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Synthesis and complete assignment of NMR data of 20 chalcones
Hwang, Doseok,Hyun, Jiye,Jo, Geunhyeong,Koh, Dongsoo,Lim, Yoongho John Wiley Sons, Ltd. 2011 Magnetic resonance in chemistry Vol.49 No.1
<P><B>Abstract</B></P><P>Chalcones, intermediates in flavonoid biosynthesis, can exhibit antibacterial, antiproliferative, and anti‐inflammatory properties. Chalcones contain two benzene rings and both hydroxylated and methoxylated analogs are frequently produced by hydroxylases and <I>O</I>‐methyltransferases in plant biosynthetic pathways. Assignments of NMR peaks in the spectra of hydroxylated and/or methoxylated chalcones can help in identifying novel chalcone derivatives isolated from natural sources by referencing these data against NMR spectra obtained from known chalcones. We report here the syntheses of 20 chalcones and complete assignments of <SUP>1</SUP>H and <SUP>13</SUP>C NMR spectra. Copyright © 2010 John Wiley & Sons, Ltd.</P>
Synthesis of methoxybenzoflavones and assignments of their NMR data
Hwang, Doseok,Jo, Geunhyeong,Hyun, Jiye,Lee, Sung Dae,Koh, Dongsoo,Lim, Yoongho John Wiley Sons, Ltd 2012 Magnetic resonance in chemistry Vol.50 No.1
<P>A phytotoxic root exudate from <I>Acroptilon repens</I> was identified as 7,8‐benzoflavone, an inhibitor of cytochrome P450 1A2 and activator of cytochrome P450 3A4. The synthetic 5,6‐benzoflavone also is a potent phytotoxin. Six 7,8‐benzoflavones and eight 5,6‐benzoflavones were synthesized in this study. The NMR data for a few of these compounds have been previously reported; however, the NMR data for most of them have not been reported. For reference purposes, the complete NMR data for the 14 benzoflavones are described. Copyright © 2012 John Wiley & Sons, Ltd.</P>
Photoluminescence Characteristics of Merocyanine Dyes in Ionic Liquids
심태규,Doseok Kim,H. H. Yoon,김현성,Jaeho Sung,Kyungbyung Yoon,Yukio Ouchi 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.48 No.6
The photoluminescence (PL) characteristics of merocyanine dye molecules in ionic liquids of 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6) and 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) with different purity grades were investigated. The absorption spectra for this dye in all the ionic liquid solvents investigated looked very similar while the PL emission spectra differed markedly depending on the type of ionic liquid and the impurity content. In all purity grades of [BMIM]BF4 and the ultrahigh grade of [BMIM]PF6, the PL spectra of these merocyanine solutions showed a single peak around 480 nm. However, when a lower grade of [BMIM]PF6 was used as the solvent, an additional PL peak appeared around 575 nm. The deprotonation from the hydroxyl group of the merocyanine molecule after photoexcitation is proposed to explain the phenomenon in this unique solvent system.n
A Peptide Produced by Pseudomonas tolaasi, Tolaasin Binds to Metal Ions
Geunhyeong Jo,Doseok Hwang,Yoonkyung Woo,Younggiu Lee,Yeonjoong Yong,강경래,Jiye Hyun,Young-Kee Kim,Dong-Woon Kim,Yoongho Lim 한국응용생명화학회 2011 Applied Biological Chemistry (Appl Biol Chem) Vol.54 No.4
Brown blotch disease in mushrooms is caused by Pseudomonas tolaasin, which produces a peptide toxin, tolaasin I, and zinc ion inhibits the channel formed by tolaasin I. NMR experiments revealed that zinc, sodium, and calcium ions can bind to tolaasin I and their binding position on tolaasin I is the lactone ring.
