• 한국자기공명학회논문지
• /
• 제25권1호
• /
• pp.1-7
• /
• 2021

Employing of 13C stable-isotopes in NMR metabolomics can give unique splitting patterns and coupling constants information originated from 13C-13C coupling interaction that provide an important structural information regarding the cellular metabolic process. But it has been known that an undesirable signal distortion in 2D heteronuclear correlation study, due to 13C-13C interaction, hampers an analysis of the coupling information. Recently, we proposed J-scaled distortion-free heteronuclear single-quantum coherence (HSQC) sequence which provides a distortion-free 13C-13C coupling information with a selective resolution enhancement of JCC splitting. In this paper, we dicuss theoretical aspect and practical feature of J-scaled HSQC pulse sequence. The conceptual explanation of orgin of the signal distortion by 13C-13C coupling interaction and design of J-scaled HSQC through exemplified results are provided in brief.

• 한국식품영양과학회지
• /
• 제24권5호
• /
• pp.702-706
• /
• 1995

A major component(compound A) in the ethylacetate fraction exhibited a strong antimicrobial activity was identified by UV, IR, FABMS and NMR. The compound A showed strong absorbance at 209, 259 and 359nm, indicating a flavonoid ring structure. IR spectrum possessed absorbance of OH at 3400∼3300cm-1, ketone at around 1650cm-1, and aromatic C=C at around 1660cm-1. Molecular weight of the compound A calculated as 478 from the information of m/z 479(M＋H)+ and m/z 477(M-H)+ in the FABMS spectrum. Molecular formula of this compound was found to be C22H22O12 from m/z 479.1220(＋3.1mmu for C22H23O12) of HRFABMS spectrum and from 13C-NMR spectrum. 1H-NMR and 13C-NMR spectra of the compound A revealed aromatic proton and benzene rings. Distortionless enhancement by polarization transfer(DEPT) exhibited that the compound A possessed 10 quaternary carbons and 3 substituted benzene rings including a methoxy group substitution. The compound A was identified as isorhamnetin 3-O-β-glucopyranoside by spectrophotometric methods in conjunction with 1H-1H COSY, 1H-13C COSY and HMBC, which revealed a flavone with OH group at 3, 5, 7, and 4' and methoxy group at 3' positions esterified to glucose.

• Natural Product Sciences
• /
• 제4권3호
• /
• pp.153-157
• /
• 1998

The aqueous ethanolic leaf extract of Ailanthus altissima was found to contain the new natural product, $luteolin\;7-O-{\beta}-(6"-galloylglucopyranoside)$, 13, along with fourteen known phenolic metabolites (1-12, 14 and 15). Structures of all compounds (1-15) were established by conventional methods of analysis and confirmed by FAB-MS, $^1H-\;and\;^{13}C-NMR$ spectral analysis.

• Bulletin of the Korean Chemical Society
• /
• 제33권5호
• /
• pp.1577-1580
• /
• 2012

The orientational and dynamic behavior of liquid crystal molecules on the alignment layer surfaces of liquid crystal display (LCD) devices is crucial to their performance, but there are only a few methods of experimentally elucidating the interactions between the liquid crystals and the alignment layers. Inspired by the natural and technical similarities between membrane proteins in lipid bilayers and liquid crystals in LCDs, we employed solid-state NMR methodologies originally developed for the study of membrane proteins in lipid bilayers for the in-situ analysis of liquid crystal display panels. In this article, we present a home-built 500 MHz narrowbore (NB) The orientational and dynamic behavior of liquid crystal molecules on the alignment layer surfaces of liquid crystal display (LCD) devices is crucial to their performance, but there are only a few methods of experimentally elucidating the interactions between the liquid crystals and the alignment layers. Inspired by the natural and technical similarities between membrane proteins in lipid bilayers and liquid crystals in LCDs, we employed solid-state NMR methodologies originally developed for the study of membrane proteins in lipid bilayers for the in-situ analysis of liquid crystal display panels. In this article, we present a home-built 500 MHz narrowbore (NB) $^{19}F-^{13}C$ double resonance solid-state NMR probe with a flat-square coil and the first application of this probe for the in-situ analysis of LCD panel samples. double resonance solid-state NMR probe with a flat-square coil and the first application of this probe for the in-situ analysis of LCD panel samples.

