Ruthenium Metal Research Articles

Enhanced ruthenium selectivity for the conversion of FAMEs to diesel-range alkanes by surface decoration of FeOx species

Ruthenium-based catalysts have been widely used in the lignin depolymerization and polystyrene hydrogenolysis reactions due to its superior hydrogenolysis activity for C-O and C-C bonds. However, serious cleavage of C-C bonds at high temperatures greatly limits its application in the production of green biodiesel from the conversion of natural oils and bio-derived fatty esters. In this work, we found that introducing a suitable second less-reactive metal (e.g., Fe, Zn) can effectively suppress the hydrogenolysis activity of ruthenium (Ru) metal for C-C bonds and exhibit a high selectivity (>90 %) to diesel-range alkanes (C15-C18 alkanes) in the conversion of fatty acid methyl esters (FAMEs) even at high reaction temperature (250 °C) over the Ru1Fe0.5 catalyst, while an obvious cracking reaction was observed from 210 °C over the monometallic Ru catalyst. Detailed characterization and theoretical calculation results reveal that the introduction of Fe species in the RuFe catalysts weakens the interaction between catalyst and the resulting alkanes, which inhibits the cracking of alkanes. Specifically, adding Fe species breaks the ensemble of Ru atoms and decreases the binding affinity of metallic Ru for H2, which suppresses the activity of Ru metal for the hydrogenolysis of C-C bonds and exhibits a high selectivity to diesel-range alkanes. This research provides valuable information for improving the hydrodeoxygenation (HDO) selectivity of Ru-based catalysts while inhibiting its high hydrogenolysis activity for C-C bonds.

Research Progress of Metal Anticancer Drugs.

Cancer treatments, including traditional chemotherapy, have failed to cure human malignancies. The main reasons for the failure of these treatments are the inevitable drug resistance and serious side effects. In clinical treatment, only 5 percent of the 50 percent of cancer patients who are able to receive conventional chemotherapy survive. Because of these factors, being able to develop a drug and treatment that can target only cancer cells without affecting normal cells remains a big challenge. Since the special properties of cisplatin in the treatment of malignant tumors were accidentally discovered in the last century, metal anticancer drugs have become a research hotspot. Metal anticancer drugs have unique pharmaceutical properties, such as ruthenium metal drugs with their high selectivity, low toxicity, easy absorption by tumor tissue, excretion, and so on. In recent years, efficient and low-toxicity metal antitumor complexes have been synthesized. In this paper, the scientific literature on platinum (Pt), ruthenium (Ru), iridium (Ir), gold (Au), and other anticancer complexes was reviewed by referring to a large amount of relevant literature at home and abroad.

A Ruthenium(II) complex based long lifetime phosphorescent probe for copper ions and pH detection

ObjectiveTransition metal ruthenium(II) complex was used to prepare a dual-functional phosphorescent probe for the detection of Cu2+ ion and pH. MethodsThe ligand (E)-6-((thiazol-2-yl methylene)amino)-1,10-phenanthrolin-5-amine (tmpa) was prepared by condensation of 5,6-diamine-1, 10-phenanthroline with 2-formylthiazole, and then ruthenium(II) complex [Ru(bpy)2tmpa](PF6) (Ru-tmpa, bpy ​= ​2,2′-bipyridine) was synthesized by the coordination of tmpa with cis-Ru(bpy)2Cl2. Phosphorescence spectra were measured to investigate its response to metal ions (Li+, Na+, K+, Mg2+, Ca2+, Mn2+, Pb2+, Cr2+, Co2+, Ni2+, Cu+, Cu2+, Fe3+, Fe2+ and Zn2+). The binding affinity and detecting limit of Ru-tmpa to copper ions were tested by titration experiment. The ability of the probe to monitor copper ion levels inside cells was tested by confocal microscopy imaging. ResultsRu-tmpa can rapidly, sensitively and selectively detect Cu2+ in water and biological sample, and shows a sensitive phosphorescence response to pH. Ru-tmpa can penetrate cell membrane, enter the cell, and monitor the level of copper ions inside cell. ConclusionA novel fluorescent probe Ru-tmpa was synthesized to provide a powerful tool for the detection of Cu2+ and pH in biological and environmental systems.

