Ruthenium Metal Research Articles

A cellular NO sensor based on aggregation-induced electrochemiluminescence and photoelectron transfer of a novel ruthenium(II) complex

Here, we present a dual amplification strategy of electrochemiluminescence (ECL) based on aggregation-induced and photoelectron transfer (PET) inhibition using a designed ruthenium-based complex for the highly sensitive detection of nitric oxide (NO). A novel ruthenium(II) complex ([Ru(phen)2(DA-phen)]2+, DA-phen: 5,6-diamino-1,10-phenanthroline) was synthesized that uses the O-diaminophenyl group for specific recognition of NO and the ruthenium metal center with 1,10-phenanthroline as the luminophore. In the first step, the 1,10-phenanthroline groups function as the aggregation part. Increasing the volume fraction of a poor solution (H2O: fw, v%) in the DMSO mixture system from 0% to 80% yielded an increase in the fluorescence (FL) and electrochemiluminescence (ECL) intensities by 3- and 42-fold when compared with the FL and ECL intensities in pure DMSO, respectively. The second step involves a PET process. Reacting the complex with NO in physiological pH aqueous media under aerobic conditions to afford its triazole derivative, [Ru(phen)2(TA-phen)]2+ (TA-phen: 5,6-triazole-1,10-phenanthroline), inhibited the electron transfer process, yielding a remarkable further increase in the FL and ECL efficiencies of the Ru(II) complex. The ECL intensities was 86-fold higher in the presence of NO. This dual amplification strategy enabled the sensitive detection of NO from 1.8 × 10–10 to 1.8 × 10–5 M with a detection limit of 60 pM (S/N = 3) and offered excellent specificity with no detectable interference by RNS and metal ions. Furthermore, selective NO detection in cells was achieved using this complex. Thus, this assay should be suitable for applications in environmental toxicology research and early clinical diagnosis.

Synthesis, cytotoxicity and antibacterial activities of ruthenium, rhodium and iridium metal complexes containing diazafluorene functionalized ligands

New structurally related Ru(II), Rh(III) and Ir(III) N∩N chelating complexes of general formula [(arene)M(κ2(N∩N)L)Cl]PF6 (where arene = p-cymene, benzene and Cp*, M = Ru, Rh and Ir and L = 4,5 diazafluorene derivative ligands) have been designed and synthesized. All the complexes have been characterized by physicochemical and spectroscopic methods (FT-IR, NMR, UV, HRMS). The presence of a distorted octahedral geometry around the metal ion was confirmed by single crystal X-ray diffraction studies. The synthesized ligands, along with their metal complexes, were screened for their in-vitro antibacterial activity against two Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and two Gram-positive (Bacillus thuringiensis and Staphylococcus aureus) bacterial strains and also for in-vitro antioxidant and cytotoxicity activities. Results of antibacterial activity revealed that the metal complexes possess good antibacterial activity. Cytotoxicity results displayed that the compounds act as potent anticancer agents.

Visible-light-harvesting basolite-A520 metal organic framework for photocatalytic hydrogen evolution

A heterogeneous photosensitizer Ru@dpdhpzBASF-A520 has been successfully synthesized following an unprecedented strategy based on the incorporation of surface dipyridyl-dihydropyridazine adducts by Diels–Alder reaction on the aluminum fumarate units of the highly porous metal-organic framework (MOF) BASF-A520 and their further coordination to ruthenium metal centers. The characterization of the resulting metal-organic framework, including the ruthenium bipyridine-like photosensitizer moieties attached to its linkers, has been carried out by a wide variety of techniques, such as X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption-desorption isotherms, solid-state cross-polarization magic angle spinning carbon-13 nuclear magnetic resonance (13C CP/MAS NMR), X-ray photoelectron spectroscopy (XPS) and ultraviolet–visible (UV–vis) spectroscopy. The light absorption in the visible region shown by the resulting material, Ru@dpdhpzBASF-A520, has allowed its application as a single-site solid photosensitizer for photochemical reactions of hydrogen evolution in conjunction with Pt nanoparticles as catalyst, EDTA as sacrificial electron donor and MV as electron carrier. A remarkable photocatalytic activity after 72 h was achieved, with a TON of 1157 based on the heterogeneous ruthenium photosensitizer, in aqueous solution at pH 5.0, which confirmed the effective stabilization of the ruthenium dipyridyl-dihydropyridazine adducts on the MOF surface and the efficient electron injection from the photoexcited Ru@dpdhpzBASF-A520 to Pt nanoparticles mediated by MV electron carrier for hydrogen generation from water.

