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Abstract  

Fourteen new complexes with the general formula of Ln(Hmna)3·nH2O (n=2 for Ln=La-Ho and n=1 for Er-Lu, H2mna=2-mercaptonicotinic acid) were synthesized and characterized by elemental analyses, IR spectra and thermogravimetric analyses. In addition, molar specific heat capacities were determined by a microcalorimeter at 298.15 K. The IR spectra of the prepared complexes revealed that carboxyl groups of the ligands coordinated with Ln(III) ions in bidentate chelating mode. Hydrated complexes lost water molecules during heating in one step and then the anhydrous complexes decomposed directly to oxides Ln2O3, CeO2, Pr6O11 and Tb4O7. The values of molar specific heat capacities for fourteen solid complexes were plotted against the atomic numbers of lanthanide, which presented as ‘tripartite effect’. It suggested a certain amount of covalent character existed in the bond of Ln3+ and ligands, according with nephelauxetic effect of 4f electrons of rare earth ions.

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Abstract  

Five new complexes M(Hmna)2 [M=Mn(II) (1), Co(II) (2), Ni(II) (3), Cu(II) (4) and Zn(II) (5), H2mna=2-mercaptonicotinic acid] have been synthesized and characterized by elemental analyses, IR spectra, thermogravimetric analyses. In addition, molar specific heat capacities and enthalpy changes of reactions were determined by a microcalorimeter at 298.15 K. All the complexes exhibited similar IR spectra, the sulfur and oxygen atoms from monoanionic Hmna ligand coordinated to M2+ in a bidentate fashion. The thermal stability of M(Hmna)2 complexes varied in the sequence 1>2>3>4>5. The complexes were stable up to about 300°C and decomposed to oxides at higher temperatures. The molar specific heat capacities of the complexes were determined in the range between 106.452±0.399 and 145.920±0.423 J mol−1 K−1. The enthalpy changes of reactions, Δr H m θ, were determined from 18.28±0.05 to 52.59±0.07 kJ mol−1 for complexes 1–5, indicating that the thermodynamic stability of M(Hmna)2 increased in the sequence from Mn2+ to Zn2+.

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Two Mn(II) chloride complexes containing guest molecules

Solvothermal syntheses, crystal structures and thermal decomposition

Journal of Thermal Analysis and Calorimetry
Authors:
Q. Yang
,
S. Chen
, and
S. Gao

Abstract  

Two phenanthroline-manganese inclusion complexes with [MnCl(H2O)(phen)2]+ core have been synthesized and characterized by single crystal X-ray diffraction, elemental analyses, IR spectra, thermogravimetric analyses. Uncoordinated 2-mercaptothiazole (tzdtH) and 2-mercaptobenzothiazole (bztzH) as guest molecules are included in the complexes with formulas [MnCl(H2O)(phen)2]Cl·tzdtH (1) and {[MnCl(H2O)(phen)2]Cl}2·bztzH (2). X-ray structural analyses for complexes revealed that the complex 1 is triclinic, space group P1 with a=9.724(1) Å, b=11.858(1) Å, c=12.644(2) Å; β=89.056(2)°; Z=2, D c=1.513 Mg m−3, F(000)=638 and the complex 2 is triclinic, space group P1 with a=9.861(1) Å, b=11.476(1) Å; c=12.908(3) Å; β=84.991(2)°; Z=1, D c=1.511 Mg m−3, F(000)=600. Two complexes exhibit high stability up to 650°C. The molar specific heat capacities for the two complexes 1 and 2 can be estimated as being 96.175±0.332 and 72.505±0.364 J mol−1 K−1 at 298.15 K by RD496-III microcalorimeter, respectively.

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Summary  

The stability constants of Eu3+ and Am3+ with the site specific humic acid (YKHA) have been determined. The humic acid has been extracted from the soil of Yongkwang area belonging geologically to the Okchon Basin of the Korean Peninsula, where the nuclear power plant is located. The total carboxylate capacity, the acidity constant (pKa), and the binding constants with Eu3+ and Am3+ have been determined for humic acid.