Antibacterial and ct-DNA binding studies of new synthesized ruthenium (III) hydroxamate complexes: Design, synthesis, DFT calculations and in-vitro study

Ruthenium (III) complexes (1–5) with general composition [Ru(L1–4)3] and [Ru(HL5)3Cl3] where L1 = benzohydroximato (1), L2 = salicylhydroximato (2), L3 = acetohydroximato (3), L4 = hydroxyureato (4), HL 5 = N‑hydroxy-N-phenylbenzamide (5) were synthesized by reacting RuCl3·3H2O with respective hydroxamic acids in 1:3 molar ratio . The complexes were characterized using various techniques including ruthenium metal analysis, elemental analysis, UV–Vis, FT-IR, NMR (1H and 13C), and mass spectrometry. Antibacterial activity of the complexes was evaluated using the agar well diffusion method against ten pathogenic strains. The complexes showed significant inhibition zones and were more active than their corresponding ligands. DNA binding studies indicated intercalative binding mode, with hypochromism and red shift observed. Computational and structural parameters were determined using Frontier Molecular Orbital (FMO) energies and Density Functional Theory (DFT) calculations. The complexes demonstrated favorable molecular geometry, chemical reactivity, and biological activity.

Synthesis and characterization of a new ruthenium (II) terpyridyl diphosphine complex

Ruthenium complexes have been prepared for several applications, mostly for electrocatalysis, catalytic hydrogenation, energy conversion, photolysis, medicinal chemistry, among other fields. Bipyridine and terpyridine ligands are commonly found in the metal coordination sphere, including ruthenium, largely due to the high stability exhibited by the resulting complex and the possibility of greater stereochemical control during synthesis. The combination of substituted terpyridine ligands with diphosphine ligands to the metal ruthenium occurs to a lesser extent and its catalytic potential has been examined in several studies. This paper describes the synthesis of a new ruthenium (II) aqua complex containing aryl diphosphine and substituted terpyridine ligands: [Ru(L)(totpy)(OH2)](ClO4)2 (L=Ph2PCH2CH2PPh2); (totpy=4´-(4-tolyl)-2,2´:6´,2´´-terpyridine). The synthesis route was conducted in three steps; the final and the intermediate products have shown good reaction yields; the results of the characterization of the aqua complex by cyclic voltammetry, UV-visible spectroscopy and elemental analysis are consistent with the proposed chemical structure.

Newly design and synthesis of Ni–Ir–Ru-doped mesoporous silica open-frameworks for admirable electrochemical water-oxidation application

As traditional non-renewable energy sources become scarcer, researchers are exploring effective strategies for producing sustainable and renewable energy. Oxygen evolution reaction through electrocatalytic water splitting (EC-OER) on the surface of a semiconductor has drawn much more attention in the worldwide as it has the principal role towards the several kind of energy applications viz. fuel cell, metal-ion rechargeable batteries and water oxidation. It is extremely difficult to develop eco-friendly, plentiful, and cost-effective nanomaterials as catalysts in order to achieve high efficiency of hydrogen production through water splitting. Furthermore, hierarchical nanostructures will become more valuable in future energy conversion applications due to their excellent physicochemical properties. Herein, we have synthesized total six different kinds of multi-metal-doped porous silica nanomaterials by utilizing the combination of nickel, iridium, and ruthenium metal slats in order to explore them as potential catalysts for electrochemical water oxidation process. We present a simple strategy to synthesize multi-metal-doped silica materials with spherical morphology, deploying a cation surfactant template (CTAB) as a structure directing agent in water-ethanol solvent mixtures. These materials are thoroughly characterized with the help of powder X-ray diffraction (PXRD), UV–Vis, FT-IR, X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HR-TEM), field emission scanning electron microscopy (FE-SEM), nitrogen-sorption isotherm, thermogravimetric (TGA) analysis. The particles are 550–600 nm in size with a fine-looking spherical morphology and surface area in the range of 111–419 m2/g. Among all of these metal-silica, Ni–Ir–Ru-doped mesoporous silica particles (NIRS) exhibit excellent electrocatalytic activity towards oxygen evolution reaction (100 mA/cm2 current density@0.5V) with long-term durability up to 10 h, and the Tafel slope is also very low (∼68 mV/dec) in 1 M KOH medium. The excellent electrical conductivity of Ni–Ir–Ru-doped silica makes it a superior electrocatalyst due to its spherical morphology, synergistic effects of the multi metallic components, and its hierarchical nanoporous structure.

