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Monocamadas auto-organizadas da 2,2\':6\' ,2\" -terpiridina formadas sobre a superficie do eletrodo de Ag e Cu foram caracterizadas através da técnica SERS (Surface Enhanced Raman Spectroscopy) em experimentos ex situ e in situ. Foram estudadas alterações nas espécies adsorvidas em função da natureza das soluções-mãe e das soluções eletrolíticas utilizadas, tais como, solvente, pH da solução, ânion-suporte e a presença de outro adsorbato orgânico: a 2-mercaptopirimidina (mpy). Para estudar-se a adsorção da tpy foram obtidos padrões espectrais em que a molécula realiza diferentes interações com a vizinhança: no estado sólido, em solução, fundida e formando complexos com os íons CU2+ e Ag+. Também foram obtidos padrões para o ânion Cl04- coordenado ao CU2+, possibilitando explicar a adsorção deste ânion à superficie. Os resultados indicam que a tpy adsorve sobre a superficie metálica através de seus átomos de nitrogênio formando complexos de superficie do tipo I e do tipo II, nos quais assume uma conformação cis-cis. A tpy protonada, preferencialmente, perde o próton para adsorver sobre o eletrodo. Em experimentos in situ, quando potenciais mais negativos são aplicados, a tpy adsorve sobre a superfície metálica em uma posição próxima à horizontal através dos elétrons π dos anéis piridínicos. Na presença da mpy a tpy adsorve horizontalmente sobre a superfície do eletrodo, não ocorrendo sua coordenação com o metal. Estudos da adsorção do composto 4\'-(5-mercaptopentil)-2,2\':6\',2\" - terpiridina (tpy-SH) sobre eletrodo de Ag indicam que a molécula adsorve através do átomo de enxofre sem que ocorra interação entre os átomos de nitrogênio da parte tpy e a superficie metálica. Isto foi confirmado pela coordenação do cátion CU2+ com a parte tpy das moléculas tpy-SH adsorvidas, bem como pela intensificação das bandas atribuídas à parte alcano-tiol da molécula devido sua proximidade com a superficie. Os estudos do complexo [Cu(II)tpyH2OCl04]Cl04 mostram que a exposição à radiação excitante produz a perda da coordenação da água ao íon metálico com o ânion Cl04- passando a coordenar por dois átomos de oxigênio. O perfil de excitação deste complexo foi realizado e constatou-se pré-ressonância do sinal Raman com a transição eletrônica da molécula na região entre 300 e 350 nm. Ao ser adsorvido sobre a superficie do eletrodo este complexo sofre redução e a tpy coordena aos átomos metálicos do eletrodo formando um complexo de superficie. / Self-assembly monolayers of 2,2\':6\',2\" - terpyridine (tpy) were grown on Ag and Cu electrode surface and studied ex situ and in situ by SERS (Surface Enhanced Raman Spectroscopy). The nature of the adsorbate species was studied as a function of the mother-sulution changing solvent, pH and supporting-anion. The effect of 2-mercaptopyrimidine (mpy) as co-adsorbate was also investigated. For comparison purposes the Raman spectrum of tpy was obtained as solid, solution, molten and as Ag+ and CU2+ complexes. A supplementary Raman study of CU2+ perchlorates was also performed to facilitate the understanding of the Cl04- adsorption on the metal surface. The results showed that tpy adsorb on the metallic surface through the nitrogen atoms forming two different surface complexes (type I and type II) that have cis-cis conformation. Protonated tpy, preferentially, loses the proton to adsorb on the electrode. In the in situ experiments, when more negative potentials were applied, the observed spectral changes were ascribed to a modification in the adsorption geometry leading to a nearly flat arrangement. In presence of mpy, tpy adsorbs flat on the electrode surface and coordination with the metal is not observed. Studies on the adsorption of the 4\'-(5-mercaptopentyl)-2,2\':6\',2\"-terpyridine (tpy-SH) on Ag electrode showed that the molecule adsorb through the sulfur atom and there is no interaction between the nitrogen atoms of tpy moiety and the metal. This was confirmed by coordination of CU2+ with the tpy moiety of adsorbed tpy-SH molecules and by the enhancement of the alkyl-thiol bands which are close to the surface. Studies of the [Cu(II)tpyH2OCl04]Cl04 complex showed that depending on the energy density used the exciting radiation may cause the release of the coordinated water, leading to a bidentate coordination of the Cl04- anion. The Raman excitation profile for this complex was obtained and pre-resonance enhancement associated with a transition between 300 e 350 nm was observed. When adsorbed on the electrode surface this complex undergoes reduction and the tpy coordinates to the metal atoms forming a surface complex.