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Abstract  

A rapid method for alpha counting with liquid scintillation is presented. The interference of beta and gamma radiation with the determination of alpha emitting nuclides by liquid scintillation counting was examined. In extractive scintillator cocktail, TOPO-PPO-naphthalene-toluene has been developed for transferring actinide elements into organic scintillator and separating the undesirable materials as well as most beta emitters. Pulse Shape Analysis (PSA) was applied for the discrimination of beta radiation. The influence of cocktail composition on PSA has been studied and compared with that of the commercial cocktail. An analytical procedure was suggested for the rapid determination of actinide elements U, Pu, Am and Cm in the nuclear fuel cycle or in environmental samples.

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Abstract  

Phosphorous containing radioisotope waste was separated and determined by liquid–liquid extraction method through liquid scintillation counter (LSC). In this process, ammonium phosphate was converted to phosphomolybdate (PMo) by the reaction of ammonium molybdate (Mo) in HCl solution (0.02 M) and maximum UV/VIS absorbance (λmax) 218 nm was observed. The PMo solution was extracted with TOA (Tri-n-Octylamine)/xylene mixture and λmax 290 nm was found for this organic layer. Absorbance of aqueous and organic layer was linear through concentration. The impurities such as Co, Cr, Gd, etc. remain in aqueous layer by treating with Mo which was determined by ICP-AES and AAS. The quenching correction curve for 32P was calculated using LSC results. No counting change was observed as the volume of quenchers increased. The recovery was 98% and 81% for the extraction and separation process from the test using H3 32PO4 as standard tracer.

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Abstract  

The determination of - and -emitting nuclides has been studied with a commercial liquid scintillation counter /Tri-Carb 2200CA/ equipped with Pulse Shape Analysis /PSA/. The results indicated that the efficiency for -emitters is virtually 100% and discrimination for -emitters is more than 99.9%. Liquid scintillation counting with PSA can be used for the determination of - and -emitting nuclides simultaneously.

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Abstract  

A preconcentration method of 13 rare earth elements (REES) was studied for neutron activation ananlysis (NAA). Hydrated magnesium oxide was used as the preconcentration agent to absorb the REES ions from aqueous solution onto the solid magnesium oxide, which was separated and analyzed. It was observed that the Langmuir equation for isothermal adsorption was well obeyed by the REES under the condition studied. The efficiency of the preconcentration process using hydrated magnesium oxide was critically examined for each of REE and for mixture of REES by preparing a known volume of solution containing known amount of trace REES. NAA was used to analyze REES recovered by the preconcentration process. It was found that the REES recoveries were satisfactory and the preconcentration process is reliable. There are several resort resort areas in Taiwan where local people are enjoying its hot spring water. It is generally believed that the hot spring water spa would bring about some sorts of therapeutic functions. The preconcentration method developed above, was applied to analyze the trace amounts of REES in hot spring wate in Taiwan.

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Summary

The stems of Uncaria rhynchophylla (Miq.) ex Havil have a long history of use in traditional Chinese medicine to treat diseases and improve health. There is evident evidence that alkaloids constituents are mainly responsible for the beneficial effects of this plant medicine. The amounts of the major bioactive alkaloids in this plant vary widely with species, habitat, and as such, and establishment of a high-performance liquid chromatography (HPLC) fingerprint for quality control of this herbal medicine is of particular importance. The most alkaloids are used for medicine treatment and research. On the basis of the chromatographic data, a consistent HPLC fingerprint pattern containing 15 common peaks was obtained. Among these common peaks, four were identified as rhynchophylline, isorhynchophylline, corynoxeine, and isocorynoxeine. On the basis of this HPLC fingerprint and principal-components analysis, the quality of fifteen samples from different producing areas of China was objectively assessed. To summarize, the data described in this study offer valuable information for quality control and proper use of U. rhynchophylla (Miq.) ex Havil.

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