Steam Reforming Catalytic Layer on Anode-Supported and Metal-Supported Solid Oxide Fuel Cells for Direct Ethanol Operation

A catalyst based on lanthanum chromite with exsolved metallic ruthenium nanoparticles (LaCrO3-Ru) was applied as a catalytic layer for internal ethanol steam reforming of anode-supported and metal-supported solid oxide fuel cells. Both the cermet anode and the metal supports exhibit limited catalytic properties for the ethanol steam reforming reaction. Thus, the LaCrO3-Ru catalysts were optimized for operating temperatures in the 600-700 °C range to promote stable ethanol reforming. The microstructure of the deposited catalytic layer was controlled using pore formers with low burnout temperature, and sintering of the catalytic layer was done in situ during cathode sintering of the metal-supported fuel cell. The performance of the fuel cells was evaluated at 700 °C under hydrogen, anhydrous ethanol, and water/ethanol mixtures. The LaCrO3-Ru catalytic layer had no significant impact on the electrochemical properties of the fuel cells, and samples with the catalytic layer or without it exhibited similar performance in hydrogen. Nonetheless, initial durability tests have shown that the catalytic layer plays a crucial role in the stability of both the anode and the metal-supported fuel cells under ethanol.

Highly active Ru/TiO2 nanostructures for total catalytic oxidation of propane.

Ruthenium is a robust catalyst for a variety of applications in environmental heterogeneous catalysis. The catalytic performance of Ru/TiO2 materials, synthesized by using the deposition precipitation with urea method, was assessed in the catalytic oxidation of C3H8, varying the ruthenium loading. The highest catalytic reactivity was obtained for a Ru loading of 2 wt. % in comparison with the 1, 1.5, 3, and 4 wt. % Ru catalysts. The physicochemical properties of the synthesized materials were investigated by XRD, N2 adsorption, TEM, FT-IR pyridine, H2-TPR, and XPS. The size of ruthenium particles was found to be greatly dependent on the pretreatment gas (air or hydrogen) and the catalytic activity was enhanced by the small-size ruthenium metal nanoparticles, leading to changes in the reduction degree of ruthenium, which also increased the Brönsted and Lewis acidity. Metal to support charge transfer enhanced the reactant adsorption sites while oxygen vacancies on the interface enabled the dissociation of O2 molecules as revealed through DFT calculations. The outstanding catalytic activity of the 2Ru/TiO2 catalysts allowed to convert C3H8 into CO2 at reaction temperatures of about 100°C. This high activity may be attributed to the metal/support interaction between Ru and TiO2, which promoted the reducibility of Ti4+/Ti3+ and Ru4+/Ru0 species, and to the fast migration of TiO2 lattice oxygen in the catalyst. Furthermore, the Ru/TiO2 catalyst exhibited high stability and reusability for 30h under reaction conditions, using a GHSV of 45,000h-1. The underlying alkane-metal interactions were explored theoretically in order to explain the C-H bond activation in propane by the catalyst.

Antibacterial Activity of PVA Hydrogels Embedding Oxide Nanostructures Sensitized by Noble Metals and Ruthenium Dye.