Process Controlled Ruthenium on 2D Engineered V-MXene via Atomic Layer Deposition for Human Healthcare Monitoring.

In searching for unique and unexplored 2D materials, the authors try to investigate for the very first time the use of delaminated V-MXene coupled with precious metal ruthenium (Ru) through atomic layer deposition (ALD) for various contact and noncontact mode of real-time temperature sensing applications at the human-machine interface. The novel delaminated V-MXene (DM-V2 CTx ) engineered ruthenium-ALD (Ru-ALD) temperature sensor demonstrates a competitive sensing performance of 1.11%°C-1 as of only V-MXene of 0.42%°C-1 . A nearly threefold increase in sensing and reversibility performance linked to the highly ordered few-layered V-MXene and selective, well-controlled Ru atomic doping by ALD for the successful formation of Ru@DM-V2 CTX heterostructure. The advanced heterostructure formation, the mechanism, and the role of Ru have been comprehensively investigated by ultra-high-resolution transmission/scanning transmission electron microscopies coupled with next-generation spherical aberration correction technology and fast, accurate elemental mapping quantifications, also by ultraviolet photoelectron spectroscopy. To the knowledge, this work is the first to use the novel, optimally processed V-MXene over conventionally used Ti-MXene and its surface-internal structure engineering by Ru-ALD process-based temperature-sensing devices function and operational demonstrations. The current work could potentially motivate the development of multifunctional, future, next-generation, safe, personal healthcare electronic devices by the industrially scalable ALD technique.

Ruthenium Metal–Organic Frameworks as Stable Nanostructures for Selective Hydrogen Production from Acetaldehyde and Water under Mild Conditions

Hydrogen is a promising energy carrier because it is a wide and sustainable source. However, it is still extremely difficult to store and transport hydrogen safely because of its active chemical properties and harsh explosion limits. Organic liquid is a popular research field for hydrogen production and storage. Inspired by its biological metabolism, here acetaldehyde is innovatively used for hydrogen production. The hydrogen content of an acetaldehyde–water solution is 10.2 wt %, which is slightly lower than that of a methanol–water solution but much higher than that of formic acid and formaldehyde. For the first time, we prepared several ruthenium metal–organic frameworks (MOFs) as stable nanostructures for selective hydrogen production from acetaldehyde and water under mild conditions (∼60 °C). Ru-MOFs all have nanoscale pores, and the turnover frequency of ruthenium 2,3,5,6-tetramethyl-1,4-phenylenediamine for acetaldehyde decomposition is up to 223 h–1 in water at 90 °C. Because C–C bond cleavage is an inevitable step for hydrogen or energy production from C2 organics, ion chromatography, high-performance liquid chromatography, 1H NMR spectroscopy, and mass spectrometry were employed to propose a catalytic process of hydrogen production from acetaldehyde decomposition. We evidently prove that water participates in acetaldehyde decomposition, thereby claiming an acetaldehyde–water reforming process. Additionally, we confirm that formic acid and acetic acid are the intermediates during the hydrogen production process. This research not only holds great promise for hydrogen production from C2 organics at low temperatures, as well as catalytic technology for C–C bond cleavage, but it also provides certain profound scientific insights for hydrogen or energy production from multicarbon organics, such as biomass.

