• Title/Summary/Keyword: $^{2}H$-NMR spectra

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Synthesis and Physicochemical Properties of Schiff Base Macrocyclic Ligands and Their Transition Metal Chelates

  • Rafat, Fouzia;Siddiqi, K.S.
    • Journal of the Korean Chemical Society
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    • v.55 no.6
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    • pp.912-918
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    • 2011
  • Tetraaza Schiff base macrocyclic ligands, $L^1$,$L^2$ and their transition metal chelates have been synthesized and characterized by elemental analyses, IR, electronic, EPR and $^1H$ NMR spectra, TGA and magnetic measurements. The molar conductance of one milli-molar solution of the complexes measured in DMF indicates that the divalent metal complexes are nonelectrolyte while those of trivalent metal ion, are 1:1 electrolytic in the same solvent. The reduction of Racah parameter from the free ion value confirms the presence of considerable covalence of metal ligand sigma bond in the Co(II) and Mn(II) complexes. The EPR spectra of Cu(II) complexes at room temperature shows axial symmetry indicating a $d_x{^2}_{-y}{^2}$ ground state with significant covalent character. The thermal analysis suggests that the complexes do not contain water molecules because only the metal is left as residue.

Studies of Oxo-Nitrosyl Complexes(Ⅱ) Synthesis and Properties of Tungsten Oxo-Nitrosyl Complexes with Butylamidoxime Derivatives (산소-니트로실 착물의 연구 (제2보) 부틸아미드옥심 유도체의 텅스텐 산소-니트로실 착물의 합성과 특성)

  • Roh, Soo Gyun;Oh, Sang Oh
    • Journal of the Korean Chemical Society
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    • v.39 no.11
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    • pp.856-862
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    • 1995
  • The tungsten oxo-nitrosyl complexes (n-Bu4N)2[W5O12(NO)2{RC(NH2)NHO}2{RC(NH)NO}2] (R=(CH3)2CH, CH3CH2CH2, CH3SCH2) have been synthesized by the reactions of polyoxotungsten complex (n-Bu4N)2[W6O19] and tungsten dinitrosyl monomeric complex [W(NO)2(acac)(CH3CN)2](BF4) with butylamidoxime derivatives. The prepared complexes have been characterized by elemental analysis, infrared, UV-visible, 1H NMR and 13C NMR spectroscopy. The pentanuclear species was formed by the interaction of the electron-withdrawing {W(NO)2}2+ unit between the two dinuclear tungsten {W2O5}2+ cores. We can estimate to exist large proton interactions viewed from the four doublet in 1H NMR spectrum of (n-Bu4N)2[W5O12(NO)2{(CH3)2CHC(NH2)NHO}2{(CH3)2CHC(NH)NO}2]. We also drew informations of the two different coordination mode and symmetry of the complexes because two ligands appear in 13C NMR spectra instead of four. The {W(NO)2}2+ unit has been cis-form and C2v symmetry in geometric structure.

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Mechanistic Study of Half-titanocene-based Reductive Pinacol Coupling Reaction

  • Kim, Young-Jo;Do, Young-Kyu;Park, Sung-Jin
    • Bulletin of the Korean Chemical Society
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    • v.32 no.11
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    • pp.3973-3978
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    • 2011
  • The reductive pinacol coupling reaction of aldehydes or ketones creating a new C-C bond has been a major tool to produce 1,2-diol compounds. The reaction mechanism is known to be composed of sequential three steps (activation, coupling, and dissociation). In this work, we studied the dissociation step of half-titanocene-based catalytic systems. Cp and $Cp^*$ derivatives of the pinacolato-bridged dinuclear complex were synthesized and evaluated as possible models for intermediates from the coupling step. We monitored $^1H$-NMR spectra of the reaction between the metalla-pinacol intermediates and $D_2O$. New reaction routes of the dissociation step including oxo- and pinacolato-dibridged dinuclear complexes and oxo-bridged multinuclear complexes have been suggested.