Nanostructured oxides (SiO2, TiO2) were synthesized using the sol-gel method and modified with noble metal nanoparticles (Pt, Au) and ruthenium dye to enhance light harvesting and promote the photogeneration of reactive oxygen species, namely singlet oxygen (1O2) and hydroxyl radical (•OH). The resulting nanostructures were embedded in a transparent polyvinyl alcohol (PVA) hydrogel. Morphological and structural characterization of the bare and modified oxides was performed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), UV-Vis spectroscopy, and X-ray photoelectron spectroscopy (XPS). Additionally, electrokinetic potential measurements were conducted. Crystallinity data and elemental analysis of the investigated systems were obtained through X-ray diffraction and X-ray fluorescence analyses, while the chemical state of the elements was determined using XPS. The engineered materials, both as simple powders and embedded in the hydrogel, were evaluated for their ability to generate reactive oxygen species (ROS) under visible and simulated solar light irradiation to establish a correlation with their antibacterial activity against Staphylococcus aureus. The generation of singlet oxygen (1O2) by the samples under visible light exposure can be of significant importance for their potential use in biomedical applications.

Highly-efficient hydrogen production from ammonia decomposition over Co-doped graphdiyne under moderate temperature

Manufacturing hydrogen from ammonia decomposition is an efficient and promising approach for hydrogen utilization. However, its scalable application is significantly impeded by the requirements of precious metal ruthenium (Ru) as catalysts. Herein, we report a type of Co-doped graphdiyne catalyst for catalytically decomposing ammonia (NH3) to generate H2. The metal-doped graphdiyne catalysts were synthesized facilely using co-precipitation approach. The resultant composite catalysts significantly enhanced the reactivity and stability of ammonia decomposition. The Co-doped graphdiyne catalyst achieved nearly complete decomposition of ammonia at 550 ℃, and the conversion rate remained stable over 18 h of continuous reaction. The adsorption and decomposition of ammonia by Co-doped graphdiyne was studied by density functional theory (DFT) calculations. Nitrogen binding strength was used as a descriptor to elucidate the catalyst's activity and reaction kinetics, further supported by the reaction energy barrier. Our study highlights the tremendous potential of metal-doped graphdiyne catalysts for facile hydrogen production via NH3 decomposition, enabling safe and scalable hydrogen utilization.

Nucleation of Co and Ru Precursors on Silicon with Different Surface Terminations: Impact on Nucleation Delay.

Early transition metals ruthenium (Ru) and cobalt (Co) are of high interest as replacements for Cu in next-generation interconnects. Plasma-enhanced atomic layer deposition (PE-ALD) is used to deposit metal thin films in high-aspect-ratio structures of vias and trenches in nanoelectronic devices. At the initial stage of deposition, the surface reactions between the precursors and the starting substrate are vital to understand the nucleation of the film and optimize the deposition process by minimizing the so-called nucleation delay in which film growth is only observed after tens to hundreds of ALD cycles. The reported nucleation delay of Ru ranges from 10 ALD cycles to 500 ALD cycles, and the growth-per-cycle (GPC) varies from report to report. No systematic studies on nucleation delay of Co PE-ALD are found in the literature. In this study, we use first principles density functional theory (DFT) simulations to investigate the reactions between precursors RuCp2 and CoCp2 with Si substrates that have different surface terminations to reveal the atomic-scale reaction mechanism at the initial stages of metal nucleation. The substrates include (1) H:Si(100), (2) NHx-terminated Si(100), and (3) H:SiNx/Si(100). The ligand exchange reaction via H transfer to form CpH on H:Si(100), NHx-terminated Si(100), and H:SiNx/Si(100) surfaces is simulated and shows that pretreatment with N2/H2 plasma to yield an NHx-terminated Si surface from H:Si(100) can promote the ligand exchange reaction to eliminate the Cp ligand for CoCp2. Our DFT results show that the surface reactivity of CoCp2 is highly dependent on substrate surface terminations, which explains why the reported nucleation delay and GPC vary from report to report. This difference in reactivity at different surface terminations may be useful for selective deposition. For Ru deposition, RuCp2 is not a useful precursor, showing highly endothermic ligand elimination reactions on all studied terminations.

