Ruthenium Metal Research Articles

Novel Approach to Generate a Self-Deliverable Ru(II)-Based Anticancer Agent in the Self-Reacting Confined Gel Space.

Finding the most effective method for cancer treatment is one of the thought-provoking tasks. Drug delivery by collapsing of metallogel to the cancer cell is an appealing way out. Cancer cells have an acidic environment due to excessive accumulation of lactic acid. In this work, the novel G5 gelator with a strategically free carboxylic acid arm has been designed and fabricated and characterized by several spectroscopic and microscopic techniques. These experiments suggest the formation of an ordered supramolecular gel with clover-leaf-like morphology. Mechanical properties from rheological measurements suggest the viscoelastic nature of the gel. Furthermore, we have obtained crystals of G5 from the pure dimethyl sulfoxide solution, whereas gelation gets induced by addition of water. This G5 gelator loses its gelation capability once the carboxylate is esterified by layering with methanol, which furnished the crystals of Me-G5' (G5' = G5-H). Further, the G5 gelator is used for the formation of ruthenium metallogel. Interestingly, we obtained the monomeric species [Ru(G5')(η6-p-cymene)Cl] [Ru(II)G5] only in confined gel space upon addition of a [Ru2(η6-p-cymene)2Cl4] dimer to G5. The Ru(II)G5 metallogel has an inherent anticancer property with an IC50 value of 10.53 μM for the A549 cancer cell line. Treatment of the Ru(II)G5 metallogel by lactic acid for mimicking the acidic environment of the malignant cell results in collapsing of the gel by releasing the ruthenium metal ion. This released ruthenium ion binds with the lactic acid derivative making the gelator G5 free and producing a new compound Ru(II)L, which has also shown the anticancer property. The molecular docking study revealed that the released G5 could interact with a monocarboxylate transporter to disrupt the lactate transport chain, which might induce apoptosis.

Vestium i Ruthenium na tle historii chemii

Trwający już ponad sto lat spór o to, czy odkryty przez Jędrzeja Śniadeckiego, a nieuznany przez jemu współczesnych pierwiastek Vestium jest odpowiednikiem rutenu, wydaje się dziś bardzo trudny do rozstrzygnięcia. Sam ten spór, który w istocie rzeczy sprowadza się do ustalenia pierwszeństwa odkrycia, nabiera w świetle historii chemii – a zwłaszcza historii badań surowej platyny – zupełnie innego znaczenia. W tym kontekście okazuje się bowiem, że Jędrzej Śniadecki był pierwszym uczonym, który starał się udowodnić istnienie szóstego platynowca. Czas pokazał, że miał rację. Późniejsze wyodrębnienie metalicznego rutenu przez Karla Ernsta Clausa tylko tę rację potwierdziło. Westium and Ruthenium against the background of the history of chemistry Abstract Is the chemical element Vestium discovered by Jędrzej Śniadecki the same as the Ruthenium? The dispute on this subject has been going on for more than one hundred years. At present, this dispute over recognition of the priority of discovery is very difficult to resolve. However, from the point of view of the history of chemistry, another aspect is more important in all this. In this context, it turns out that Jędrzej Śniadecki was the first researcher who tried to prove the existence of the sixth platinum metal. Time showed that Śniadecki was right. The confirmation of this was the subsequent separation of the metallic ruthenium by Karl Ernst Claus.

