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Ru(III) chlorocomplexes are poorly extracted into organic solvents, which is due to the charge of the complex as well as those inert character in chloride solutions, that is, formation of RuCl6-n(H2O)n(3-n)- (n=0-6). Therefore, it is difficult to extract Ru(III) by solvent extraction, and Ru(III) is currently separated and purified by the oxidative distillation method. If Ru can be separated and recovered from chloride solutions by solvent extraction, an efficient separation and recovery process for PGMs can be established. Therefore, it is important to investigate the solvent extraction of Ru(III) from chloride solutions. The authors have previously studied solvent extraction of Ru(III) with 2-ethylhexylamine (EHA), which is a primary amine extractant, from chloride solutions and shown that the extraction of Ru(III) with EHA from chloride solutions without the addition of Sn (II)was high. However, the stripping of Ru(III) was difficult. In the present study, extractions of Ru from hydrochloric acid solutions with EHA and octylamine (OA), which are primary amines, were tested to clarify the extraction of Ru and the stripping of Ru with various stripping solutions. The extraction efficiency of Ru with EHA and OA from hydrochloric acid solutions without the addition of Sn (II) was high. And also, it was found that Ru could be easily stripped from EHA with sodium sulfate solutions.

The platter of hard disk drives contains valuable metals such as the Ruthenium and Platinum. However, these metals were not recycled from the disk for a long time because the low-cost separation and concentration technologies have not been established. In this study, we applied the electrical pulsed discharge method to the separation of the metal layer from the glass substrate in the platter. The relationship between the input voltage and the exfoliating rate by the pulsed discharge was investigated. The discharge plasma was generated between the electrodes placed at the center and the outer boundary of the platter. The metal layer along the path of discharge plasma was separated from the substrate. The exfoliating rate was increased by increasing the charging voltage. The exfoliating mechanism was discussed through by the surface observation and the evaluation of plasma temperature caused by the plasma using an electronic microscope and a spectroscope, respectively. [ABSTRACT FROM AUTHOR]

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This comprehensive article summarizes our recent efforts to design functional star polymers via living radical polymerization as functional nanospaces for catalysis and molecular recognition. Metal-bearing star polymer catalysts are efficiently obtained from the ruthenium-mediated linking reaction of arm polymers in the presence of a ligand monomer. Star polymer catalysts (nanoreactors) were effective for oxidation of sec-alcohols, (asymmetric) hydrogenation of ketones, and living radical polymerization, performing activity, stability, functionality-tolerance, and practicability (catalyst recycle, easy product recovery) higher than conventional polymer catalysts and analogues of in-core metal complexes. Core-functionalized star polymer nanocapsules selectively capture and stimuli-responsively release functional molecules. The key is to condense functional groups such as poly(ethylene glycol) (PEG), perfluoroalkane, and quaternary ammonium groups into the cores. Single-chain star polymers are created as a new class of star polymers via the self-folding of amphiphilic random copolymers with intramolecular hydrophobic interaction in water. [ABSTRACT FROM AUTHOR]

Lipid packaged dinuclear ruthenium (II,III) complexes of class III mixed-valent state produce a reversible hypochromic effect in dichloromethane upon external physical stimuli, such as shaking, due to the arrangement of transition dipole moments. In addition, the complexes display morphological changes with aging of the solution. Formation of a bilayer structure causes morphological evolution from microtapes to microtubes, giving rise to changes in absorption spectral intensities. Moreover, these morphological and spectral changes can be reversed by standing and shaking. The concept of lipid packaging could also be expanded to other useful coordination compounds and will allow us to further develop the nanochemistry of coordination materials. [ABSTRACT FROM AUTHOR]

This comprehensive article summarizes our recent efforts to enhance the catalytic activity for living radical polymerization. We designed ligands, solvents and cocatalysts to promote dynamic transformation of the metal complex that is responsible for the catalysis, i.e., the reversible activation of carbon-halogen bond via a one-electron redox reaction. The catalytic activity of ruthenium complexes was dramatically enhanced, which allowed a universal catalysis for a variety of functional monomers, a highly active catalysis in water, and an autonomous catalysis independent of cocatalyst. More importantly, the activity was high enough to reduce the catalyst amount without any loss of controllability, even for the syntheses of higher molecular weight polymers and block copolymers. Iron- and nickel-based complexes were also developed to provide improved catalysis, i.e., faster polymerization and narrower molecular weight distribution than the vanguards. Importantly, some of them were tolerant of polar groups to control the polymerization of functional monomers. [ABSTRACT FROM AUTHOR]

The chemical labeling of proteins with synthetic small compounds is a key technique in chemical biology, protein-based therapy, and material science. Much of the chemical labeling of native proteins, however, depends on the labeling of lysine and cysteine residues. While those methods have contributed significantly to native protein labeling, alternative methods that can modify different amino acid residues are still required. Here we report the development of a novel methodology of oxidative tyrosine labeling, which was inspired by the single-electron transfer reaction in biological systems. The tyrosine labeling methods were developed using small compounds such as N-methyl luminol derivative, N'-acyl-N,N-phenylenediamine, and 1-methyl-4-aryl-urazole under labeling conditions using a hemin, peroxidase, or ruthenium photocatalyst. These methods were applied to target- and site-selective protein modification.