3-acetyl-coumarin-substituted thiosemicarbazones and their ruthenium, rhodium and iridium metal complexes: An investigation of the antibacterial, antioxidant and cytotoxicity activities

A series of ruthenium, iridium and rhodium half-sandwich complexes containing 3-acetyl chromen-2-one-4(N)-substituted thiosemicarbazone derivatives have been prepared for use as antibacterial and anticancer agents. These complexes have been isolated as cationic bidentate (N, S) and neutral bidentate (N, S) complexes. The complexes have been characterized by spectral techniques (FT-IR, UV-Vis, NMR and HRMS) and single-crystal X-ray crystallography methods. The structure of complex 6 has been determined by a single-crystal X-ray diffraction study, which shows that coordination of the 3-acetyl chromen-2-one-4(N)-substituted thiosemicarbazone ligand to the metal occurs via azomethine nitrogen and thiolate sulfur atoms. Vitro antibacterial activity against gram-positive Staphylococcus aureus and gram-negative Escherichia coli, Klebsiella pneumonia strains and antioxidant activity have been evaluated. Also, the said complexes were tested for anticancer efficacy (in vitro for 48h) in Dalton's lymphoma (DL) cancer cell lines using cell cytotoxicity (MTT) and apoptosis tests. The results were compared with cisplatin (standard drug) under identical experimental conditions. The cell cytotoxicity results showed that complex 5 induced higher cytotoxicity in DL cells, followed by complex 4, 1, and 2.

Dissolution of Ruthenium Metal by Combined Oxidizing and Reducing Action of Sodium Hypochlorite and HCl Solution

ABSTRACT Ruthenium (Ru) is an important platinum group metal for the manufacture of advanced materials owing to its chemical and physical properties. Generally, it is extremely difficult to dissolve Ru metal by using acidic solutions containing strong oxidizing agents. Therefore, pretreatments like alkali fusion roasting at high temperature are practiced to render the Ru metal soluble in aqueous solution. In this work, a simple procedure was proposed to dissolve Ru metal at room temperature without any pretreatments. The dissolution procedure consisted of two steps: (i) oxidation of Ru metal to RuO4 – by using pure NaClO solution; (ii) reduction of RuO4 – to stable Ru2OCl10 4– by using HCl as a reducing agent. The role of NaClO and HCl in the dissolution of Ru metal was discussed on the basis of the potential-pH diagram and the corresponding oxidation and reduction reactions. The effect of several parameters like the concentration of NaClO and HCl, temperature, time, and pulp density was investigated. Optimum conditions were obtained to completely dissolve Ru metal by using NaClO and HCl solution without alkali fusion.

Immobilization of ruthenium nanoparticles on magnetic hollow mesoporous carbon spheres and investigation of peroxidase-like activity in the oxidation of amine compounds

BackgroundNanoenzymes with properties such as stability, high catalytic activity, easy recycling, and low cost have been subjected to considerable research to develop new enzyme-like heterogeneous catalysts. Carbon supports are very important in the construction of heterogeneous catalysts due to their biocompatibility and proper interaction with organic reactants. MethodsIn this study, ruthenium nanoparticles were immobilized on magnetic hollow mesoporous carbon spheres. At first, hollow mesoporous carbon structures were synthesized by Stober's method. Through carbonization and subsequent etching with NaOH, the synthesized structures were transformed into hollow mesoporous spherical carbon structures. These hollow carbon spheres have been transformed into magnetic hollow carbon spheres after being impregnated with iron ions, freeze-drying, and then calcinated under inert conditions. Finally, these spheres were immobilized with ruthenium metal nanoparticles by wet chemical reduction. Significant FindingsThe peroxidase-like activity of the synthesized nanocomposites was evaluated in the oxidation of amine chromatic compounds of dopamine, ortho-phenylenediamine, and tetramethylbenzidine. Based on the results, these compounds have a lower Michaelis constant constant than hydrogen peroxide, which indicates a strong tendency to the enzymatic reaction. This high reactivity of the synthesized catalyst can be attributed to the synergistic effects of magnetite and ruthenium nanoparticles as well as the role of the carbon support.

