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Solutions in acetonitrile of three mixed complexes of rare-earth elements (terbium and samarium) with organic ligands with various pyridine substituents were studied in this work. The ratios of ligands and metals in the resulting complexes were determined, and the stability constants of samarium complexes were calculated using the spectrophotometric titration method. Measurements of absorption-, emission-, and excitation spectra of luminescence, luminescence kinetics of solutions of mixed complexes of rare-earth elements with an excess of metal relative to the ligand were carried out at various temperatures in the range 298–328 K. For the first time, an increase of luminescence intensity of a samarium ion in complex upon heating was observed. The dependences of the luminescence quantum yield and lifetime of mixed complexes on temperature were obtained. A thermometric parameter—the ratio of the integral luminescence intensities of samarium and terbium ions—was proposed, and the temperature sensitivity coefficient of this parameter was determined for different complexes. [ABSTRACT FROM AUTHOR]

The results of studying the effect of the central metal ion on the stability of gadolinium and holmium complexes with 1,10'-phenanthroline-2,9-dicarboxylic acid diamide are presented. The obtained values of the stability constants of the complexes turned out to be an order of magnitude lower than the previously known values for the complexes of these elements with 4,7-dichloro-1,10'-phenanthroline-2,9-dicarboxylic acid diamide. [ABSTRACT FROM AUTHOR]

Effect of structure of phosphorylketones containing flexible alkyl and conformationally rigid fragments in the linker on extraction ability toward actinides and lanthanides has been studied. It has been shown that the introduction of conformationally rigid cycloalkanediyl and alkenediyl fragments in the bridge between P=O and C=O groups in the structure of molecule decreases efficiency of extractants for both actinides and lanthanides. At the same time, the introduction of flexible alkyl groups in linker structure increases complexing and extraction ability. This dependence has been explained theoretically by modeling complexation (DFT, PBE, cc-pVDZ), monodentate coordination was observed for all studied phosphorylalkanones [ABSTRACT FROM AUTHOR]

The extraction properties of a series of diamides of 2,2-bipyridine-6,6-dicarboxylic acids with respect to americium, curium, neptunium, thorium, light lanthanides and a series of d-elements present in solutions of highly radioactive wastes have been studied in this work. It has been shown that the extraction properties of diamides are determined not only by the structure of the heterocyclic framework, but also by the nature of substituents in positions remote from oxygen centers. The influence of substituents in a series of extractants is determined by differences in their electronic nature, and also depends on their volume and position. In the work, effective and selective extractants were found for the separation of the Am/Eu pair (SF up to 27), and fundamental patterns were revealed between the structure of the extractant and the efficiency of extracting metal ions. [ABSTRACT FROM AUTHOR]

New readily accessible aminodiol and diaminoalcohol were obtained using simple condensation and reduction reactions. On their basis, earlier unknown ligands of bicyclophosphite nature with asymmetric phosphorus atoms were synthesized. [ABSTRACT FROM AUTHOR]

N-Diphenylphosphoryl-N'-[ω-(alkoxy/tetrahydrofuryl)alkyl]ureas have been synthesized based on a highly efficient one-pot catalytic process and their extraction properties have been studied with respect to f-elements in nitric acid media. The influence on the extraction characteristics of the presence of an alkoxy or tetrahydrofuryl group located in the ω-position of the normal N'-alkyl radical of phosphorylurea has been revealed. It has been shown that N-(diphenylphosphoryl)urea containing N'-[2-(tetrahydrofur-2-yl)ethyl] radical has the best extraction properties with respect to the studied f-elements, especially this effect is pronounced for uranium(VI). This dependence has been theoretically substantiated when simulating complex formation by the density functional theory method (DFT, PBE, cc-pVDZ), since the coordination of the f‑element ion to the oxygen atom of the furyl radical attached to the ethylene carbon chain turns out to be preferable. [ABSTRACT FROM AUTHOR]

Extraction properties toward actinides and lanthanides of phosphorylketones on varying the number of functional phosphoryl and carbonyl groups in the structure of organic ligand have been modeled. Presented data have shown that the studied phosphorylketones I–III as extractants display higher extraction ability with respect to lanthanides as compared with TBP, TOPO, and CMPO. 4,4-Bis(diphenylphosphoryl)butan-2-one III exhibits high extraction ability and selectivity toward U(VI). This compound can be used for the selective recovery and preconcentration of U(VI) from nitric acid solutions [ABSTRACT FROM AUTHOR]

The absorption and luminescence spectra and the luminescence decay kinetics of uranyl ions (UO22+) in the presence of organic reagents based on 2,2'-bipyridyldicarboxamides with various substituents have been studied. The quantum yields and luminescence lifetimes of uranyl nitrate hexahydrate and uranyl complexes with organic ligands in acetonitrile solutions have been determined. The mechanism of energy transfer in uranyl complexes is proposed. [ABSTRACT FROM AUTHOR]