Molecular nitrogen promotes catalytic hydrodeoxygenation

Although molecular dinitrogen (N2) is widely used as a carrier or inert gas for many catalytic reactions, it is rarely considered as a catalytic promoter. Here, we report that N2 could be used to reduce the activation energy for catalytic hydrodeoxygenation over ruthenium-based catalysts. Specifically, we report a 4.3-fold activity increase in the catalytic hydrodeoxygenation of p-cresol to toluene over a titanium oxide supported ruthenium catalyst (Ru/TiO2) by simply introducing 6 bar N2 under batch conditions at 160 °C and 1 bar hydrogen. Detailed investigations indicate that N2 can be adsorbed and activated on the metallic ruthenium surface to form hydrogenated nitrogen species, which offer protic hydrogen to lower the activation energy of direct carbonaromatic–oxygen bond scission and the hydrogenation of hydroxy groups. Thus, by employing different ruthenium catalysts, including Ru/TiO2, Ru/Al2O3, Ru/ZrO2 and Ru/C, we demonstrate that N2 promotion of hydrodeoxygenation can be regarded as a general strategy. Due to its stability nitrogen is often employed as an inert gas during catalytic reactions. Now, a study shows that N2 can act as promoter for the catalytic hydrodeoxygenation of p-cresol on supported ruthenium catalysts through the formation of hydrogenated nitrogen species acting as a source of protic hydrogen.

Two-layer anode electrode with non-noble catalysts as CO tolerant structure for PEM fuel cell

Many studies on platinum-based dual-metal or multi-metal alloys catalysts are underway to strengthen the resistance of the anode catalyst layer against hydrogen fuel contamination, especially carbon monoxide. The change in the structure of the catalyst layer can also be a new and effective way to remove Carbon Monoxide. In the few multi-layer electrode structure reported cases, ruthenium metal is used in the outer layer, for sieving the Carbon Monoxide molecules before reaching to the Pt/C catalyst in the inner layer. In this study, we make two-layer catalyst anode electrode with SnO2/C and Sn20.Co80/C in outer layer and commercial Pt/C in inner layer. The performance of these electrodes for Carbon Monoxide electro-oxidation evaluate by cyclic voltammetry and the results compare with the activity of an electrode with commercial platinum catalyst only. Our two-layer electrodes have the same efficiency as commercial platinum electrodes and even more for pure hydrogen oxidation and much better activity for pure Carbon Monoxide electro-oxidation at low potentials, in half-cell media. These electrodes have better stability for Carbon Monoxide oxidation after 100 cycles along with Carbon Monoxide gas bubbling and electrode with bi-metal catalyst in outer layer has almost no loss in performance.

Coverage and Stability of NHx-Terminated Cobalt and Ruthenium Surfaces: A First-Principles Investigation

In the atomic layer deposition (ALD) of cobalt (Co) and ruthenium (Ru) metals using nitrogen plasma, the structure and composition of the post N-plasma NHx-terminated (x = 1 or 2) metal surfaces are not well-known but are important in the subsequent metal-containing pulse. In this paper, we use the low-index (001) and (100) surfaces of Co and Ru as models of the metal polycrystalline thin films. The (001) surface with a hexagonal surface structure is the most stable surface, and the (100) surface with a zigzag structure is the least stable surface but has high reactivity. We investigate the stability of NH and NH2 terminations on these surfaces to determine the saturation coverage of NHx on Co and Ru. NH is most stable in the hollow hexagonal close-packed site on the (001) surface and the bridge site on the (100) surface, while NH2 prefers the bridge site on both (001) and (100) surfaces. The differential energy is calculated to find the saturation coverage of NH and NH2. We also present results on mixed ...

Well-dispersed ultrasmall ruthenium on TiO2(P25) for effective photocatalytic N2 fixation in ambient condition

Photocatalytic nitrogen fixation has been burgeoning since the 20th century because the conventional Haber–Bosch process is quite energy-intensive, so other sustainable alternatives are highly required. This work uses a facile way to synthesize ultrasmall metal ruthenium on TiO2(P25) for photocatalytic nitrogen fixation at ambient temperature and pressure. The metal ruthenium is 2–3 nm in size and evenly dispersed over TiO2(P25). Both Indophenol method and ion chromatography are used to detect the ammonia yield, and possible mechanism is also proposed.

