Le travail présenté dans ce mémoire est dédié à l'élaboration de complexes de ruthénium(II) photo-commutables originaux incorporant le couple photochrome Diméthyldihydropyrène (DHP) / Cyclophanediène (CPD), pour de futurs dispositifs moléculaires optoélectroniques.Dans le but de réaliser des systèmes complexes pouvant reproduire les fonctions d'un circuit logique, une stratégie intéressante repose sur l'association de molécules photo-commutables et de complexes métalliques. Cependant, cette stratégie se confronte à certains obstacles majeurs, généralement associés à la perte des propriétés de commutation des photochromes organiques. En réponse aux précédents résultats confirmant cette tendance, deux nouvelles familles de complexes terpyridiniques de ruthénium(II) à base de DHP ont été synthétisées. Sachant que la présence de fonction pyridinium améliore significativement les propriétés d'isomérisation du cœur DHP, les centres métalliques ont été connectés soit via un lien benzyle pyridinium (Ru-Lpy+tpy) soit via un lien aryle pyridinium (Ru-LZincke). Bien que fonctionnant à plus faible énergie, le complexe Ru-LZincke présente des performances amoindries, en revanche les complexes Ru-Lpy+tpy affichent une préservation notable de leurs propriétés de commutation. Suite à la découverte d'une photo-réactivité originale favorisée par la présence du centre métallique, une famille analogue à base de complexes bipyridiniques de ruthénium(II) (Ru-Lpy+bpy) a été étudiée. Même si les mécanismes ne sont pas complètement rationalisés, les complexes Ru-Lpy+bpy se sont révélés être de remarquables candidats pour la réalisation de photo-commutateurs réversibles quantitativement dans le domaine du visible. / The work of this thesis is devoted to the development of original photo-switchable ruthenium(II) complexes incorporating the photochromic Dimethyldihydropyrene (DHP) / Cyclophanediene (CPD), for future optoelectronic molecular devices.In order to realize complex systems capable of reproducing the functions of a logic circuit, an interesting strategy is based on the association of photo-switchable molecules and metal complexes. However, this strategy is confronted with some major obstacles, generally associated with the loss of the switching properties of organic photochromes. In response to previous results confirming this trend, two new families of DHP-based terpyridine ruthenium(II) complexes have been synthesized. Since the presence of pyridinium function significantly improves the isomerization properties of the DHP core, the metal centers were connected either via a pyridinium benzyl linkage (Ru-Lpy+tpy) or via an aryl pyridinium linkage (Ru-LZincke). Although operating at lower energy, Ru-LZincke complex exhibits lessened performance, whereas Ru-Lpy+tpy complexes exhibit a notable preservation of their switching properties. Following the discovery of an original photo-reactivity favored by the presence of metal center, an analogue family based on ruthenium (II) bipyridine complexes (Ru-Lpy+bpy) was studied. Even if the mechanisms are not completely rationalized, Ru-Lpy+bpy complexes have proved to be remarkable candidates for the realization of quantitatively reversible photo-switches in the visible domain.

