Voici les éléments 1 - 10 sur 10
  • Publication
    Accès libre
    Hydrogen-bonded metalla-assemblies
    (2018)
    Zhang, Fan
    ;
    Les liaisons hydrogènes sont les interactions non-covalentes les plus utilisées dans les systèmes biologiques, en raison de leur directionnalité, stabilité, réversibilité et diversité. La faible interaction de la liaison hydrogène peut être modifiée en combinant plusieurs liaisons hydrogènes dans la même unité, comme dans le système mélamine∙acide cyanurique/barbiturique rosette.
    Les métallo-assemblages d’arene ruthenium ont montré un grand prometteur biologique. Inspirés par la combinaison de la liaison hydrogène et de la complexation des métaux du groupe de Mendoza, nous avons récemment préparé une série des métallo-assemblages. Par conséquent, pour étudier plus en profondeur les métallo-assemblages liés par des liaisons hydrogènes, nous avons utilisé le système mélamine/barbiturique rosette avec complexes de type tabouret de piano ou métallo-clips dinucléaires. L'introduction d'un groupe pyridyle sur le fragment acide barbiturique ou le fragment mélamine permet la coordination des métaux à la périphérie de la rosette.
    Des nouveaux métallo-assemblages rosettes ont été préparés et caractérisés. Des métallo-assemblages rosette trinucléaires neutres et cationiques ont été synthétisés, ainsi que des métallo-assemblages rosette hétéro-hexanucléaires. La coordination de métallo-clips dinucléaires a produit des métallo-assemblages hexanucléaires cationiques. Globalement, les assemblages rosette avec des complexes de type tabouret de piano offrent des grandes opportunités dans le domaine de la chimie supramoléculaire., Hydrogen bonds are the most utilized non-covalent interactions in biological systems, due to their directionality, stability, reversibility and diversity. The weak strength of hydrogen-bond can be modified by combining several hydrogen bonds in the same unit, like in the melamine∙cyanuric/barbituric acid rosette-type system.
    Arene ruthenium metalla-assemblies have showed a great biological potential. Inspired by the combination of hydrogen bonding and metal complexation from the group of de Mendoza, we have recently prepared a series of hydrogen-bonded metalla-assemblies. Therefore, to further investigate hydrogen-bonded metalla-assemblies, we used the melamine/barbituric rosette-type system with piano-stool complexes or dinuclear metalla-clips. The introduction of a pyridyl group on the barbituric acid moiety or the melamine moiety allows coordination of metals at the periphery of the rosette.
    New rosette-type metalla-assemblies have been prepared and characterized. Neutral and cationic trinuclear rosette-type metalla-assemblies have been synthesized, as well as hetero-hexanuclear rosette-type metalla-assemblies. Coordination of dinuclear metalla-clips has produced cationic hexanuclear metalla-assemblies. Overall, rosette-type assemblies with piano-stool complexes offer great opportunities in the field of supramolecular chemistry.
  • Publication
    Accès libre
    Synthesis, characterization and exploration of the catalytic, supramolecular and biological applications of dinuclear complexes
    (2013)
    Johnpeter, Justin Paul Raj
    ;
    The work presented in this thesis involves the synthesis and characterization of dinuclear ruthenium, rhodium and iridium complexes. The catalytic, supramolecular and biological applications of these dinuclear complexes will be discussed. In the first part, the synthesis of sawhorse-type diruthenium tetracarbonyl complexes and their catalytic applications in the supercritical carbon dioxide (scCO2) are presented. Synthesis of sawhorse-type molecular tweezers derived from pyrenyl and porphyrin carboxylic derivatives are presented in the second part. The host-guest interactions between the sawhorse-type molecular tweezers with different guest molecules will be discussed. In the final part, the anticancer potential of dinuclear ruthenium, rhodium and iridium complexes are evaluated with different cancer cell lines.