Mo doped Ru-based cluster to promote alkaline hydrogen evolution with ultra-low Ru loading

Green hydrogen energy developed through electrochemistry is one of the solutions to current energy problems. The less noble metal ruthenium (Ru) plays an important role in alkaline electrocatalytic hydrogen evolution reaction (HER) as an effective electrocatalyst. Nevertheless, the high cost (> 110 RMB per gram) hinders the large-scale application of Ru in industrial hydrogen production. Moreover, the strong adsorption of OH∗ intermediates over Ru limits the electrocatalytic performance in alkaline HER. Here, we report the Mo-doped Ru nanocluster embedded on N-doped carbon framework (RuMo/NC) as alkaline HER catalyst, which shows excellent catalytic performance with an overpotential of 24.2 mV to reach 10 mA cm−2 with only 0.4 wt% of Ru, much lower than that of most reported Ru-based catalysts. DFT calculations reveal the introduction of Mo has improved the activity by alleviating the poisoning effect of OH∗ over Ru in HER. Through fully utilizing Ru in the catalyst, this work marks a step forward in the development of Ru-based catalysts in alkaline HER.

Synthesis, Characterization, and Antibacterial Properties of mixed ligand Complexes of (L-leucine and 8-hydroxyquinoline) with Fe (III ),Cr (III) La(III)) and Ru(III ) ions

The research includes the synthesis and identification of the mixed ligands complexes of M+3 Ions in general composition ,[M(Leu)2(Q)]
 Where L-leucin (C6H13NO2)symbolized as( Leu H) as a primary ligand and
 8-hydroxyqinoline,(C9H7NO) symbolized as (8-HQ) as a secondary ligand .
 The ligands and the metal chlorides were brought in to reaction at room temperature in ethanol as solvent. The reaction required the following molar ratio [(1:1:2)(metal): Q-:2Leu-] with M(III ) ions, were 
 M(III) = Fe (III ),Cr (III) La(III)) and Ru(III )
 The reaction gave solid crystalline complexes which have been characterized us the following techniques: Thermal stability, Solubility, Molar conductivity, Determination the percentage of the metal in the complexes by (AAS). Spectroscopic Methods [FT-IR and UV-Vis], and. The proposed structure of the complexes using program, chem. office 3D(2006) .], Biological effects for some complexes were investigated .
 Numerous papers have been published on metal complexation of amino acids and derivatives during the past ten years. Metal amino acid complexes have long been of interest as models for metal –Ligand systems and interaction which may occur in nature(1)Biological importance of several amino acids their complexes with transition metals is well documented(2-3)The amino acid L- leucin and various transition metals are important in the biological functions of humans, animals, and plants. L- leucine is one of the twenty major amino acids and is considered an essential amino acid (4)
 8-hydroxyqinoline or 8-qinolineis an organic compound with the formula C9H7NO2 is the name most commonly used ,while its trivial name is (oxine),which is conventionally used for the description of chelate compounds Oxinates ,as out of seven possible hydroxyqinoles, only 8-hydroxyqinoline forms chelate with metal ions . [5-6]
 Ruthenium polypyridyl and phenanthroline complexes have been extensively investigated because of their interesting photochemical[7],catalytic [8], biological [9] and electrochemical [10,11] properties.
 Lanthanide(III) carboxylates have been widely studied in recent years due to their physico-chemical properties, variety of structural types and potential uses as fluorescent sensors. The isomers of mono-,di- and trimethoxybenzoates of rare earth elements(III) have been examined. [12-13]
 A series of ruthenium metal complexes involving mono-sulfonylated non-innocent o-phenylenediamine ligands have been characterized in detail using NMR, MS, FT-IR, X-Ray, UV-vis and electrochemical studies. [14]
 In this paper we present the synthesis and study of Cr(III),Fe(III) La(III) and Ru(III) complexes with amino acid (L-leucin) as a primary ligand and 8-hydroxyqinoline as a secondary ligand have been used, respectively.

Synthesis, characterization, photophysical and electrochemical properties, and biomolecular interaction of 2,2'-biquinoline based phototoxic Ru(II)/Ir(II) complexes.

