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        검색결과 47

        41.
        2010.07 KCI 등재 서비스 종료(열람 제한)
        A new N3O2 pentadentate ligand, N,N'-Bis(2-hydroxybenzyl)-ethylenetriamine(H-BHET․3HCl) was synthesized. The hydrochloric acid salts of Br-BHET․3HCl, Cl-BHET․3HCl, CH3O-BHET․3HCl and CH3-BHET․3HCl containing Br-, Cl-, H-, CH3O- and CH3- groups at the para-site of the phenol group of the H-BHEP were synthesized. The structures of the ligands were confirmed by C. H. N. atomic analysis and 1H NMR, 13C NMR, UV-visible and mass spectra. The calculated stepwise protonation constants(logKnH) of the synthesized N3O2 ligands showed six steps of the proton dissociation. The orders of the overall protonation constants(logβp) of the ligands were Br-BHET < Cl-BHET < H-BHET < CH3O-BHET < CH3-BHET. The orders agreed well with that of para Hammett substituent constants(δp). The calculated stability constants(logKML) between the ligands and heavy metal ions (Co(Ⅱ) , Ni(Ⅱ), Cu(Ⅱ), Zn(Ⅱ), Cd(Ⅱ) and Pb(Ⅱ)) agreed well with the order of the overall proton dissociation constants of the ligands but they showed a reverse order in para Hammestt substituent constants(δp). The order of the stability constants between the heavy metal ions with the synthesized ligands were Co(Ⅱ) < Ni(Ⅱ) < Cu(Ⅱ) > Zn(Ⅱ) > Cd(Ⅱ) > Pb(Ⅱ).
        42.
        2009.07 KCI 등재 서비스 종료(열람 제한)
        Hydrochloric acid salt of a new N2O3 pentadentate ligand, N,N'-Bis(2-Hydroxybenzyl)-1,3-diamino-2-propanol(H-BHDP․2HCl) was synthesized. Br-BHDP․2HCl, Cl-BHDP․2HCl, CH3-BHDP․2HCl and CH3O- BHDP․2HCl having Br, Cl, CH3 and CH3O substituents at 5-position of the phenol group of H-BHDP․2HCl were also synthesized. The potentiometry study in aqueous solution revealed that the proton dissociations of the synthesized ligands occurred in four steps and their order of the calculated overall proton dissociation constants(logβp) was Br-BHDP〈 Cl-BHDP〈 H-BHDP〈 CH3O-BHDP〈 CH3-BHDP. The order showed a similar trend to that of Hammett substituent constants(δp). The order of the stability constants(logKML) was Co(Ⅱ)〈 Ni(Ⅱ)〈 Cu(Ⅱ)〈 Zn(Ⅱ)〈 Cd(Ⅱ)〈 Pb(Ⅱ). The order in their stability constants (logKML) of each transition metal complex agreed with that of the overall proton dissociation constants (logβp).
        43.
        2006.08 KCI 등재 서비스 종료(열람 제한)
        Hydrobromic acid salts of new N, N, O tridentate ligands containing phenol, 2-[(2-Methylamino- ethylamino)-methyl]-phenol(H-MMP․2HBr), 5-Bromo-2-[(2-Methylamino-ethylamino)-methyl]-phenol (Br- MMP․2HBr), 5-Chloro-2-[(2-Methylamino-ethylamino)-methyl]-phenol(Cl-MMP․2HBr), 5-Methyl-2-[(2-Methylamino- ethylamino)-methyl]-phenol(Me-MMP․2HBr), 5-Methoxy-2-[(2-Methylamino-ethylamino)- methyl]-phenol(MeO- MMP․2HBr) and 1-[(2-Methylamino-ethylamino)- methyl]-naphthalen-2-ol(Nap- MMP․2HBr) were synthesized. The synthesized ligands were confirmed by C. H. N. atomic analysis, UV-visible and IR spectroscopies, 1H NMR, 13C NMR and mass analysis. The potentiometry study revealed that the proton dissociation constants(logKnH) of the synthesized ligands and stability constants (logKML, logKML2) of transition metal complexes of Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Pb(II) ions occurred in three steps and the order of the calculated overall proton dissociation constants(logβp) and stability constants (logKML) of ligands was Br-MMP․2HBr < Cl-MMP․2HBr < H-MMP․2HBr < Nap-MMP․2HBr < Me-MMP․2HBr < MeO-MMP․2HBr. The order showed a similar trend to that of Hammett substituent constants(δp). The synthesized ligands usually form 2:1(ML2) complexes with transition metal ions. The order of the stability constants of each transition metal ions was Co(II) < Ni(II) < Cu(II) > Zn(II) > Cd(II) > Pb(II).
        44.
