• Journal of Magnetics
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• v.2 no.2
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• pp.35-37
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• 1997

A sample of YBa2Cu3O7-x fluorinated by a high temperature (400$^{\circ}C$) gas exchange technique has been investigated by means of 19F NMR (nuclear magneti resonance) measurements in both superconducting and normal state. As a result, behaviors characteristic of the superconductor, including a peculiarity in the spin-lattice relaxation rate (1/T1) around 250 K, were observed.

• Journal of the Korean Chemical Society
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• v.55 no.2
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• pp.317-322
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• 2011

• Natural Product Sciences
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• v.3 no.2
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• pp.127-134
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• 1997

Two new dimeric phenolic conjugates, 2,3-di-O-dehydrodigallicmonocarboxyl-$({\alpha},{\beta})$-$^4C_1$-glucopyranose and ellagic acid 3,3'-dimethylether-4-0-$SO_3K$ were isolated from the debarked heart wood of Tamarix tetragyna (Tamaricaceae) along with the known phenolic compounds, isoferulic acid, ferulic acid, gallic acid, gallic acid 4-methyl ether, syringic acid, ellagic acid 3,3'-dimethyl ether and ellagic acid. All structures were determined mostly by ESI-MS, ID and 2D-NMR spectroscopy.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.1
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• pp.27-34
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• 2013

Quantitative analysis of 5-hydroxymethylfufural (5-HMF) conversion from fructose by dehydration and rearrangement was investigated by $^1H$-NMR spectroscopic method. Fructose was converted to 5-HMF in dimethylsulfoxide (DMSO)-$d^6$ or acidic deuterium hydroxide at controlled reaction temperature and time. With addition of internal standards (biphenyl for DMSO-$d^6$ solvent, and 2,5-dihydroxybenzoic acid for deuterium oxide solvent), conversion from fructose to 5-HMF was analyzed by $^1H$-NMR spectroscopy. Quantitative analysis was run by comparison with peak area integration between of 5-HMF and internal standard. In DMSO solvent, 5-HMF was stable end product but part of 5-HMF was converted to formic and levulinic acid at acidic aqueous medium.

• Journal of the Korean Magnetic Resonance Society
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• v.21 no.4
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• pp.145-151
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• 2017

Rhodiola rosea, also known as gold root or rose root, is a perennial plant in the family of Crassulaceae. The rhizhome of R. rosea has been widely used as a hemostatic, tonic for burns and contusions in traditional Chinese medicine. Recent studies reported its strong antioxidant and adaptogenic properties. In this paper, we attempted to isolate compounds from the methanolic extract of R. rosea rhizomes. Four compounds including one new compound (1), two kaempferol glycosides (3 and 4) were isolated from chloroform and ethyl acetate soluble fraction of R. rosea extract. The structures of 1~4 including relative stereochemistry were determined by MS and NMR analysis.

• Journal of the Korean Chemical Society
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• v.54 no.4
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• pp.429-436
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• 2010

A series of some biologically active halogenopurines were synthesized from commercially available guanine (1). The reaction of guanine with acetic anhydride yielded 2,9-diacetylguanine (2-1) by acetylation reaction. Further treatment of 2-1 with $POCl_3$ by PEG-2000 phase transfer catalysis furnished the important compound 3a, then 2-amino-6-halogenopurines (3b-d) were obtained through chlorine-exchange halogenations between KX and 3a by TPPB phase transfer catalyst. Further, 2-halogenopurines (2-2a-d, 4-2a-d, 5a-d) were efficiently prepared from 2-amino-6-substituted purines (1, 3a, 4-1) via a diazotization catalyzed by their corresponding CuX, and some new compounds 2-2a, 2-2c, 2-2d, 4-2c, 4-2d, 5b, 5c and 5d have been discovered. The structures of synthesized compounds were mainly established on the basis of their elemental analysis, $^1H$ NMR, as well as their mass spectral data. All the title compounds were screened for their antifungal activities, and some of the compounds showed promising activity.

• Journal of the Korean Chemical Society
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• v.38 no.3
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• pp.194-199
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• 1994

The solubilization sites of some phenyl alkanols such as phenol, benzyl alcohol, phenethyl alcohol, 3-phenyl-1-propanol solubilized in 0.2 M aqueous sodium dodecylsulfate micelle solution was studied by two dimensional heteronuclear correlation spectroscopy (2D C-H COSY). The results show more quantitative and clear solubilization sites in the SDS micelle than previous results using $^1H$-NMR spectrum integration. We found that most of the phenyl alkanols penetrate into the core of SDS micelle, and the insertion depth was 6.5∼7.0 methylene units from ${\alpha}$-methylene.

• Natural Product Sciences
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• v.12 no.1
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• pp.62-66
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• 2006

A steroidal saponin, $3-O-{\alpha}-L-rhamnopyranosyl-(1{\rightarrow}2)-[{\alpha}-L-rhamnopyranosyl-(1{\rightarrow}3)]-{\beta}-D-glucopyranosylpennogenin$ ;(1, spiroconazole A) was isolated from the tubers of Dioscorea bulbifera L. var sativa and $^1H-and\;^{13}C-NMR$ assignment was completed using HMBC correlation. In addition, four phenolic substances, 2,7-dihydroxy-4-methoxyphenanthrene (2), quercetin (3), $quercetin-3-O-{\beta}-D-glucopyranoside$ (4), and $quercetin-3-O-{\beta}-D-galactopyranoside$ (5) were also isolated.

• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.984-988
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• 2010

1-(Fluoren-2-yl)-benzo[d][1,2,3]triazoles 5a-b were synthesized starting from 2-nitrofluorene. 2-Nitrofluorenes 1a-b were reduced by catalytic hydrogenation, reacted with 2,4-dinitrofluorobenzene followed by catalytic hydrogenation to afford 2-(N-2,4-diaminophenyl)aminofluorenes 4a-b. Diazotization of 4a-b with $NaNO_2/H_2SO_4$ followed by treatment with $H_3PO_2$ gave 5a-b. Sulfonation of 5a-b yielded 7-benzotriazol-1-yl-fluorene-2-sulfonic acids 6a-b. The structures of 5b and 6b were firmly identified by X-ray crystal analysis in addition to $^1H$ NMR, $^{13}C$ NMR, and elemental analysis.

• Biomolecules & Therapeutics
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• v.24 no.2
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• pp.191-198
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• 2016

The vitamin D receptor (VDR) is a member of the nuclear receptor (NR) superfamily. The VDR binds to active vitamin $D_3$ metabolites, which stimulates downstream transduction signaling involved in various physiological activities such as calcium homeostasis, bone mineralization, and cell differentiation. Quercetin is a widely distributed flavonoid in nature that is known to enhance transactivation of VDR target genes. However, the detailed molecular mechanism underlying VDR activation by quercetin is not well understood. We first demonstrated the interaction between quercetin and the VDR at the molecular level by using fluorescence quenching and saturation transfer difference (STD) NMR experiments. The dissociation constant ($K_d$) of quercetin and the VDR was $21.15{\pm}4.31{\mu}M$, and the mapping of quercetin subsites for VDR binding was performed using STD-NMR. The binding mode of quercetin was investigated by a docking study combined with molecular dynamics (MD) simulation. Quercetin might serve as a scaffold for the development of VDR modulators with selective biological activities.