The phototoxic nature of drugs has been seen to convey immense importance in photo activated chemotherapy (PACT) for the selective treatment of disease. Rationally, in order to eradicate the vehemence of cancer in a living body, the design of phototoxic molecules has been of growing interest in research to establish a selective strategy for cancer therapy. Therefore, the present work portrays the synthesis of a phototoxic anticancer agent by incorporating ruthenium(II) and iridium(III) metals into a biologically active 2,2'-biquinoline moiety, BQ. The complexes, RuBQ and IrBQ, have been revealed as effective anticancer agents with remarkable toxicity in the presence of light compared to the dark towards HeLa and MCF-7 cancer cell lines due to the production of a profuse amount of singlet oxygen (1O2) upon irradiation by visible light (400-700 nm). Complex IrBQ exhibited the best toxicity (IC50 = 8.75 μM in MCF-7 and 7.23 μM in HeLa) in comparison to the RuBQ complex under visible light. RuBQ and IrBQ displayed considerable quantum yields (Φf) along with a good lipophilic property, indicating the cellular imaging capability of both complexes upon significant accumulation in cancer cells. Also, the complexes have shown significant binding propensity with biomolecules, viz. deoxyribonucleic acid (DNA) as well as serum albumin (BSA, HSA).

Methanol Synthesis from CO2 and H2O Using a Solid Phosphate Electrolyzer at 240 °C and 28 Bar

It has been demonstrated that it is possible to produce methanol in one step in reasonable amounts by electrolysis of CO2 and H2O gasses dissolved under 28 bar and at 240 °C in contact with an electrolyte consisting of solid CsH2PO4 with additions of polyvinyl butyral (PVB) acting as a binder. The cathode was designed as a sandwich with a layer of a copper methanol catalyst and a porous platinum electrode. The anode consisted of porous ruthenium metal covered by a layer of RuO2. The system was operated with current densities of up to ca. 100 mA cm−2 with a voltage of less than 2 volts producing methanol with a Faradaic efficiency of up to ca. 7%. There seems to be nothing against recirculating the rest of reactant gases to improve the conversion. The question is of course whether the present approach can compete with a more traditional conversion starting with electrochemical produced hydrogen.

Preparation of Ruthenium Hollow Spheres as Catalysts for Selective Hydrogenation of Benzene to Cyclohexene

In this paper, a simple and effective method was used to synthesize monodisperse metal Ruthenium nanospheres (Ru-HNSs), and the silicon dioxide (SiO2) nanospheres synthesized by Stober method were used as hard templates. The surface of SiO2 was double modified by γ-aminopropyltriethoxysilane (KH550) and salicylaldehyde, so that Ru3+ grew uniformly on the surface of modified SiO2 and reduced to form a stable and durable layer of Ru metal. Then the hard template SiO2 was corroded by chemical etching to obtain Ru-HNSs hollow spheres. The results show that the diameter of SiO2 microspheres was about 300nm, the wall thickness of Ru-HNSs was about 3nm, and the diameter was about 100nm.

Low-resistivity ruthenium metal thin films grown via atomic layer deposition using dicarbonyl-bis(5-methyl-2,4-hexanediketonato)ruthenium(II) and oxygen

Herein, low-resistivity Ru metal films were fabricated via atomic layer deposition (ALD) using dicarbonyl-bis(5-methyl-2,4-hexanediketonato)Ru(II) and O2 as the Ru precursor and co-reactant, respectively. ALD-grown Ru showed excellent growth characteristics, with high growth per cycle (0.89–1.44 Å/cycle), short incubation period (<3 cycles), and good conformality at deposition temperatures of 240–300 °C. Polycrystalline Ru films with a dense grain structure were obtained, and the crystallinity and grain size of the Ru metal films increased with increasing deposition temperature. The Ru films contained negligible carbon impurities at all investigated deposition temperatures; however, oxygen-impurity contents of 16, 8, and 3 at% were observed at 240, 270, and 300 °C, respectively. Interestingly, despite the presence of significant oxygen impurities, the as-prepared ALD-grown Ru metal films showed a very low resistivity of 13.6–16.5 μΩ cm. Post-deposition annealing at 400–700 °C enhanced the electrical resistivity of the film (to as low as ∼10.4 μΩ cm), owing to the increased grain size, dense and smooth surface morphology, and negligible oxygen-impurity content. Modeling of the electron scattering mechanism of the ALD-grown Ru films revealed that the grain size of the films substantially influences the film resistivity, whereas the oxygen impurity in the Ru film had a relatively insignificant effect.