Recent Advances and Perspectives in Ru Hybrid Electrocatalysts for the Hydrogen Evolution Reaction

The water-splitting reaction for green hydrogen generation requires highly efficient catalysts on the side for the hydrogen evolution reaction (HER), and metal ruthenium (Ru) is considered a promising catalyst as a result of its similar property in hydrogen-bonding ability but low cost compared to Pt-based materials. The performance is further boosted by the recently developed hybrid Ru-based electrocatalysts. To reveal the relationship between the hybrid catalyst systems and activity for Ru-based catalysts, the research progress of heterostructured Ru hybrid catalysts in the HER is reviewed in this effort. The enhancement of HER activity of Ru hybrid catalysts is first described on the basis of the synergistic effect, strain effect, and electronic effect, and then, the latest progress is discussed in three categories of single ruthenium catalysts, ruthenium-related compounds, and ruthenium alloy catalysts. It is concluded that the heterostructured interface engineering strategy plays an important role in enhancing the activity of Ru-based catalysts in the HER. In the end, the actual problems and challenges are discussed, e.g., the intrinsic activity and stability, application in the real device, etc. It is recommended to pay attention to the long-term stability, performance, and structural evolution as well as the application of the catalysts in the devices. It is hoped that this effort will help with understanding the progress of Ru-based hybrid catalysts in the field of HER catalysis.

Steam Reforming Catalytic Layer on Anode-Supported and Metal-Supported Solid Oxide Fuel Cells for Direct Ethanol Operation

A catalyst based on lanthanum chromite with exsolved metallic ruthenium nanoparticles (LaCrO3-Ru) was applied as a catalytic layer for internal ethanol steam reforming of anode-supported and metal-supported solid oxide fuel cells. The metal support exhibits limited catalytic properties for the ethanol steam reforming reaction. Thus, the LaCrO3-Ru catalysts were optimized for operating temperatures in the 600-700 °C range to promote stable ethanol reforming. The catalytic layer had no significant impact on the electrochemical properties of the fuel cell, and samples with and without the catalytic layer exhibited similar performance in hydrogen. Initial durability tests with LaCrO3-Ru layer have shown that the catalytic layer plays a crucial role in the stability of the metal-supported fuel cell under ethanol.

Metal Identity Effects in the Pincer Complex-Catalyzed Dehydrogenative Coupling of Formamides with Alcohols to Form Carbamates

This manuscript describes the impact of metal (ruthenium versus iron versus manganese) on the PNP pincer complex-catalyzed dehydrogenative coupling of formamides with alcohols to yield carbamates. Studies are conducted to compare the structure and reactivity of key organometallic intermediates as a function of metal. These reveal that all three pincer catalysts undergo fast reaction with isocyanates (the initial organic products of formamide dehydrogenation) to form off-cycle metallacyclic species. However, the structures and reactivities of these intermediates vary as a function of metal. The N-bound isomer of the metallacycle is formed with Fe (literature) and Ru (this work), while both O-bound (kinetic) and N-bound (thermodynamic) metallacycles are observed with Mn (this work). At 100 °C, the O-bound Mn cycloadduct reacts rapidly with cyclohexanol to release the pincer catalyst along with the corresponding carbamate. In contrast, all three of the N-bound metallacycles show dramatically lower reactivity toward catalyst regeneration under analogous conditions. The reactivity of the pincer complexes toward formamide dehydrogenation also varies as a function of metal, with Ru and Fe ≫ Mn at 100 °C. Overall, the Mn pincer complex is an effective catalyst for the conversion of a variety of formamides and alcohols to carbamates at 150 °C with catalyst loadings as low as 1 mol %. The catalyst performance and substrate scope are comparable to those of the Fe analogue.

