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The efficiency and mechanism of electron- and energy transfer events occurring in both in natural and synthetic donor-acceptor systems depend on their distance, relative orientation, and the nature of the surrounding media. Fundamental knowledge gained from model studies is key in building efficient energy harvesting and optoelectronic devices. Faster charge separation and slower charge recombination in donor-acceptor systems is often sought out. In our continued effort to build donor-acceptor systems using near-IR sensitizers, in the present study, we report ground and excited state charge transfer in newly synthesized, directly linked, tetrads featuring bisdonor (donor = phenothiazine and ferrocene), BF2-chelated azadipyrromethane (azaBODIPY) and C60 entities. The tetrads synthesized using multi-step synthetic procedure revealed strong charge transfer interactions in the ground state involving the donor and azaBODIPY entities. The near-IR emitting azaBODIPY acted as a photosensitizing electron acceptor along with fullerene while the phenothiazine and ferrocene entities acted as electron donors. The triads (bisdonor-azaBODIPY) and tetrads revealed ultrafast photoinduced charge separation leading to D•+-azaBODIPY•–-C60 and D•+-azaBODIPY-C60•– (D = phenothiazine or ferrocene) charge separated states from the femtosecond transient absorption spectral studies in both polar and nonpolar solvent media. The charge separated states populated the triplet excited state of azaBODIPY prior returning to the ground state.

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This is my thesis research on the preparation of borylazadipyrromethene (azaBODIPY) dyes bearing an anchoring group, such as a carboxylic acid group, at the β-pyrrolic position of the azadipyrromethene scaffold. Carboxylate groups form covalent bonds to oxide semiconductors such as TiO2 (n-type) or Cu2O (p-type) in dye-sensitized solar cells (DSCs) or photogalvanic dye-sensitized solar cells (P-DSCs). Oxide-binding azaBODIPY dyes can be used to investigate the rate and mechanism of electron injection from the dyes to the semiconductors. Two different types of azaBODIPY (difluoroboryl and dialkynylboryl) were prepared by following previously developed methods. To convert difluoroborylazaBODIPY to the final dyes having a carboxylic acid in the β-pyrrolic position, several distinct synthetic routes were designed, adopting various reactions, such as halogenation, Sonogashira coupling, Knoevenagel condensation, Grignard reagents, Vilsmeir-Haack, and Steglich esterification. Some of these reactions were successful, but the overall synthesis to the targeted final molecule couldn’t be accomplished. Even though further studies on the synthesis of oxide-binding azaBODIPYs are needed, at least my thesis research suggests what reactions can be implemented to complete this synthesis in the future. Proton NMR (nuclear magnetic resonance) and carbon NMR were commonly used to confirm the synthesized compounds, and sometimes crystallographic information was obtained by XRD (X-ray diffraction) whenever crystals of sufficient size and quality were grown. NMR spectra, interpreted by SpinWorks 3 software, and crystal structures will be introduced in each chapter.