Nano-porous ruthenium-palladium and ruthenium-platinum alloys and their application as hydrogenation catalysts

Nano-alloys of platinum or palladium attract considerable attention in several catalytic applications. Specifically, nano-porous alloys of these metals serve as catalysts or gas adsorbents. Still, preparing such nano-porous alloys with precise and well-controlled metal composition is considered a synthetic challenge. Previous studies have shown a new approach for the fabrication of nano-porous metals and alloys with controlled compositions through the chemical reduction of metal complex salts. In this work, we obtained two bi-complex salts as precursors for Ru-Pd and Ru-Pt alloys. Single crystals of these salts were also obtained and structurally characterized using X-ray crystallography. Then, using the mentioned procedure, the following nano-porous metallic materials were prepared: Ru2Pd3 and Ru2Pt3 alloys, pure ruthenium, platinum, and palladium metals. Powder X-ray diffraction analysis determined the crystalline phases of these metallic materials. High-resolution scanning electron microscopy indicated that they assemble as clusters of interconnected nanoscale metallic ligaments separated by pores of similar dimensions. Each cluster preserves the microscale morphology of its salt precursor. Energy-dispersive X-ray spectroscopy measurements enabled the determination of the precise molar ratio between the two metals within the salts and alloys. Focused ion beam tomography enabled the 3D structural representation of the metals and alloys and the determination of their porosity and specific surface areas using geometrical analysis. All the metallic materials acquired more than 60% porosity and more than 50 m2/g of specific surface area. Specifically, Ru2Pd3 alloy acquired the highest values of ∼91% porosity and a surface area of 386 m2/g. The nano-porous metals and alloys exhibit high selectivity in the catalytic hydrogenation of phenyl-acetylene compared to other non-porous commercial catalysts, implying that their structure improved the selectivity. In addition, the alloys showed high conversions and overall high yields in the same reaction, specifically compared to the pure metals. Subsequently, these results support and extend our previous research and suggest a class of palladium or platinum nano-porous alloys that may serve as new and promising catalysts.

Self-Assembled Monolayers of Molecular Conductors with Terpyridine-Metal Redox Switching Elements: A Combined AFM, STM and Electrochemical Study

Self-assembled monolayers (SAMs) of terpyridine-based transition metal (ruthenium and osmium) complexes, anchored to gold substrate via tripodal anchoring groups, have been investigated as possible redox switching elements for molecular electronics. An electrochemical study was complemented by atomic force microscopy (AFM) and scanning tunneling microscopy (STM) methods. STM was used for determination of the SAM conductance values, and computation of the attenuation factor β from tunneling current-distance curves. We have shown that SAMs of Os-tripod molecules contain larger adlayer structures compared with SAMs of Ru-tripod molecules, which are characterized by a large number of almost evenly distributed small islands. Furthermore, upon cyclic voltammetric experimentation, Os-tripod films rearrange to form a smaller number of even larger islands, reminiscent of the Ostwald ripening process. Os-tripod SAMs displayed a higher surface concentration of molecules and lower conductance compared with Ru-tripod SAMs. The attenuation factor of Os-tripod films changed dramatically, upon electrochemical cycling, to a higher value. These observations are in accordance with previously reported electron transfer kinetics studies.