Domino reactions, which enable formations of several chemical bonds and multi-step transformation in one-pot process, have received much attention as an efficient synthetic methodology to preserve chemists from time-consuming purification protocols and protection-deprotection procedures. Furthermore, the domino processes containing skeletal rearrangement have been utilized for constructions of complex molecules because of their potential that they could afford entirely different valuable structures from readily available simple substrates. We recently developed novel domino reactions including ring enlargement process, which could afford biologically important cyclopentanones and nitrogen heterocycles. In this review, we will describe 1) a novel type of palladium-catalyzed domino insertion-ring expansion reaction of dienylcyclobutanols, which could enable a stereospecific synthesis of (Z)-2-(3-aryl-1-propenyl)cyclopentanones, 2) ruthenium-catalyzed domino ring expansion-insertion reaction of 1-acetylenylcyclobutanols for a construction of 2-alkylidenecyclopentanones, and 3) DIBALH-mediated reductive ring expansion reaction of oximes and studies on the reaction mechanisms. The rationales for the observed stereoselectivities in each reaction are also discussed.

Two new catalysts, ruthenium hydride with a nitrogen-containing heterocyclic carbene (A) and an organopalladium catalyst supported on a sulfur-terminated semi-conductor, gallium arsenide (001) (B) were discovered. Both catalysts are environmentally benign, because A can yield indole derivatives with good atom economy, and B can catalyze the Mizoroki-Heck reaction more than 10 times with only trace amounts of leached palladium (ppb level). Substituted 1,2-dihydroquinoline, indole and 3-methylene-2,3-dihydroindole were also prepared selectively from the common starting material, N-allyl-o-vinylaniline, and catalyst by slight modification of the reaction conditions. These procedures address an important issue in diversity-oriented synthesis. These methods utility were demonstrated by application to biologically active natural products synthesis.

Nitrato nitrosylruthenium complexes [RuNO(NO3)x(H2O)5-x] (3-x)+ readily dissociate in aqueous solutions with decrease in pH and increase in electrical conductivity of the solutions. This study aimed to elucidate the behaviours of dissociation of the complexes with time. The change in the amount of undissociated complexes was determined with time. The results indicated that the dissociation was a multi-order reaction involving both protolysis and hydrolysis. The protolysis completed in relatively short period within(several tens of minutes), but it depended on the concentration of the complexes in the solution. The completion of the protolysis and the formation of the resulting dissociation products were observed by absorption spectrometry. The dissociation products, which were assumed as aquohydroxy complexes, underwent the successive step-wise dissociation for a prolonged period as revealed by pH measurements. The rate constants involved in the step-wise dissociation, process were obtained. The degree of dissociation and dissociation constant of the complexes were measured by conductometry.

Tracer experiments were done in order to establish a decontamination process of 106Ru in radioactive waste solution by column method paying special attention on the solution of nitratonitrosyl complex of Ru which is often encountered as a low level radioactive waste solution. It turned out that metallic iron was the most effective decontaminating agent among the several tens of materials tested. The decontamination factor (DF) of 106Ru increased in proportion to the total surface area of iron and it sensitively depended on the oxidation state of the surface as revealed by the batchwise and columnwise tests. Iron samples with high corrosiveness gave a much larger DF than those with low corrosiveness. The decontamination process proceeded as iron was being oxidized via Fe(metal)leads toFe(II)leads toFe(III). As the results, the DF initially increased after initiating the passage of water through the column but it then decreased as the oxidation process became inactive. An excellent durability up to 10000 bed volumes was demonstrated by the column method at a high average DF of 150.

This study aimed to elucidate the protolysis and condensation processes of the Ru complexes in relation to the concentration of nitric acid. The compositions of the dissociated and undissociated complexes were determined by the extraction with tributyl phosphate (TBP) and absorption spectroscopy in order to follow the rather rapid protolysis reaction of the complexes. The test solutions were prepared by dissolving the freshly obtained complexes into 0.50-0.001 M nitric acid solutions. The amounts of the undissociated complexes were determined at different elapses of time in the test solutions. The protolysis became significant when the concentration was below 0.15 M, and the dissociation rate suddenly increased at this concentration. At the concentrations above 0.2 M, the absorption peak of the complexes at 480 nm survived even after 144 hours. But below 0.15 M, the formation of dissociation products by protolysis was observed after the disappearance of the absorption peak. The amount of dissociation products rapidly increased after the preparation of the test solution as the concentration decreased below 0.15 M.