  • Publication
    Accès libre
    Mono and dinuclear complexes of half-sandwich platinum group metals (Ru, Rh and Ir) bearing a flexible pyridyl-thiazole multidentate donor ligand
    (2010)
    Prasad, Kota Thirumala
    ;
    ;
    Rao, Kollipara Mohan
    The mononuclear cationic complexes [(η6-C6H6)RuCl(L)]+ (1), [(η6-p-iPrC6H4Me)RuCl(L)]+ (2), [(η5-C5H5)Ru(PPh3)(L)]+ (3), [(η5-C5Me5)Ru(PPh3)(L)]+ (4), [(η5-C5Me5)RhCl(L)]+ (5), [(η5-C5Me5)IrCl(L)]+ (6) as well as the dinuclear dicationic complexes [{(η6-C6H6)RuCl}2 (L)]2+ (7), [{(η6-p-iPrC6H4Me)RuCl}2 (L)]2+ (8), [{(η5-C5H5)Ru(PPh3)}2 (L)]2+ (9), [{(η5-C5Me5)Ru(PPh3)}2 (L)]2+ (10), [{(η5-C5Me5)RhCl}2 (L)]2+ (11) and [{(η5-C5Me5)IrCl}2 (L)]2+ (12) have been synthesized from 4,4′-bis(2-pyridyl-4-thiazole) (L) and the corresponding complexes [(η6-C6H6)Ru(μ-Cl)Cl]2, [(η6-p-iPrC6H4Me)Ru(μ-Cl)Cl]2, [(η5-C5H5)Ru(PPh3)2Cl)], [(η5-C5Me5)Ru(PPh3)2Cl], [(η5-C5Me5)Rh(μ-Cl)Cl]2 and [(η5-C5Me5)Ir(μ-Cl)Cl]2, respectively. All complexes were isolated as hexafluorophosphate salts and characterized by IR, NMR, mass spectrometry and UV–vis spectroscopy. The X-ray crystal structure analyses of [3]PF6, [5]PF6, [8](PF6)2 and [12](PF6)2 reveal a typical piano-stool geometry around the metal centers with a five-membered metallo-cycle in which 4,4′-bis(2-pyridyl-4-thiazole) acts as a N,N′-chelating ligand.
  • Publication
    Accès libre
    Anticancer activity of new organo-ruthenium, rhodium and iridium complexes containing the 2-(pyridine-2-yl)thiazole N,N-chelating ligand
    (Elsevier, 2010)
    Gras, Michaël
    ;
    ; ;
    Angela Casini
    ;
    Edafe, Fabio
    ;
    Paul Dyson
    The dinuclear dichloro complexes [(η6-arene)2Ru2(μ-Cl)2Cl2] and [(η5-C5Me5)2M2 (μ-Cl)2Cl2] react with 2-(pyridine-2-yl)thiazole (pyTz) to afford the cationic complexes [(η6-arene)Ru(pyTz)Cl]+ (arene = C6H61, p-iPrC6H4Me 2 or C6Me63) and [(η5-C5Me5)M(pyTz)Cl]+ (M = Rh 4 or Ir 5), isolated as the chloride salts. The reaction of 2 and 3 with SnCl2 leads to the dinuclear heterometallic trichlorostannyl derivatives [(η6-p-iPrC6H4Me)Ru(pyTz)(SnCl3)]+ (6) and [(η6-C6Me6)Ru(pyTz)(SnCl3)]+ (7), respectively, also isolated as the chloride salts. The molecular structures of 4, 5 and 7 have been established by single-crystal X-ray structure analyses of the corresponding hexafluorophosphate salts. The in vitro anticancer activities of the metal complexes on human ovarian cancer cell lines A2780 and A2780cisR (cisplatin-resistant), as well as their interactions with plasmid DNA and the model protein ubiquitin, have been investigated.