Density Profiles of Liquid/Vapor Interfaces Away from Their Critical Points
Bu, Wei,Kim, Doseok,Vaknin, David American Chemical Society 2014 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.118 No.23
<P>We examine the applicability of various model profiles for the liquid/vapor interface by X-ray reflectivities on water and ethanol and their mixtures at room temperature. Analysis of the X-ray reflecivities using various density profiles shows an error-function like profile is the most adequate within experimental error. Our findings, together with recent observations from simulation studies on liquid surfaces, strongly suggest that the capillary-wave dynamics shapes the interfacial density profile in terms of the error function.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2014/jpccck.2014.118.issue-23/jp504374z/production/images/medium/jp-2014-04374z_0006.gif'></P>
Ao, Mingqi,Kim, Doseok American Chemical Society 2013 Journal of chemical and engineering data Vol.58 No.6
<P>The interfacial and bulk properties of the aqueous solutions of imidazolium-based ionic liquids with different halide anions ([C<SUB>12</SUB>mim]Cl, [C<SUB>12</SUB>mim]Br, [C<SUB>12</SUB>mim]I) were investigated by surface tension and electrical conductivity measurements. The lowest surface tension (γ<SUB>cmc</SUB>) and maximum surface excess concentration (Γ<SUB>max</SUB>) values from the surface tension measurements showed that [C<SUB>12</SUB>mim]I had the highest surface activity. The thermodynamic pontentials of micellization (Δ<I>G</I><SUP>0</SUP><SUB>m</SUB>, Δ<I>H</I><SUP>0</SUP><SUB>m</SUB>, Δ<I>S</I><SUP>0</SUP><SUB>m</SUB>) indicated that the micellization of [C<SUB>12</SUB>mim]Cl and [C<SUB>12</SUB>mim]Br was entropy-driven, while that of [C<SUB>12</SUB>mim]I was enthalpy-driven at 15 °C but entropy-driven above 20 °C. This distinct behavior for [C<SUB>12</SUB>mim]I was thought to be due to the higher binding affinity of I<SUP>–</SUP> to the micellar interface.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jceaax/2013/jceaax.2013.58.issue-6/je301147k/production/images/medium/je-2012-01147k_0003.gif'></P>
Photophysical properties of solutions of several cyanovinylaniline derivatives
이명희,Dohyung Kim,Doseok Kim,윤국로,이후성 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.45 No.1
The photophysical properties of donor-acceptor conjugated organic chromophores such as f4-(1,2,2-tricyanovinyl)-[N,N-bis(2-hydroxyethyl)g-aniline (TCVA) and its derivatives with slight structural changes were studied by investigating the steady-state absorption, emission, and the uorescence decay lifetime. TCVA trimer in dichloromethane (DCM) showed a uorescence spectrum peaked at 590 nm, and its uorescence decay lifetime in solution was 3.7 ns. For TCVA, the uorescence intensity was markedly quenched in comparison with TCVA trimer and the decay lifetime shortened to the value of a few tens of ps. The quenching eect shown in TCVA can be explained by the hydrogen bonding between OH and N atoms. Also, it was found that the uorescence lifetime of the chromophore was aected by the presence of the hydroxyalkyl group attached to the N atom of the aniline moiety. Fluorescence characteristics of the molecules in solvents of dierent polarities were investigated to ascertain the underlying mechanism.
Anion exchange in ionic liquid mixtures
Cha, Seoncheol,Kim, Doseok The Royal Society of Chemistry 2015 Physical chemistry chemical physics Vol.17 No.44
<P>Advantage of ionic liquids as designer solvents can be maximized by mixing different ionic liquids (ILs) for a possibility of continuous tunability of material properties. The property of these mixed ILs would be determined by their microscopic conformation between cations and anions. The mixtures of two ILs having 1-butyl-3-methylimidaolium cations and different anions were investigated by IR and NMR spectroscopy, utilizing that the vibrational frequencies of the C–H stretching and bending modes of the most acidic proton in the imidazolium ring of the cation and the NMR chemical shift for the corresponding proton were clearly distinct between the ILs having different anions. The IR absorption spectra of the IL mixtures at different concentrations were well-matched to weighted sums of the two spectra of the pure ILs. In contrast, the two distinct peaks in the NMR spectra of the pure ILs coalesced into a single peak, which shifted continuously following the relative portion of two different ILs in the mixture. IR spectroscopy in the optical frequency range seems to take the instantaneous snapshot of the cation–anion interaction, while NMR spectroscopy in the radio-frequency (∼500 MHz) range samples over a much longer timescale, enough for the cation to interact with different anion species in the mixture.</P> <P>Graphic Abstract</P><P>Anion exchange in ionic liquid mixtures measured by IR and NMR spectroscopy. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c5cp04276c'> </P>