Tout au long de cette thèse, de nouveaux colorants organométalliques ont été élaborés dont le but est de les utiliser en tant que photosensibilisateurs au sein des cellules solaires DSSC dont la simplicité de mise en œuvre, le faible coût de production et un design attractif en sont les atouts majeurs. Des analogues du black dye ont dans un premier temps été élaborés, une étude approfondie par des calculs DFT a permis une approche plus constructive sur le choix des designs moléculaires. Des aldéhydes dérivés de la biomasse comme la vanilline, le syringaldéhyde ou le 5-hydroxyméthylfurfural ont permis de substitués le ligand terpyridine par différents groupes (hétéro)aromatiques en position 4’ pour moduler les transferts de charges. Dans un second temps, une chaîne hexyloxyméthyle est introduite en position 4’’ pour diminuer les recombinaisons de charges lors du fonctionnement de la cellule solaire et par la même occasion placer la LUMO plus proche des points d’ancrages pour de meilleures injections de charges vers le semi-conducteur. L’utilisation de groupes cyanoacrylates a aussi été envisagé à la place des acides carboxyliques afin d’obtenir des absorptions plus panchromatiques. Des complexes du type [Ru(tpy)2] et [Ru(tpy)(bpy)NCS] ont également été synthétisés et étudiés pour leur stabilités plus accrues au cours du temps au sein de la cellule solaire par rapport aux complexes à ligands NCS. Certains colorants ont été testés en cellules solaires en combinaison du dioxyde de titane comme semi-conducteur et du couple I3-/I- en tant que médiateur rédox. / Throughout this thesis, new organometallic dyes have been developed to use them as photosensitizers in dye-sensitized solar cells (DSSCs), whose simplicity of implementation, low cost production and attractive design are major assets. Black dye analogues were first developed, a thorough study of DFT calculations allowed a more constructive approach to the choice of molecular designs. Biomass-derived aldehydes such as vanillin, syringaldehyde or 5-hydroxymethylfurfural have been used to substitute the terpyridine ligand by different (hetero)aromatic groups in the 4’ position in order to modulate charge transfers. In a second step, a hexyloxymethyl chain was introduced in the 4'' position with the aim of reduce charge recombination during the solar cell operation and in the same time to place the LUMO closer to the anchoring groups for better charge injections to the semiconductor. The use of cyanoacrylate groups was also considered in place of the carboxylic acids in order to obtain more panchromatic absorptions. [Ru(tpy)2] and [Ru(tpy)(bpy)NCS] complexes have also been synthesized and studied for their increased stability over time in the solar cell compared to the NCS ligand complexes. Some dyes have been tested in solar cells in combination of titanium dioxide as the semiconductor and the I3-/I- couple as the redox mediator.

