Showing papers on "Ruthenium published in 2012"
2,317 citations
TL;DR: The strategies that have led to the discovery of metal-based and organometallic ruthenium-based drugs NAMI-A and KP1019 are highlighted and their main biological/pharmacological characteristics and expectations for further development are reported.
460 citations
449 citations
TL;DR: In this paper, a review of recent developments in photocatalytic and electrocatalytic CO 2 reduction is presented, where a complete cell with two photo-electrodes, one for water oxidation and the other for CO2 reduction to formate has been set up successfully.
421 citations
TL;DR: The use of intramolecular strain may be applied as a general paradigm to develop light-activated ruthenium complexes for PDT applications to display potencies superior to cisplatin against 3D tumor spheroids.
Abstract: Strained ruthenium (Ru) complexes have been synthesized and characterized as novel agents for photodynamic therapy (PDT). The complexes are inert until triggered by visible light, which induces ligand loss and covalent modification of DNA. An increase in cytotoxicity of 2 orders of magnitude is observed with light activation in cancer cells, and the compounds display potencies superior to cisplatin against 3D tumor spheroids. The use of intramolecular strain may be applied as a general paradigm to develop light-activated ruthenium complexes for PDT applications.
398 citations
TL;DR: Cationic ruthenium(II) complexes enabled oxidative C-H bond functionalizations with anilines bearing removable directing groups and provided general access to various bioactive indoles.
324 citations
TL;DR: In this paper, a sustainable process for the hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) is reported, using a commercial ruthenium supported catalyst in combination with a heterogeneous acid co-catalyst, such as the ion exchange resins Amberlyst A70 or A15.
289 citations
TL;DR: The first metal-cation-based anion exchange membranes (AEMs) were synthesized by copolymerization and cross-linking of a norbornene monomer functionalized with a water-soluble bis(terpyridine)ruthenium(II) complex and dicyclopentadiene, showing anion conductivities and mechanical properties comparable to those of traditional quaternary-ammonium-based AEMs.
Abstract: Here we present the first metal-cation-based anion exchange membranes (AEMs), which were synthesized by copolymerization and cross-linking of a norbornene monomer functionalized with a water-soluble bis(terpyridine)ruthenium(II) complex and dicyclopentadiene. Each ruthenium complex has two associated counteranions, unlike most ammonium- and phosphonium-based membranes with single cation–anion pairs. The resulting AEMs show anion conductivities and mechanical properties comparable to those of traditional quaternary-ammonium-based AEMs as well as good alkaline stability and methanol tolerance. These results suggest that metal-cation-based polymers hold promise as a new class of materials for anion-conducting applications.
279 citations
TL;DR: The synthesis and detailed characterization of two novel inert Ru(II) complexes are presented and it could be demonstrated that, although 3 binds to calf-thymus DNA by intercalation, the biological effects that it induces did not involve a nuclear DNA related mode of action.
Abstract: A great majority of the Ru complexes currently studied in anticancer research exert their antiproliferative activity, at least partially, through ligand exchange. In recent years, however, coordinatively saturated and substitutionally inert polypyridyl Ru(II) compounds have emerged as potential anticancer drug candidates. In this work, we present the synthesis and detailed characterization of two novel inert Ru(II) complexes, namely, [Ru(bipy)2(Cpp-NH-Hex-COOH)]2+ (2) and [Ru(dppz)2(CppH)]2+ (3) (bipy = 2,2′-bipyridine; CppH = 2-(2′-pyridyl)pyrimidine-4-carboxylic acid; Cpp-NH-Hex-COOH = 6-(2-(pyridin-2-yl)pyrimidine-4-carboxamido)hexanoic acid; dppz = dipyrido[3,2-a:2′,3′-c]phenazine). 3 is of particular interest as it was found to have IC50 values comparable to cisplatin, a benchmark standard in the field, on three cancer cell lines and a better activity on one cisplatin-resistant cell line than cisplatin itself. The mechanism of action of 3 was then investigated in detail and it could be demonstrated t...
266 citations
TL;DR: Ruthenium-catalyzed oxidative C-H bond olefination of N-methoxybenzamides using an oxidizing directing group with a broad substrate scope is reported.
253 citations
TL;DR: In this article, a range of solvent free conditions have been investigated with complete LA conversion obtained at temperatures as low as 25 °C with support provided by a variety of supported catalysts.
