• Natural Product Sciences
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• v.26 no.2
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• pp.171-175
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• 2020

Liriodendron tulipifera, belonging to the family Magnoliaceae, is commonly called tulip tree. Four N-acetylated aporphine alkaloids, N-acetylnornuciferine (1), N-acetylanonaine (2), N-acetyl-3-methoxynornuciferine (3), and N-acetyl-3-methoxynornantenine (4) were isolated from the roots of L. tulipifera. Although the purity of each compound (1 - 4) was determined to be 97, 96, 99, and 98%, respectively, the ¹H and ¹³C NMR spectroscopic data of the aporphine alkaloids 1 - 4 displayed all signals in duplicate, indicating the presence of two rotamers due to restricted rotation of N-COCH₃ functionality in solution status. The absolute configurations of 1 - 4 w ere established by measuring specific rotation and comparison with the reported data. This is the first report on the ¹H and ¹³C NMR assignments of N-acetyl-3-methoxynornuciferine (3) and N-acetyl-3-methoxynornantenine (4). This study provides advanced NMR spectroscopic data for the structure determination of rotameric aporphine alkaloids.

• Macromolecular Research
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• v.13 no.6
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• pp.467-476
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• 2005

The main objective of this study was to develop and characterize pH-sensitive biodegradable polymeric materials. For pH-sensitivity, we employed three kinds of moieties: 2-amino-3-(lH-imidazol-4-yl)-propionic acid (H), N-[4-( 4,6-dimethyl-pyrimidin-2ylsulfamoyl)-phenyl]succinamic acid (SM), and 2- {3-[ 4-( 4,6-dimethyl-pyrim­idin- 2-ylsulfamoyl)-phenylcarbamoyl]-propionylamino} -3-(3 H - imidazol-4-yl)-propionic acid (SH). The pH -sensitive diblock copolymers were synthesized by ring opening polymerization and coupling reaction from poly(ethylene glycol) (MPEG), $\varepsilon$-caprolactone (CL), D,L-lactide (LA) and pH-sensitive moieties. The pH-sensitive SH molecule was synthesized in a two-step reaction. The first step involved the synthesis of SHM, a methyl ester derivative of SH, by coupling reaction of SM and L-histidine methyl ester dihydrochloride, whereas the second step involved the hydrolysis of the same. The synthesized SM, SHM and SH molecules were characterized by FTIR, $^{1}H$-NMR and $^{13}C$-NMR spectroscopy, whereas diblock copolymers and pH-sensitive diblock copolymer were characterized by $^{1}H$-NMR and GPC analysis. The critical micelle concentrations were determined at various pH conditions by fluorescence technique using pyrene as a probe. The micellization and demicellization studies of pH-sensitive diblock copolymers were also done at different pH conditions. The pH-sensitivity was further established by acid-based titration and DLS analysis.

• Korean Journal of Crystallography
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• v.13 no.2
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• pp.82-85
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• 2002

From the reaction of cis,cis,trans- [MoBr/sub 2/(CO)/sub 2/(PPh/sub 3/)/sub 2/］with 2,6-dimethylphenyl isocyanide, a molybdenum oxohaloisocyanide compound cis,fac-[Mo(O)Br/sub 2/,(CN-C/sub 6/H/sub 3/,-2,6-Me/sub 2/)sub 3/] (1) was iso-lated. Compound 1 was characterized by spectroscopy (/sup 1/H-NMR, /sup 13/C｛/sup 1/H｝-NMR, IR) and X-ray diffraction. Crystallographic data for 1: triclinic space group P(equation omitted), a=9.172(2) (equation omitted), b ＝ 11.550(3) (equation omitted), c ＝ 15.106(3) (equation omitted), α ＝ 100.44(2)°, β＝ 107.12(2)°, γ＝ 107.83(1)°, Z ＝ 2, R(wR/sub 2/) ＝ 0.0529(0.1344).

• 한국초전도학회:학술대회논문집
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• v.16
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• pp.10-10
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• 2006

• Applied Biological Chemistry
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• v.47 no.2
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• pp.270-273
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• 2004

Two prenylated flavonoids were isolated from a chloroform extract of the root bark of Cudrania tricuspidata. Both compounds (1, 2) showed antibacterial activity against Gram positive bacteria, Staphylococcus aureus, Bacillus subtilis and Bacillus cereus. Their structures were determined as euchrestaflavanone B (1) and euchrestaflavanone C (2) on the basis of $^1H\;NMR,\;^{13}C\;NMR$ and long-range coupling NMR techniques.

