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Bulletin of the Korean Chemical Society 33건

  1. [국내논문]   Dynamic Kinetic Resolutions and Asymmetric Transformations by Enzyme-Metal Combo Catalysis   피인용횟수: 3

    Kim, Mahn-Joo (National Research Laboratory of Chirotechnology and Department of Chemistry, Division of Molecular and Life Sciences, Pohang University of Science and Technology ) , Ahn, Yang-Soo (National Research Laboratory of chirotechnology and Department of Chemistry, Division of Molecular and Life Sciences, Pohang University of Science and Technology ) , Park, Jai-Wook (National Research Laboratory of chirotechnology and Department of Chemistry, Division of Molecular and Life Sciences, Pohang University of Science and Technology)
    Bulletin of the Korean Chemical Society v.26 no.4 ,pp. 515 - 522 , 2005 , 0253-2964 ,

    초록

    Enzyme-metal combo catalysis is described as a useful methodology for the synthesis of optically active compounds. The key point of the method is the use of enzyme and metal in combination as the catalysts for the complete transformation of racemic substrates to single enantiomeric products through dynamic kinetic resolution (DKR). In this approach, enzyme acts as an enantioselective resolving catalyst and metal does as a racemizing catalyst for the efficient DKR. Three kinds of enzyme-metal combinations - lipase-ruthenium, subtilisin-ruthenium, and lipase-palladium ?have been developed as the catalysts for the DKRs of racemic alcohols, esters, and amines. The scope of the combination catalysts can be extended to the asymmetric transformations of ketones, enol acetates, and ketoximes via the DKRs. In most cases studied, enzyme-metal combo catalysis provided enantiomerically-enriched products in high yields.

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  2. [국내논문]   Preparation and Characterizations of Poly(ethylene glycol)-Poly(ε-caprolactone) Block Copolymer Nanoparticles   피인용횟수: 1

    Choi, Chang-Yong (Department of Polymer Science and Engineering, Sunchon National University ) , Chae, Su-Young (Department of Polymer Science and Engineering, Sunchon National University ) , Kim, Tai-Hyoung (Department of Polymer Science and Engineering, Sunchon National University ) , Jang, Mi-Kyeong (Department of Polymer Science and Engineering, Sunchon National University ) , Cho, Chong-Su (School of Agricultural Biotechnology, Seoul National University ) , Nah, Jae-Woon (Department of Polymer Science and Engineering, Sunchon National University)
    Bulletin of the Korean Chemical Society v.26 no.4 ,pp. 523 - 528 , 2005 , 0253-2964 ,

    초록

    Diblock copolymers with different poly( $\varepsilon$ -caprolactone) (PCL) block lengths were synthesized by ringopening polymerization of $\varepsilon$ -caprolactone in the presence of monomethoxy poly(ethylene glycol) (mPEG-OH, MW 2000) as initiator. The self-aggregation behaviors of the diblock copolymer nanoparticle, prepared by the diafiltration method, were investigated by using $^1H$ NMR, dynamic light scattering (DLS), and fluorescence spectroscopy. The PEG-PCL block copolymers formed the nano-sized self-aggregate in an aqueous environment by intrsa- and/or intermolecular association between hydrophobic PCL chains. The critical aggregation concentrations (cac) of the block copolymer self-aggregate became lower with increasing hydrophobic PCL block length. On the other hand, reverse trends of mean hydrodynamic diameters were measured by DLS owing to the increasing bulkiness of the hydrophobic chains and hydrophobic interaction between the PCL microdomains. The hydrodynamic diameters of the block copolymer nanoparticles, measured by DLS, were in the range of 65-270 nm. Furthermore, the size of the nanoparticles was scarcely affected by the concentration of the block copolymers in the range of 0.125-5 mg/mL owing to the negligible interparticular aggregation between the self-aggregated nanoparticles. Considered with the fairly low cac and nanoparticle stability, the PEG-PCL nanoparticles can be considered a potential candidate for biomedical applications such as drug carrier or imaging agent.