TL;DR: The Os dimer is an outstanding catalyst for the hydrogenation of alkenoates and triglycerides, and allows production of fatty alcohols from olive oil.
Abstract: There and back again: hydrogenation of esters and the reverse reaction of dehydrogenative coupling of alcohols are efficiently catalyzed by dimeric complexes of Ru and Os under neutral conditions. The Os dimer is an outstanding catalyst for the hydrogenation of alkenoates and triglycerides, and allows production of fatty alcohols from olive oil. This complex converts ethanol into ethyl acetate and hydrogen under reflux.
TL;DR: An inexpensive cationic ruthenium(II) catalyst enabled the expedient synthesis of isocoumarins through oxidative annulations of alkynes by benzoic acids and was shown to proceed by rate-limiting C-H bond rUThenation.
TL;DR: A cationic ruthenium(II) complex enabled efficient oxidative alkenylations of anilides in water as a green solvent and proved applicable to double C-H bond functionalizations of (hetero)aromatic amides with ample scope.
TL;DR: Aromatic and heteroaromatic ketoximes underwent cyclization with alkynes in the presence of a catalytic amount of [{RuCl(2)(p-cymene)}(2)] and NaOAc to give isoquinoline derivatives in good to excellent yields in a highly regioselective manner.
TL;DR: The highly regioselective aerobic oxidative cyclization of aromatic, heteroaromatic and alkenyl acids with alkynes in the presence of catalytic amounts of AgSbF(6) and Cu(OAc)(2)·H(2)O providing isocoumarin derivatives was investigated.
TL;DR: An experimental and computational investigation to understand the nature of the interactions between cobalt redox mediators and TiO(2) surfaces sensitized by ruthenium and organic dyes, and their impact on the performance of the corresponding dye-sensitized solar cells (DSSCs).
Abstract: We report a combined experimental and computational investigation to understand the nature of the interactions between cobalt redox mediators and TiO(2) surfaces sensitized by ruthenium and organic dyes, and their impact on the performance of the corresponding dye-sensitized solar cells (DSSCs). We focus on different ruthenium dyes and fully organic dyes, to understand the dramatic loss of efficiency observed for the prototype Ru(II) N719 dye in conjunction with cobalt electrolytes. Both N719- and Z907-based DSSCs showed an increased lifetime in iodine-based electrolyte compared to the cobalt-based redox shuttle, while the organic D21L6 and D25L6 dyes, endowed with long alkoxy chains, show no significant change in the electron lifetime regardless of employed electrolyte and deliver a high photovoltaic efficiency of 6.5% with a cobalt electrolyte. Ab initio molecular dynamics simulations show the formation of a complex between the cobalt electrolyte and the surface-adsorbed ruthenium dye, which brings the [Co(bpy)(3)](3+) species into contact with the TiO(2) surface. This translates into a high probability of intercepting TiO(2)-injected electrons by the oxidized [Co(bpy)(3)](3+) species, lying close to the N719-sensitized TiO(2) surface. Investigation of the dye regeneration mechanism by the cobalt electrolyte in the Marcus theory framework led to substantially different reorganization energies for the high-spin (HS) and low-spin (LS) reaction pathways. Our calculated reorganization energies for the LS pathways are in excellent agreement with recent data for a series of cobalt complexes, lending support to the proposed regeneration pathway. Finally, we systematically investigate a series of Co(II)/Co(III) complexes to gauge the impact of ligand substitution and of metal coordination (tris-bidentate vs bis-tridentate) on the HS/LS energy difference and reorganization energies. Our results allow us to trace structure/property relations required for further development of cobalt electrolytes for DSSCs.
TL;DR: In this paper, the proposed mechanisms, catalytic activities and reaction kinetics of catalytic water oxidation with transition metal complexes in homogeneous systems with an emphasis on the last decade are discussed.
TL;DR: In this paper, a 5 cm2 single proton exchange membrane water electrolyzer with ruthenium and iridium-based materials was examined by various physicochemical techniques in order to understand their electrochemical behavior as anodes in the PEM electrolyzer.
