• Journal of the Korean Chemical Society
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• v.38 no.1
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• pp.50-54
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• 1994

Spectrophotometric determination of some light lanthanide ions by flow injection method is described. Chromeazurol S forms water soluble complex with lanthanide ions in the presence of DTAB. The absorption maximum of the complexes are from 650 nm to 655 nm and the molar absorptivities were ca. $1.8{\times}10^5\;L mol^{-1}cm^{-1}$ on Tris buffer (pH 10.5). The calibration curves for Nd(III), Eu(III) and Sm(III) obtained by FIA are over the range of 0.1 to 0.6 ppm and the correlation coefficient were ca. 0.9993. The detection limits (S/N) were from 10 ppb for Nd(III) and Eu(III) to 20 ppb for Sm(III). The relative standard deviations was ${\pm}$.2% for 0.4 ppm sample. The samples throughput was ca. $50\;cm^{-1}$.

• Journal of the Korean Chemical Society
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• v.55 no.4
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• pp.594-602
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• 2011

The effect of ${\alpha}$-, ${\beta}$- and ${\gamma}$-picolines on the stereochemistry of the coordination compounds of lanthanide(III) nitrates derived from 4[N-(furfural)amino]antipyrine semicarbazone (FFAAPS) has been studied. The general composition of the present coordination compounds is [Ln(FFAAPS)$(NO_3)_3$Pic] (Ln=La, Pr, Nd, Sm, Gd, Tb, Dy or Ho and Pic=${\alpha}$-, ${\beta}$- or ${\gamma}$-picolines). All these coordination compounds have been characterized by elemental analyses, molecular weight, molar conductance, magnetic susceptibility, infrared and electronic spectra. The infrared studies suggest that the FFAAPS behaves as a neutral tridentate ligand with N, N, O donor while ${\alpha}$-, ${\beta}$- or ${\gamma}$-picoline is coordinated to the lanthanide(III) ions via heterocyclic N-atom. Nitrates are bicovalently bonded in these compounds. From the electronic spectral data, nephelauxetic effect (${\beta}$), covalence factor ($b^{1/2}$), Sinha parameter (${\delta}%$) and the covalence angular overlap parameter (${\eta}$) have been calculated. Thermal stabilities of these complexes have been studied by thermogravimetric analysis. The coordination number of lanthanide(III) ions in the present compound is found to be ten. The antibacterial studies screening of the primary ligand FFAAPS and the complexes showed that the present complexes have moderate antibacterial activities.

• Analytical Science and Technology
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• v.9 no.3
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• pp.244-252
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• 1996

Spectrophotometric properties of lanthanide complexes with methylthymol blue(MTB) and cetyltrimethylammonium bromide(CTAB) were studied and also lanthanide(III) ions were determined by flow injection analysis on the base of the above results. The absorption maxima of lanthanide(III)-MTB complexes in the presence of CTAB are 635nm with molar absorptivity of $4.51{\sim}6.11{\times}10^4Lmol^{-1}cm^{-l}$ at pH 5.8. The mole ratio of lanthanide(III) complexes with MTB is 1:2 in the presence of CTAB. The calibration curves of lanthanide(III) ions obey the Beer's law in the range of 0.1 to 0.4ppm under the optimum condition. The samples throughput was ca. $60hr^{-1}$. The interfering effect of some cations and anions was investigated. The ligand anions such as tartrate and citrate, many transition and rare earth elements interfered severely and must be removed before the determination of lanthanide(III) ions.

• Journal of the Korean Chemical Society
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• v.33 no.5
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• pp.496-503
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• 1989

The chemical behavior of trivalent lanthanide (Pr(III) and Yb(III)) and 2, 2, 6, 6-tetramethyl-3, 5-heptanedione(dipivaloylmethane) complexes was investigated by the use of direct current, differential pulse polarography and cyclic voltammetry. In this study, it was founded that the reduction of trivalent lanthanide complexes was observed by one electron transfer process at Epc = -0. 13 V and -0.80 V of Pr(III), and -0.02 V of Yb(III) vs. Ag-AgCl electrode. Also, it was founded that the treatment of DP and CV to the case of a first-order chemical equilibrium reaction preceding a reversible and irreversible one electron transfer reaction, (a >0. 5) the socalled ErCr electrode process. The equilibrium constant (lnK) obtained, of various solvents, these constant were founded to be increases with decreasing dielectric constant of the solvents. Plots of lnK for these reaction against ln(l/D) for the solvents was fairly straight lines, and the behavior of the heavier lanthanides was decreased equilibrium constant with increasing atomic number.