Highly efficient decomposition of ammonia using high-entropy alloy catalysts

Ammonia represents a promising liquid fuel for hydrogen storage, but its large-scale application is limited by the need for precious metal ruthenium (Ru) as catalyst. Here we report on highly efficient ammonia decomposition using novel high-entropy alloy (HEA) catalysts made of earth abundant elements. Quinary CoMoFeNiCu nanoparticles are synthesized in a single solid-solution phase with robust control over the Co/Mo atomic ratio, including those ratios considered to be immiscible according to the Co-Mo bimetallic phase diagram. These HEA nanoparticles demonstrate substantially enhanced catalytic activity and stability for ammonia decomposition, with improvement factors achieving >20 versus Ru catalysts. Catalytic activity of HEA nanoparticles is robustly tunable by varying the Co/Mo ratio, allowing for the optimization of surface property to maximize the reactivity under different reaction conditions. Our work highlights the great potential of HEAs for catalyzing chemical transformation and energy conversion reactions.

Anomalous Segregation in Lithium-Rich Layered Oxide Uncovers New Theoretical Design Rule for Stable Cathode in Lithium-Ion Battery

Here we report the TEM, X-ray, and first-principle investigation of a promising high-capacity lithium-rich 3d-4d (Mn-Ru) transition-metal layered compound. The incorporation of 4d transition metals here offers an uncharted phase space for mechanistic exploration as compared to the well documented 3d transition metal (TM) oxides. Using state-of-the-art electron and X-ray based techniques, we find surprisingly, after cycling, ruthenium segregates out as metallic nanoclusters on the reconstructed surface. Our calculations show that the unexpected ruthenium metal segregation is due to its thermodynamic insolubility in the oxygen deprived surface. This insolubility can disrupt the reconstructed surface, which explains the formation of a porous structure in this material. The revealed mechanism allows us to provide predictive guidance for the future design of lithium-rich as well as stoichiometric layered cathode materials. This research used resources of the Center for Functional Nanomaterials, which is a U.S. DOE Office of Science Facility, and the Scientific Data and Computing Center, a component of the Computational Science Initiative, at Brookhaven National Laboratory under Contract No. DE-SC0012704. Dr. Enyuan Hu, Dr. Seongmin Bak, and Dr. Xiao-Qing Yang were supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Vehicle Technology Office of the U.S. Department of Energy through the Advanced Battery Materials Research (BMR) Program, including Battery500 Consortium under Contract DE-SC0012704. Work done by R.Z. is partially supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) under the Award Number: DE-EE0008444. The work at IOP was supported by funding from Ministry of Science and Technology of China (Grants 2016YFA0202500) and the National Natural Science Foundation of China (51822211). H.C. and J-C.Z. were supported by the National Natural Science Foundation of China (51661135011). This research used resources 8-ID, 23-ID-2, and 28-ID-2 of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704. This research used resources of beamline 8.0.1 of the Advanced Light Source, which is a DOE Office of Science User Facility under contract no. DE-AC02-05CH11231. We acknowledge the technical support from beamline scientists Dr. Jianming Bai and Dr. Eric Dooryhee at the XPD beamline of NSLSII.

Sol-Gel Synthesis of Ruthenium Oxide Nanowires To Enhance Methanol Oxidation in Supported Platinum Nanoparticle Catalysts.

A template-directed, sol–gel synthesis is utilized to produce crystalline RuO2 nanowires. Crystalline nanowires with a diameter of 128 ± 15 nm were synthesized after treating the nanowires at 600 °C in air. Analysis of these nanowires by X-ray powder diffraction revealed the major crystalline phase to be tetragonal RuO2 with a small quantity of metallic ruthenium present. Further analysis of the nanowire structures by high-resolution transmission electron microscopy reveals that they are polycrystalline and are composed of interconnected, highly crystalline, nanoparticles having an average size of ∼25 nm. Uniform 3 nm Pt nanoparticles were dispersed on the surface of RuO2 nanowires using an ambient, solution-based technique yielding a hybrid catalyst for methanol oxidation. Linear sweep voltammograms (LSVs) and chronoamperometry performed in the presence of methanol in an acidic electrolyte revealed a significant enhancement in the onset potential, mass activity, and long-term stability compared with analogous Pt nanoparticles supported on commercially available Vulcan XC-72R carbon nanoparticles. Formic acid oxidation LSVs and CO stripping voltammetry revealed that the RuO2-supported Pt nanoparticles exhibit significantly higher CO tolerance, which leads to higher catalytic stability over a period of several hours. X-ray photoelectron spectroscopy results suggest that crystalline RuO2 leads to less-significant oxidation of the Pt surface relative to more widely studied hydrous RuO2 supports, thereby increasing catalytic performance.