Recent Advances in Noble Metal Nanoparticles for Cancer Nanotheranostics

The limitations of current treatment strategies for cancer management have prompted a significant shift in the research and development of new effective strategies exhibiting higher efficacy and acceptable side effects. In this direction, nanotheranostics has gained significant interest in recent years, combining the diagnostic and therapeutic capabilities of nanostructures for efficient disease diagnosis, treatment, and management. Such nano-assisted platforms permit the site-specific release of bioactive cargo in a controlled fashion while permitting non-invasive real-time in situ monitoring. A plethora of materials has been developed as pharmacologically relevant nanoformulations for theranostic applications ranging from metallic to lipid and polymer-based composite systems, with each offering potential opportunities and its own limitations. To improve advancements with better clarity, the main focus of this review is to highlight the recent developments focusing on using different noble metal nanoparticles (noble MNPs) as cancer nanotheranostic agents, highlighting their properties, advantages, and potential modifications for their successful utilization in personalized medicine. The advantage of using noble metals (not all, but those with an atomic number ≥76) over metal NPs is their tendency to provide additional properties, such as X-ray attenuation and near-infrared activity. The combination of these properties translates to noble MNPs for therapeutic and diagnostic applications, independent of the need for additional active molecules. Through this review, we highlighted the potential application of all noble MNPs and the limited use of osmium, iridium, palladium, rhodium, and ruthenium metal NSs, even though they express similar physicochemical characteristics. The literature search was limited by PubMed, full-text availability, and studies including both in vitro and in vivo models.

Two-dimensional ruthenium nanoparticles between graphite layers: The effect of reduction temperature

A mixture of graphite powder and ruthenium chloride (III) anhydrous was treated at 723 K under 0.3 MPa chlorine for 3 days, followed by reduction under 40 kPa of hydrogen for 1 h to produce ruthenium metal particles intercalated between graphite layers (Ru-GIC). The structures of ruthenium particles depended on the reduction temperatures. Sheet-like ruthenium particles with 1–3 nm thickness and 10 to several hundred nm width containing numerous irregularly shaped holes with round edge, were formed by reduction at 573 K. A Ru-GIC sample treated at 653 K possessed two-dimensional ruthenium nanosheets with hexagonal holes (straight lines intersect at an angle of 120°) in a similar range of thickness and width. On the other hand, Ru-GIC samples reduced at 773 and 823 K showed two-dimensional plate morphology with a thickness of 1–4 nm. In addition, ruthenium nanoparticles supported on the graphite surface (Ru/Gmix) were also prepared from a slurry of ruthenium chloride (III) hydrate and graphite powder by impregnation and hydrogen reduction. The ruthenium particles in Ru/Gmix were spherical at about 3.6 nm, and the reduction temperature did not affect their particles size. Both Ru-GIC and Ru/Gmix samples were evaluated for cinnamaldehyde (CAL) hydrogenation in supercritical carbon dioxide solvent at 323 K, and they were active to produce cinnamyl alcohol (COL) and hydrocinnamaldehyde (HAL). However, Ru-GIC samples showed higher COL selectivity than Ru/Gmix prepared at the same reduction temperature, and COL selectivity over Ru-GIC increased with the reduction treatments at 773 and 823 K.

Coordination attitude of benzothiazole hydrazone in ruthenium(II) complexes: Catalytic applications on direct formation of imines via acceptorless dehydrogenative process

New Ru(II) complexes (1–5) comprising hydrazone of the type [Ru(L1-3)(CO)(PPh3)2]Cl or [Ru(L4-5)H(CO)(PPh3)2] [L1 = (salicyl((2-(benzothiazol-2yl)hydrazono)methylphenol)) (SAL-HBT), L2 = 2-((2-(benzothiazol-2-yl)hydrazono)methyl)-6 methoxyphenol) (VAN-HBT), L3 = naphtyl-2-((2-(benzothiazol-2-yl)hydrazono)methylphenol) (NAP-HBT), L4 = 1-((benzothiazol-2-yl)-2-(furan-2-ylmethylene)hydrazine) (FUR-HBT) or L5 = 1-((benzothiazol-2-yl)-2-(thiophen-2 ylmethylene)hydrazine) (THI-HBT)] have been formulated by reacting [RuHCl(CO)(PPh3)3] with hydrazones in equal molar ratios in ethanol and chloroform medium. The formation of new complexes have been identified by spectral techniques (IR, (1H, 13C &31P) NMR), micro analyses and mass spectrometry. Single crystal XRD study was used to identify solid state structure of the compound 1 and found octahedral geometry around ruthenium metal. The dehydrogenative coupling of alcohol and amine for formation of imines have been performed using the new ruthenium(II) complexes as catalysts.