A Triterpene Glycoside in Berries of Rubus coreanus (복분자(覆盆子)의 Triterpene 배당체)

  • Kim, Eun;Kim, Young-Choong
    • Korean Journal of Pharmacognosy
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    • v.18 no.3
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    • pp.188-190
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    • 1987
  • A triterpene glycoside was first isolated from berries of Rubus coreanus Miquel in the family of Rosaceae, which have been used as a tonic in chinese drug. The compound was identified as $28-{\beta}-D-glycopyranosyl$ ester of $2{\alpha},3{\beta},19{\alpha},23-tetrahydroxyurs-12-en-28-oic$ acid by IR, MS, $^{1}H-NMR$, $^{13}C-NMR$ spectra.

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Diaminoplatinum(II) Complexes of Glutamic Acid: Obvious Chelating Isomerization

  • Young-A Lee;Jongki Hong;Ok-Sang Jung;Youn Soo Sohn
    • Bulletin of the Korean Chemical Society
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    • v.15 no.8
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    • pp.669-673
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    • 1994
  • Coordination isomers of cis-(N-N)Pt(Glu) prepared by reaction of cis-(N-N)Pt($SO_4$) (N-N=2$NH_3$, ethylenediamine(en),(R,R)-1,2-diaminocyclohexane (DACH), N,N,N',N'-tetramethylethylenediamine (TMEDA)) with barium glutamate in water have been monitored and characterized by $^1H-NMR$, $^{13}C-NMR$, IR, and mass spectra. The reaction at room temperature affords the mixture of O,O'-and N, ${\alpha}$ O-chelated platinum(II) complexes. The O,O'-chelate initially formed isomerized to N,${\alpha}$O-chelate on standing for a long time or increasing temperature. The ratio of the two isomers at room temperature depends on the nature of the nitrogen donor coligand (N-N).

Analysis of Beauvericin and Unusual Enniatins Co-Produced by Fusarium oxysporum FB1501 (KFCC 11363P)

  • Song Hyuk-Hwan;Ahn Joong-Hoon;Lim Yoong-Ho;Lee Chan
    • Journal of Microbiology and Biotechnology
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    • v.16 no.7
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    • pp.1111-1119
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    • 2006
  • Beauvericins and enniatins are cyclohexadepsipeptides exhibiting various biological activities on animal systems, including humans. Fusarium oxysporum FB1501 (KFCC 11363P) that produces four different cyclohexadepsipeptides was isolated from soil in Korea and the structures of the four cyclohexadepsipeptides elucidated by HPLC, MS, IR, and NMR analyses. The molecular weights for compounds 1,2,3, and 4 were determined to be 654.5, 784.5, 668.6, and 682.5, respectively, on the basis of ESI-MS measurements. The IR spectra for all the compounds exhibited absorptions for ester $(1,733-1,743\;cm^{-1})$ and amide $(1,649-1,655\;cm^{-1})$ bonds that were very similar to those for beauvericin and enniatins with ester and amide absorptions. The results of the NMR analysis $(^{1}H,\;^{13}C,\;135-DEPT,\;COSY,\;HMQC,\;and\;HMBC;\;in\;COCl_{3})$ revealed that compounds 1,3, and 4 consisted of $_{L}-N-methyl\;valine$ (N-MeVal), $_{D}-{\alpha}-hydroxyisovaleic\;acid$ (Hiv), and 2-hydroxy-3-methylpentanoic acid (Hmp) residues (compound 1: three N-MeVal residues, two Hiv residues, and one Hmp residue; compound 3: three N-MeVal residues, one Hiv, and two Hmp residues; compound 4: three N-MeVal residues and three Hmp residues). Therefore, the compounds were identified as enniatin H (compound 1), enniatin I (compound 3), and enniatin MK1688 (compound 4). Compound 2 was analyzed as beauvericin according to 1D and 2D NMR analyses. This study is the first report related to the co-production of beauvericin with other unusual enniatins, such as enniatin H, enniatin I, and enniatin MK1688, by Fusarium oxysporum.