Abstract: Powders of ruthenium and iridium-based materials were synthesized by the thermal decomposition process. The suitable heat treatment of the polymeric precursors allowed to recover metal oxides free from organic carbon, which can be oxidized to carbon dioxide during H2O splitting at elevated potentials. The materials were examined by various physicochemical techniques in order to understand their electrochemical behavior as anodes in a 5 cm2 single proton exchange membrane water electrolyzer. Although the presence of Ir in the electrocatalyst composition contributes undoubtedly to its stability against ruthenium dissolution and the Faradaic efficiency of the PEM electrolysis cell, its great amount increases the overpotential value. The activity of the home made RuxIr1−xO2 anodes towards the oxygen evolution reaction occurs at ca. 1.5 V at 25 °C.
TL;DR: The observed lifetimes are the highest documented lifetimes for unimolecular ruthenium(II) complexes and are four orders in magnitude higher than that associated with [Ru(terpy)(2)](2+).
Abstract: A series of heteroleptic bis(tridentate) ruthenium(II) complexes, each bearing a substituted 2,2′:6′,2″-terpyridine (terpy) ligand, is characterized by room temperature microsecond excited-state lifetimes. This observation is a consequence of the strongly σ-donating and weakly π-accepting tridentate carbene ligand, 2′,6′-bis(1-mesityl-3-methyl-1,2,3-triazol-4-yl-5-idene)pyridine (C∧N∧C), adjacent to the terpy maintaining a large separation between the ligand field and metal-to-ligand charge transfer (MLCT) states while also preserving a large 3MLCT energy. The observed lifetimes are the highest documented lifetimes for unimolecular ruthenium(II) complexes and are four orders in magnitude higher than that associated with [Ru(terpy)2]2+.
TL;DR: The complex [Ru(PNP)(H)(2)(HBpin)] 2 (HBpin = pinacolborane), which was identified at the end of the reaction and prepared independently, is proposed as the direct precursor to the catalytic cycle involving rearrangement of coordinated alkyne to Z-vinylidene as a key step for the apparent trans-hydroboration.
Abstract: The nonclassical ruthenium hydride pincer complex [Ru(PNP)(H)(2)(H(2))] 1 (PNP = 1,3-bis(di-tert-butyl-phosphinomethyl)pyridine) catalyzes the anti-Markovnikov addition of pinacolborane to terminal alkynes yielding Z-vinylboronates at mild conditions. The complex [Ru(PNP)(H)(2)(HBpin)] 2 (HBpin = pinacolborane), which was identified at the end of the reaction and prepared independently, is proposed as the direct precursor to the catalytic cycle involving rearrangement of coordinated alkyne to Z-vinylidene as a key step for the apparent trans-hydroboration.
TL;DR: Aiming at developing robust molecular Ru-bda (H2bda = 2,2′-bipyridine-6,6′-dicarboxylic acid) water oxidation catalysts, density functional theory studies were carried out, the robustness of catalysts against hydration was correlated with the highest occupied molecular orbital levels of a set of ligands, and the synthesis of robust Ru(bda)L2 was directed.
Abstract: Water oxidation catalysts are essential components of light-driven water splitting systems, which could convert water to H2 driven by solar radiation (H2O + hν → 1/2O2 + H2). The oxidation of water (H2O → 1/2O2 + 2H+ + 2e-) provides protons and electrons for the production of dihydrogen (2H+ + 2e- → H2), a clean-burning and high-capacity energy carrier. One of the obstacles now is the lack of effective and robust water oxidation catalysts. Aiming at developing robust molecular Ru-bda (H2bda = 2,2′-bipyridine-6,6′-dicarboxylic acid) water oxidation catalysts, we carried out density functional theory studies, correlated the robustness of catalysts against hydration with the highest occupied molecular orbital levels of a set of ligands, and successfully directed the synthesis of robust Ru-bda water oxidation catalysts. A series of mononuclear ruthenium complexes [Ru(bda)L2] (L = pyridazine, pyrimidine, and phthalazine) were subsequently synthesized and shown to effectively catalyze CeIV-driven [CeIV = Ce(NH4)2(NO3)6] water oxidation with high oxygen production rates up to 286 s-1 and high turnover numbers up to 55,400.
TL;DR: The reusability experiments show that Ru(0)@MWCNTs are isolable and redispersible in aqueous solution; when redispersed they are still active catalyst in the hydrolysis of AB exhibiting a release of 3.0 equivalents of H₂ per mole of NH₁BH₃ and preserving 41% of the initial catalytic activity even after the fourth run of hydrolytic activity.
