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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]

Novel near IR absorbing zinc 2,3-naphthalocyanine with bulky 2-naphthyl groups was obtained from corresponding 2,3-dicyanonaphthalene and characterized by mass spectrometry, UV-Vis, infrared and nuclear magnetic resonance spectroscopy (NMR). Two-dimensional NMR was employed for full proton and carbon signal assignment in initial 2-naphthyl-substituted 2,3-dicyanonaphthalene. The main absorption maximum of 2-naphthyl-substituted naphthalocyanine complex at 790 nm shows a shift of 6 nm to the near IR region compared to phenyl-substituted analogues. The UV-Vis spectrum of the complex in o-DCB shows strong aggregation, which can be suppressed by N-containing agents or ternary ammonium salt due to steric hindrance or electrostatic repulsion. Pyridine demonstrates the most pronounced effect that reaches maximum value at 2 vol% pyridine. The monomeric form of the naphthalocyanine complex has a narrow Q band and well-resolved satellites. Since pyridine may play a role of both coordinating and reducing agent, fluorescence and electron paramagnetic resonance spectroscopy were used to clarify the mechanism of its influence on the naphthalocyanine complex. Fluorescence properties (fluorescence and excitation spectra, fluorescence quantum yield) as well as electrochemical and spectroelectrochemical behavior were studied in o-DCB. The addition of pyridine results in a slight shift towards a higher value for the first oxidation and first reduction potentials. Moreover, the first oxidation process shows a split that increases after the addition of pyridine. Nevertheless, a single reversible one-electron transition was confirmed by spectroelectrochemical titration in the region of the first oxidation. The first oxidation process of the naphthalocyanine complex was accompanied by reversible color change from olive to bright green, which is not typical for naphthalocyanine complexes with other functional groups (e.g. unsubstituted, alkyl). [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 new phosphine oxide ligand demonstrates high selectivity for the Am–Cm pair with SF = 2.9–3.5 and the Am–Eu pair with SF = 7.3–8.5 in a range of 0.1–3 M nitric acid. Thermodynamic measurements show that the entropy factor is responsible for selectivity observed in the extraction experiment. The most prevalent complexes of all three metal ions were (Ph2PyPO)2M(NO3)3. According to their DFT modelling, the M–N distances for the Cm ion were larger than those for Am, so the last ion enters deeper into the pseudo-cavity of the ligand, which causes the observed selectivity. [ABSTRACT FROM AUTHOR]

Novel synthetic protocols based on both template and multi-step methods were developed for phenyl-substituted pyrazinoporphyrazine complexes of rare-earth elements (Y, Eu, Gd, Dy, Er and Lu). p-Hydroquinone was employed as a reaction medium and as a reducing agent in the process of porphyrazine macrocycle formation. Both thermal and microwave irradiation techniques were successfully applied for activation of the template macrocyclization process. An alternative multi-step approach involving the initial stage of free-base ligand formation was realized for the lutetium compound. The target complexes were identified by high-resolution mass spectrometry, infrared spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. Electrochemical behavior in solution and UV-vis absorbance in solutions and films were studied as well. Shifts in the position of the Q band and oxidation–reduction potentials in comparison with corresponding phthalocyanine analogues were noticed. Using the IR absorption spectra recorded in the temperature range of 170–300 K, the position of the Fermi level of −4.7 ± 0.1 eV and a characteristic energy diagram were obtained for the erbium complex. [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]

N,N′-Dialkyl-N,N′-diaryl-1,10-phenanthroline-2,9-dicarboxamides (IV) were predicted (DFT simulation) and then were proved experimentally to be efficient donor ligands with high and unusual selectivity for the extraction separation of lanthanides. Distribution coefficients D of lanthanide cations in two-phase aqueous solution–polar organic solvent decrease with increasing Ln3+ atomic number. The selectivity factors SFLn1/Ln2 for adjacent lanthanide ions were found to be about 3. [ABSTRACT FROM AUTHOR]

The extraction of americium and lanthanides by diamides of 2,2′-dipyridyl-6,6′-dicarboxilic acid solutions in polar diluents was investigated. The dependence of extraction properties of the diamides on their structure was studied and the distribution ratios of americium and lanthanides from nitric acid solutions were determined. The highest extraction was found for the compounds with the ethyl-group and the alkyl-substituted aryl-group on the amidic nitrogen. The Am/Ln separation factors higher than 10 were achieved for extraction from high acidity media. [ABSTRACT FROM AUTHOR]