Orientador: Prof. Dr. André Sarto Polo / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Ciência & Tecnologia - Química, 2014. / O trabalho desenvolvido teve como foco sintetizar compostos tris-heterolepticos de rutenio(II), o cis-[Ru(phen)(dcbH2)(NCS)2], o cis-[Ru(Me2-phen)(dcbH2)(NCS)2] e o cis-[Ru(Ph2-phen)(dcbH2)(NCS)2]. Estes compostos foram sintetizados pela rota one-pot que forneceu rendimentos superiores a 60%. A escolha dos substituintes nas posicoes 4 e 7 da fenantrolina foram feitas com o intuito de analisar o efeito causado por um grupo retirador de eletrons (Ph - fenila) e por um grupo doador de eletrons (Me - metila). Os compostos sintetizados foram caracterizados por analise elementar, espectroscopia eletronica, espectroscopia vibracional, emissao e ressonancia magnetica nuclear de 1H. Pelo espectro vibracional constatou-se que o aumento da densidade eletronica causado pelo grupo doador de eletrons desloca o ¿Þ(CN)NCS para uma regiao de maior energia e apresenta um efeito contrario para o grupo retirador de eletrons. Com o auxilio da ressonancia magnetica nuclear de 1H foi possivel comparar os sinais dos protons H2 e verificou-se que o composto com o substituinte com o grupo doador de eletrons foi deslocado para campo alto em relacao ao composto com o substituinte com o grupo retirador de eletrons. Os grupos substituintes influenciam muito pouco nas propriedades eletronicas dos compostos sintetizados. Os espectros de emissao dos compostos apresentam bandas largas e nao estruturadas, tipicas de emissao proveniente do estado thexi 3MLCT. Os tres compostos foram utilizados como corantes sensibilizadores de celulas solares. Com este trabalho observou-se que pela escolha adequada dos grupos substituintes e possivel modular as propriedades dos corantes sensibilizadores. O desempenho fotoeletroquimico foi avaliado por testes de curvas de corrente potencial e apresentaram os seguintes resultados: cis-[Ru(phen)(dcbH2)(NCS)2]: Voc = 0,733 V, Jsc = 8,67 mA cm-2, ff = 0,61 e £b = 3,78%; cis-[Ru(Me2-phen)(dcbH2)(NCS)2]: Voc = 0,683 V, Jsc = 12,72 mA cm-2, ff = 0,55 e £b = 4,60%; cis-[Ru(Ph2-phen)(dcbH2)(NCS)2]: Voc = 0,738 V, Jsc = 13,28 mA cm-2, ff = 0,63 e £b = 6,18%. / The developed work focused on synthesizing compounds tris-heteroleptic ruthenium(II), cis-[Ru(phen)(dcbH2)(NCS)2], cis-[Ru(Me2-phen)(dcbH2)(NCS)2] and were synthesized cis-[Ru(Ph2-phen)(dcbH2)(NCS)2]. These compounds were synthesized by one-pot route which provided higher yields at 60%. The choice of the substituents at positions 4 and 7 of phenanthroline were made in order to analyze the effect caused by an electron withdrawing group (Ph - phenyl) and an electron donating group (Me - methyl). The synthesized compounds were characterized by elemental analysis, electronic spectroscopy, vibrational spectroscopy, emission and 1H nuclear magnetic resonance. For the vibrational spectrum it was found that increasing the electron density caused by the electron donating group displaces the ¿Þ(CN)NCS for a higher energy region and has an opposite effect to the electron withdrawing group. With the aid of 1H nuclear magnetic resonance was possible to compare the signals of the protons H2, and it was found that the compound of the substituent with electron donating group was shifted upfield compared to the compound with the substituent withdrawing group electrons. The substituent groups very little influence on the electronic properties of the synthesized compounds. Emission spectra of the compounds show broad and unstructured bands, typical of emission from the 3MLCT thexi state. The three compounds were used as sensitizing dyes of solar cells. With this work it was observed that with the appropriate choice of substituents is possible to modulate the properties of the dyes. The photoelectrochemical performance was evaluated by testing current and potential curves showed the following results: cis-[Ru(phen)(dcbH2)(NCS)2]: Voc = 0.733 V, Jsc = 8.67 mA cm- 2, ff = 0.61 and £b = 3.78 %; cis-[Ru(Me2-phen)(dcbH2)(NCS)2]: Voc = 0.683 V, Jsc = 12.72 mA cm-2, ff = 0.55 and £b = 4.60 %; cis-[Ru(Ph2-phen phen)(dcbH2)( NCS)2]: Voc = 0.738 V, Jsc = 13.28 mA cm-2, ff = 0.63 and ç = 6.18 % .