Abstract: Ruthenium(0) nanoparticles supported on multiwalled carbon nanotubes (Ru(0)@MWCNT) were in situ formed during the hydrolysis of ammonia–borane (AB) and could be isolated from the reaction solution by filtration and characterized by ICP-OES, XRD, TEM, SEM, EDX, and XPS techniques. The results reveal that ruthenium(0) nanoparticles of size in the range 1.4–3.0 nm are well-dispersed on multiwalled carbon nanotubes. They were found to be highly active catalyst in hydrogen generation from the hydrolysis of AB with a turnover frequency value of 329 min–1. The reusability experiments show that Ru(0)@MWCNTs are isolable and redispersible in aqueous solution; when redispersed they are still active catalyst in the hydrolysis of AB exhibiting a release of 3.0 equivalents of H2 per mole of NH3BH3 and preserving 41% of the initial catalytic activity even after the fourth run of hydrolysis. The lifetime of Ru(0)@MWCNTs was measured as 26400 turnovers over 29 h in the hydrolysis of AB at 25.0 ± 0.1 °C before deactivatio...
TL;DR: Air-stable dimers of sandwich compounds including rhodocene and (pentamethylcyclopentadienyl)(arene)ruthenium and iron derivatives can be used for n-doping electron-transport materials with electron affinities as small as 2.8 eV.
Abstract: Air-stable dimers of sandwich compounds including rhodocene and (pentamethylcyclopentadienyl)(arene)ruthenium and iron derivatives can be used for n-doping electron-transport materials with electron affinities as small as 2.8 eV. A p-i-n homojunction diode based on copper phthalocyanine and using rhodocene dimer as n-dopant shows a rectification ratio of greater than 10(6) at 4 V.
TL;DR: Ruthenium-catalyzed aerobic oxidative annulations of alkynes were accomplished with co-catalysistic amounts of Cu(OAc)2·H2O under ambient air as mentioned in this paper.
Abstract: Ruthenium-catalyzed aerobic oxidative annulations of alkynes were accomplished with co-catalytic amounts of Cu(OAc)2·H2O under ambient air. The C–H/N–H bond functionalization occurred with unparalleled selectivities and ample scope to deliver structural analogs of bioactive marine alkaloids.
TL;DR: In this paper, the main developments on ruthenium and rhodium-catalyzed carbonylation are summarized and compared with palladium catalysts, they are a powerful method for activating CH bonds under mild and phosphine free conditions.
Abstract: Over the last few decades, carbonylation reactions have been accepted as important chemical transformations for both academic and industrial research. Carboxylic acid derivatives are the main product of carbonylation and are widely used in organic synthesis and fine chemicals preparation. Carbonylation reactions can increase the carbon chain of parent molecules, while introducing a carbonyl group. Herein, the main developments on ruthenium- and rhodium-catalyzed carbonylation are summarized. Compared with palladium catalysts, ruthenium and rhodium catalyzed reactions are a powerful method for activating CH bonds under mild and phosphine free conditions.
TL;DR: There are numerous reports on the synthesis of 2,3-dihydrobenzofurans, but newefficient and highlyantioselective methods that permit access to the corresponding reduced analogues are highly desirable.
Abstract: were successfully hydrogen-ated to the corresponding tetrahydroquinolines, tetrahydro-quinoxalines, and indolines with more than 90% ee by usinghomogeneous transition-metal catalysts or Bronsted acidorganocatalysts. However, despitethe effort put into this areainthelastyears,somevaluableclassesofsubstrates,especially(non-N) heterocycles, such as furans, thiophenes, benzofur-ans, and benzothiophenes, are much less explored and stillconstitute a challenge for the field of asymmetric hydro-genation.Therefore,newefficientandhighlyenantioselectivemethodologies that permit access to the correspondingreduced analogues are highly desirable.There are numerous reports on the synthesis of 2,3-dihydrobenzofurans.
TL;DR: A review of recent developments in the use of iron catalysts for asymmetric transformations, including hydrogenations, transfer hydrogenation, hydrosilylation and oxidation reactions, can be found in this paper.
TL;DR: Ruthenium-catalyzed direct arylations of phenols bearing removable directing groups were accomplished through carboxylate assistance via six-membered ruthenacycles as key intermediates.