• Journal of the Korean Chemical Society
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• v.55 no.4
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• pp.612-619
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• 2011

Lanthanide(III) complexes of 1,2-diphenyl-4-butyl-3,5-pyrazolidinedione(phenylbutazone, PB) have been synthesized and characterized by elemental analyses, molar conductance measurements, IR, UV-Vis. and NMR spectra. The spectral data reveal that the PB acts as a bidentate and mono-ionic ligand coordinating through both the carbonyl oxygens of the pyrazolidinedione ring. The molar conductance data suggest that the complexes are non-electrolytes. The thermal behaviour of the complexes was studied by TG and DTG in air atmosphere and the results provide information about dehydration, thermal stability and thermal decomposition. The final products are found to be the corresponding metal oxides. The thermodynamic parameters and kinetic parameters were evaluated for the dehydration and decomposition stages. The negative entropy values of the decomposition stages indicate that the activated complexes have a more ordered structure than the reactants and that the reactions are slower than normal. Based on these studies, the complexes have been formulated as $[Ln(PB)_3]{\cdot}5H_2O$(Ln=La and Ce) and $[Ln(PB)_3(H_2O)_2]{\cdot}2H_2O$(Ln=Pr, Nd and Sm).

• Journal of the Korean Chemical Society
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• v.43 no.5
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• pp.596-600
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• 1999

• Analytical Science and Technology
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• v.6 no.1
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• pp.83-92
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• 1993

The electrochemical behaviors of lanthanide ion(La and Nd) and lanthanide complexes with 2, 2, 6, 6-tetramethyl-3, 5-heptanedione(THD), sym-hydroxydibenzo-16-crown-5(HD16C5) and sym-dibenzo-16-crown-5-oxyacetic acid(D16C5A) ligands in acton solution have been investigated by the use of cyclic voltammetry and direct current polarography. The peak potential and peak current, their dependency on the concentration, temperature, the reversibility of the eleotrode reactions are described. The reduction of the lanthanide ions and complexes in 0.05 M TEAP proceeded one-electron step in first step and one two-electron step in second step. These reduction step was irreversible and the reduction current was diffusion controlled. Macrovcyclic crown ethers, sym-hydroxydibenzo-16-crown-5(HD16C5) and sym-dibenzo-16-crown-5-oxyacetic acid(D16C5A), were prepared from 1, 5-bis-(2-hydroxyphenoxy)-3-oxapentane with epichlorohydrin. The voltammetric behaviors of Ln(III)-HD16C5 and Ln-D16C5A complexes in aceton solution have been investigated by the voltammetric method. The composition and stability constants of lanthanide complexes were determined.

• Journal of the Korean Chemical Society
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• v.36 no.6
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• pp.840-848
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• 1992

An ionizable macrocyclic ligand, diaza-18-crown-6-diisopropionic acid(K22DAP) has been synthesized. Protonation constants of this compound and stability constants with some lanthanides were determined by potentiometric titration method. The protonation constants are log$K_1$ = 9.05, log$K_2$ = 8.37, log$K_3$ = 1.88 and log$K_4$ = 0.99. The logarithmic values of stability constants with La(III), Nd(III), Gd(III) and Lu(III) are 11.14, 11.43, 11.74 and 10.88 respectively. Extraction behavior of Ln(III) ion was investigated using TTA(thenoyltrifluoroacetone) as extractant in the presence of K22DAP as macrocyclic ionophore. It was observed that Ln(K22DAP)TTA is the dominating species in aqueous complexes of La(III) and Nd(III).

• Journal of the Korean Chemical Society
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• v.37 no.4
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• pp.442-447
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• 1993

The thermodynamic parameters (${\Delta}$G, ${\Delta}$H and ${\Delta}$S) of lanthanides(III)-benzoylformate complexes in aqueous solution have been determined in the ionic medium of 0.1M $NaClO_4$ at 25$^{\circ}C$, using pH and enthalpy titration method. The stability constants of the lanthanide(III)-benzoylformate complexes (1 : 1) agree well with the general relationships for the bidentate ligands (e.g., log${\beta}_1$ vs. p$K_a$). Thermodynamic evidences show that the oxygen atom in ketone group is coordinated along with the carboxylate group. It is ascribed to the increasing charge density on the oxygen atom in ketone group due to the conjugation effect in the benzoylformate ligand. Thermodynamic results also indicate that the complexes are stabilized by the enthalpy effect caused by the ionic interaction of metal-oxygen bond as well as the entropy effect.

• Journal of the Korean Chemical Society
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• v.37 no.10
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• pp.895-902
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• 1993

The chemical behavior of trivalent lanthanide ($Pr^{3+}\;and\;Dy^{3+}$) and organo ligands (phen' and terpy') complexes was investigated by the use of UV/vis-spectrophotometric, magnetization and electrochemical method. The magnitude of crystal field splitting energy, the pairing energy and spin state was obtained from the spectra of complexes. These complexes were founded to be diamagnetics, delocalization and low spin complexes. The electrochemical behavior of complexes was observed by the use of cyclic voltammetry in aprotic media. These reduction peaks were irreversible two step reduction processes by electron transfer.