Effects of chelate ligands containing NN, PN, and PP on the performance of half-sandwich ruthenium metal complexes as sensitizers in dye sensitized solar cells (DSSCs): Quantum chemical investigation

In this study, the structural and electronic properties of ruthenium dye derivatives of the type half sandwiches complexes presented to be utilized in dye-sensitized solar cells (DSSCs) as sensitizers were examined employing Density Functional Theory (DFT) and Time Dependent Density Functional Theory (TD-DFT) techniques. To design new ligands that raise dye performances in dye sensitized solar cells, O and N atoms in the donor ligand moiety were changed to S and P atoms respectively, in our substitution. Six dye derivatives Ru1(NO), Ru1(NS), Ru1(PS), Ru2(NO), Ru2(NS) and Ru2(PS) were theoretically built. Apart from the effect of ligand donor bonding modes on electronic properties, the impact of the lone pair of heteroatom N has also been investigated. The proposed dyes' absorption maxima have been studied. The substitution of (NO) bonding modes with (NS) or (PS) ones has a considerable impact on the electronic properties. Going from (NO) to (NS) or (PS), the intense absorption is shown in the absorption spectra of the suggested dyes. According to the photovoltaic characteristics of open circuit photovoltage (Voc), light harvesting efficiency (LHE), electron injection driving force (Ginj) and regeneration's free energy (Greg) the complexes Ru1(NS), Ru1(PS), and Ru2(PS) are showing promise in order to create novel dyes for solar cells.

Half-sandwich ruthenium(II), rhodium(III) and iridium(III) fluorescent metal complexes containing pyrazoline based ligands: DNA binding, cytotoxicity and antibacterial activities

A series of nine new complexes of ruthenium(II), rhodium(III), and iridium(III) incorporated with pyrazoline-based ligands were synthesized and characterized by various spectroscopic techniques such as FTIR, 1H NMR, 13C NMR, UV-Vis spectroscopy, ESI-MS spectrometry and X-ray crystallographic studies. All the synthesized compounds were assessed for their antibacterial abilities against Gram-positive and Gram-negative bacterial strains. The compounds showed better antibacterial activity against two Gram-positive bacteria (Staphylococcus aureus and Bacillus Thuringiensis), with activities superior to standard kanamycin. Antioxidant studies revealed the mild radical scavenging proficiency of the compounds. DNA binding studies using fluorescence spectroscopy showed that the compounds could bind to Salmon Milt DNA electrostatically via external contact and groove surface binding with moderate affinity. The synthesized complexes were tested for anticancer activity using cell cytotoxicity and apoptosis assays in Dalton's lymphoma (DL) cell lines. The findings were compared to cisplatin (the standard drug) under identical experimental conditions. The cell viability results showed that complex 7 induced higher cytotoxicity in the DL cell line than the other tested compounds. The results of the molecular docking analysis further suggest that selective complexes have complete contact with the active amino acids sites of anti-apoptotic Bcl-2 family protein.

Direct production of olefins from syngas with ultrahigh carbon efficiency

Syngas conversion serves as a competitive strategy to produce olefins chemicals from nonpetroleum resources. However, the goal to achieve desirable olefins selectivity with limited undesired C1 by-products remains a grand challenge. Herein, we present a non-classical Fischer-Tropsch to olefins process featuring high carbon efficiency that realizes 80.1% olefins selectivity with ultralow total selectivity of CH4 and CO2 (<5%) at CO conversion of 45.8%. This is enabled by sodium-promoted metallic ruthenium (Ru) nanoparticles with negligible water-gas-shift reactivity. Change in the local electronic structure and the decreased reactivity of chemisorbed H species on Ru surfaces tailor the reaction pathway to favor olefins production. No obvious deactivation is observed within 550 hours and the pellet catalyst also exhibits excellent catalytic performance in a pilot-scale reactor, suggesting promising practical applications.

