Ruthénium | EPFL Graph Search

Le ruthénium est l'élément chimique de numéro atomique 44, de symbole Ru. Le ruthénium fait partie du groupe du platine, un sous-groupe de métaux de transition. Le corps simple ruthénium est un métal dur et cassant à température ambiante. Histoire et généralité sur l'élément Le ruthénium a été identifié dans les résidus poudreux noirs de production de platine et isolé en 1844 par le chimiste Carl Ernst Klaus, dit affectueusement en russe Karl Karlovitch (Klaus) ou Karl Karlovic Klaus en ukrainien. Il a montré que l'oxyde de ruthénium contenait un nouveau métal inconnu et en a extrait six grammes de la partie insoluble dans l'eau régale du platine brut. Le ruthénium, probablement en faible teneur ou à l'état de traces, avait déjà échappé à l'analyse de Smithson Tennant en 1803 et 1804. Jöns Jacob Berzelius émit un doute suivi d'un véto scientifique sur les travaux, probablement maladroitement rédigés, du pharmacien chimiste Gottfried Osann, alors en poste à l'école de chi

Catalytic Enantioselective Transformations with Chiral Cyclopentadienyl Ruthenium(II) Complexes

Sung Hwan Park

The chemistry of cyclopentadienyl ruthenium(II) complexes plays an important role in ruthenium catalysis because of its high potential for various transformations. However, asymmetric catalysis with chiral cyclopentadienyl ruthenium(II) complexes is still at an infant stage, but rapidly developing because of its expected impact on multiple enantioselective applications. This thesis discusses the synthesis of a novel class of chiral cyclopentadienyl ligands, which can be readily accessed by a two-step process from alpha, beta-unsaturated aldehydes and cyclopentadiene. The novel C2-symmetric chiral cyclopentadienyl ligands were complexed with ruthenium(II) and successfully applied in asymmetric catalysis. The cyclopentane-fused CpxRu complex enables the enantioselective synthesis of benzonorcaradienes by coupling of oxa-benzonorbornadienes with internal alkynes in high enantioselectivity (up to 97.5:2.5 er). The reaction mechanism was investigated by computational studies and control experiments. The chiral cyclopentadienyl ruthenium(II) complexes show promising results for other transformations. An alkylative cycloetherification of allenols and aryl vinyl ketones was investigated using binaphthyl-derived chiral cyclopentadienyl ruthenium(II) complex. After an initial optimization study, allenol and phenyl vinyl ketone gave the desired enantio-enriched cyclic ether with a promising enantioselective ratio of 90:10. Furthermore, preliminary studies were undertaken for the [2+1] cycloaddition of enynes via ruthenium vinyl carbenes. Model substrate, 1,6-enyne, delivered the desired enantio-enriched bicyclo[3.1.0]hexane in a good yield of 72% (E:Z = 1.6:1), with enantiomeric ratios of 72.5:27.5 and 63.5:36.5 for the E- and Z-isomer, respectively.

EPFL2020

Rational design of organic and organometallic thermoresponsive or tumor-selective anticancer drugs and their in vitro and in vivo biological evaluation

Catherine Marie Amélie Clavel

Conventional chemotherapy leads to severe side-effects such as nephrotoxicity, nausea and vomiting and fatigue along with drug resistance. Alkylating agents used to treat cancer were even shown to provoke second cancers, often years after the end of chemotherapy treatment. Innovative treatments in the clinic are being explored, using hyperthermia in conjunction with chemotherapy to enhance the cytotoxicity of anticancer drugs in tumor cells or as a drug delivery system along with liposomal formulations. In this dissertation, a new duotherapy with regional hyperthermia and chemotherapy concept is described including low molecular weight thermoactive chlorambucil- and ruthenium(II)-based drugs with fluorous chains that are selectively triggered by mild hyperthermia, i.e. essentially inactive at 37¿°C and active under mild hyperthermia. These new compounds were prepared, characterized, and evaluated for their in vitro cytotoxicity against a panel of human cancer cell lines and non-cancerous immortalized cells. The compounds show considerable chemothermal selectivity towards cancer cells for compounds with the longest fluorous chain. The presence of fluorine was found to be critical for thermoresponsive behavior. Furthermore, in vitro assays such as cell motility, cell uptake and cell cycle arrest and in vivo studies on the CAM for assessing antiangiogenic and antitumor effects were performed to gain insights into their mechanism of action. In parallel, a ruthenium(II)¿arene complex with a cleavable perfluoroalkyl-ligand was found to display remarkable selectivity toward cancer cells. IC50 values on several cancer cell lines are in the range of 25 ¿ 45 ¿M, with no cytotoxic effect observed on nontumorigenic (HEK-293) cells. Consequently, this complex was used as the basis for the development of a number of related derivatives, which were screened in cancerous and noncancerous cell lines. Promising derivatives and the lead compound were further studied in vitro and also evaluated in vivo for antiangiogenic activity in the CAM model and in a xenografted ovarian carcinoma tumor (A2780) grown on the CAM. A 90% reduction in the tumor growth was observed for the lead compound. Lastly, thermoresponsive compounds and the tumor-selective lead complex were evaluated in an in vivo xenografted mouse model, validating the thermoresponsive concept in this preclinical model. Indeed, duotherapy with hyperthermia and chemotherapy showed a synergistic tumor growth reduction of 78.7 and 89.9% for thermoresponsive compounds, while the tumor-selective compound led to a tumor reduction of 89.6%, with no toxicity observed relative to body weight of the mice. Biodistribution was additionally assessed for ruthenium-based complexes by ICP-MS measurements.

EPFL2014

Formic Acid Dehydrogenation Catalysed by Tris(TPPTS) Ruthenium Species: Mechanism of the Initial "Fast" Cycle

Andrew Francis Dalebrook, Ewan Patrick Frost-Pennington, Gabor Laurenczy, Arnaud Thevenon

Water-soluble ruthenium m-triphenylphosphinetrisulfonate (TPPTS) complexes are excellent catalysts for formic acid dehydrogenation. Interestingly, the choice of metal catalyst precursor has a direct influence on initial activities. The reaction with hexaaquaruthenium(II) tosylate directly yields bisphosphine complexes in the presence of TPPTS and formic acid, whereas trisphosphine adducts are involved if the reaction starts with ruthenium(III) chloride. We present the results of a series of manometric and spectroscopic experiments that reveal the true nature of these highly active species, and subsequently propose a rational "fast" cycle mechanism explaining this peculiar activity profile.

Wiley-V C H Verlag Gmbh2014

Rational design of organic and organometallic thermoresponsive or tumor-selective anticancer drugs and their in vitro and in vivo biological evaluation

Catherine Marie Amélie Clavel

EPFL2014