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  3. [국내논문]   PYE [2-(1-pyrenyl)ethyldimethylsilylated silica] Column HPLC and HR-GC-(micro) ECD in the Accurate Determination of Toxic Co-planar PCBs and Polybrominated Diphenyl Ethers (PBDEs)  

    Kannan, Narayanan (Korea Ocean Research and Development Institute, South Sea Institute ) , Hong, Sang-Hee (Korea Ocean Research and Development Institute, South Sea Institute ) , Oh, Jae-Ryoung (Korea Ocean Research and Development Institute, South Sea Institute ) , Yim, Un-Hyuk (Korea Ocean Research and Development Institute, South Sea Institute ) , Li, Donghao (Korea Ocean Research and Development Institute, South Sea Institute ) , Shim, Won-Joon (Korea Ocean Research and Development Institute, South Sea Institute)
    Bulletin of the Korean Chemical Society v.26 no.4 ,pp. 529 - 536 , 2005 , 0253-2964 ,

    초록

    Measurement of toxicologically relevant polychlorinated biphenyl (PCB) congeners such as non-ortho(IUPAC#) 77, 81, 126, 169 and mono-ortho 105, 114, 118, 123, 156, 157, 189 and di-ortho 170, 180 and polybrominated diphenyl ethers (PBDEs) such as 47, 66, 85, 99, 100, 138, 153, 154 in environmental samples become almost mandatory in several countries now. However, most of the available methods involve expensive instrumentations such as HRGC-HRMS or ECNI-LRMS, apart from expensive extraction and clean-up (with large volume of solvents) steps. A method has been devised combining the analytical separation power of PYE [2-(1-pyrenyl)ethyldimethysilylated silica] column HPLC and high-resolution gas chromatographic techniques including micro-electron capture detection (ECD) and two dimensional gas chromatograpy-ECD techniques to determine these eco-toxic substances at parts-per-trillion (ppt) levels. This combination resolves co-elution of congeners that occur in disproportionate ratios (e.g. CB-110 and -77) and allows accurate congener-specific determination of target compounds. This method is cost effective as it requires only hexane, that in small quantities (10 mL) and GC-ECD. The elution and analysis time are optimized to less man hours. This method is effectively utilized in the analysis of co-planar PCBs and PBDEs from archived solvent extracts of samples previously analyzed for pesticides and PCBs. Structure based separation of contaminant classes improves GCECD determination at ppt levels.

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  4. [국내논문]   DNA Mediated Energy Transfer from 4',6-Diamidino-2-phenylindole to Ru(II)[(1,10-phenanthroline)2L]2+ : Effect of Ligand Structure   피인용횟수: 5

    Youn, Mi-Ryung (Department of Chemistry, Yeungnam University ) , Moon, Seok-Joon (Department of Chemistry, Yeungnam University ) , Lee, Bae-Wook (Department of Chemistry, Yeungnam University ) , Lee, Dong-Jin (Department of Advanced Materials and Environmental Engineering, Kyoungil University ) , Kim, Jong-Moon (Department of Chemistry, Yeungnam University ) , Kim, Seog-K. (Department of Chemistry, Yeungnam University ) , Lee, Chong-Soon (Department of Biochemistry, Yeungnam University)
    Bulletin of the Korean Chemical Society v.26 no.4 ,pp. 537 - 542 , 2005 , 0253-2964 ,

    초록

    It was proposed that Ru(II)[(1,10-phenanthroline) $_2$ dipyrido[3,2-a:2',3'-c]phenazine ([Ru(phen) $_2$ DPPZ] $^{2+}$ )complexes and 4',6-diamidino-2-phenylindole (DAPI) simultaneously bind to poly[d(A-T) $_2$ ] (Biophysics. J. 2003, 85, 3865). Forster type resonance energy transfer from excited DAPI to [Ru(phen)2DPPZ] $^{2+}$ complexes was observed. In this study, we synthesized $\Delta$ - and $\wedge$ -[Ru(phenanthroline) $_2$ dipyrido[3,2-a:2'3'c]6-azaphenazine] ([Ru(phen) $_2$ DPAPZ] $^{2+}$ ) at which the DNA intercalating ligand DPPZ was replaced and we studied its binding properties to poly[d(A-T) $_2$ ] in the presence and absence of DAPI using polarized spectroscopy and fluorescence techniques. All the spectroscopic properties of the [Ru(phen) $_2$ DPAPZ] $^{2+}$ -poly[d(A-T) $_2$ ] complex were the same in the presence and absence of DAPI that blocks the minor groove of polynucleotide, suggesting both $\Delta$ - and $\wedge$ -[Ru(phen) $_2$ DPAPZ] $^{2+}$ complexes are located at the major groove of poly[d(A-T)2]. On the other hand, in contrast with [Ru(phen) $_2$ DPPZ] $^{2+}$ , both $\Delta$ - and $\wedge$ -[Ru(phen) $_2$ DPAPZ] $^{2+}$ exhibited almost twice the efficiency in the fluorescence quenching of DAPI that binds at the minor groove of poly[d(A-T) $_2$ ]. This observation indicates that the efficiency of the Forster type resonance energy transfer can be controlled by a small change in the chemical structure of the intercalated ligand.