Selective Self-Assembly of a Rectangular Ruthenium Supramolecule from an Unsymmetrical Bridging Unit.

Herein, we report the synthesis of an unsymmetrical diruthenium bridging unit containing a multidentate oxamate ligand and the subsequent formation of a rectangular supramolecule. The reaction of oxamate 1, 2-((4-bromo-2,6-dimethylphenyl)amino)-2-oxo-acetic acid, and [(p-cymene)RuCl2]2 affords a novel unsymmetrical diruthenium acceptor clip 2, where two ruthenium metal centers are ligated with either [O,O] or [N,O]. The molecular clip 2 and bipyridine donor self-assemble to form two-dimensional rectangular supramolecule 3. Self-assembly can produce seven possible isomers depending on the position of the substituted bromoaryl groups. However, 1H NMR spectroscopic investigation indicated only two different isomers in the reaction mixture. A single isomer is isolated via crystallization, and X-ray crystallography confirms that the product is a C1 symmetric two-dimensional rectangular supramolecule, in which two bromoaryl groups are located in the farthest position from each other. Theoretical calculations suggest that the self-assembly of supramolecule 3 occurred via 1:1 adducts of the diruthenium molecular clip and bipyridine as an intermediate to predominantly form a single isomer.

Mechanism of Formation of Highly Dispersed Metallic Ruthenium Particles on Ceria Support by Heating and Reduction

The structural change of Ru/CeO2 and Ru/SiO2 catalysts during pretreatments was investigated by in situ Ru K edge quick-scanning X-ray absorption fine structure (XAFS) combined with temperature-pro...

Novel ruthenium(ii) and iridium(iii) BODIPY dyes: insights into their application in photodynamic therapy in vitro.

Organic-metal complexes are promising molecules for use in photodynamic therapy (PDT). The aim of this study was to investigate in vitro effects of novel Ru(ii) and Ir(iii) BODIPY complexes for PDT. These hybrid organic-metal molecules (Ru-BD and Ir-BD) have been synthesized via reactions of a BODIPY precursor (BD) with a phenanthroline unit bearing Ru(ii) (3) and novel Ir(iii) (4) compounds. The crystal structures of the new distyryl BODIPY (BD) and Ru(ii) complex (3) are also reported. The photophysical and singlet oxygen generation properties of Ru-BD and Ir-BD were investigated in comparison with unsubstituted BODIPY (BD). Moreover, Ru-BD and Ir-BD have been biologically evaluated in vitro in chronic myeloid leukemia and cervical cancer cell lines in terms of photodynamic therapy efficacy in the presence of BD control. These complexes were not toxic in the dark but red light was needed to induce cell death. These data support the fact that Ru-BD could be accepted as a valuable photosensitizer-drug for further PDT treatment.

A New and Eco‐Friendly Method for Reduction of Ketones in Water

AbstractThis paper reports a new, practical, and environmentally friendly catalytic system for reduction of the ketones to the related alcohols with efficient reaction performance in water. Catalysts were generated in situ from rhodium, ruthenium and iridium transition metal compounds with commercially available piperidines [Piperidine (L1), 2‐hydroxymethylpiperidine (L2), 3‐hydroxymethylpiperidine (L3), 4‐hydroxymethylpiperidine (L4), 4‐hydroxypiperidine (L5)] as bifunctional ligands. Catalyst generated from RuCl2(PPh3)3 and 4‐hydroxymethyl piperidine have shown the best activity in aqueous media which gave a 100% product yield. RuCl2(PPh3)3, has showed a better efficiency than [RuCl2(p‐cymene)]2, IrCl(PPh3)3, or RhCl(PPh3)3 in HCOOH–HCOONa buffer solution. This study was also investigated the relationship between the structure of hydroxymethyl piperidine ligands and the catalytic activity.