  • Publication
    Accès libre
    Syntheses and characterization of mono and dinuclear complexes of platinum group metals bearing benzene-linked bis(pyrazolyl)methane ligands
    (2010)
    Prasad, Kota Thirumala
    ;
    ;
    Rao, Kollipara Mohan
    Reaction of the benzene-linked bis(pyrazolyl)methane ligands, 1,4-bis{bis(pyrazolyl)-methyl}benzene (L1) and 1,4-bis{bis(3-methylpyrazolyl)methyl}benzene (L2), with pentamethylcyclopentadienyl rhodium and iridium complexes [(η5-C5Me5)M(μ-Cl)Cl]2 (M = Rh and Ir) in the presence of NH4PF6 results under stoichiometric control in both, mono and dinuclear complexes, [(η5-C5Me5)RhCl(L)]+ {L = L1 (1); L2 (2)}, [(η5-C5Me5)IrCl(L)]+ {L = L1 (3); L2 (4)} and [{(η5-C5Me5)RhCl}2(μ-L)]2+ {L = L1 (5); L2 (6)}, [{(η5-C5Me5)IrCl}2(μ-L)]2+ {L = L1 (7); L2 (8)}. In contrast, reaction of arene ruthenium complexes [(η6­arene)Ru(μ-Cl)Cl]2 (arene = C6H6, p-iPrC6H4Me and C6Me6) with the same ligands (L1 or L2) gives only the dinuclear complexes [{(η6-C6H6)RuCl}2(μ-L)]2+ {L = L1 (9); L2 (10)}, [{(η6-p-iPrC6H4Me)RuCl}2 (μ-L)]2+ {L = L1 (11); L2 (12)} and [{(η6-C6Me6)RuCl}2(μ-L)]2+ {L = L1 (13); L2 (14)}. All complexes were isolated as their hexafluorophosphate salts. The single-crystal X-ray crystal structure analyses of [7](PF6)2, [9](PF6)2 and [11](PF6)2 reveal a typical piano-stool geometry around the metal centers with six-membered metallo-cycle in which the 1,4-bis{bis(pyrazolyl)-methyl}benzene acts as a bis-bidentate chelating ligand.
  • Publication
    Accès libre
    Mono and dinuclear half-sandwich platinum group metal complexes bearing pyrazolyl-pyrimidine ligands: Syntheses and structural studies
    (2010)
    Prasad, Kota Thirumala
    ;
    ;
    Geib, Steven
    ;
    Rao, Kollipara Mohan
    Reactions of 0.5 eq. of the dinuclear complexes [(η6-arene)Ru(μ-Cl)Cl]2 (arene = η6-C6H6, η6-p-iPrC6H4Me) and [(Cp)M(μ-Cl)Cl]2 (M = Rh, Ir; Cp = η5-C5Me5) with 4,6-disubstituted pyrazolyl-pyrimidine ligands (L) viz. 4,6-bis(pyrazolyl)pyrimidine (L1), 4,6-bis(3-methyl-pyrazolyl)pyrimidine (L2), 4,6-bis(3,5-dimethyl-pyrazolyl)pyrimidine (L3) lead to the formation of the cationic mononuclear complexes [(η6-C6H6)Ru(L)Cl]+ (L = L1, 1; L2, 2; L3, 3), [(η6-piPrC6H4Me)Ru(L)Cl]+ (L = L1, 4; L2, 5; L3, 6), [(Cp)Rh(L)Cl]+ (L = L1, 7; L2, 8; L3, 9) and [(Cp)Ir(L)Cl]+ (L = L1, 10; L2, 11; L3, 12), while reactions with 1.0 eq. of the dinuclear complexes [(η6-arene)Ru(μ-Cl)Cl]2 and [(Cp)M(μ-Cl)Cl]2 give rise to the dicationic dinuclear complexes [{(η6-C6H6)RuCl}2(L)]2+ (L = L1, 13; L2, 14; L3, 15), [{(η6-p-iPrC6H4Me)RuCl}2(L)]2+ (L = L1, 16; L2, 17; L3, 18), [{(Cp)RhCl}2(L)]2+ (L = L1, 19; L2, 20; L3, 21) and [{(Cp)IrCl}2 (L)]2+ (L = L1 22; L2, 23; L3 24). The molecular structures of [3]PF6, [6]PF6, [7]PF6 and [18](PF6)2 have been established by single crystal X-ray structure analysis.