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  5. [국내논문]   Effects of External Current Constraint on the Belousov-Zhabotinskii System Measured by a Pt Electrode   피인용횟수: 1

    Wei, Guoying (Institute of Chemical Physics, College of Science, China Jiliang University ) , Jin, Yongdong (Institute of Chemical Physics, College of Chemistry, Sichuan University ) , Ge, Hongliang (Institute of Chemical Physics, College of Science, China Jiliang University ) , Luo, Jiuli (Institute of Chemical Physics, College of Chemistry, Sichuan University)
    Bulletin of the Korean Chemical Society v.26 no.4 ,pp. 543 - 547 , 2005 , 0253-2964 ,

    초록

    The Belousov-Zhabotinskii system measured by a Pt electrode is investigated under external electrode current constraint. A dynamical analysis of the electrode reaction phase has been made by means of a linearized stability criterion valid for three-variable system. It turns out that limit cycle oscillatory regime and dynamical behaviors of the electrode reaction phase have been degenerated under periodical electrode current.

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  6. [국내논문]   The Interaction between Hexadecyltrimethylammonium Bromide to Poly (Ethylene Glycol) with Different Molecular Weights and Some Schiff-Bases Investigated by Surfactant Ion Selective Electrode   피인용횟수: 1

    Ghoreishi, Sayed Mehdi (Department of Chemistry, Science Faculty, Kashan University ) , Naeimi, Hossein (Department of Chemistry, Science Faculty, Kashan University ) , Navid, Mohammad Davodi (Department of Chemistry, Science Faculty, Kashan University)
    Bulletin of the Korean Chemical Society v.26 no.4 ,pp. 548 - 552 , 2005 , 0253-2964 ,

    초록

    The interaction between ionic surfactants and different nonionic molecules and polymers are studied using ion surfactant selective electrode. From the experimental data, critical concentrations of the interaction and binding process are evaluated. The interaction between hexadecyltrimethylammonium bromide (HTAB) with polyethylene glycol (PEG) in three molecular weights (1000, 10000 and 100000) and also schiff-bases, 2-[2-carboxyphenyl nitrilomethylidyne]-phenol (ortho CNP), 2-[3-carboxyphenyl nitrilomethylidyne]-phenol (meta CNP)and 2-[4-carboxyphenyl nitrilomethylidyne]-phenol (para CNP) with the potentiometric method were investigated using HTAB membrane selective electrode. In the case of PEG with increasing molecular weights more interaction to HTAB occurs. The electromotive force (EMF) data also showed that interaction between para CNP with HTAB is more than the other schiff-bases. It seems this case related to less space interference of COOH group for that compound. The onset of binding ( $T_1$ ) of course is the same for three schiffbase molecules.

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  7. [국내논문]   Nano-identification for the Cleavage of Disulfide Bond during the Self-Assembly Processes of Unsymmetric Dialkyl Disulfides on Au(111)   피인용횟수: 1

    Noh, Jae-Geun (Department of Chemistry, Hanyang University)
    Bulletin of the Korean Chemical Society v.26 no.4 ,pp. 553 - 557 , 2005 , 0253-2964 ,

    초록

    The formation of striped phases of unsymmetric hexyl octadecyl disulfide ( $CH_3(CH_2)_5SS(CH_2)_{17}CH_3$ , HOD) and 1-hydroxyundecyl octadecyl disulfide ( $CH_3(CH_2)_{17}SS(CH_2)_{11}$ OH, HUOD) on Au(111) and graphite has been investigated by scanning tunneling microscopy (STM) to understand the self-assembly processes of dialkyl disulfides. STM imaging clearly shows the formation of striped phases having corrugation periodicities that are nearly consistent with the molecular length of alkanethiolate moieties formed after the S-S bond cleavage of dialkyl disulfide on a gold surface. On the other hand, self-assembled monolayers (SAMs) of dialkyl disulfides on a graphite surface displayed long-range, well-ordered monolayers with one striped pattern that shows periodicity as a function of molecular length via nondissociative adsorption. From a nonoscopic viewpoint, we have clearly demonstrated that dialkyl disulfide SAMs on gold form via S-S bond cleavage of disulfide.

