Voici les éléments 1 - 6 sur 6
  • Publication
    Accès libre
    Insight into the rules dictating the formation of arene ruthenium metalla-assemblies
    Le processus d'auto-assemblage est un phénomène naturel capable d'organiser des systèmes biologiques. Son utilisation par les chimistes comme procédé de synthèse a permis la formation de structures esthétiques et de systèmes supramoléculaires hautement complexes, avec des fonctions biologiques avérées. Depuis 1990, la stratégie d'auto-assemblage dirigée par des métaux a largement contribué à la conception et à la synthèse d'architectures discrètes. La formation de ces architectures spécifiques nécessite un contrôle minutieux des différents facteurs dirigeant le processus d'auto-assemblage.
    L'objectif de cette thèse est d'offrir un aperçu des règles dictant la formation des assemblages métalliques arène-ruthénium. Ceux-ci sont construits à l’aide de clips métalliques stables et de ligands polypyridiniques. La caractérisation des échanges dynamiques des ligands, au moyen d’une stratégie de marquage isotopique 1H/2D a démontré la stabilité et l'inertie relative de la structure rectangulaire. En outre, l'étude par résonance magnétique nucléaire, des espèces intermédiaires impliquées dans l'assemblage de cycles métalliques, a permis de mettre en exergue la nature dynamique de la liaison Ru-N en solution, avant la fermeture définitive des cycles métalliques. Cela nous a permis de décrire une voie de germination thermodynamique plausible avec une réactivité spécifique de ces assemblages métalliques.
    Par ailleurs, l’activité anticancéreuse prometteuse des complexes mononucléaires arène-ruthénium, ainsi que l’accumulation préférentielle de leurs espèces macromoléculaires dans les cellules cancéreuses, confèrent un potentiel antiprolifératif très intéressant aux cages métalliques arène-ruthénium. Ainsi notre stratégie pour optimiser l'activité biologique des prismes métalliques comportait deux approches. Dans un premier temps, la fonctionnalisation des ligands pontés, a permis d’améliorer la sélectivité des composés actifs contre les cellules cancéreuses. Dans un second temps, la modification de la taille des ouvertures, de la cavité des cages métalliques, a permis de contrôler la libération d’un photosensibilisateur hydrophobe dans une lignée cellulaire humaine du cancer du côlon HT-29., The self-assembly process is a natural phenomenon with the ability to organize biological systems. Its development by chemists as a synthetic process allowed the formation of esthetical structures as well as highly complex supramolecular systems with remarkable biological functions. Since 1990, metal directed self-assembly strategy has largely contributed to the design and synthesis of discrete architectures. The formation of these specific architectures needs some control over the different factors ruling the coordination self-assembly process.
    The aim of this thesis was to offer an insight into the rules dictating the formation of arene ruthenium metalla-assemblies built from stable dinuclear metalla-clips and polypyridyl linkers. The characterization of the dynamic ligand exchanges using the 1H/2D isotope labeling strategy showed relative stability and inertness of the final structure. In addition, the study of the intermediate species involved during the assembly of metalla-cycles by NMR experiments highlighted the dynamic nature of the Ru-N bond in solution before the final closure of the metalla-cycles. This helped us to describe a plausible thermodynamic germination pathway together with the specific reactivity of such metalla-assemblies.
    The promising anticancer-activities of the mononuclear arene ruthenium complexes along with the preferential accumulation of macromolecular species in the cancer cells led to more interest in the anti-proliferative potential of arene ruthenium metalla-cages. Our strategies in order to optimize the biological activity of arene ruthenium metalla-prisms were: Functionalization of the bridging linkers resulted in selectivity improvements of the active compounds towards target cancer cells; and the modification of the portal’s size of metalla-cages to control the release of a hydrophobic photosensitizer on the human colon cancer cell line HT-29.
  • Publication
    Accès libre
    The Adaptable Coordination Chemistry of 6-Chloro-2-(quinolin-2-yl)-2,4-dihydro-1H-benzo[d][1,3]oxazine Towards Zinc(II) and Mercury(II)
    (2010)
    Attilio Ardizzoia, G.
    ;
    Brenna, Stefano
    ;
    The coordination chemistry of 6-chloro-2-(quinolin-2-yl)-2,4-dihydro-1H-benzo[d][1,3]oxazine (LH2) towards zinc and mercury has been explored. The ligand exhibits high versatility and provides different environments to the metal centre as a function of its diverse coordination modes. In one of the isolated and characterized complexes, [Zn(LOH)Cl2], the zinc centre is found pentacoordinated with the ligand present in an iminic “open” structure. The oxidized form, which contains the 4H-benzo[d][1,3]oxazine part (L), is also encountered in [Zn(L)Cl2], whereas the crystal structure of the trinuclear compound [Hg3(LH2)2Cl6] shows the ligand LH2 in its original arrangement.