  • Publication
    Accès libre
    Pentamethylcyclopentadienyl rhodium and iridium complexes containing oxinato ligands
    (2009)
    Thai, Trieu-Tien
    ;
    ;
    The neutral chloro complexes [(η5-C5Me5)M(η2-NC9H6O)Cl] as well as the cationic aqua complexes [(η5-C5Me5)M(η2-NC9H6O)(H2O)]+ (M = Rh, Ir) have been synthesized from the reaction of the dinuclear precursors [(η5-C5Me5)MCl2]2 and 8-hydroxyquinoline. The single crystal X-ray structure analysis of [(η5-C5Me5)Ir(η2-NC9H6O)Cl] reveals for these complexes a piano-stool arrangement with the aromatic ligand, the chelating oxinato ligand and the terminal chloro or aqua ligand surrounding the metal center in a pseudo-tetrahedral fashion.
  • Publication
    Accès libre
    Study of novel η5-cyclopentadienyl and η6-arene platinum group metal complexes containing a N4-type ligand and their structural characterization
    (2009)
    Gupta, Gajendra
    ;
    Yap, Glenn P.A.
    ;
    ;
    Rao, Kollipara Mohan
    The mononuclear η5-cyclopentadienyl complexes [(η5-C5H5)Ru(PPh3)2Cl], [(η5-C5H5)Os(PPh3)2Br] and pentamethylcyclopentadienyl complex [(η5-C5Me5)Ru(PPh3)2Cl] react in the presence of 1 eq. of the tetradentate N,N′-chelating ligand 3,5-bis(2-pyridyl)pyrazole (bpp-H) and 1 eq. of NH4PF6 in methanol to afford the mononuclear complexes [(η5-C5H5)Ru(PPh3)(bpp-H)]PF6 ([1]PF6), [(η5-C5H5)Os(PPh3)(bpp-H)]PF6 ([2]PF6) and [(η5-C5Me5)Ru(PPh3)(bpp-H)]PF6 ([3]PF6), respectively. The dinuclear η5-pentamethylcyclopentadienyl complexes [(η5-C5Me5)Rh(μ-Cl)Cl]2 and [(η5-C5Me5)Ir(μ-Cl)Cl]2 as well as the dinuclear η6-arene ruthenium complexes [(η6-C6H6)Ru(μ-Cl)Cl]2 and [(η6-p-iPrC6H4Me)Ru(μ-Cl)Cl]2 react with 2 eq. of bpp-H in the presence of NH4PF6 or NH4BF4 to afford the corresponding mononuclear complexes [(η5-C5Me5)Rh(bpp-H)Cl]PF6 ([4]PF6), [(η5-C5Me5)Ir(bpp-H)Cl]PF6 ([5]PF6), [(η6-C6H6)Ru(bpp-H)Cl]BF4 ([6]BF4) and [(η6-p-iPrC6H4Me)Ru(bpp-H)Cl]BF4 ([7]BF4). However, in the presence of 1 eq. of bpp-H and NH4BF4 the reaction with the same η6-arene ruthenium complexes affords the dinuclear salts [(η6-C6H6)2Ru2 (bpp)Cl2]BF4 ([8]BF4) and [(η6-p-iPrC6H4Me)2Ru2 (bpp)Cl2]BF4 ([9]BF4), respectively. These compounds have been characterized by IR, NMR and mass spectrometry, as well as by elemental analysis. The molecular structures of [1]PF6, [5]PF6 and [8]BF4 have been established by single crystal X-ray diffraction studies and some representative complexes have been studied by UV–vis spectroscopy.