Dans un contexte où l’approvisionnement énergétique mondial du 21e siècle est un enjeu majeur, le développement de sources d’énergie renouvelables suscite l’attention croissante de la communauté scientifique et industrielle. L’énergie solaire est définitivement l’une des meilleures alternatives aux combustibles fossiles en tant que source d’énergie du monde de demain. Ce mémoire traite donc du développement de nouveaux matériaux organométalliques pour des applications de photorécoltage d’énergie en photovoltaïque et en production d’hydrogène. Le premier chapitre présente la synthèse assistée par microondes de quatre nouveaux complexes de Co(II), Ni(II), Cu(II) et Zn(II) basés sur le ligand tétra-p-méthoxyphényl-azadipyrrométhène (ADPM) avec des rendements variant de 89% à quantitatif. Ces complexes sont mis en relation avec d’autres complexes homoleptiques connus portant le tétraphényl-ADPM comme ligand ainsi qu’avec leurs chélates de BF2+ pour une meilleure compréhension des tendances engendrées par la substitution de l’agent coordonnant et/ou des substituants p-méthoxy. Pour ce faire, le comportement électrochimique et photophysique est présenté. De façon générale, la présence des quatre groupements p-méthoxy semble rendre les dérivés de cet ADPM plus susceptibles à la dégradation électrochimique en conditions d’oxydation et induire un déplacement bathochromique des propriétés optiques d’absorption et d’émission. Les structures rayons X du ligand tétra-p-méthoxyphényl-ADPM et de son complexe homoleptique de Co(II) sont aussi discutées. Cette étude a été effectuée dans l’espoir de fournir des informations utiles sur la stabilité des ADPM aux chercheurs du domaine photovoltaïque en quête de nouveaux chromophores dans le proche infrarouge (NIR). Le deuxième chapitre présente quant à lui les propriétés de senseur envers les anions F-, OAc- et H2PO4- de deux nouveaux complexes neutres de Re(I) de type mono- et dinucléaire basés sur une phénanthroline substituée en position 5 contenant un récepteur thio-urée. Ces composés ont été obtenus dans des rendements de 81% et 60%, respectivement. L’effet de la formation de ponts hydrogène lors de l’ajout d’anions versus la déprotonation du récepteur a été évalué par des titrations UV/Vis et RMN 1H et semble indiquer que la formation de la base conjuguée du récepteur est favorisée pour ce type de système. De plus, la structure rayons X d’un des précurseurs est présentée et permet une discussion sur la chiralité des complexes mono- et dinucléaire obtenus. L’obtention d’un complexe bimétallique par autoassemblage ouvre la voie à la préparation d’antennes moléculaires pour des systèmes de photosynthèse artificielle. / The world's energy supply is rapidly becoming the major issue of the 21st century. Instead of the status quo approach of finding and extracting more hydrocarbons from the ground, the development of renewable energy sources is attracting much interest from both the scientific and industrial communities. Solar energy is definitively one of the best sources to power the World of tomorrow. In such a framework, this dissertation discusses the development of new organometallic materials able to harvest solar energy for photovoltaic or H2 photoproduction applications. The first chapter presents the synthesis by a microwaves-assisted methodology of four new homoleptic complexes of Co(II), Ni(II), Cu(II) and Zn(II) based on the tetra-p-methoxyphenyl-azadipyrromethene (ADPM) ligand in yields ranging from 89% to quantitative. Those complexes are put in relation with already known ADPM homoleptic complexes of the same M(II) series and related BF2+ chelates (Aza-BODIPY) for a better understanding of trends arising from substitution of the chelate and/or electron-donating effect of the p-methoxy substituents. This is achieved by the study of electrochemical behavior of the compounds and their photophysical properties. From a general point of view, the presence of the four p-methoxy substituents leads to an electrochemical decomposition of the derivatives based on that ADPM in oxidative conditions, along with a bathochromic shift of the optical properties. X-Ray structures for the tetra-p-methoxyphenyl-ADPM ligand and related Co(II) complex are also discussed. Hopefully, this study will provide useful insights to researchers on the substituents to install for stable ADPM derivatives in their quest for NIR chromophores utilizable for photovoltaic application. The second chapter report anion sensing properties toward F-, OAc- and H2PO4- of new neutral mononuclear and dinuclear Re(I) complexes based on a 5-substituted phenanthroline moiety bearing a thiourea hydrogen-bonding receptor. Those complexes were obtained in 81% and 60% yields, respectively. The effect of hydrogen-bonding versus deprotonation of the thiourea receptor upon addition of the anions was also evaluated by UV/vis and 1H NMR titration techniques. Observations made support the hypothesis that formation of the conjugated base of the receptor is favored. In addition, an X-ray structure of the Re(I) precursor complex is reported and the chirality of the mononuclear and dinuclear complexes is discussed. Achievement of a bimetallic complex by self-assembly paves the way for the preparation of light-harvesting molecular antennae utilizable in artificial photosynthesis systems.