The Structure of Phenolic Compounds and Their Antibiotic Activities in Umbilicaria vellea (Umbilicaria vellea 중 페놀성 화합물의 구조 및 항균활성)

  • Min, Tae Jin;Bae, Kang Gyu
    • Journal of the Korean Chemical Society
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    • v.40 no.9
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    • pp.623-629
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    • 1996
  • In order to identify antibiotic substances in the extract of a lichen, Umbilicaria vellea, the extract was chromatographed and two compounds were isolated. Compound I which showed antifungal and antibacterial activities, melted around 129∼132$^{\circ}C$ and showed UV absorption at 217, 265 and 300 nm. It showed a molecular ion at m/z 196. Its molecular formular was confirmed to be $C_{10}H_{12}O_4$ from elemental analysis. From its IR and NMR data it was identified to be ethyl 2,4-dihydroxy-6-methyl benzoate. Compound II melted around 58∼59$^{\circ}C$ and showed UV absorption at 212, 276 and 282 nm. It showed a molecular ion at m/z 124 and molecular formular was confirmed to be $C_7H_8O_2.$ From the analysis of its IR and NMR spectra it was identified to be 5-methyl-1,3-benzenediol.

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Extraction Spectrophotometric Determination of Antihistamines with Picric Acid (피크린 산에 의한 항히스타민제의 추출분광광도 정량)

  • 신태용;엄동옥
    • YAKHAK HOEJI
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    • v.37 no.2
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    • pp.119-123
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    • 1993
  • A spectrophotomertic method is proposed for the determination of antihistamines. The method is based on solvent extraction of the ion pair formed between antihistamines and colored picric acid into chloroform. The binding state of antihistamines-picric acid complexes were presumed by IR and $^{1}$H-NMR spectra as intermolecular hydrogen bonding. This method was applicable to the determination of antihistamines in the pharamaceutical preparations.

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Isolation and Characterization of α-Glucosidase Inhibitor Produced by Bacillus sp. SKU31-1 Strain (Bacillus sp. SKU31-1가 생산하는 α-Glucosidase 저해제 분리 및 특성 조사)

  • Kim, Shin-Duk
    • Korean Journal of Microbiology
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    • v.50 no.4
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    • pp.381-383
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    • 2014
  • In the course of screening for ${\alpha}$-glucosidase inhibitor produced by microorganism, the active compound was isolated from the culture filtrate of Bacillus sp. SKU31-1 using a series of chromatography procedures. The structure of the active compound was elucidated as 5-amino-1-hydroxymethyl-1, 2, 3, 4-cyclohexanetetrol on the basis of spectroscopic evidence obtained and comparison with data from the literature. The active compound showed potent inhibitory activity against ${\alpha}$-glucosidase with an $IC_{50}$ value of $1.9{\mu}M$ for maltose and 4.9 mM for sucrose. A Lineweaver-Burk plot indicated that its inhibition of ${\alpha}$-glucosidase was competitive, with a $K_i$ value of 0.15 mM.

Precise Control of Thermoresponsive Properties of Polymers with Hydroxy Groups in the Side Chains (곁가지에 다양한 길이의 알코올 그룹을 지닌 고분자들의 저임계 용액온도 민감성 제어)

  • Lee, Hyung-Il
    • Polymer(Korea)
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    • v.39 no.1
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    • pp.165-168
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    • 2015
  • Thermoresponsive polymers were successfully synthesized by a combination of atom transfer radical polymerization (ATRP) and Cu(I)-catalyzed 1,3-dipolar cycloaddition of azide and alkynes (click chemistry). Poly(2-hydroxyethyl methacrylate) (PHEMA) was synthesized by ATRP, followed by introduction of alkyne groups using pentynoic acid, leading to HEMA-alkyne. Homopolymers having secondary amine groups, tertiary amines with hydroxyethyl and hydroxypropyl groups were synthesized by adding 2-azido-N-ethyl-ethanamine, 2-[(2-azidoethyl)amino]ethanol, and 2-[(2-azidoethyl)amino]propanol, respectively, to the PHEMA-alkyne backbone using click chemistry. Molecular weight (MW), molecular weight distribution (MWD), and click reaction efficiency were determined by gel permeation chromatography (GPC) and $^1H$ NMR spectroscopy. The transmission spectra of the 1.0 wt% aqueous solutions of the resulting polymers at 650 nm were measured as a function of temperature. Results showed that the lower critical solution temperature (LCST) could be easily controlled by the length of the hydroxyalkyl groups.