• Title/Summary/Keyword: Gd-complexes

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Synthesis and Characterization of Novel Rare-earth Oxides Precursors

  • Lee, Euy Jin;Park, Bo Keun;Chung, Taek-Mo;Kim, Chang Gyoun
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.366.1-366.1
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    • 2014
  • The rare-earth oxides M2O3 (M=La, Pr, Gd) are good insulators due to their large band gap (3.9eV for Pr2O3, 5.6eV for Gd2O3), they have high dielectric constants (Gd2O3 K=16, La2O3 K=27, Pr2O3 K=26-30) and, compared to ZrO2 and HfO2, they have higher thermodynamic stability on silicon making them very attractive materials for high-K dielectric applications. Another attractive feature of some rare-earth oxides is their relatively close lattice match to that of silicon, offering the possibility of epitaxial growth and eliminating problems related to grain boundaries in polycrystalline films. Metal-organic chemical vapor deposition (MOCVD) has been preferred to PVD methods because of the possibility of large area deposition, good composition control and excellent conformal step coverage. Herein we report on the synthesis of rare-earth oxide complexes with designed alkoxide and aminoalkoxide ligand. These novel complexes have been characterized by means of FT-IR, elemental analysis, and thermogravimetric analysis (TGA).

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Studies on the Spectrophotometric Determination and Electrochemical Behavior of Heavy Lanthanide Ions in Nonaqueous System and Heavy Metal Chelate Complexes with Bidentate Legands: (Part I) Flow Injection Spectrophotometric Determination of Heavy Lanthanide Ions with Xylenol Orange

  • Sam-Woo Kang;Chong-Min Park;Kwang-Hee Cho;Hong-Seock Han
    • Bulletin of the Korean Chemical Society
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    • v.14 no.1
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    • pp.59-62
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    • 1993
  • Spectrophotometric determination of some heavy lanthanide ions by flow injection method is described. Xylenol Orange forms water soluble chelates with lanthanide ions in a tris[hydroxymethyl]-aminomethane-buffered medium having pH 8.3 and containing cetyltrimethylammonium bromide. The molar absorptivities of Ln(III)-XO complexes were increased by the ternary system with cetyltrimethylammonium bromide with the concomitant bathochromic shift of absorption maxium compared to those of the binary system without cetyltrimethylammonium bromide. The calibration curves are linear in the range 0.25-1.00 ppm for Gd(III), Dy(III), Er(III), Tm(III) and Yb(III) and the dynamic range are very wide. The detection limits (S/N=2) are from 2 ppb for Gd(III) to 30 ppb for Yb(III) and the relative standard deviations are from 1.2% for 0.5 ppm Gd(III) to 1.8% for 0.5 ppm Yb(III). The sample throughput was ca. 50 $h^{-1}$.

A Study on the Electronic Properties and Electrochemical Behavior of Rare Earch Metal(Ⅲ) Complexes (Ⅲ) (희토류금속(Ⅲ) 착물들의 전자적 성질과 전기화학적 거동에 관한 연구 (Ⅲ))

  • Choe, Chil Nam;Son, Hyo Yeol
    • Journal of the Korean Chemical Society
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    • v.38 no.8
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    • pp.590-597
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    • 1994
  • The chemical behavior of the trivalent lanthanide$(Pr^{3+}, Eu^{3+}, Gd^{3+} 그리고 Yb^{3+})$complexes with organo-ligand (2,2,6,6-tetramethyl-3,5-heptanedione) has been investigated by the use of UV/Vis-spectrophotometric, magnetics, and electrochemical method. The two or three energy absorption bands are observed by the spectra of these complexes. The magnetitude of crystal field splitting energy, the spin pairing energy and bond stength was obtained from the spectra of the complexes. These are found to be localization, low-spin (or high-spin state, and strong bonding strength. The magnetic dipole moment are found to be diamagnetic complexes (or paramagnetic). The electrochemical behavior of complexes was observed by the use of cyclic voltammetry in aprotic media. These reduction peaks were irreversible two and three step reduction processes by electron transfer.

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Synthesis and evaluation of metal purine-type complexes for lung cancer imaging

  • Kang, Kyeung Jun;Ko, In Ok;Park, Ji-Ae;Kim, Jung Young
    • Journal of Radiopharmaceuticals and Molecular Probes
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    • v.5 no.1
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    • pp.61-68
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    • 2019
  • Purine type compounds has been recently reported to cause the death for lung cancer cell, related to microtubules-targeting agents (MTAs). Therefore it can be used to develop as theranostic radiopharmceuticals in nuclear medicine or gadolinium-based MRI imaging agents by chelate chemistry. In the study, we tried to chemically bind a DOTA chelate on the end of purine compound and obtained a specific conjugate of DOTA-purine for metal coordination. In particular, radiometal like Cu-64, for the development of MRI imaging agents, can be utilized to choice good candidates before the synthesis of gadolinium complexes. By the screening of radioisotope technique, Gd-DOTA-purine type complex was successfully prepared and showed MRI imaging for lung cancer cell into the mouse model.