Influence of Ru on structure and corrosion behavior of passive film on Ti-6Al-4V alloy in oil and gas exploration conditions

In order to investigate the influence of minor Ru on the electrochemical behaviour and structural characteristics of passive films on the surface of Ti-6Al-4V alloys under various oil and gas exploration conditions, electrochemical techniques, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and corrosion simulation tests were carried out. The results revealed that the oil and gas exploration conditions had a serious impact on the electrochemical behaviour and corrosion resistance of the tested alloys. The passivation film resistance and corrosion potential of the tested titanium alloys were significantly reduced with increasing acidity and temperature. With the addition of minor ruthenium, the potential of the passive film on the Ti-6Al-4V-0.11Ru alloy surface increased because of the high surface potential of the ruthenium element. The contents of metallic ruthenium and tetravalent titanium oxide TiO2 in the surface film of the Ti-6Al-4V-0.11Ru alloy both increased with increasing temperature, which led to increase the thickness, stability, corrosion resistance and repairability of the passive film on the surface of the Ti-6Al-4V-0.11Ru alloy being better than those qualities of Ti-6Al-4V. These results were also confirmed by corrosion simulation tests.

Metallo-Drugs in Cancer Therapy: Past, Present and Future.

Cancer treatments which include conventional chemotherapy have not proven very successful in curing human malignancies. The failures of these treatment modalities include inherent resistance, systemic toxicity and severe side effects. Out of 50% patients administrated to chemotherapy, only 5% survive. For these reasons, the identification of new drug designs and therapeutic strategies that could target cancer cells while leaving normal cells unaffected still continues to be a challenge. Despite advances that have led to the development of new therapies, treatment options are still limited for many types of cancers. This review provides an overview of platinum, copper and ruthenium metal based anticancer drugs in clinical trials and in vitro/in vivo studies. Presumably, copper and ruthenium complexes have greater potential than Pt(II) complexes, showing reduced toxicity, a new mechanism of action, a different spectrum of activity and the possibility of non-cross-resistance. We focus the discussion towards past, present and future aspects.

Impacts of ruthenium valence state on the electrocatalytic activity of ruthenium ion-complexed graphitic carbon nitride/reduced graphene oxide nanosheets towards hydrogen evolution reaction

Design and engineering of effective electrode catalysts represents a critical first step for hydrogen production by electrochemical water splitting. Nanocomposites based on ruthenium atomically dispersed within a carbon scaffold have emerged as viable candidates. In the present study, ruthenium metal centers are atomically embedded within graphitic carbon nitride/reduced graphene oxide nanosheets by thermal refluxing. Subsequent chemical reduction/oxidation leads to ready manipulation of the ruthenium valence state, as evidenced in microscopic and spectroscopic measurements, and hence enhancement/diminishment of the electrocatalytic activity towards hydrogen evolution reaction in both acidic and alkaline media. This is largely ascribed to the increased/reduced contribution of the Ru valence electrons to the density of state near the Fermi level which dictates the binding and reduction of hydrogen. Results from this study highlight the significance of the valence state of metal centers in the manipulation and optimization of the catalytic performance of single atom catalysts.

Ruthenium Metallotherapeutics: Novel Approaches to Combatting Parasitic Infections.

Human parasitic infections cause a combined global mortality rate of over one million people per annum and represent some of the most challenging diseases for medical intervention. Current chemotherapeutic strategies often require prolonged treatment, coupled with subsequent drug-induced cytotoxic morbidity to the host, while resistance generation is also a major concern. Metals have been used extensively throughout the history of medicine, with more recent applications as anticancer and antimicrobial agents. Ruthenium metallotherapeutic antiparasitic agents are highly effective at targeting a range of key parasites, including the causative agents of malaria, trypanosomiasis, leishmaniasis, amoebiasis, toxoplasmosis and other orphan diseases, while demonstrating lower cytotoxicity profiles than current treatment strategies. Generally, such compounds also demonstrate activity against multiple cellular target sites within parasites, including inhibition of enzyme function, cell membrane perturbation, and alterations to metabolic pathways, therefore reducing the opportunity for resistance generation. This review provides a comprehensive and subjective analysis of the rapidly developing area of ruthenium metal- based antiparasitic chemotherapeutics, in the context of rational drug design and potential clinical approaches to combatting human parasitic infections.