Sorption of a complex of europium (III) with acetylacetone on hydrophobized hexadecyl silica gel and hyper crosslinked polysterene

The sorption of a complex of europium (III) with acetylacetone on silica gel chemically modified with hexadecyl groups (SiO₂-C₁₆) and hyper crosslinked polystyrene (HLPS) was studied. Maximum extraction was observed at pH 5–7 when SiO₂-C₁₆ was used as the sorbent and at pH 4–7 in the case of crosslinked polystyrene. The partition coefficients for HLPS and silica gel were calculated as 7 × 10³ and 1 × 10² cm³/g, respectively. Quantitative extraction of the europium (III) complex was possible in dynamic conditions using a microcolumn (length, 10 mm; internal diameter, 3mm) packed with HLPS at pH 5 (10–50 mL sample volume). Desorption of europium using solutions of nitric acid at different concentrations was investigated. Quantitative desorption was achieved using 5 mL of 1 M HNO₃. A linear range of detection was observed at an amount of europium from 5 to 25 μg in a 10-mL sample (650 nm).     

Oxygen and Carbon Isotope Variations of Carbonates and Silicates from the Carbonatite Massif Tiksheozero (Northern Karelia)

Abstract

Carbon and oxygen isotope compositions have been determined for carbonate minerals from different types of carbonatites (large carbonatite bodies, veins, eruptive breccia), as well as from different temperature classes of carbonatites (according to Samoilov [1]). It could be shown, that only high temperature carbonatites exhibit small variations of δ¹⁸O and δ¹³C falling in the range of “high temperature mantle carbonates”, whereas low temperature calcites and dolomites show wide variations in δ¹⁸O. These changes in both isotope and mineral compositions of low temperature carbonatites are interpreted as a result of repeated interaction with fluids. The oxygen isotope ratios in most of the eruptive breccia have been changed by secondary processes. The primary deep-seated isotope record has been preserved only in samples, in which carbonate occurs as fine-grained calcite groundmass.

Preliminary results on oxygen isotope composition of different silicate minerals (amphibole, magnetite, biotite, albite, apatite) indicate isotope equilibrium for the mineral pair calcite-amphibole with isotope temperatures representing superimposed processes.     

Synthesis and study of properties of the sulfonaphthylazophenoxyphthalonitrile and related phthalocyanine

The 4-[4′-(5-sulfonaphthylazo)phenoxy]phthalonitrile potassium salt was synthesized by the reaction of 4-chlorophthalonitrile with 5-(4′-hydroxyphenylazo)-1-naphthalenesulfonic acid, and on its basis was obtained tetra-4-[4′-(5-sulfonaphthylazo)phenoxy]phthalocyanine. The products were characterized by elemental analysis, IR and electron spectroscopy. The effect of the introduced substituent on the spectral and other properties of the synthesized compounds was demonstrated.     

High pressure phase transformations in ammonium halides emerged in conductivity

Comparative studies of high pressure effect on the resistance of ammonium halides NH₄ X (X = F, Cl, Br, I) at 77–400 K are presented. Conditions and characteristic times of various high-pressure phases formation are determined as a function of the time of pressure treatment duration and temperature. Conductivity and magnetoresistance of NH₄I at pressures above 10 GPa are studied for the first time.     

Synthesis of glycyrrhetinic acid by hydrolysis of licorice root extract in subcritical water

A procedure for the synthesis of glycyrrhetinic acid (glycyrrhyzic acid aglicone) by hydrolysis of licorice root extract in subcritical water was developed. The procedure was shown to be more effective than conventional hydrolysis. Glycyrrhetinic acid was identified and its concentration in the product determined by high-performance liquid chromatography. A ¹³C NMR spectroscopic study confirmed that glycyrrhetinic acid obtained in subcritical water had a β configuration at the C₁₈ atom.     

Diethyl (biscyclohexano)BODIPY dicarboxylates. Chelation of alkaline-earth metal ions and sensor properties

meso-Aryl-substituted (biscyclohexano)bis(ethoxycarbonyl)BODIPY [aryl = phenyl, 3,4-dimethoxyphenyl, and 2,3,5,6,8,9,11,12-octahydro-1,4,7,10,13-benzopentaoxacyclopentadecin-15-yl-(m-{benzo-15-crown-5}-yl)] were synthesized. The effect of alkaline-earth metals on the absorption and fluorescence spectra of these compounds was investigated. In all compounds along with the mechanism of the photoinduced electron transfer (PET), well-known for the crown-containing BODIPY-based sensors, one more response pattern is observed. The large excess of Ca²⁺ and Ba²⁺ ions in the system leads to the changes both in the UV-Vis and emission spectra. The complex formation results in the decrease of emission intensity and in its red shift. Besides, a new longwave absorption band appears in the UV-Vis spectrum of the BODIPY-metal ion complex. The formation constants of the complexes corresponding to this response pattern is about 100 times less than the formation constant of Ca²⁺-crown ether complex. ¹H, ¹³C, ¹¹B, and ¹⁹F NMR spectra, the results of quantum-chemical calculations, and their comparison with the literature data of X-ray diffraction study suggest that the binding of Ca²⁺ and Ba²⁺ ions occurs in the cavity formed by the fluorine atoms and the carbonyl oxygen atoms of the ester groups.     

Synthesis and Study of the Properties of Magnetic Adsorbents Based on Hydrophobized Silica

Moscow University Chemistry Bulletin - We proposed a method for producing magnetic nanocomposite adsorbents, based on the adsorption of Fe3O4 magnetic nanoparticles (MNPs) on hydrophobized silicas...     

Metal complexes of tetrakis(2-carboxyphenylsulfanyl)phthalocyanine. Synthesis,spectral and catalytic properties

Russian Chemical Bulletin - Carboxylic acid sodium salts of the phthalocyanine derivatives with phenylsulfanyl fragments at the periphery containing MgII, CoII, CuII, and ZnII ions as central metal...     

On-line investigation of short-lived Os and Re isotopes as a test for chemical studies of 108 (Hs) and 107 (Bh) elements in HCl solutions by continuous chromatography

On-line chemistry studies of short-lived isotopes of Os and Re, as homologs of 108 (Hs) and 107 (Bh), respectively, produced in the nuclear reactions at the (LNR, Dubna) cyclotron have been carried out. It was shown, that Os and Re are not sorbed on cation exchangers, but very strongly sorbed on anion exchangers from diluted HCl solutions. Re is also retained by a TOPO containing sorbent and may be separated from Os. The possibilities of chemical species and oxidation states investigation of short-lived transactinide elements by continuous chromatography have been shown. This revised version was published online in July 2006 with corrections to the Cover Date.