Reactions of heteroaromatic chromophores with lanthanide complexes of p-sulfonatothiacalix[4]arene

The conditions for the formation of heteroleptic complexes of a lanthanide(iii) ion (Ln = La, Gd, and Tb) with p-sulfonatothiacalix[4]arene and a heteroaromatic chromophore in water were found using X-ray diffraction analysis, pH-metry, ¹H NMR and UV—Vis spectroscopy, and nuclear magnetic relaxation. In the resulting complexes, the heteroaromatic chromophore is in the calix[4]arene cavity and the lanthanide ion is coordinated by the electron-donating groups of the upper or lower calix[4]arene rim. Emission spectroscopic studies revealed changed emission properties of Tb^III ions in the terbium(iii)—p-sulfonatothiacalix[4]arene—bipy complex. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1871–1878, September, 2008.     

Dilute-and-shoot approach for determination of several biomarkers and pharmaceuticals in wastewater using nanoflow liquid chromatography – Orbitrap mass spectrometry

A new method for quantitative analysis of several biomarkers and pharmaceutical compounds in wastewater has been developed employing nanoflow liquid chromatography with Orbitrap mass spectrometry. An easy dilute-and-shoot approach has been used for sample preparation with a dilution factor of 5. Improved retention of ionic and highly polar compounds has been achieved by the addition of tetrabutylammonium bromide as an ion pair reagent into the final diluted sample. The new nanoflow liquid chromatography method has demonstrated low matrix effects (70%–111%), high sensitivity in terms of limits of quantification (0.005 to 0.3 μg/L), low injection volume (70 nl) and solvent consumption, and the ability to analyze diverse polar and ionic analytes within one run using a single reversed-phase nanoflow liquid chromatography column. Wastewater samples (n = 116) from the wastewater treatment plants of different cities in Latvia were analyzed using the developed method. The observed concentrations of biomarkers were in line with the literature data.     

An X-ray photoelectron study of the electronic structure of Cu(II) complexes with dia- and paramagnetic derivatives of 2-imidazoline

The electronic structure of free radicals and Cu(II) complexes with the nitronyl nitroxide radical and aminonitrone is studied by X-ray photoelectron spectroscopy (XPS). N1s XPS spectra of nitrogen atoms of Cu(II) complexes with aminonitrones confirm the diamagnetic nature of the ligands. The binding energies of the main peak and the intense satellite structure in the Cu2p _3/2,1/2 spectra of the complexes under study correspond to the Cu(II) state. The structure of the satellite in the Cu2p _3/2,1/2 spectrum depends on the environment of the metal ion.     

Layer Systems on the Base of Nitrogen-Doped Tantalum and Niobium with Enhanced Stability

There are presented the results of the investigation of tantalum- and niobium-based metal-oxide bilayers degration in dependence on chemical composition of base metal. Nitrogen dissolved in metal increases stability of chemical composition and electrical properties of oxide films grown on the metal surface by anodic oxidation. This improves reliability and life time of electronic devices containing tantalum- or niobium-based layer systems. The best positive effect of doping tantalum and niobium by nitrogen was achieved after preliminary refining of these metals from oxygen. When nitrogen concentration in the base metal essentialy exceeds its solubility limit at room temperature and nitride phases are formed the dielectrical properties of oxide film get worsen.     

Nitropyridines as 2π-Partners in 1,3-Dipolar Cycloadditions with N-Methyl Azomethine Ylide: An Easy Access to Condensed Pyrrolines

1,3-Dipolar cycloaddition reactions of 2-substituted 5-R-3-nitropyridines and isomeric 3-R-5-nitropyridines with N-methyl azomethine ylide were studied. The effect of the substituent at positions 2 and 5 of the pyridine ring on the possibility of the [3+2]-cycloaddition process was revealed. A number of new derivatives of pyrroline and pyrrolidine condensed with a pyridine ring were synthesized.     

Development of nanosized oxide composites for catalytic CO oxidation

Abstract

Effect of composition and morphology on the catalytic activity in CO oxidation of Co-, Cu-, Ce-containing oxide materials prepared by citrate method has been studied. It was shown that composites consist of well-dispersed oxides Со₃O₄, CuO and CeO₂ with average crystallite sizes 13–24?nm, 14–26?nm and 3–7?nm, respectively. It was established that Co-, Cu-, Ce-oxide nanocomposites demonstrated higher catalytic activity in CO oxidation in comparison with individual oxides. The ternary oxide system Со₃O₄–CuO–СеO₂ (Со:Cu:Се=10:1:1) was found to possess the highest catalytic activity due to formation finely dispersed particles of CuO and СеO₂ oxides simultaneously with nanosized Со₃O₄ species and formation of large quantity of mobile oxygen at the interfaces between the oxide nanoparticles.