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Abstract  

Pyridine-2,5-dicarboxylic acid, known as isocinchomeric acid is one of six isomers containing two carboxylic groups. Light lanthanide (III) complexes with pyridine-2,5-dicarboxylic acid with general formula Ln2L3·nH2O, where n = 8, 9, were obtained. Their thermal and spectroscopic properties were studied. Sodium salt was obtained as Na2L·H2O. Hydrated complexes of La(III), Ce(III), Pr(III), Nd(III), Sm(III), Eu(III) and Gd(III) are stable to 313–333 K, whereas Na2L·H2O is stable to about 333 K. Dehydration process for all compounds runs in one stage, next they decompose into appropriate lanthanide oxalates, oxocarbonates carbonates and finally to metal oxides. Bands of νCOOH vibrations at 1736 and 1728 cm−1 disappear on complex spectra and νas and νs of COO groups appear thus indicating that complexation process took place.

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Abstract  

Absorption spectroscopic properties for various Pu oxidation states in nitric and hydrochloric acid solutions were investigated with UV-Visible spectrophotometry. As a result, it was confirmed that the intensities of the major absorption peaks had a tendency to decrease for Pu(III), Pu(IV) and Pu(VI) in HCl and HNO3 media, and the major peak positions were shifted to longer or shorter wavelengths depending on the complexforming abilities of Pu(III), Pu(IV) and Pu(VI) with the chloride or nitrate ion with increasing acid concentrations. The values of the wavelength and the molar absorptivity for the principal peaks of Pu(III), Pu(IV) and Pu(VI) in NHO3 and HCl solutions were similar to those reported in other works. The values of the molar absorptivity for the principal peaks of Pu(III), Pu(IV) and Pu(VI) in the HNO3 solution were a little higher than those in the HCl solution.

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Danczowska-Burdon , A , Sienkiewicz-Gromiuk , J . 2010 . Thermal and spectroscopic properties of light lanthanides (III) and sodium complexes of 2,5-pyridinedicarboxylic acid . J Therm Anal Calorim . 101 : 671 – 677 10.1007/s10973-010-0941-3 .

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of electron transitions (spectroscopic properties) [ 1 – 4 ]. Such compounds of special interest include heterometallic systems obtained based on metal complexes with organic ligands and salts being derivatives of Prussian blue [M(CN) 6 ] n

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Abstract  

Investigations of lysozyme–polyethylene glycol system were made by differential scanning calorimetry, fluorescence and density techniques. The values of unfolding enthalpies, ΔH N U, unfolding temperatures, T m, excess molar heat capacities, ΔC p, and apparent molar volumes, V Φ , were determined as functions of PEG concentration. The three PEGs of average molecular mass (MW) 6000, 10000, 20000 were used as macromolecular crowding agents. The concentration of polymers was changed in the range 0–30% mass per volume (w/v). The values of ΔH N U remained constant with no dependence on PEG concentration, while PEG addition to buffered lysozyme solutions caused linear decrease of T m. The values of ΔC p and V Φ of lysozyme dramatically changed in the range of 8–10% of PEG concentration. The fluorescence spectroscopy was used in order to investigate the polymer influence on possible solvent–lysozyme interactions. The electrical properties of polymer–water and polymer–buffer systems, the dielectric constants of solutions were determined with use of impedance spectroscopy.

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Abstract  

New solid compounds of Tb(III), Ho(III), Er(III) and Yb(III) with chrysin were synthesized and characterized by elementary analysis, thermogravimetric studies and magnetic measurements. The molecular formula of the complexes is Ln(C15H9O4)3 · 4H2O where Ln is the cation of lanthanides. The oxidation state of metal ion in the complexes does not change and equals +3. The thermogravimetric analysis shows that two water molecules are present in the inner coordination sphere of the complex and the two molecules are in the outer sphere. The structure of the complexes was determined on the basis of UV–visible, IR and 1H NMR spectroscopies. It was found that chelation of the metal ion occurs at the 5-hydroxy-4-keto site.

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Abstract

The magnesium sulphate complex compounds of general formulae [Mg(H2O)6]2+·2(C6H12N4)·SO4 2−·5(H2O) (1) and Mg(C12H8N2)(H2O)3SO4 (2) have been synthesized, characterised by elemental and thermal analysis, IR, UV–VIS and fluorescence spectroscopy, and X-ray crystallography. The obtained compounds are air stable at room temperature and well soluble in water. In the structures of the investigated complex compounds the O–H…O, O–H…N, and C–H…O hydrogen bonds exist, and they create N2C2 2(8), R2 2(8) (compound 1) and N1C1 1(6), N1R2 2(12) (compound 2) patterns. Their thermal decomposition processes in the investigated atmospheres (air and helium) are different. After the slightly similar dehydratation, the observed transitions and the obtained final products are different (in helium atmosphere the sulphate ion of studied compounds undergoes decomposing what does not take place in air atmosphere). The UV–VIS spectrum of 2 shows maxima that are typical for π π* and nπ* transitions, and fluorescence spectrum of the same compound displays its great fluoresce properties. The 1 does not exhibit absorption in the investigated region of electromagnetic spectrum due to the absence of respect chromophore groups. The IR spectrum of 2 shows typical vibrations for chelating amine molecule. An interesting fact is that in 1 the SO stretching vibrations (existing at 1119 and 1182 cm−1) are doubled in comparison to the magnesium sulphate whilst in 2 these vibrations are absent.

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Abstract  

The [Tc(phen)3] (PF6)3 complex has been synthesized by ligand substitution on [Tc(tu)6]3+. The reaction proceeds quickly in aqueous solution. A pure compound is obtained with 40% yield. It was characterized by Tc elemental analysis, cerimetric titration, conductometry and electrophoresis. The corresponding spectroscopic properties (UV, Vis, IR and NMR) are also reported and discussed.

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Abstract  

EPR-spectroscopic properties (line-intensity,-width, andg-factors) of pyrolized at 550°C sucrose, MgO and MgO doped with Mn2+ ions (500∶1) remain unchanged after high-dose (1–100 kGy) irradiation, whereas CaO gives an EPR signal. These properties of these materials make it possible to use them as internal reference EPR standards in the work under conditions of strong ionisation environment, for precise determination of theG-values of other materials, for obtaining exact magnitudes of increase of the EPR response when the method of additional dose is applied, to follow the kinetics of decay of some radiation induced defects.

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