  • Publication
    Accès libre
    Mono and dinuclear rhodium, iridium and ruthenium complexes containing chelating 2,2′-bipyrimidine ligands: Synthesis, molecular structure, electrochemistry and catalytic properties
    (2007)
    Govindaswamy, Padavattan
    ;
    Canivet, Jérôme
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    ; ;
    Štěpnička, Petr
    ;
    Ludvík, Jiří
    The mononuclear cations [(η5-C5Me5)RhCl(bpym)]+ (1), [(η5-C5Me5)IrCl(bpym)]+ (2), [(η6-p-PriC6H4Me)RuCl(bpym)]+ (3) and [(η6-C6Me6)RuCl(bpym)]+ (4) as well as the dinuclear dications [{(η5-C5Me5)RhCl}2 (bpym)]2+ (5), [{(η5-C5Me5)IrCl}2 (bpym)]2+ (6), [{(η6-p-PriC6H4Me)RuCl}2 (bpym)]2+ (7) and [{(η6-C6Me6)RuCl}2 (bpym)]2+ (8) have been synthesised from 2,2′-bipyrimidine (bpym) and the corresponding chloro complexes [(η5-C5Me5)RhCl2]2, [(η5-C5Me5)IrCl2]2, [(η6-PriC6H4Me)RuCl2]2 and [(η6-C6Me6)RuCl2]2, respectively. The X-ray crystal structure analyses of [3][PF6], [5][PF6]2, [6][CF3SO3]2 and [7][PF6]2 reveal a typical piano-stool geometry around the metal centres; in the dinuclear complexes the chloro ligands attached to the two metal centres are found to be, with respect to each other, cis oriented for 5 and 6 but trans for 7. The electrochemical behaviour of 1–8 has been studied by voltammetric methods. In addition, the catalytic potential of 1–8 for transfer hydrogenation reactions in aqueous solution has been evaluated: All complexes catalyse the reaction of acetophenone with formic acid to give phenylethanol and carbon dioxide. For both the mononuclear and dinuclear series the best results were obtained (50 °C, pH 4) with rhodium complexes, giving turnover frequencies of 10.5 h−1 for 1 and 19 h−1 for 5.
  • Publication
    Accès libre
    Square-Planar Diacetatopalladium Complexes with trans-Configured Secondary Amine Ligands that Avoid Orthometalation: Ligand Synthesis, Coordination, Molecular Structure and Catalytic Potential for Suzuki Cross-Coupling Reactions
    (2007)
    Chahen, Ludovic
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    ;
    The trans-configured square-planar palladium complexes [Pd(OAc)2 (LNtBu)2] (1), [Pd(OAc)22-LN∩NtBu)] (2), [Pd(OAc)2 (LNPh)2] (3), and [Pd(OAc)22-LN∩NPh)] (4), have been synthesized by treating palladium acetate with the amines NHtBuCH2-2,4,6-Me3C6H2 (LNtBu) or NHPhCH2-2,4,6-Me3C6H2 (LNPh) or with the diamines NHtBuCH2-2,4,6-Me3C6H-CH2-2,4,6-Me3C6H-CH2-NHtBu (LN∩NtBu) or NHPh-CH2-2,4,6-Me3C6H-CH2-2,4,6-Me3C6H-CH2-NHPh (LN∩NPh). The single-crystal X-ray structure analysis of complexes 1-3 confirms a trans arrangement of the two acetato groups and of the two nitrogen atoms. Orthometalation leading to palladacycles is impossible in all cases as the ortho positions in the benzylic rings are blocked by methyl substituents. All complexes are found to catalyze Suzuki cross-coupling reactions of deactivated and even sterically hindered arene substrates.
  • Publication
    Accès libre
    Self-assembled chloro-bridged metallo-prismatic cations of the general formula [M65-C5Me5)63-tpt)2 (μ-Cl)6]6+ (M = Rh, Ir; tpt = 2,4,6-tri(pyridin-4-yl)-1,3,5-triazine)
    (2007)
    Govindaswamy, Padavattan
    ;
    ;
    Two cationic pentamethylcyclopentadienyl metal-based hexanuclear complexes with trigonal prismatic architecture have been synthesised through a two-step strategy. The dinuclear complexes [M(η5- C5Me5)(μ-Cl)Cl]2 (M = rhodium and iridium) react with 2,4,6-tri(pyridin-4-yl)-1,3,5-triazine (tpt) in dichloromethane to give the trinuclear complexes [Rh35-C5Me5)33-tpt)Cl6] (1) and [Ir35-C5Me5)33-tpt)Cl6] (2), respectively. Addition of silver triflate to 1 and 2 in dichloromethane connects two identical triangular panels to form the hexanuclear metallo-prismatic cations [Rh65-C5Me5)63-tpt)2 (μ-Cl)6]6+ (3) and [Ir65-C5Me5)63-tpt)2 (μ-Cl)6]6+ (4), respectively. Cations 3 and 4 have been isolated as their triflate salts and characterised by 1H NMR, IR and UV/visible spectroscopy.
  • Publication
    Accès libre
    Mono and dinuclear arene ruthenium complexes containing 6,7-dimethyl-2,3-di(pyridine-2-yl)quinoxaline as chelating ligand: Synthesis and molecular structure
    (2007) ; ;
    Govindaswamy, Padavattan
    ;
    Saïd-Mohamed, Cynthia
    The mononuclear cations of the general formula [(η6-arene)RuCl(dpqMe2)]+ (dpqMe2 = 6,7-dimethyl-2,3-di(pyridine-2-yl)quinoxaline; arene = C6H6, 1; C6H5Me, 2; p-PriC6H4Me, 3; C6Me6, 4) as well as the dinuclear dications [(η6-arene) 2Ru2Cl2(μ-dpqMe2)]2+ (arene = C6H6, 5; C6H5Me, 6; p-PriC6H4Me, 7; C6Me6, 8) have been synthesised from 6,7-dimethyl-2,3-di(pyridine-2-yl)quinoxaline (dpqMe2) and the corresponding chloro complexes [(η6-C6H6)Ru(μ-Cl)Cl]2, [(η6-C6H5Me)Ru(μ-Cl)Cl]2, [(η6-p-PriC6H4Me)Ru(μ-Cl)Cl]2 and [(η6-C6Me6)Ru(μ-Cl)Cl]2, respectively. The X-ray crystal structure analyses of [1][PF6], [3][PF6] and [6][PF6]2 reveal a typical piano-stool geometry around the metal centre; in the dinuclear complexes the two chloro ligands, with respect to each other, are found to be trans oriented.