Ce travail intitulé " Libération du monoxyde d'azote induite par deux photons à partir de complexes ruthénium-nitrosyle contenant des ligands de capacités push-pull différentes " a été consacré à l'étude des principaux facteurs qui déterminent l'efficacité des complexes ruthénium- nitrosyles (Ru(NO)) dans l'absorption à deux photons (ADP) et à l'amélioration de leur section efficace ADP par modification de la nature et de la structure de leurs ligands. A partir de complexes précédemment obtenus dans le groupe de recherche du Prof. I. Malfant, nous avons effectué diverses modifications structurales. Il a été montré que la substitution des ligands monodentes par la 2,2'-bipyridine dans les complexes de Ru(NO) conduit à une légère augmentation de la section efficace, mais cette modification diminue le rendement quantique du relargage du monoxyde d'azote NO. La partie synthétique du travail a principalement porté sur la modification du ligand. / The work "Two-photon induced photorelease of nitric oxide from ruthenium-nitrosyl complexes containing ligands of various push-pull capabilities" was devoted to the revealing of main factors that determine the efficiency of ruthenium-nitrosyl complexes in two-photon absorption (TPA) and the improvement of TPA cross-section through modification of the ligands nature and their structure. Starting from complexes previously obtained by the research group of Prof. I. Malfant, we have modified their structure in several directions. It was shown that substitution of monodentate ligands by 2,2'-bipyridine in ruthenium complexes with nitrosyl ligands leads to a slight increase of their TPA cross- section, however this modification decreases the quantum yield of the nitric oxide photo release. Synthetic part of the work was mainly aimed at the modification of the ligand.

Ce mémoire est consacré à la synthèse et la caractérisation de complexes bis-terdentates de ruthénium pour leur potentielle utilisation dans des triades photosensibles, ou pour la fabrication de dispositifs photosensibles. La première partie se concentre sur les propriétés photophysiques de deux complexes de RuII bis-terdentates. Le premier est un complexe homoleptique, formé de ligands tridentates comprenant deux sous-unités carbène (CNC), le second est un complexe hétéroleptique composé d'un ligand CNC et d'une terpyridine. Ce complexe hétéroleptique est luminescent à température ambiante, contrairement à ses deux complexes parents homoleptiques. Les propriétés électrochimiques et photoélectrochimiques de complexes de type [M(tpy)2]2+ (M=FeII ou RuII), dont les ligands terpyridine sont substitués par des groupements thiols, sont étudiées dans une seconde partie. Ces complexes électropolymérisent de manière organisée sur des électrodes d'or, par oxydation des thiols en disulfures. Ces propriétés ont été utilisées pour construire des diades [RuII]-[FeII] sur des électrodes d'or, dont le photocourant a pu être mesuré. Dans le dernier chapitre, les propriétés photophysiques et d'électropolymérisation du complexe de ruthénium décrit dans le chapitre 2 sont utilisées pour tenter de fabriquer un transistor pho-toactivable. / This thesis deals with the synthesis and characterization of several bis-terdentate complexes, and their potential use for the construction of photoactive molecular triads, or the fabrication of photoactive devices. The first chapter focuses on the photophysical properties of two new bis-terdentate RuII com-plexes. The first one is a homoleptic complex containing two N-heterocyclic carbene-based ligands (CNC) allowing close-to-perfect octahedral coordination geometry. The second one is a heteroleptic complex bearing a CNC ligand and an ancillary terpyridine ligand. This second complex displays room temperature luminescence whereas both homoleptic terpyridine-based and CNC-based RuII complexes are only luminescent at 77 K. The second chapter describes the electrochemical properties of a [M(tpy)2]2+-type (M = RuII or FeII) complex bearing thiol groups on both of the terpyridines are described. These complexes display electropolymerization properties through oxidation of thiols into disulfides. This phenomenon happens only on gold, suggesting that the polymer chains organize on the surface of the electrodes. Moreover, self-assembled monolayers of the RuII complexes were formed on gold, and their ability to exchange charges with the electrode upon irradiation was studied. Finally, self-organisation and electropolymerization properties were used to form [RuII]-[FeII] diads on a gold surface, and their photoresponse was recorded. The last chapter describes the attempts to construct a molecular photosensitive device by electropolymerizing the RuII complexes depicted in the second chapter in nanogaps between gold electrodes.