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2017-01-11T14:10:54Z No. of bitstreams: 2 Dissertação - Raquel Santos faria - 2015.pdf: 1687258 bytes, checksum: 06640eb0bb4f0895f2f882027093c950 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-01-11T14:11:18Z (GMT) No. of bitstreams: 2 Dissertação - Raquel Santos faria - 2015.pdf: 1687258 bytes, checksum: 06640eb0bb4f0895f2f882027093c950 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-01-11T14:11:18Z (GMT). No. of bitstreams: 2 Dissertação - Raquel Santos faria - 2015.pdf: 1687258 bytes, checksum: 06640eb0bb4f0895f2f882027093c950 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2014-03-30 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The estimate of IARC indicates that occur 27 million new cases of cancer in the world by 2030. Due to the increase in the number of cancer cases in the world, there was intensification in the search for new chemotherapeutic agents that are effective for the treatment of cancer. The pharmaceutical industry therefore intensified the search for new metal-based drugs that offer the possibility of oral administration, reduction of serious side effects and reduced clinical costs. Due to the foregoing, we assessed the cytotoxic, genotoxic, interference on the cell cycle kinetics and mechanism of cell death of [RuCl(bcn)(phen)(dppb)]PF6, a new complex of ruthenium (II). Cytotoxicity was assessed by the MTT assay and it has shown that the compound tested showed inhibition of tumor cell viability in Sarcoma 180 (S180) in lower concentrations (IC50 8.89 μM ± 3.9) and cytotoxicity at higher concentrations for normal lymphocytes (IC50 17 μM). [RuCl(bcn)(phen)(dppb)]PF6 also showed a significant lethality to brine shrimp nauplii Artemia salina (CL50 300.31 μg mL). The comet assay indicated that the compound is not genotoxic for lymphocytes cells, because there was no significant increase in DNA damage in cells treated, and exhibits low genotoxicity to tumor cells (S180). The Ru complex 25 induced changes in cell cycle identified by flow cytometric test, increasing the number of cells in G0 / G1 phase and lowering synthesis phase within 24 hours of treatment. The complex induced an increase of cells positive for Annexin-V/PI for flow cytometric test, suggesting cell death by apoptosis. By Western Blot assay, it was possible to infere that the complex may be triggering cell death by caspase-independent intrinsic apoptosis. However, others specifics markers are needed to understand the cascade of events which the intrinsic apoptosis pathway that is effecting this process of cell death, and if only this pathway is being activated in apoptosis, thus elucidating the mechanism of action in cells S180. Thus, this compound showed cytotoxicity to tumor cells, high safety of use, due to absent genotoxicity in normal cells, low genotoxicity in tumor cell, and possibly acts by caspase-independent apoptosis intrinsic pathway. / A estimativa do IARC aponta que ocorrerão 27 milhões de novos casos de câncer no mundo até 2030. Em decorrência do aumento no numero de casos de câncer no mundo, houve uma intensificação na busca de novos quimioterápicos que sejam eficientes para o tratamento do câncer. A indústria farmacêutica, portanto, intensificou a busca por novas drogas à base de metal que ofereçam possibilidade de administração oral, diminuição de efeitos colaterais graves e redução de custos clínicos. Devido ao exposto, foi avaliado o potencial citotóxico, genotóxico, a interferência na cinética do ciclo celular e o mecanismo de morte celular de [RuCl(bcn)(phen)(dppb)]PF6,um novo complexo de rutênio (II). A citotoxicidade foi avaliada pelo teste do MTT e este mostrou que o complexo testado apresentou inibição da viabilidade na célula tumoral de Sarcoma 180 (S180) em concentrações baixas (IC50 8.89 μM ± 3.9) e uma citotoxicidade em concentração maior para linfócitos normais (IC50 17 μM). [RuCl(bcn)(phen)(dppb)]PF6 também apresentou letalidade significativa no teste de Artemia salina (CL50 300.31 μg mL). O teste cometa indicou que o composto não é genotóxico para células de linfócitos, pois não apresentou aumento significativo de dano ao DNA nos linfócitos tratados, e apresenta baixa genotoxicidade para as células tumorais (S180). O complexo [RuCl(bcn)(phen)(dppb)]PF6 induziu mudanças no ciclo celular, identificado pelo teste de citometria de fluxo, aumentando a quantidade de células na fase G0/G1 e diminuindo na fase de síntese em 24 horas de tratamento. O complexo também induziu o aumento da quantidade de células positivas para Anexina-V/PI pelo teste de citometria de fluxo, sugerindo morte celular por apoptose. Pelo teste de Western Blot, foi possível inferir que o complexo pode estar desencadeando morte celular por apoptose via intrínseca e independente de caspase. Porém, outros marcadores específicos são necessários para compreender qual a cascata de eventos de apoptose via intrínseca que está efetivando esse processo de morte celular, e se somente esta via está sendo ativada no processo de apoptose, elucidando assim, o mecanismo de ação nas células de S180. Portanto, este composto apresentou citotoxicidade para células tumorais, com alta segurança de uso, devido ausente genotoxicidade em células normais, baixa genotoxicidade em células tumorais, e que possivelmente atua via apoptose intrínseca e independente de caspases.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2016-08-09T14:22:46Z No. of bitstreams: 2 Dissertação - Alarisse Arçari Fachetti Zoghaib - 2015.pdf: 1188040 bytes, checksum: 9ab52dc612351ab19ab98e90e7ce6ec9 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-08-09T14:24:14Z (GMT) No. of bitstreams: 2 Dissertação - Alarisse Arçari Fachetti Zoghaib - 2015.pdf: 1188040 bytes, checksum: 9ab52dc612351ab19ab98e90e7ce6ec9 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-08-09T14:24:14Z (GMT). No. of bitstreams: 2 Dissertação - Alarisse Arçari Fachetti Zoghaib - 2015.pdf: 1188040 bytes, checksum: 9ab52dc612351ab19ab98e90e7ce6ec9 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2015-09-28 / The ruthenium (II)/amino acid complex (rutrpII) demonstrated high anticancer activity against murine breast cancer (tumor of Ehrlich) in vitro and in vivo, and increased the median survival of animals. There was then necessary to investigate the pharmacokinetic parameters of the drug prototype as a requirement to pre-clinical knowledge of it. This study aimed to obtain the pharmacokinetic profile of ruthenium (II) / tryptophan administered to rats intraperitoneally in a single dose by quantifying this substance in plasma using validated analytical methodology in UV-VIS spectrophotometer. The methodology consisted of the administration of the prototype rutrpII to 3 rats at a dose of 6 mg/kg, intraperitoneally. Samples of blood 1.0 ml were collected by cannulation of the left jugular vein with heparinized syringe, the intervals from 0 to 9 hr. After centrifugation the plasma was frozen at -20 until the time of analysis. The bioanalytical method to quantify rutrpII was developed and validated in UV-VIS at a wavelength of 417 nm. From the construction of the concentration versus time curve, the kinetic parameters were calculated (Software WinNonlin 5.0 (Pharsight ™) Results were: Tmax = 8 h, Cmax = 169.86 mg/mL, t1/2 = 1.04 ± 0.02 h, ClT/F = 1.32 ± 0.05 mL/min/kg, Vd/F = 1,98 ± 0,05 L/kg. The developed and validated bioanalytical method was suitable for the detection and quantification of RutrpII in rat plasma. The values of pharmacokinetic profiles found, and extrapolated on allometric scaling allow us to understand that the compound studied showed a slow tissue distribution profile and / or was eliminated slowly (Vd low and low value CLT), due to a possible affinity between RutrpII and plasma proteins. This affinity may be explained by the similarity of their chemical structure with iron, enabling it to be transported by biomolecules such as transferrin, albumin or any other, and having as a target the DNA of cancer cells. In general, the compounds of ruthenium (II) / amino acids may be promising drugs for the amino acids present in the complex, may facilitate the recognition of the complex as a whole by DNA, and thus less toxic. / O complexo de rutênio(II)/aminoácido (rutrpII) demonstrou alta atividade antineoplásica contra carcinoma de mama murino (tumor de Ehrlich) in vitro e in vivo, sendo que neste último, aumentou a média de sobrevida dos animais. Fez-se necessária então a investigação dos parâmetros farmacocinéticos deste protótipo