Polymères de coordination et éponge cristalline : de nouveaux matériaux pour la conversion de l’énergie solaire et la résolution de la structure cristalline de composés huileux

Le premier volet de ce travail portera sur l’expérience acquise lors d’un stage d’étude à Tokyo, au Japon, dans le groupe de recherche du Pr. Makoto Fujita, une sommité d’envergure internationale dans le domaine de l’auto-assemblage. En continuité avec les plus récents travaux du Pr. Fujita, des systèmes poreux auto-assemblés présentant des cavités fonctionnalisées ont été développés dans le but d’encapsuler des acides gras afin d’en déterminer la structure cristalline. Ces éponges ont été caractérisées par des techniques courantes telles que la spectroscopie à résonance magnétique nucléaire 1H, 13C{1H} et Cosy, la spectrométrie de masse, l’analyse élémentaire, la microscopie optique infrarouge ainsi que la diffraction des rayons X. Une autre approche employée pour obtenir de meilleures propriétés spectroscopiques fut la synthèse de dendrimères métalliques de génération 0. Un nouveau ligand de type 1,3,5-triazine a été synthétisé par une réaction typique de cyclisation de nitrile en présence catalytique d’hydrure de sodium. Des espèces mono-, bis- et trinucléaire de Ru(II) furent synthétisés ainsi que deux espèces hétérométalliques de Ru(II)/Pt(II) et de Ru(II)/Os(II). Tous les complexes obtenus furent caractérisés par spectroscopie à résonance magnétique nucléaire (1H, 13C{1H} et Cosy) à l’état liquide, par spectroscopie de masse à haute résolution et par analyse élémentaire. La génération de dihydrogène à partir de l’espèce hétérométallique a été étudiée. Les propriétés optiques et électroniques ont été analysées par spectroscopie UV-Vis, par analyse de la luminescence, du temps de vie de luminescence, par des analyses de rendement quantique ainsi que par des analyses de voltampérométrie cyclique à balayage. Finalement, dans le but d’améliorer les propriétés spectroscopiques d’absorption de complexes métalliques, nous avons synthétisé une série de polymères homo- et hétérométalliques, intégrant des ligands de type bis(2,2’:6,2’’-terpyridine). Les complexes générés furent caractérisés par diverses techniques tel que la spectroscopie à résonance magnétique nucléaire (1H, 13C{1H} et Cosy) à l’état liquide, par spectroscopie de masse à haute résolution ainsi que par analyse élémentaire. Les propriétés optiques et électroniques ont été analysées par spectroscopie UV-Vis, par analyse de la luminescence, du temps de vie de luminescence, par des analyses de rendement quantique ainsi que par des analyses de voltampérométrie cyclique à balayage.It is well known that the self-assembly of small molecules into macromolecular species gives rise to an amplification and amelioration of their general properties. A first section on self-assembly will emphasize the acquired experience during an internship in Tokyo, Japan, in Pr. Makoto Fujita’s research group, a worldwide Figure in the area of self-assembly. Concomitant with the latest results obtained in Pr. Fujita research group on the self-assembly of molecular sponges, studies on molecular sponges with functionalized cavities will be presented. Such sponges were used to encapsulate fatty acids in order to determine their crystal structure. The sponges were characterized in different ways, such as 1H and 13C NMR, mass spectrometry, elemental analysis, optical microscopy coupled with infrared detection as well as X-ray diffraction. Another path of investigation to gain good spectroscopic properties is to synthesize metallodendrimers. A new 1,3,5-triazine ligand was synthesized by a typical nitrile cyclization in the presence of sodium hydride. Mono-, bis- and trimetallic Ru(II) species as well as heterometallic Ru(II)/Pt(II) and Ru(II)/Os(II) complexes were synthesized. All the complexes were characterized by nuclear magnetic resonance spectroscopy (1H, 13C{1H} and Cosy NMR) in the liquid state, high-resolution mass spectrometry, elemental analysis as well as X-ray diffraction in some cases. Attempts to generate H2 with the heterometallic species as catalysts have been investigated. The optical and electronic properties were also investigated by UV-Vis spectroscopy, luminescence analysis, excited state lifetimes, quantum yield efficiency and cyclic voltammetry.Finally, with the goal of having enhance light absorption, we synthesized a series of homo- and heterometallic coordination polymers with a ligand of the “back-to-back” terpyridine type. The complexes obtained were characterized by various techniques, such as nuclear magnetic resonance spectroscopy, high-resolution mass spectrometry as well as elementary analysis. The optical as well as the electronic properties were also investigated, using luminescence spectroscopy, excited state lifetime analysis, quantum yield determination and by cyclic voltammetry

Étude de complexes métalliques d6 à base de ligands tridentés N^N^N et de leurs processus photo-induits inusités

Les trente dernières années ont vue l’apparition et l’évolution de la chimie supramoléculaire, une branche de la chimie permettant de faire le lien entre la chimie moléculaire traditionnelle et la chimie des composés macroscopiques. Le couronnement récent de pionniers de la chimie des supramolécules par le comité Nobel, Jean-Pierre Sauvage et James Fraser Stoddart, mais en évidence l’importance de ce domaine d’actualité. Ce projet s’inscrit dans une démarche de recherche fondamentale visant à élaborer une antenne de chromophore capable d’absorber l’énergie solaire de façon optimale, et ce dans le but de la transférer à un centre réactionnel capable de convertir l’énergie lumineuse en énergie chimique. La méthodologie employée vise à exploiter divers processus photochimiques afin d’élaborer des architectures supramoléculaires discrètes et d’en étudier les propriétés optiques et électroniques.The last thirty years have seen the emergence and evolution of supramolecular chemistry, a branch of chemistry that makes the link between traditional molecular chemistry and the chemistry of macroscopic compounds. The recent crowning of pioneers in supramolecular chemistry by the Nobel Committee, Jean-Pierre Sauvage and James Fraser Stoddart, but highlighting the importance of this news domain. This project is part of a fundamental research approach aimed at developing a chromophore antenna capable of optimally absorbing solar energy, with the aim of transferring it to a reaction center capable of converting light energy into light. chemical energy. The methodology used aims at exploiting various photochemical processes in order to develop discrete supramolecular architectures and to study their optical and electronic properties