Studies on the Synthesis and Structure of Macrocyclic Complexes for Transition Metals. (Part 1) Effects of Stability Constant on the Co-formation of Mixed Chelates (EDTA and IMDA) with Lanthanon (La, Nd, Gd, Ho, Yb) (전이금속 착물들의 합성 및 결정구조 연구 (제 1 보) EDTA 와 IMDA 복합 킬레이트가 란탄족 원소들 (La, Nd, Gd, Ho, Yb)의 안정도 상수에 미치는 영향)

  • Young-Gu Ha;E. Y. Kim;Q. Won Choi;Hasuck Kim
    • Journal of the Korean Chemical Society
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    • v.31 no.5
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    • pp.434-443
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    • 1987
  • The formation constants of the complexes between Ln-EDTA 1 : 1 complex and IMDA have been investigated by a potentiometric titration method at 20.0${\pm}$0.2 degree C and ${\mu}$ = 0.1 (KNO$_3$). Unusually large stability in Ln(EDTA) mixed ligand complexes was found. Trends in the formation constants vs. atomic number of the lanthanide metals were discussed on the basis of coordination number and ionic radius of the metals.

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Spectral, Electrochemical, Fluorescence, Kinetic and Anti-microbial Studies of Acyclic Schiff-base Gadolinium(III) Complexes

  • Vijayaraj, A.;Prabu, R.;Suresh, R.;Kumari, R. Sangeetha;Kaviyarasan, V.;Narayanan, V.
    • Bulletin of the Korean Chemical Society
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    • v.33 no.11
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    • pp.3581-3588
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    • 2012
  • A new series of acyclic mononuclear gadolinium(III) complexes have been prepared by Schiff-base condensation derived from 5-methylsalicylaldehyde, diethylenetriamine, tris(2-aminoethyl) amine, triethylenetetramine, N,N-bis(3-aminopropyl)ethylene diamine, N,N-bis(aminopropyl) piperazine, and gadolinium nitrate. All the complexes were characterized by elemental and spectral analyses. Electronic spectra of the complexes show azomethine (CH=N) within the range of 410-420 nm. The fluorescence efficiency of Gd(III) ion in the cavity was completely quenched by the higher chain length ligands. Electrochemical studies of the complexes show irreversible one electron reduction process around -2.15 to -1.60 V The reduction potential of gadolinium(III) complexes shifts towards anodic directions respectively upon increasing the chain length. The catalytic activity of the gadolinium(III) complexes on the hydrolysis of 4-nitrophenylphosphate was determined. All gadolinium(III) complexes were screened for antibacterial activity.

Design of Home or Hetero Polynuclear Metal Dendritic Molecule for PDD or PDT

  • Choi, Chang-Shik
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2021.10a
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    • pp.646-648
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    • 2021
  • The syntheses and properties of polynuclear metal complexes have been reported to develop the easy syntheses and noble photo-characteristics of those complexes for photodynamic diagnosis (PDD) or photodynamic therapy (PDT). We have been focused on the design and synthesis of polynuclear lanthanide dendritic molecule due to long life time of fluorescence. Therefore, we will be presented on the design of home (Eu or Gd) or hetero (Tb or Lu) polynuclear lanthanide dendritic molecule.

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Chemical Equilibria of Lanthanide {Ln(III)=Pr, Sm, Gd, Dy}-Macrocyclic Complexes with Auxiliary Ligands in $CH_3OH$(Part III); Study of the Coordination of Nitrogen-or Oxygen-Containing Bases ($CH_3OH$ 용매에서 란탄족 원소 {Ln(III)=Pr, Sm, Gd, Dy}-거대고리 착물과 보조리간드 간의 화학평형(제3보); 두자리 리간드(주게원자:N혹은 O)를 중심으로 고찰)

  • Byun, Jong-Chul;Park, Yu-Chul;Han, Chung-Hun
    • Journal of the Korean Chemical Society
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    • v.44 no.2
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    • pp.95-101
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    • 2000
  • Macroacyclic transition metal complexes such as $Cu(H_2L[A]).H_2O$, $Cu(H_2L[B]).H_2O$, CuFe(L[A]($NO_3$).$4H_2O$, CuFe(L[B])($NO_3$).$4H_2O$, [$CuGd(H_2L[A])(NO_3)_2](NO_3).2CH_3OH$, [CuGd($H_2L$[B])($NO_3)_2$]($NO_3).2CH_3OH were prepared from the corresponding hexadentate compartmental ligands, $H_4L[A]$ and $H_4L[B]$, which were obtained by the condensation of 2-hydroxy-3-hydroxymethy1-5-methyIbenzaldehyde(HHNNB) and ethylenediamine or l,3-diaminopropane. Ln-macrocyclic([20]DOTA) complexes,[Ln([20]DOTA)($NO_3)(H_2O)$]($NO_3$)2.$xH_2O${Ln(III)=Pr, Sm, Gd, Dy, which had been synthesized from 2,6-diformyl-p-cresol(DFPC), was placed in methanol for 2 days, and [Ln([20] DOTA)($NO_3)(CH_3OH)]^{2+}$ was formed The equilibrium constants (k) for the substitution of coordinated $CH_3OH$ in the Ln-[20]DOTA complexes by various bidentate auxiliary ligands, $L_a$(=o-phenylenediamine,1,10-phenanthroline, ethylenediamine,oxalicacid, malonic acid, acethylacetone) were determined by spectroscopic method at $25^{\circ}C$ and 0.1M $NaClO_4$.The pKa of auxiliary ligands is in the order of o-phenylenediamine < 1,10-phenanthroline < ethylene-diamine, oxalic acid < malonic acid < acethylacetone. However, the equilibrium constant(K) has shown thetrend of ethyleneiamine < 1,10-phenanthroline < o-phenylenediamine, acethylacetone < malonic acid < oxalic acid.

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