de fármaco como requisito ao conhecimento pré-clínico do mesmo. O objetivo deste trabalho foi obter o perfil farmacocinético do rutênio(II)/triptofano administrado a ratos, via intraperitoneal, em dose única por meio da quantificação desta substância em plasma utilizando metodologia analítica validada em espectrofotômetro UV-VIS. A metodologia consistiu na administração do protótipo rutrpII a 3 ratos em dose de 6 mg/kg, por via intraperitonal. Foram coletadas amostras de 1,0 mL de sangue, por canulação da veia jugular esquerda, com seringa heparinizada, nos intervalos de tempo de 0 a 9 h. Após centrifugação, o plasma foi congelado a -20ºC até o momento da análise. O método bioanalítico de quantificação do rutrpII foi desenvolvido e validado em espectrofotômetro UV-VIS no comprimento de onda de 417 nm. A partir da construção da curva de concentração versus tempo, foram calculados os parâmetros cinéticos (Software Winnonlin 5.0 (Pharsight™)). Os resultados encontrados foram: Tmax= 8h, Cmax= 169,86 µg/mL, t(1/2) =1,04 ± 0,02 h,ClT/F = 1,32 ± 0,05 mL/min/kg, Vd/F = 1,98 ± 0,05 L/kg. O método bioanalítico desenvolvido e validado foi adequado para a detecção e quantificação do RutrpII em plasma de rato. Os valores dos perfis farmacocinéticos encontrados, e extrapolados em escala alométrica, permitem entender que o composto estudado apresentou um perfil lento de distribuição tecidual e/ou foi eliminado lentamente (baixo Vd e baixo valor de CLT), devido a uma possível afinidade entre o RutrpII e as proteínas plasmáticas. Esta afinidade pode ser explicada pela semelhança de sua estrutura química com o ferro, possibilitando que ele seja transportado por biomoléculas como a transferrina, albumina ou alguma outra, e tendo como alvo, o DNA da células cancerosas. De maneira geral os compostos de rutênio(II)/ aminoácidos podem ser fármacos promissores pois os aminoácidos presentes nos complexos, podem facilitar o reconhecimento do complexo como um todo pelo DNA, sendo assim menos tóxicos.

<p>Processes where a molecule absorbs visible light and then converts the solar energy into chemical energy are important in many biological systems, such as photosynthesis and also in many technical applications e.g. photovoltaics. This thesis describes a part of a multidisciplinary project, aiming at a functional mimic of the natural photosynthesis, with the overall goal of production of a renewable fuel from sun and water. More specific, the thesis is focused on design and photophysical characterization of new photosensitizers, i.e. light absorbers that should be capable of transferring electrons to an acceptor and be suitable building blocks for supramolecular rod-like donor-photosensitizer-acceptor arrays.</p><p>The excited state lifetime, the excited state energy and the geometry are important properties for a photosensitizer. The work presented here describes a new strategy to obtain longer excited state lifetimes of the geometrically favorable Ru(II)-bistridentate type complexes, without a concomitant substantial decrease in excited state energy. The basic idea is that a more octahedral coordination around the Ru will lead to longer excited state lifetimes. In the first generation of new photosensitizers a 50-fold increase of the excited state lifetime was observed, going from 0.25 ns for the model complex to 15 ns for the best photosensitizer. The second generation goes another step forward, to an excited state lifetime of 810 ns. Furthermore, the third generation of new photosensitizers show excited state lifetimes in the 0.45 - 5.5 microsecond region at room temperature, a significant improvement. In addition, the third generation of photosensitizers are suitable for further symmetric attachment of electron donor and acceptor motifs, and it is shown that the favorable properties are maintained upon the attachment of anchoring groups. The reactivity of the excited state towards light-induced reactions is proved and the photostability is sufficient so the new design strategy has proven successful.</p>