• Bulletin of the Korean Chemical Society
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• v.17 no.8
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• pp.696-699
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• 1996

Silicate and borosilicate gels were prepared by the sol-gel process and thermally treated in the 150-850 ℃ temperature range. Solid-state 1H MAS and 29Si CP/MAS NMR spectroscopy were used to investigate the effects of heat treatments on the silicate gel to glass conversion process. The 1H NMR isotropic chemical shifts and the relative intensities of hydrogen bonded and isolated silanol groups have been used to access the information concerning the dehydration process on the silicate gel surface. The 29Si NMR isotropic chemical shifts affected by the local silicon environment have been used to determine the degree of crosslinking, i.e. the number of siloxane bonds. These NMR results suggest that the silicate gel to glass conversion process is occurred by two stages which are dependent on the temperature; (1) the formation of particles up to 450 ℃ and (2) the formation of large particles by aggregation of each separated single particle above 450 ℃. In addition, the effects of B atom on the formation of borosiloxane bonds in borosilicates have been discussed.

• Journal of the Korean Magnetic Resonance Society
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• v.1 no.2
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• pp.95-102
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• 1997

Deuterium quadrupole coupling constant (e2qzzQ/h) of ($\mu$3-C2H)[Co(CO)3]3 was determined by using solid-state deuterium MAS NMR spectroscopy. The small quadrupole coupling constant of bridging methyne unit relative to sp-acethylene in propyne is discussed in terms of the C-H bond length and the negative charge on the carbon.

• Journal of the Korean Wood Science and Technology
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• v.37 no.1
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• pp.114-120
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• 2009

The bark of Populus alba ${\times}$ glandulosa was collected, air-dried and extracted with 70% aqueous acetone. Then it was successively partitioned with n-hexane, $CH_2Cl_2$, EtOAc and $H_2O$. Repeated Sephadex LH-20 column chromatography and preparative TLC on the EtOAc soluble fraction gave a grandidentatin isomer. The structure was elucidated as grandidentatin A (cis-2-hydroxycyclohexyl 6-O-p-coumaroyl-${\beta}$-D-glucopyranoside) on the basis of spectroscopic evidences such as $^1H$-NMR, $^{13}C$-NMR, 2D-NMR and MALDI TOF-MS spectrum followed by acid hydrolysis. Grandidentatin A was identified here for the first time in Populus alba ${\times}$ glandulosa bark, and to the bset of our knowledge it has not been reported in any other literature.

• Journal of Plant Biotechnology
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• v.33 no.4
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• pp.283-288
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• 2006

Discrimination of 5 rice cultivars (Sangjubyeo , Dongjinbyeo Simbaekbyeo , Hwamanbyeo , and Simbaek-hetero ) using metabolic profiling was carried out. Whole cell extracts from each cultivar were subjected to $^1H$ NMR spectroscopy. When spectral data were analyzed by principal component analysis, 5 cultivars were clustered into 3 groups: SJ, DJ + SB, and HM + SH. Thecultivars showed great difference in carbohydrate region of $^1H$ NMR spectra, suggesting that qualitative and quantitative differences in carbohydrate compounds play a major role in discrimination of the cultivars. In addition, it was readily possible to determine relative quantification of major carbohydrates including sucrose, glucose, maltose from spectral data of the cultivars. SJ showed 2 to 4 times higher content of maltose than the other rice cultivars. Overall results indicate that metabolic discrimination of rice cultivars using $^1H$ NMR spectroscopy combined by multivariate statistical analysis can be used for rapid discrimination of numerous rice cultivars and simple quantitative analysis system of major carbohydrate compounds in rice grains.

• Journal of the Korean Applied Science and Technology
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• v.37 no.5
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• pp.1323-1329
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• 2020

To characterize the molecular structure of PhE-gal synthesized using Escherichia coli 𝛽-gal, NMR (¹H- and ¹³C-) spectroscopy and mass spectrometry of PhE-gal were conducted. ¹H NMR spectrum of PhE-gal showed multiple peaks corresponding to the galactosyl group, which is an evidence of galactosylation on 2-phenylethanol (PhE). Downfield proton peaks at 𝛿_H 7.30~7.21 ppm showed the presence of aromatic protons of PhE as well as benzyl CH₂ protons at 𝛿_H 2.88 ppm. Up field proton peaks at 𝛿_H 4.31 ppm, 4.07 ppm and multiple peaks from 𝛿_H 3.86~3.38 ppm are indicative of galactocylation on PhE. ¹³C NMR spectrum revealed the presence of 12 carbons suggestive of PhE-gal. Among 12 carbon peaks from PhE-gal, the four peaks at 138.7, 129.0, 128.6 and 126.5 were assigned aromatic carbons in the phenyl ring. Three peaks at 129.0, 128.6 and 126.5 showed high intensities, indicating CH aromatic carbons. ¹³C NMR data of PhE-gal showed 6 monosaccharide peaks from galactose and 2 peaks from aliphatic chain of PhE, indicating that PhE-gal was galactosyl PhE. The mass value (sodium adduct ion of PhE-gal, m/z = 307.1181) from mass spectrometry analysis of PhE-gal, and ¹H and ¹³C NMR spectral data were in good agreement with the expecting structure of PhE-gal. We are expecting that through future study it will eventually be able to develop a new additive with low cytotoxicity.