Promoting Subordinate, Efficient Ruthenium Sites with Interstitial Silicon for Pt‐Like Electrocatalytic Activity

AbstractThe fundamental understanding and rational manipulation of catalytic site preference at extended solid surfaces is crucial in the search for advanced catalysts. Herein we find that the Ru top sites at metallic ruthenium surface have efficient Pt‐like activity for the hydrogen evolution reaction (HER), but they are subordinate to their adjacent, less active Ru3‐hollow sites due to the stronger hydrogen‐binding ability of the latter. We also present an interstitial incorporation strategy for the promotion of the Ru top sites from subordinate to dominant character, while maintaining Pt‐like catalytic activity. Our combined theoretical and experimental studies further identify intermetallic RuSi as a highly active, non‐Pt material for catalyzing the HER, because of its suitable electronic structure governed by a good balance of ligand and strain effects.

Promoting Subordinate, Efficient Ruthenium Sites with Interstitial Silicon for Pt-Like Electrocatalytic Activity.

The fundamental understanding and rational manipulation of catalytic site preference at extended solid surfaces is crucial in the search for advanced catalysts. Herein we find that the Ru top sites at metallic ruthenium surface have efficient Pt-like activity for the hydrogen evolution reaction (HER), but they are subordinate to their adjacent, less active Ru3 -hollow sites due to the stronger hydrogen-binding ability of the latter. We also present an interstitial incorporation strategy for the promotion of the Ru top sites from subordinate to dominant character, while maintaining Pt-like catalytic activity. Our combined theoretical and experimental studies further identify intermetallic RuSi as a highly active, non-Pt material for catalyzing the HER, because of its suitable electronic structure governed by a good balance of ligand and strain effects.

Biocompatibility and therapeutic potential of glycosylated albumin artificial metalloenzymes

The ability of natural metalloproteins to prevent inactivation of their metal cofactors by biological metabolites, such as glutathione, is an area that has been largely ignored in the field of artificial metalloenzyme (ArM) development. Yet, for ArM research to transition into future therapeutic applications, biocompatibility remains a crucial component. The work presented here shows the creation of a human serum albumin-based ArM that can robustly protect the catalytic activity of a bound ruthenium metal, even in the presence of 20 mM glutathione under in vitro conditions. To exploit this biocompatibility, the concept of glycosylated artificial metalloenzymes (GArM) was developed, which is based on functionalizing ArMs with N-glycan targeting moieties. As a potential drug therapy, this study shows that ruthenium-bound GArM complexes could preferentially accumulate to varying cancer cell lines via glycan-based targeting for prodrug activation of the anticancer agent umbelliprenin using ring-closing metathesis. Biocompatibility plays a crucial role for the development of artificial metalloenzymes (ArMs) for therapeutic applications. This work presents an ArM with a ruthenium catalyst that is protected from physiological glutathione and accumulates in cancer cell lines for metathesis-mediated prodrug activation.

Estimating the Interrelation between the Rate of Atomic Layer Deposition of Thin Platinum-Group Metal Films and the Molecular Mass of Reactant Precursors

The published data on the atomic layer deposition of thin platinum-group metal (Ru, Rh, Pd, Os, Ir, and Pt) films with the use of different reactant precursors and second reactants (O2, O3, H2, etc.) are generalized in the context of microelectronic technologies. A procedure for analyzing the data on the atomic layer deposition kinetics is discussed. The rate of atomic layer deposition of metallic ruthenium is not higher than 0.15 nm/cycle. An inverse dependence of the limiting atomic layer deposition growth rate on the precursor molecular mass is established. The rates of atomic layer deposition of thin films of all the remaining metals in the group range between 0.03–0.07 nm/cycle, which is lower than the values for a monolayer of these metals by several times. The methodology and ways of enhancing the reliability of the kinetic data on the atomic layer deposition are discussed, including the need for taking into account the sample surface types and effects of nucleation delays at the initial growth stages of the thin platinum-group metal film. The possible occurrence of chemical deposition reactions with intermediate products involved at the pulsed injection of the reactants is considered.