Electron transfer, ET, and proton-coupled electron transfer, PCET, reactions are central to biological reactions involving catalysis, energy conversion and energy storage. The movement of electrons and protons in either a sequential or concerted manner are coupled in a series of elementary reaction steps in respiration and photosynthesis to harvest and convert energy consumed in foodstuffs or by absorption of light into high energy chemi-cal bonds in the form of ATP. These electron transfer processes may be modulated by conformational dynamics within the protein matrix or at the protein-protein interface, the energetics of which are still not well understood. Photoacoustic calorimetry is an estab-lished method of obtaining time-resolved reaction enthalpy and volume changes on the nanosecond to microsecond timescale. Photoacoustic calorimetry is used here to probe 1) the energetics and volume changes for ET between the self-assembled anionic uroporphy-rin:cytochrome c complex and the role of the observed volume changes in modulating ET within the complex, 2) the enthalpy and volume change for the excited state PCET reac-tion of a tyramine functionalized ruthenium(II) bis-(2,2'-bipyridine)(4-carboxy-4'-methyl-2,2'-bipyrine) meant to be a model for the tyrosine PCET chemistry carried out by cyto-chrome c oxidase and photosystem II, 3) the enthalpy and volume changes related to car-bon monoxide and tryptophan migration in heme tryptophan catabolic enzyme indoleam-ine 2,3-dioxygenase.

Processes where a molecule absorbs visible light and then converts the solar energy into chemical energy are important in many biological systems, such as photosynthesis and also in many technical applications e.g. photovoltaics. This thesis describes a part of a multidisciplinary project, aiming at a functional mimic of the natural photosynthesis, with the overall goal of production of a renewable fuel from sun and water. More specific, the thesis is focused on design and photophysical characterization of new photosensitizers, i.e. light absorbers that should be capable of transferring electrons to an acceptor and be suitable building blocks for supramolecular rod-like donor-photosensitizer-acceptor arrays. The excited state lifetime, the excited state energy and the geometry are important properties for a photosensitizer. The work presented here describes a new strategy to obtain longer excited state lifetimes of the geometrically favorable Ru(II)-bistridentate type complexes, without a concomitant substantial decrease in excited state energy. The basic idea is that a more octahedral coordination around the Ru will lead to longer excited state lifetimes. In the first generation of new photosensitizers a 50-fold increase of the excited state lifetime was observed, going from 0.25 ns for the model complex to 15 ns for the best photosensitizer. The second generation goes another step forward, to an excited state lifetime of 810 ns. Furthermore, the third generation of new photosensitizers show excited state lifetimes in the 0.45 - 5.5 microsecond region at room temperature, a significant improvement. In addition, the third generation of photosensitizers are suitable for further symmetric attachment of electron donor and acceptor motifs, and it is shown that the favorable properties are maintained upon the attachment of anchoring groups. The reactivity of the excited state towards light-induced reactions is proved and the photostability is sufficient so the new design strategy has proven successful.

Interactions of Metal Cations in Bioorganic Environment Computational Study Using Quantum Mechanics and Molecular Mechanics Tools Zdeněk Futera Biologically relevant interactions of piano-stool ruthenium(II) complexes with ds-DNA are studied by QM/MM computational technique. The whole re- action mechanism is divided into three phases - hydration of [RuII (η6 - benzene)(en)Cl]+ , consequent binding DNA and final intra-strand cross-link formation between two adjacent guanines. Free energy profiles of all reactions are explored by QM/MM MD umbrella sampling approach where the Ru(II) complex is described by DFT. For that purpose, special QM/MM software was developed to couple Gaussian and Amber programs. Calculated free energy barriers of Ru(II) hydration as well as DNA binding process are in good agreement with experimentally determined rate constants. Reaction pathway for cross-link formation was predicted that is feasible from both thermodynamical and kinetical point of view.