Self-assembly of supramolecular triangles with neutral trans-PdCl2 directing units

Pd(II)-directed self-assembly of homoleptic metal–polypyridyl complexes functionalized with 3-pyridyl groups gives rise to supramolecular metallo-triangles as confirmed by a combination of analytical techniques

Self-assembly of supramolecular triangles with neutral trans-PdCl2 directing units

Pd(II)-directed self-assembly of homoleptic metal–polypyridyl complexes functionalized with 3-pyridyl groups gives rise to supramolecular metallo-triangles as confirmed by a combination of analytical techniques

One- and two-dimensional polymerisation of homoleptic M(II)-complexes of 4′-(3-pyridyl)-2,2′;6′,2″-terpyridine in the solid state: A combined study by XRD, cyclic voltammetry, NMR and UV–Vis spectroscopies

Homoleptic Fe(II), Co(II), Ni(II), Cu(II) and Ru(II) complexes based on the tridentate ligand 4′-(3-pyridyl)-2,2′:6′,2″-tpy (tpy = terpyridine) have been synthesized in good yields and characterized with different techniques. Although the Fe(II) and Ru(II)-complexes exhibit diamagnetic behaviour in their solution 1H NMR spectra, the Co(II), Ni(II) and Cu(II) centres displaced the 1H resonances between 0 and 100 ppm. The electrochemical and spectroscopic properties of the complexes indicated that the pyridyl group exhibits electron-withdrawing character. Furthermore, a deep insight into the solid state packing of Co(II)- and Cu(II)-complexes, as their hexafluorophosphate (PF6) salts, reveals a two-dimensional terpyridine embrace, formed by face-to-face intermolecular π–π interactions that give rise to extended sheets in two dimensions. Modification of the PF6 anions by bulky tetraphenylborate [BPh4]− anions totally eliminates the intermolecular interactions between cations in one dimension and an extended one-dimensional polymer is formed in the other dimension

Highly photoreactive Ir(III) complexes for theranostic applications

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Two RuIILinkage Isomers with Distinctly Different Charge Transfer Photophysics

The ligand PHEHAT (PHEHAT = 1,10-phenanthrolino[5,6-b]1,4,5,8,9,12-hexaazatriphenylene) presents a structural asymmetry that has a dramatic influence on the photophysical properties depending on the chelation site of the metal ion in the linkage isomers. While [RuII(phen)2HATPHE]2+ behaves classically, like [RuII(bpy)3]2+, [RuII(phen)2PHEHAT]2+ exhibits an unusual behavior. It appears that this complex has two 3MLCT bright states, the lower one being weakly emissive or nonemissive depending on the solvent and temperature. Different photophysical techniques involving a wide range of various temperatures and timescales are essential to analyze this difference. A full photophysical scheme is proposed based on experimental data and density functional theory calculations. While previous studies focused on high temperatures and longer timescale emission, we explore the complexes at very low temperatures and very short times in order to obtain a more complete picture of the intriguing photophysical behavior of these complexes.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Ultrafast charge transfer excited state dynamics in trifluoromethyl-substituted iridium( iii ) complexes

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Ultrafast charge transfer excited state dynamics in trifluoromethyl-substituted iridium(iii) complexes

Time-resolved spectroscopy was exploited to gain new insights into the nature and dynamics of charge transfer excited states of bis-cyclometalated Ir(III) complexes. We showed that its dynamics is strongly influenced by the nature of the diimine ligand due to the existence of a ligand-ligand charge transfer process in the picosecond timescale. All the results are supported by DFT/TD-DFT calculations and spectroelectrochemistry

Highly photoreactive Ir(III) complexes for theranostic applications

Among all small mols. that interfere with DNA replication, photodynamic therapeutic agents are of key interest in developing new strategies to design more specific and efficient anti-cancer treatments. Compared to classical chemotherapeutic agents, their activity can be finely controlled thanks to the light-triggering of their photoreactivity. Usually, the mechanism of photodynamic therapy relies on the generation of singlet oxygen by energy transfer from a photosensitizer. However, the activity of these type-II photosensitizers is significantly limited in hypoxic tumors. Therefore, the development of Type-I photosensitizing agents, which do not rely on the prodn. of ROS, is highly desirable. In this context, we developed new iridium(III) complexes which are able to photoreact with biomols.; namely, our Ir(III) complexes can oxidize guanine residues under visible light irradn. We report the synthesis and the extensive photophys. characterization of four new Ir(III) complexes. In addn. to an extensive exptl. and theor. study of the photophysics of these complexes, we characterize their photoreactivity towards model redox-active targets and the relevant biol. target, the guanine base. We demonstrate that photo-induced electron transfer takes place between the excited Ir(III) complex and guanine which leads to the formation of stable photoproducts, indicating that the targeted guanine is irreversibly damaged. These results pave the way to the elaboration of new Type-I photosensitizers for targeting cancerous cells