  • Publication
    Accès libre
    Cationic half-sandwich complexes (Rh, Ir, Ru) containing 2-substituted-1,8-naphthyridine chelating ligands: Syntheses, X-ray structure analyses and spectroscopic studies
    (2008)
    Prasad, Kota Thirumala
    ;
    ;
    Mohan Rao Kollipara
    Reactions of the dinuclear complexes [(η6-arene)Ru(μ-Cl)Cl]2 (arene = C6H6, p-iPrC6H4Me) and [(η5-C5Me5)M(μ-Cl)Cl]2 (M = Rh, Ir) with 2-substituted-1,8-naphthyridine ligands, 2-(2-pyridyl)-1,8-naphthyridine (pyNp), 2-(2-thiazolyl)-1,8-naphthyridine (tzNp) and 2-(2-furyl)-1,8-naphthyridine (fuNp), lead to the formation of the mononuclear cationic complexes [(η6-C6H6)Ru(L)Cl]+ {L = pyNp (1); tzNp (2); fuNp (3)}, [(η6-p-iPrC6H4Me)Ru(L)Cl]+ {L = pyNp (4); tzNp (5); fuNp (6)}, [(η5-C5Me5)Rh(L)Cl]+ {L = pyNp (7); tzNp (8); fuNp (9)} and [(η5-C5Me5)Ir(L)Cl]+ {L = pyNp (10); tzNp (11); fuNp (12)}. All these complexes are isolated as chloro or hexafluorophosphate salts and characterized by IR, NMR, mass spectrometry and UV/Vis spectroscopy. The molecular structures of [1]Cl, [2]PF6, [4]PF6, [5]PF6 and [10]PF6 have been established by single crystal X-ray structure analysis.
  • Publication
    Accès libre
    Mono and dinuclear iridium, rhodium and ruthenium complexes containing chelating carboxylato pyrazine ligands: Synthesis, molecular structure and electrochemistry
    (2007)
    Govindaswamy, Padavattan
    ;
    ; ;
    Štěpnička, Petr
    ;
    Ludvík, Jiří
    The mononuclear complexes [(η5-C5Me5)IrCl(L1)] (1), [(η5-C5Me5)RhCl(L1)] (2), [(η6-p-PriC6H4Me)RuCl(L1)] (3) and [(η6-C6Me6)RuCl(L1)] (4) have been synthesised from pyrazine-2-carboxylic acid (HL1) and the corresponding complexes [{(η5-C5Me5)IrCl2}2], [{(η5-C5Me5)RhCl2}2], [{(η6-p-PriC6H4Me)RuCl2}2], and [{(η6-C6Me6)RuCl2}2], respectively. The related dinuclear complexes [{(η5-C5Me5)IrCl}2 (μ-L2)] (5), [{(η5-C5Me5)RhCl}2 (μ-L2)] (6), [{(η6-p-PriC6H4Me)RuCl}2 (μ-L2)] (7) and [{(η6-C6Me6)RuCl}2 (μ-L2)] (8) have been obtained in a similar manner from pyrazine-2,5-dicarboxylic acid (H2L2). Compounds isomeric to the latter series, [{(η5-C5Me5)IrCl}2 (μ-L3)] (9), [{(η5-C5Me5)RhCl}2 (μ-L3)] (10), [{(p-PriC6H4Me)RuCl}2 (μ-L3)] (11) and [{(η6-C6Me6)RuCl}2 (μ-L3)] (12), have been prepared by using pyrazine-2,3-dicarboxylic acid (H2L3) instead of H2L2. The molecular structures of 2 and 3, determined by X-ray diffraction analysis, show the pyrazine-2-carboxylato moiety to act as an N,O-chelating ligand, while the structure analyses of 5–7, confirm that the pyrazine-2,5-dicarboxylato unit bridges two metal centres. The electrochemical behaviour of selected representatives has been studied by voltammetric techniques.