Orientadora: Profa. Dra. Paula Homem de Mello / Tese (doutorado) - Universidade Federal do ABC. Programa de Pós-Graduação em Ciência e Tecnologia/Química, 2017. / Pesquisas sobre dispositivos fotovoltaicos têm como objetivo aumentar sua eficiência, durabilidade e baixar seus custos de fabricação. Entre os dispositivos fotovoltaicos estão as células solares sensibilizadas por corantes (DSSC). Sendo o corante um dos parâmetros mais estudados e importantes das DSSC, este trabalho teve como objetivo principal estudar, utilizando métodos de química computacional, as propriedades eletrônicas de alguns corantes baseados em complexos de rutênio(II). Neste trabalho, as propriedades eletrônicas do N3 (cis-Ru[(dcbH2)2(NCS)2], dcbH2 = ácido 2,2¿-bipiridina-4,4¿-dicarboxílico), foram calculadas e comparadas com isômeros do N719 (N3 duplamente desprotonado) e com corantes mono (mMS) e dimetil substituídos (dMS), em relação aos grupos carboxílicos do N3. Os resultados sugerem que os isômeros do N719 se encontram em equilíbrio à temperatura ambiente. Os grupos mMS, dMS e desprotonados derivados do N3 apresentam menores energias de oxirredução, quando o metil ou o carboxilato, respectivamente, estão localizados em oposição à bipiridina. A correlação com dados experimentais dos corantes N3, C101, N945 e K19 sugere que as diferenças de energias de orbitais e grupos doadores/aceptores afetam a eficiência da DSSCs. Para ter um parâmetro de comparação entre os níveis de energia eletrônicos do corante e as bandas do semicondutor, foi realizado o cálculo de TD-DFT para o cluster Ti42O77H18. O estudo metodológico para verificar o efeito de diferentes funcionais e da inclusão do efeito do solvente na obtenção do espectro eletrônico de absorção mostrou que podem ocorrer variações significativas. Os funcionais M06 e B3LYP se mostraram bastante adequados para a previsão do gap HOMO-LUMO, mas para a previsão do espectro como um todo, o funcional CAM-B3LYP é o mais adequado para os complexos de rutênio(II) aqui estudados. / Research on photovoltaic devices aims to increase their efficiency and durability, as well as lower their manufacturing costs. Among the photovoltaic devices, there are the dyes-sensitized solar cells (DSSC). The dye is one of the most studied and important parameter of DSSC; so, in this work, we had as main objective to study, using computational chemistry methods, the electronic properties of some dyes based on ruthenium(II) complexes. In this work, the electronic properties of N3 (cis-Ru[(dcbH2)2(NCS)2], dcbH2 = 2,2'-bipyridine-4,4'-dicarboxylic acid) were calculated and compared with N719 isomers (N3 double-deprotonated), mono (mMS) and dimethyl substituted (dMS) dyes. The results suggest that N719 isomers are in equilibrium at room temperature. The mMS, dMS and deprotonated N3-derived groups exhibit lower oxidation energy when methyl or carboxylate, respectively, are located in opposition to bipyridine group. Correlation with experimental data of N3, C101, N945 and K19 dyes suggest that differences in orbital energies and donor / acceptor groups affect the efficiency of DSSCs. In order to establish a comparison parameter between the electronic energy levels of the dye and the semiconductor bands, the calculation of TD-DFT for the Ti42O77H18 cluster was performed. The methodological study to verify the effect of different functionals and the inclusion of the solvent effect in obtaining the electronic spectrum showed that significant variations can occur. M06 and B3LYP functionals are recommended to estimate HOMO-LUMO gap, but CAM-B3LYP functional is the most suitable for the prediction of the whole spectrum characteristics for the ruthenium(II) complexes studied here.

This thesis explores the design, synthesis and optoelectronic properties of supramolecular photoactive materials based on chiral iridium(III) and ruthenium(II) metalloligands. Our design strategies aim to create a high concentration of chromophoric units that, when self-assembled in well-defined geometrical arrangements, exhibit emergent photophysical properties.