Use of triazole-ring formation to attach a Ru/TsDPEN complex for asymmetric transfer hydrogenation to a soluble polymer

The cycloaddition of a chiral ligand containing a terminal alkyne to a soluble polymer containing an azide provides a convenient means for the attachment of an asymmetric transfer hydrogenation catalyst to a soluble polymer support. Using these ligands in complexes with Ru(II), gave good results in terms of conversion and enantioselectivity (up to 95% ee) in ketone reduction reactions

Photochemical versus Thermal Synthesis of Cobalt Oxyhydroxide Nanocrystals

Photochemical methods facilitate the generation, isolation, and study of metastable nanomaterials having unusual size, composition, and morphology. These harder-to-isolate and highly reactive phases, inaccessible using conventional high-temperature pyrolysis, are likely to possess enhanced and unprecedented chemical, electromagnetic, and catalytic properties. We report a fast, low-temperature and scalable photochemical route to synthesize very small (~3 nm) monodisperse cobalt oxyhydroxide (Co(O)OH) nanocrystals. This method uses readily and commercially available pentaamminechlorocobalt(III) chloride, [Co(NH3) 5Cl]Cl2, under acidic or neutral pH and proceeds under either near-UV (350 nm) or Vis (575 nm) illumination. Control experiments showed that the reaction proceeds at competent rates only in the presence of light, does not involve a free radical mechanism, is insensitive to O 2, and proceeds in two steps: (1) Aquation of [Co(NH3) 5Cl] 2+ to yield [Co(NH3) 5(H2O)] 3+, followed by (2) slow photoinduced release of NH3 from the aqua complex. This reaction is slow enough for Co(O)OH to form but fast enough so that nanocrystals are small (ca. 3 nm). The alternative dark thermal reaction proceeds much more slowly and produces much larger (~250 nm) polydisperse Co(O)OH aggregates. UV-Vis absorption measurements and ab initio calculations yield a Co(O)OH band gap of 1.7 eV. Fast thermal annealing of Co(O)OH nanocrystals leads to Co3O4 nanocrystals with overall retention of nanoparticle size and morphology. Thermogravimetric analysis shows that oxyhydroxide to mixed-oxide phase transition occurs at significantly lower temperatures (up to T = 64 degrees C) for small nanocrystals compared with the bulk

Assessment of Metal Pollution Based on Multivariate Statistical Modelling of Soils from Gediz and Buyuk Menderes Rivers

In this study, two economically important rivers of Turkey, Gediz and Buyuk Menderes are studied to determine their environmental pollution levels. Soil samples are analysed using graphic-furnace atomic absorption spectroscopy for the trace metals Cu, Co, Cr, Mn, Zn, Pb and Ni. The results show that the pollution levels are significant especially for Pb, Cr, Ni in the Gediz River and Cr, Zn, Co in the Buyuk Menderes river. Factor analysis technique, which is some of the statistical analyses, was used in order to explain relation between the elements

R-mode factor analysis applied to the exploration of radioactivity in the Gediz River

WOS: 000083559400030Sediment samples were collected from the river bed at 10 km intervals and have been analysed for eU, eTh, %K, Ra-226, Ca, Ti, Mn, Zn, Rb, Sr, Y, Zr, Ba, La and Ce. R-mode factor analysis was used to describe the relationship among 15 remotely sensed and geochemical data sets (variables) for the Gediz River. Four factors were extracted in the sediments and they account for 57.6% of the total variance in the data These factors are interpreted as granite (felsic), economy, volcano and industry factors, respectively