• 제목/요약/키워드: Macrocycles

검색결과 52건 처리시간 0.02초

Studies on the Macrocycle-mediated Transport of Divalent Metal Ions in a Supported Liquid Membrane System

  • 조문환;신상철
    • Bulletin of the Korean Chemical Society
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    • 제16권1호
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    • pp.33-36
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    • 1995
  • Macrocyclic ligands have been studied as cation carriers in a supported liquid membrane system. Cd2+ has been transported using nitrogen substituted macrocycles as carriers and several divalent metal ions (M2+=Zn, Co, Ni, Cu, Pb, Mg, Ca, and Sr) have been transported using DBN3O2, DBN2O2and PolyNtnoen as carriers in a supported liquid membrane system. Competitive Cd2+-M2+ transport studies have also been carried out with the same system. Ligand structure, stability constant, membrane solvent and carrier concentration are also important parameters in the transport of metal ions.

Macrocyclic Isomers with S2O-Donor Set as Silver(I) Ionophores

  • Park, Sung-Bae;Yoon, Il;Seo, Joo-beom;Kim, Hyun-Jee;Kim, Jae-Sang;Lee, Shim-Sung
    • Bulletin of the Korean Chemical Society
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    • 제27권5호
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    • pp.713-717
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    • 2006
  • $S_2O$-donor macrocyclic isomers incorporating a xylyl group in o- ($L^1$), m- ($L^2$) and p-positions ($L^3$) extract no metal ions except silver(I) from aqueous to chloroform phase. And the magnitudes of %Ex for silver(I) are in the order of $L^1$ > $L^2$ > $L^3$. Taking this result into account, $L^1$-$L^3$ were utilized as membrane active components to prepare potentiometric silver(I)-selective electrodes. The proposed macrocycles-based electrodes E1 ($L^1$), E2 ($L^2$) and E3 ($L^3$) exhibited comparable results which show considerable selectivity toward silver(I) over alkali, alkali earth and other transition metal ions. Comparative NMR study on $L^1$-$L^3$ and their complexes with silver(I) in solution was also accomplished. In addition, a unique sandwich-type complex $[Ag(L^1)_2]CIO_4$ was prepared from the assembly reaction of $L^1$ with $AgClO_4$ and structurally characterized by an X-ray diffraction analysis.

Preparation and Crystal Structures of Silver(I), Mercury(II), and Lead(II) Complexes of Oxathia-Tribenzo-Macrocycles

  • Siewe, Arlette Deukam;Ju, Huiyeong;Lee, Shim Sung
    • Bulletin of the Korean Chemical Society
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    • 제34권3호
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    • pp.725-730
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    • 2013
  • An investigation of the coordination behavior of sulfur-containing mixed-donor tribenzo-macrocycles $L^1-L^3$ ($L^1$: 20-membered $O_3S_2$, $L^2$: 20-membered $O_2S_3$, and $L^3$: 23-membered $O_4S_2$) with $d^{10}$-metal ($Ag^+$, $Hg^{2+}$, and $Pb^{2+}$) salts is reported. The X-ray structures of five complexes (1-5) with different structural types and stoichiometries, including mono- to dinuclear species have been determined. Reactions of $L^2$ and $L^3$ with the silver(I) salts ($PF_6{^-}$ and $SCN^-$) afforded two dinuclear 2:2 (metal-to-ligand) complexes with different arrangements: a sandwich-type cyclic dinuclear complex $[Ag_2(L^2)_2](PF_6)_2{\cdot}3CH_2Cl_2$ (1) and a linear dinuclear complex $[Ag_2(L^3)_2(SCN)_2]$ (2), in which two monosilver(I) complex units are linked by an Ag-Ag contact. Reactions of $L^1$ and $L^2$ with mercury(II) salts ($SCN^-$ and $Cl^-$) gave a mononuclear 1:1 complexes $[Hg(L^1)(SCN)_2]$ (3) and $[Hg(L^2)Cl_2]$ (4) with anion coordination in both cases. $L^2$ reacts with lead(II) perchlorate to yield a mononuclear sandwich-type complex $[Pb(L^2)_2(ClO_4)_2]$ (5), giving an overall metal coordination geometry of eight with a square antiprism arrangement. From these results, the effects of the donor variation and the anioncoordination ability on the resulting topologies of the soft metal complexes are discussed.

A Non-Pt Catalyst for Improved Oxygen Reduction Reaction in Microbial Fuel Cells

  • Kim, Jy-Yeon;Han, Sang-Beom;Oh, Sang-Eun;Park, Kyung-Won
    • 전기화학회지
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    • 제14권2호
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    • pp.71-76
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    • 2011
  • Fe-tetramethoxyphenylporphyrin on carbon black (Fe-TMPP/C) is examined and compared with carbon (C) and Pt-coated carbon (Pt/C) for oxygen reduction reaction in a two chambered microbial fuel cell (MFC). The Fe-TMPP/C is prepared by heat treatment and characterized using SEM, TEM, and XPS. The electrochemical properties of catalysts are characterized by voltammerty and single cell measurements. It is found that the power generation in the MFC with Fe-TMPP/C as the cathode is higher than that with Pt/C. The maximum power of the Fe-TMPP/C is 0.12 mW compared with 0.10 mW (Pt/C) and 0.02 mW (C). This high output with the Fe-TMPP/C indicates that MFCs are promising in further practical applications with low cost macrocycles catalysts.

Photochemical Approach to the Preparation of Lariat Crown Ethers Containing Peptide Sidearms

  • Cho, Dae-Won;Quan, Chunsheng;Park, Hea-Jung;Yoon, Ung-Chan;Mariano, Patrick S.
    • Bulletin of the Korean Chemical Society
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    • 제32권2호
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    • pp.503-509
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    • 2011
  • New types of lariat type crown ethers containing peptide sidearms were prepared by using a novel strategy employing single electron transfer (SET)-induced photocyclization reactions of $\alpha$-silylether terminated phthalimides. Reactions of chiral substrates in this series produced diastereomeric mixtures of crown ether products as a result of the formation of new stereogenic center generation in the photocyclization process.