• Bulletin of the Korean Chemical Society
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• v.23 no.4
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• pp.623-625
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• 2002

• Bulletin of the Korean Chemical Society
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• v.30 no.10
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• pp.2213-2216
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• 2009

A novel carbazole functionalized bis-$\beta$-diketone type organic ligand, 1,1′-(2,6-bispyridyl)bis-3-(9-ethylcarbazole- 3-yl)-1,3-propanedione ($H_2L$) and its corresponding lanthanide complexes $Eu_2(L)_3\;and\;Tb_2(L)_3$ were successfully prepared. The ligand and complexes were characterized in detail based on FT-IR spectra, $^1H$ NMR and elemental analysis. The observed UV-Vis absorption and photoluminescence properties of the complexes were investigated, it shows that the Eu(III) and Tb(III) ions can be sensitized efficiently by the ligand ($H_2L$) to some extent, in particular, the complex $Tb_2(L)_3$ exhibits a more excellent luminescence property than the Eu(III) complex. Meanwhile, the introduction of the carbazole moiety can enlarge the $\Pi$-conjugated system of the ligand and enhance the luminescent intensity of the complexes. The results show that the complexes would be used as excellent luminescent materials.

• Journal of the Korean Applied Science and Technology
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• v.18 no.1
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• pp.12-19
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• 2001

Eu(III) exhibits one electron-transfer reduction at $E_{1/2}$ = -0.564 V(vs. Ag/AgCl) and the hypersensitive peak at 615 ㎚ corresponding to $^{5}D_{0}{\rightarrow}^{7}F_{2}$ transition in 0.1 M $LiClO_{4}$ aqueous solution. Upon the addition of 2,6-pyridine dicarboxylic acid(PDA) to the Eu(III) aqueous soultion, the reduction potential shifts negatively and the PDA, and the Eu(III)-PDA complex emits great fluorescence than free-Eu(III) ion at 615 nm. The results are interpreted in term of the electrochemical and spectrofluorometric studies.

• Bulletin of the Korean Chemical Society
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• v.16 no.7
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• pp.654-657
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• 1995

A series of excitation spectra (7Fo→5Do transition) of Eu(Ⅲ) ion in aqueous solution ([Eu(Ⅲ)]=1.12 × 10-2 mol L-1; pH 1.0 to 7.0) were obtained under CO2 free atmosphere using a pulsed tunable dye laser system. The broad and low intensity spectra (peak maximum: 578.89 nm) showed that the trivalent ion (Eu3+) underwent a low degree of hydrolysis at pH below 6.0. Eu(Ⅲ) hydroxo complex formation seemed more significant at pH above 6.0, shown by the occurrence of intense new peak at 578.63 nm. The spectra of those solutions prepared in N2 atmosphere showed no signs of the presence of interfering carbonate species. The Eu(Ⅲ) hydroxo complex formation was not observed when complexation studies between Eu(Ⅲ) ion and weak organic acids (e.g. glutarate and diglycolate) were conducted at pH 6.0 or below.

• Rapid Communication in Photoscience
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• v.2 no.1
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• pp.34-37
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• 2013

Two novel antenna complexes of $Eu^{III}$ with 1-naphthoic acid (NA) as primary ligand and two aromatic N-donor ligands namely N-hexyl-N-(pyridin-2-yl) pyridin-2-amine (1) and 4-((dipyridin-2-ylamino)methyl)benzoic acid (2) have been synthesized and characterized by various spectroscopic techniques. The room-temperature (298 K) photoluminescence spectrum of $Eu^{III}$ complexes composed of typical line like emissions, assigned to transitions between the first excited state $^5D_0$ to the $^7F_J$ (J = 0-4), resulting in red emission along with the residual emission from the 1-naphthoic acid moiety in the blue region. The determined CIE color coordinate value for the complex 2 is (x = 0.36, y = 0.34), which is in white region.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1745-1747
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• 2011

• 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. $50\;cm^{-1}$.

• Bulletin of the Korean Chemical Society
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• v.26 no.7
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• pp.1057-1064
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• 2005

Photoluminescence (PL) spectra of Eu(III) and Tb(III) complexes with mixed oxydiacetate (ODA) and 1,10-phenanthroline (phen) ligands and with homoleptic ODA reveal characteristic line-splitting at 10 K, depending on the site-symmetry of the lanthanide ion in the complex. The energy-level schemes of the $^7F_J$ states and the emitting levels for Eu(III) and Tb(III) ions have been proposed by simulating the line splitting in the framework of crystal-field Hamiltonian. The sets of refined crystal-field parameters for the experimentally determined sitesymmetry satisfactorily reproduce the experimental energy-level schemes. In addition, the PL quantum yield and the decay time were determined at room temperature. The PL quantum yields of [$Eu(ODA){\cdot}(phen){\cdot}4H_2O]^+$ and [Tb$(ODA){\cdot}(phen){\cdot}4H_2O]^+$ in the crystalline state (Q = 17.7 and Q = 56.6%, respectively) are much greater than those of [Eu($ODA)_3]^{3-}and\;[Tb(ODA)_3]^{3-}$(Q = 1.1 and Q = 1.3, respectively), due to the energy transfer from phen to the lanthanide ion. In the aqueous state, the relaxation of the phen moiety due to the solvent results in the reduction of the quantum yield and the shortening of the lifetime.

• Bulletin of the Korean Chemical Society
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• v.19 no.1
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• pp.83-86
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• 1998

The luminescence spectra of Eu(Ⅲ) complexes have been measured as a function of molar metal-to-ligand ratio and pH. The ligands used in this study are tridentate iminodiacetate (IDA) and methyliminodiacetate (MIDA). The 620 nm emission band, attributed to the $^5D_0{\to}^7F_2$ transition, is monitored to investigate the optimum condition for $EuL_3^{3-}$ complex formation in aqueous state. In addition, the sensitivity of the 465 nm absorption band, attributed to the $^7F_0{\to}^5D_2$ transition, to the ligand environment has been also investigated.

• Economic and Environmental Geology
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• v.42 no.5
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• pp.495-500
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• 2009

Actinide sorption to the geological materials can reduce the mobility and bioavailability of radionuclides released to the environment through the development of nuclear weapons and nuclear energy. Under circumneutral pH conditions, actinide sorption can be enhanced by phosphate anions sorbed on oxide mineral surfaces as indicated by the sorption of trivalent lanthanide ions ($Ln^{3+}$), the chemical analog for trivalent actinide ions ($Ac^{3+}$). In this paper, we examined a ternary sorption system of trivalent europium ions ($Eu^{3+}$) sorbed onto boehmite (${\gamma}$-AlOOH) surfaces pre-sorbed with phosphate anions (${PO_4}^{3-}$), using extended X-ray absorption fine structure (EXAFS) spectroscopy. In the Eu-$PO_4$-boehmite ternary sorption system, $EuPO_4$ surface precipitates were formed as implicated by Eu $L_{III}$-edge EXAFS spectroscopy. Phosphorus K-edge EXAFS fingerprinting indicated a bidentate mononuclear surface complex formation of phosphate sorbed on boehmite surfaces as well as $EuPO_4$ surface precipitate formation.