Lors de ces travaux de thèse, des unités monomériques appelées unimères ont été synthétisées et utilisées pour le développement de polymères métallo-supramoléculaires (MSPs). Ces unités se composent (i) d’un bloc central: 2,5-dithiénylphosphole, (ii) dA’un chélate : 2,2':6',2''-terpyridine-4'-yl (tpy) et (iii) de connecteurs variés assurant la jonction entre le bloc central et le chélate. Les propriétés physico-chimiques de ces unimères ont été mesurées afin d’établir des relations structures/propriétés. Par exemple, l’unimère ne comportant pas de connecteurs entre l’unité central et le chélate présente un maximum d’absorption fortement décalé vers le rouge par rapport à l’unimère bis(tpy)terthiophène. Cette observation montre que la délocalisation électronique est accrue dans ces systèmes et permet de couvrir un large domaine spectral. L’introduction de connecteurs (éthynediyle, éthynediyle-thiophène-2,5-diyle, éthynediyle-1,4-phénylène) entre le bloc central et le chélate a un effet mineur sur l’écart HO-BV et sur la position des maxima d'absorption. Puis tous les unimères synthétisés ont été mis en présence de différents ions métalliques (Co2+, Cu2+, Fe2+, Ni2+ et Zn2+) pour former les MSPs correspondants. Ce phénomène de polymérisation a été étudié en détail en utilisant les spectroscopies d’absorption, d’émission et la chromatographie d’exclusion stérique. Ainsi, cette polymérisation présente 3 étapes : (i) la formation des dimères U-M-U, (ii) la prolongation de chaine de polymères qui atteint un une longueur maximale pour le ratio 1/1 ion métallique/unimère; (iii) terminaison réalisée avec des ions métalliques lorsque ces ions sont présent en excès. Les propriétés optiques de ces nouveaux polymères ont également été étudiées montrant qu’elles dépendent fortement de la nature de l’ion métallique utilisé. / New π-conjugated building blocks (unimers) for metallo-supramolecular polymers (MSPs), whose comprise: (i) substituted phosphole ring surrounded by two thiophene rings as the central block, (ii) 2,2':6',2''-terpyridine-4'-yl (tpy) end-groups as ion-selectors, and (iii) different linkers inserted between the central block and tpy end-groups, are described. Chemical and physical properties of those unimers were studied with attention on correlation between properties and structure of unimers. For example the unimer without linkers shows the UV/vis absorption maximum red shifted about 60 to 100 nm compared to bis(tpy)terthiophenes, which proves that replacing of the thiophene with phosphole unit significantly enhances the delocalization of electrons within the unimer molecule and significant area of absorption spectra can be covered. Introduction of linkers (ethynediyl, ethynediyl-thiophene-2,5-diyl, ethynediyl-1,4-phenylene) has a minor effect on the bandgap energy. All prepared unimers underwent self-assembling process with various metal ions (Co2+, Cu2+, Fe2+, Ni2+ and Zn2+) resulting into metallo-supramolecular polymers. Three stages of the assembly of unimers into related MSPs were observed and characterized by absorption, fluorescence spectroscopy and size exclusion chromatography: 1) formation of dimer species: U-M2+-U (U stands for unimer); 2) prolongation of polymer chain to reach the maximum length at equimolar ratio of unimer and metal ions; 3) end-capping of polymer chains and their partial decomposition at stoichiometric excess of ion couplers. Optoelectronic properties of newly formed metallo-supramolecular polymers were investigated and choice of the metal ions was shown to be of crucial importance. / V rámci této disertační práce byly připraveny stavební bloky (nazývající se unimery) pro tvorbu konjugovaných metalo-supramolekulárních polymerů (MSPs), které ve své struktuře obsahují: (i) substituovaný fosfolový kruh obklopený dvěma thiofenovými cykly jako centrální blok, (ii) 2,2':6',2''-terpyridin-4'-yl (tpy) jako koncovou skupinu