein.mol.cm-1 in aerated aqueous solution. The pharmacological studies showed that the proposed mixture in phosphate buffer, under visible irradiation, induce 75% of relaxation in aorta pre-contracted with KC while this system incorporated into drug delivery system as water-in-oil emulsion, HEG gel and sol-gel membrane, the nitric oxide generated induced 40%, 35% and 35% of relaxation, respectively. The quantification of cytosolic calcium concentration, using confocal image, showed that vasodilatation pathway observed was via cGMP (cyclic guanosine monophosphate) activation. The anti-tumoral studies using NO donors were carried out for B16F10, Melan A, HL-60, WMs and Jurkat cells. Those experiments showed decrease from 50% to 75% of cell viability of tumor cells and no toxicity in melanoma cells and 95% of reduction of leukemic cells (HL-60). The obtained results described in this work permit to glimpse that the use of NO donor species and singlet oxygen maybe is a useful tool in the future in clinical therapy.