Extraction of lanthanides and actinides from nitric acid solutions with N-(diphenylphosphoryl)-N'-n-propylureas containing imidazolyl, diethylamino, pyrid-2-yl, 2-oxopyrrolidino fragments in the ω position of the alkyl substituent has been studied. It has been shown that Ho(III) and Yb(III) related to the yttrium subgroup of lanthanides are extracted much better than La(III) and Nd(III) related to the cerium subgroup. N-(Diphenylphosphoryl)urea containing ω-(2-oxopyrrolidino)propyl fragment at the terminal nitrogen atom shows the best extraction properties. This dependence has been theoretically explained by modeling complexation because the coordination of f-block element ion with amide oxygen atom is more preferable [ABSTRACT FROM AUTHOR]

The extraction capacities to f elements are studied in a series of bidentate organophosphoric reagents that contain deprotonatable phenol moieties. The dependence of metal [thorium(IV), lanthanum(III), neodymium(III), and holmium(III)] recovery as a function of nitric acid concentration is represented by curves with a maximum, typical of extraction by monodentate organophosphoric reagents. The uranium recovery as a function of acid concentration is presented by curves with a minimum, indicating a change in extraction mechanism from ion exchange to solvation. The quantum-chemical modeling of reagent molecules and their complexes with uranyl ion is carried out. The reagents are structurally similar to reagent V, whose structure was determined by single-crystal X-ray diffraction. The results can be used in the hydrometallurgy of f elements. [ABSTRACT FROM AUTHOR]

A number of copolyamides containing main-chain phenanthroline groups and their metal-polymer complexes with iridium and europium are synthesized. All the obtained polymers possess high mechanical properties and thermal stability. The synthesized europium complexes display an intense luminescence in the range of 610–620 nm. [ABSTRACT FROM AUTHOR]

223Ra and 211Pb/211Bi radionuclides with radiochemical purity were obtained from 227Ac/223Ra generator on DGA resin. Covalent grafting of organic complexons (ethylenediaminetetraacetic acid—EDTA and derivatives of amino acids—L1 and L2 to aminated nanodiamonds (ND) was performed by carbodiimide method. Adsorption behavior of Ra and Pb in plasma volume expander on modified nanodiamonds was studied in detail. Effective adsorption have been found for 211Pb in physiologically acceptable conditions. Sorption behavior of generator radionuclides 223Ra and 211Pb on the surface of ND-L1 and ND-L2 in aqueous solution (pH = 6.3) was studied. It was shown that the labeling yield of 211Pb from the solution was about 94%. The sorption of 223Ra under the same conditions was weak. The sorption/desorption kinetics of 211Pb on the surface of ND-EDTA in the plasma volume expander was studied. The desorption rate of 211Pb did not exceed 2.5% within 60 min (pH 7.2-7.4). [ABSTRACT FROM AUTHOR]

The thermal stability of 2,6-pyridinedicarboxylic acid di(N-ethyl-4-fluoroanilide), 2,2'-bipyridine- 6,6'-dicarboxylic acid di(N-ethyl-4-ethylanilide), and 2,2'-bipyridine-6,6'-dicarboxylic acid di(N-ethyl-4- hexylanilide) at atmospheric pressure was studied. The course of their decomposition before and after saturation with nitric acid was compared to determine the influence of nitric acid on the thermal effects accompanying the oxidation of these substances. [ABSTRACT FROM AUTHOR]

Chelating ligands based on polydentate diamides of 2,2'-bipyridyl-6,6'-dicarboxylic acid with a high affinity for lanthanide ions have been synthesized. The effect of the size of lipophilic aliphatic substituents in the ligand on the photophysical characteristics of europium complexes in acetonitrile solutions and in the solid state, as well as on the morphology of thin films obtained by the spin-coating method, was studied. The external and internal luminescence quantum yields have been measured, the luminescence lifetimes at 300 and 77 K were determined, and the sensitization efficiency values for europium complexes were calculated. The phosphorescence of gadolinium(III) complexes was used to determine the energy difference between the triplet level of the ligand and the resonance level of europium. [ABSTRACT FROM AUTHOR]

Reactions of L-methionine, L-serine, and L-valine with 5-substituted-2-hydroxybenzene-1,3-dicarbaldehydes gave a series of chiral Schiff base pincer ligands which were reduced to the corresponding diamines. The new Schiff base ligands reacted with copper(II) chloride to form dinuclear copper complexes which were found to be capable of recognizing tyrosine enantiomers in aqueous solution. The structure of the complexes was determined on the basis of their spectral parameters. [ABSTRACT FROM AUTHOR]

The article focuses on the characteristics of amino acids complexes. It states that polydentate ligands based on natural amino acids and their complexes attract much attention as models of the active sites of enzymes [2] and also of center of chiral induction in asymmetrical catalysis [3-5]. Another interesting aspect of amino acids complexes are their capability to perform chiral recognition of optically active substrates.

[1+2]-Condensation of 2,3-diaminomaleodinitrile with dialdehydes of the aromatic and heterocyclic series gave a number of new acyclic Schiff bases which attract interest as ligands for the synthesis of transition metal complexes and as building blocks for the synthesis of macrocyclic compounds. [ABSTRACT FROM AUTHOR]