pro navázání iontů, a (iii) různé spojky mezi uvedeným centrálním blokem a tpy skupinou. Chemické a fyzikální vlastnosti těchto unimerů byly prostudovány s důrazem na korelaci mezi vlastnostmi a strukturou unimeru. Například unimer bez přídavných spojek vykazuje posun UV/vis absorpčního maxima do červené oblasti o 60 až 100 nm v porovnání s bis(tpy)terthiofenem, což značí, že nahrazením thiofenu fosfolem se značně zvyšuje delokalizace elektronů v molekule unimeru a může být pokryta značná část spektra. Začlenění spojek (ethynediyl, ethynediyl-thiofen-2,5-diyl, ethynediyl-1,4-fenylen) do struktury unimeru má jen malý vliv na šířku zakázaného pásu, a tedy pozici absorpčního maxima. Všechny připravené unimery byly podrobeny procesu samo-seskupování s různými kovovými ionty (Co2+, Cu2+, Fe2+, Ni2+ a Zn2+) za vzniku organokovových polymerů. Tři stadia provázející proces samo-seskupování byla pozorována pomocí absorpční a fluorescenční spektroskopie a gelové permeační chromatografie (SEC): 1) tvorba dimerů U-M2+-U (U = unimer), 2) prodlužování polymerních řetězců a dosažení maximální délky při ekvimolárním poměru unimeru a kovových iontů, 3) vazba kovových iontů na koncové terpyridinové skupiny a rozklad polymerního řetězce na kratší při stechiometrickém přebytku kovových iontů. Optické vlastnosti nově připravených organokovových polymerů byly prozkoumány a ukázalo se, že velmi závisí na vybraném kovovém iontu.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Os Clusters de acetato de rutênio de fórmula geral [Ru3O(AcO)6L3]n proporcionam blocos de montagem interessantes para sistemas supramoleculares, exibindo características eletrocrômicas e redox reversível, cobrindo uma ampla faixa de potenciais em solventes aquosos e orgânicos. Nesta Tese, estas espécies foram combinadas com o ligante tridentado, 4\'-piridil-2,2\':6\',2\"-terpiridina (pytpy), produzindo complexos do tipo [Ru3O(AcO)6(pytpy)3]n e [Ru3O(AcO)6(py)2(pytpy)]n, que foram totalmente caracterizados em estado sólido e solução. Nestes complexos a terpiridina permanece disponível para ligar-se a íons metálicos como o Fe(II), gerando um complexo binuclear de baixo spin muito estável, do tipo {Fe[Ru3O(AcO)6(py)2(pytpy)]2}n. Este processo pode ser monitorado eletroquimicamente, partindo de íons Fe(III), que exibem uma baixa afinidade pela terpiridina central, e ciclando o potencial para gerar íons de Fe(II). Desta forma, pode-se executar um procedimento típico de click chemistry, que leva a uma estrutura estendida, Fe-cluster-pytpy na superfície do eletrodo. Este filme conserva a funcionalidade dos blocos de montagem, permitindo aplicações interessantes em dispositivos moleculares, tais como sensores e smart Windows. / Ruthenium acetate clusters of general formula [Ru3O(AcO)6L3]n provide interesting building blocks for assembling supramolecular systems, displaying reversible redox and electrochromic characteristics, over a wide range of potentials in aqueous and organic solvents. In this thesis, such species has been combined with the tritopic, 4\'-pyridil-2,2\':6\',2\"-terpiridine (pytpy) ligand, yielding complexes of the type [Ru3O(AcO)6(pytpy)3]n and [Ru3O(AcO)6(py)2(pytpy)]n, which have been fully characterized in solid state and solution. In these complexes, the terpyridine moiety remains available for binding metals ions, such as Fe(II), generating very stable, low spin binuclear complexes, of the type n. This process can be monitored electrochemically, starting from Fe(III) ions, which exhibits a much lower affinity for the terpyridine center, and cycling the potentials in order to generate Fe(II) ions. In this way, one can start a click chemistry, ending up with an extended structure of Fe-cluster-pytpy film at the electrode surface. This film preserves the functionality of the building block complexes, a llowing many possible applications in molecular devices, such as sensors and smart windows.