Synthesis of Porphyrinoids, BODIPYs, and (Dipyrrinato)ruthenium(II) Complexes from Prefunctionalized Dipyrromethanes

The introduction of functional groups into the meso‐position of dipyrromethanes, boron‐dipyrromethenes (BODIPYs) and porphyrinoids, is of fundamental importance in designing such dye systems for material sciences or photomedicine. One route that has proven to be particularly useful in this respect is the nucleophilic aromatic substitution (SNAr) on porphyrinoids and their precursors carrying electron‐withdrawing substituents. To further expand this methodology, the potential of the 4‐fluoro‐3‐nitrophenyl and the 3,4,5‐trifluorophenyl moieties for the synthesis of functionalized dipyrromethanes, BODIPYs, and porphyrinoids has been evaluated. The 3,4,5‐trifluorophenyl moiety proved not to be applicable in the SNAr with nucleophiles. The introduction of the 4‐fluoro‐3‐nitrophenyl group, however, allowed fast and efficient SNAr with various amine nucleophiles. The synthesized 4‐amino‐3‐nitrophenyl‐substituted dipyrromethanes were successfully applied in the synthesis BODIPYs and were tested in the synthesis of “trans”‐A2B2 porphyrins and A2B corroles. Furthermore, the dipyrromethanes – after oxidation to the dipyrromethenes – were found to be suitable ligands for metal ions giving access to functionalized ruthenium(II) metal complexes.

Lactam Hydrogen Bonds as Control Elements in Enantioselective Transition-Metal-Catalyzed and Photochemical Reactions.

In the last two decades, hydrogen bonds have been established as useful interactions to control the selectivity of various chemical transformations. In this Perspective, the contributions by our group to this growing field of research are summarized and analyzed. In the first section, a chiral template is presented which displays a 1,5,7-trimethyl-3-azabicyclo[3.3.1]nonan-2-one skeleton with a lactam binding site and that has been used in superstoichiometric quantities in a variety of photochemical and radical reactions. Chiral catalysts with a related architecture evolved from the template by introducing a suitable chromophore for harvesting photons in the ultraviolet (benzophenone, xanthone) or visible region (thioxanthone). They act mainly by sensitization and allow for a high catalytic turnover in enantioselective [2 + 2] photocycloadditions and in deracemization reactions. Eventually, the concept of lactam hydrogen bonding was transferred to transition-metal catalysis, and catalysts have been developed which combine, in an enzyme-like fashion, a site for substrate binding and a catalytically active site. Substrate binding has been mainly achieved by a V-shaped ligand based on a tricyclic octahydro-1H-4,7-methanoisoindol-1-one scaffold with a lactam hydrogen-bonding site. The catalytically active metal (ruthenium, manganese, rhodium) is perfectly positioned to the substrate for a site- and enantioselective transfer of an oxygen atom (oxidation, oxygenation) or a nitrogen-based fragment (aziridination, amination).

Mitochondrial Localization of Highly Fluorescent and Photostable BODIPY-Based Ruthenium(II), Rhodium(III), and Iridium(III) Metal Complexes.

A new N,O-based BODIPY ligand was synthesized and further utilized to develop highly fluorescent and photostable Ru(II), Rh(III), and Ir(III) metal complexes. The complexes were fully characterized by different analytical techniques including single-crystal XRD studies. The photostabilities and live cell imaging capabilities of the complexes were investigated via confocal microscopy. The complexes localized specifically in the mitochondria of live cells and showed negligible cytotoxicities at a concentration used for imaging purposes. They also exhibited high photostabilities, with fluorescence intensities remaining above 50% after 1800 scans.