• Bulletin of the Korean Chemical Society
• /
• 제30권11호
• /
• pp.2535-2541
• /
• 2009

Prebiotic isomaltooligosaccharide preparations contain $\alpha$-D-glucooligosaccharides comprising isomaltooligosaccharides (IMOs) and non-prebiotic maltooligosaccharides (MOs). They are both glucose oligosaccharides characterized by their degree of polymerization (DP) value (from 2 to $\sim$10), linkages types and positions (IMOs: $\alpha$-(1$\rightarrow$2, 3, 6 and in a lower proportion internal 1$\rightarrow$4) linkages, MOs: α-(1$\rightarrow$4) linkages). Their structure is the key factor for their prebiotic potential. In order to determine and elucidate the exact structure of unknown IMOs and MOs, unambiguous assignments of $^{13}C$ and $^1H$ chemical shifts of commercial standards, representative of IMOs and MOs diversity, have been determined using optimized standard one and two-dimensional experiments such as $^1H$ NMR, $^{13}C$ NMR, APT and ${^1}H-{^1}H$ COSY, TOCSY, NOESY and <$^1H-{^{13}}C$ heteronuclear HSQC, HSQC-TOCSY, and HMBC. Here we point out the differential effect of substitution by a glucose residue at different positions on chemical shifts of anomeric as well as ring carbons together with the effect of the reducing end configuration for low DP oligosaccharides and diasteroisotopic effect for H-6 protons. From this study, structural $^{13}C$ specific spectral features can be identified as tools for structural analysis of isomaltooligosaccharides.

• 대한화학회지
• /
• 제50권3호
• /
• pp.183-189
• /
• 2006

초음파를 이용한 응축 반응을 이용하여 다양한 치환기가 붙은 4-methoxy-1-naphthyl ketone화합물들을 90% 이상의 높은 수율로 합성하였으며, 생성된 화합물물들을 미세 분석법, IR, 1H, 13C NMR 분석법 등을 이용하여 확인하였다. IR 스펙트럼에서 s-cis와 s-trans C=O stretching 모드를 확인하였으며, NMR 데이터로부터 에틸렌의 탄소와 수소에 대한 chemical shift를 확인하였다. 이러한 분광데이터를 이용하여 여러 분자들에 대한 Hammet 치환기 상수 값 들을 얻을 수 있었으며, 이들로부터 가용매 분해반응에 미치는 치환기 효과를 해석할 수 있었다.

• 대한약학회:학술대회논문집
• /
• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.1
• /
• pp.179.2-179.2
• /
• 2003

The cytotoxic activity of 13(E)-Labd-13-ene-8$\alpha$, 15-diol(1), isolated from the ethanol extract of Brachyglottis monroi was evaluated against tumor cell lines such as P388, SNU-C4 MDA-MB231, B 16 melanoma and A549 in vitro. By mean of spectral analysis particularly by the aid of various two dimensional NMR experiments, 1H-NMR and 13C-NMR signals of (1) was completely assigned, and thus the structure of (1) was established unambiguously. (omitted)

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2005년도 춘계학술대회
• /
• pp.615-617
• /
• 2005

[ $^{13}C$ ] NMR spectra were obtained for pure $CH_4$ hydrate in order to identify hydrate structure and cage occupancy of guest molecule. The NMR technique can provide both qualitative and quantitative hydrate characteristics. The moles of methane captured into pure $CH_4$ hydrate per mole of water were found to be similar to the full occupancy value. The overall results drawn from this study can be usefully applied to storage and transportation of natural gas.

• Bulletin of the Korean Chemical Society
• /
• 제29권2호
• /
• pp.405-407
• /
• 2008

Functionalized SAB-15 samples by octadecyltrimethoxysilane (OTC) were studied by 13C magic angle spinning (MAS) cross polarization (CP) nuclear magnetic resonance (NMR) spectroscopy. In the SBA-15 sample fully functionalized by 3-aminopropyltrimethoxysilane (APS) and OTC in 1:1 molar ratio, octadecyl chains were observed to have, on average, more trans conformation than those in the SBA-15 samples fully modified by OTC only. Our results confirm that long chain molecules tend to organize themselves better in the co-presence of short chain molecules on the surface of mesoporous materials by packing of the different length chains in an interdigitized fashion even when the short chains are long enough to have three carbons and a functional group at the ends. In addition, our results indicate that solid-state 13C CP MAS NMR spectroscopy is a simple and non-destructive method to probe the molecular structures of the domains composed of long alkyl chains.

• 분석과학
• /
• 제10권2호
• /
• pp.139-145
• /
• 1997

합성 윤활기유로 사용되고 있는 알킬벤젠들 중에 단일, 그리고 이중치환된 알킬벤젠의 양과 알킬사슬에 존재하는 탄소원자의 수를 $^{13}C$-NMR, 근적외선 및 UV-Vis 분광법으로 분석하였다. 또한 엔진윤활유에 포함되어 있는 직선형 긴 사슬 알킬벤젠을 적외선분광법으로 분석하였다.