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  8. [국내논문]   Selective Crystallization of SAPO-5 and SAPO-34 Molecular Sieves in Alkaline Condition: Effect of Heating Method   피인용횟수: 3

    Yoon, Ji-Woong (Research Center for Nanocatalysts, Korea Research Institute of Chemical Technology ) , Jhung, Sung-Hwa (Research Center for Nanocatalysts, Korea Research Institute of Chemical Technology ) , Kim, Young-Ho (Department of Fine Chemicals Engineering & Chamistry, Chungnam National University ) , Park, Sang-Eon (Department of Chemistry, Inha University ) , Chang, Jong-San (Research Center for Nanocatalysts, Korea Research Institute of Chemical Technology)
    Bulletin of the Korean Chemical Society v.26 no.4 ,pp. 558 - 562 , 2005 , 0253-2964 ,

    초록

    Crystallization of SAPO-5 and SAPO-34 molecular sieves with microwave and conventional electric heating of the same gel has been investigated in an alkaline condition using N,N,N'N'tetraethylethylenediamine as a template molecule. SAPO-5 structure can be selectively prepared with microwave heating because of the fast crystallization of the technique. On the other hand, SAPO-34 is the sole product with usual conventional electric heating because SAPO-5 can be gradually transformed into SAPO-34 structure with an increase in crystallization time. This phase selectivity is probably because of the relative stability of the two phases at the reaction conditions (kinetic effect). Crystallization with microwave heating can be suggested as a phase selective synthesis method for relatively unstable materials because of fast crystallization.

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  9. [국내논문]   Effect of Preparation Conditions on the Hydrogenation Activity and Metal Dispersion of Pt/C and Pd/C Catalysts   피인용횟수: 1

    Jhung, Sung-Hwa (Research Center for Nanocatalysts, Korea Research Institute of Chemical Technology ) , Lee, Jin-Ho (Research Center for Nanocatalysts, Korea Research Institute of Chemical Technology ) , Lee, Jong-Min (Research Center for Nanocatalysts, Korea Research Institute of Chemical Technology ) , Lee, Ji-Hye (Research Center for Nanocatalysts, Korea Research Institute of Chemical Technology ) , Hong, Do-Young (Research Center for Nanocatalysts, Korea Research Institute of Chemical Technology ) , Kim, Myong-Woon (DNF Solution Co. ) , Chang, Jong-San (Research Center for Nanocatalysts, Korea Research Institute of Chemical Technology)
    Bulletin of the Korean Chemical Society v.26 no.4 ,pp. 563 - 568 , 2005 , 0253-2964 ,

    초록

    The Pt/C and Pd/C catalysts were prepared from conventional chloride precursors by adsorption or precipitation-deposition methods. Their activities for hydrogenation reactions of cyclohexene and acetophenone were compared with those of commercial catalysts. The Pt/C and Pd/C catalysts obtained from the adsorption procedure reveal higher hydrogenation activity than commercial catalysts and the catalysts prepared by the precipitation-deposition method. Their improved performances are attributed to the decreased metal crystallite sizes of Pt or Pd formed on the active carbon support upon the adsorption of the precursors probably due to the same negative charges of the chloride precursor and the carbon support. Under the preparation conditions studied, the reduction of the supported catalysts using borohydrides in liquid phase is superior to a gas phase reduction by using hydrogen in the viewpoint of particle size, hydrogenation activity and convenience.

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  10. [국내논문]   Separation of Burnup Monitors in Spent Nuclear Fuel Samples by Liquid Chromatography  

    Joe, Kih-Soo (Korea Atomic Energy Research Institute ) , Jeon, Young-Shin (Korea Atomic Energy Research Institute ) , Kim, Jung-Suck (Korea Atomic Energy Research Institute ) , Han, Sun-Ho (Korea Atomic Energy Research Institute ) , Kim, Jong-Gu (Korea Atomic Energy Research Institute ) , Kim, Won-Ho (Korea Atomic Energy Research Institute)
    Bulletin of the Korean Chemical Society v.26 no.4 ,pp. 569 - 574 , 2005 , 0253-2964 ,

    초록

    A coupled column liquid chromatography system was applied for the separation of the burnup monitors in spent nuclear fuel sample solutions. A reversed phase column was studied for the adsorption behavior of uranyl ions using alpha-hydroxyisobutyric acid as an eluent and used for the separation of plutonium and uranium. A cation exchange column prepared by coating 1-eicosylsulfate onto the reversed phase column was used for the separation of the lanthanides. In addition, retention of Np was checked with the reversed phase column and cation exchange column, respectively, according to the oxidation states to observe the interference effect for the separation of burnup monitors. This chromatography system showed a great reduction in separation time compared to a conventional anion exchange method. A good agreement from the burnup data was obtained between for this method and a conventional anion exchange method to within 1% of a difference for the spent nuclear fuel samples of about 40 GWD/MTU.

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    Fig. 1 이미지

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