        2004.09 KCI 등재 서비스 종료(열람 제한)
        N,N-bis(2-salicylaldehyde)dipropylenetriamine(5-Hsaldipn), N,N-bis(5-bromosalicyl-aldehyde) dipropylenetriamine (5-Brsaldipn), N,N-bis(5-chlorosalicylaldehyde)dipropylene-triamine(5-Clsaldipn), N,N-bis(2-hydroxy-5-methoxybenzaldehyde)dipropylenetriamine(5-OCH3saldipn) and N,N-bis (2-hydroxy-5-nitrobenzaldehyde)dipropylenetriamine (5-NO2saldipn) were synthesized and characterized by elemental analysis, infrared spectrometry, NMR spectrometry and mass spectrometry. Their proton dissociation constants were determined in 70% dioxane/30% water solution by potentiometric. Stability constants of the complexes between these ligands and the metal ions such as Cu(Ⅱ), Ni(Ⅱ) and Zn(Ⅱ) were measured in dimethyl sulfoxide by a polarographic method. Stability constants for the ligands were in the order of 5-OCH3 > 5-H > 5-Br > 5-Cl > 5-NO2saldipn. Enthalpy and entropy changes were obtained in negative values.
        45.
        1999.06 KCI 등재 서비스 종료(열람 제한)
        The medical mineral menas a single mineral or a complex of minerals. It is natural material. using the medical action of he major or the minor elements, and traditional medicine stuff which has been used since long time ago. Jusa, cinnabar as the mineral name, is the product of the hydrothermal process. It is used to relax the body and cure high blood pressure, apoplexy and cardiopathy. Jusais the major component of "An shin hwan" and "Woo hwang chung shim hwan" nowadays because it has such an excellent calm effect. In addition, it is used to cure cancers such as esophageal cancer and gastric cancer. Jusa composed of mercuric sulfide causes mercury poisoning such as Minamata disease. It is dealt with mineralogical property and chemical composition medical stuff in Korea and China, as well asmercury poisoning and medical action of Jusa in this study. In order to predct accumulation of the interior of the body of the major and minor elements in Jusa, leaching experiment of Jusa by artificial gastric juice was done as well as thermodynamic reaction modelling to know concentration of each species of body fluid. The minor elements of 24 species such as As, Pb, Cd, a and Fe by leaching reaction of Jusa and artificial gastric juice were leached. We can know the fact that as is less than 1 ppm, Hg is less than 25 ppm and Cd and m are not detected. In addition, mercury exists as species of Hg2+, HgCl+, HgCl2, HgCl3-, HgCl42-, HgClOH, HgS(H2S)2, Hg(HS)3-, HgS22-, HgOH and Hg(OH)2 by reaction modelling between Jusa and artificial gastric juice. The concentration of sulfide complexes is 24.2 ppm and that of others is less than 10 ppm. According to increasing pH, the concentration of HgS(H2S)2, Hg(HS)3+, HgS22- and Hg(OH)2 increases, whereas the concentration of HgCl+, HgCl2, HgCl3- and HgCl42- decreases. Therefore, Jusa is very useful for the development of new medicine because it is possible to predict formation of the body species and species accumulation on mercury known as a toxic element and concentration changes of toxicity and efficiency.city and efficiency.
        46.
        1996.10 KCI 등재 서비스 종료(열람 제한)
        This study is involved to develop new catalysts to decompose plastics, detergents and surfactants containing synthetic peptide bonds. As the first year research, the catalytic hydrolysis of amide bond in copper complex was accomplished. The hydrolysis reaction in aqueous solution was monitored by UV/VIS spectroscopy. As the pH of the solution is increased and the temperature is raised, the reaction rate increases. The reaction rate is observed as the first order kinetic behavior for the copper complex. The metal catalyzed hydrolysis mechanism is proposed via metal-hydroxide in the pH region of 5.5 to 6.3. The results of characterization of the catalytic reaction mechanism can be applied to develop new catalysts for peptide bond degradation in further research.
        47.
        1994.12 KCI 등재 서비스 종료(열람 제한)
        In aqueous acid solution [Cr(CN)_6]^3- aquates via a series of stepwise stereospecific reactions to give [Cr(H_2O)_6]^3+ as the final product.Some of the intermediate cyanoaquo complexes in the sequence have been isolated.These complexes aquate by both acid independent and acid denpendent pathways,the latter involving protonation of the cyano ligands followed by aquation of the singly protonated species. The kinetic data for the aquation of [CrCN(H_2O)_5]^2+ are consistent with the transition state structure, [(H_2O)_4Cr(CN)-OH-Cr(H_2O)_5]^3+.Addition of Cr^2+ to solutions of cyanocobalt(III) complexes produces the metastable intermediate[CrNC(H_2O]^2)+.This isomerizes to in a Cr^2+ -catalyzed reaction which occurs by a ligand-bridged electron-change mechnism. From acid catalysis on these aquation reactions, it product HCN. Especially, HSO_3 ions do the role of catalyst in the formation of HCN from CrCN^3+.
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