• Bulletin of the Korean Chemical Society
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• 제19권5호
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• pp.519-524
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• 1998

In this work, we applied the 1D 11B nutation NMR method for the analysis of the local structural environments in powdered borosilicates (SiO2-B2O3). Spin dynamics during a rf irradiation for spin I=3/2 was analytically calculated with a density matrix formalism. Spectral simulation programs were written in MATLAB on a PC. Two borosilicates prepared by the sol-gel process at different stabilization temperature were used for the 1D 11B nutation NMR experiment. The 11B NMR parameters, quadrupole coupling constants (e2qQ/h) and asymmetry parameters (η), for each borosilicate were extracted from the nonlinear least-squares fitting. The effects of heat treatments on the local structures of boron sites in borosilicates were discussed.

• 대한화학회지
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• 제55권6호
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• pp.940-951
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• 2011

Reaction of 1-methylpyrimidine-(1H,3H,5H)-2,4,6-trione (1-MBA 1) as an unsymmetrical barbituric acid with cyanogen bromide and various aldehydes in the presence of triethylamine and/or pyridine afforded diastereomeric mixtures of new class of heterocyclic stable 5-aryl-1,1'-dimethyl- and 5-aryl-3,1'-dimethyl-1H,1'H-spiro[furo[2,3-d]pyrimidine-6,5'-pyrimidine]2,2',4,4',6'(3H,3'H,5H)-pentaones which are dimeric forms of 1-methyl barbiturate at the range of $0^{\circ}C$ to room temperature. In the reaction of some aldehydes with 1-MBA and BrCN were afforded a mixture of diastereomers. Another two aldehydes such as 4-cyano- and 2-hydroxybenzaldehydes gave exclusively two diastereomers in which binded to the salt of triethylammonium hydrobromide by intermolecular H-bond in ratio of 1:1. 4-Hydroxybenzaldehyde and 2-pyridinecarbaldehyde gave exclusively one diastereomer under the same condition. Aldehydes possessing strong electron-donor were produced exclusively two geometric isomers of Knoevenagel adduct (E- and Z-isomers). The structures of compounds were deduced by $^1H$ NMR, $^{13}C$ NMR and FT-IR spectroscopy. Mechanism of the formation is discussed.

• 대한화학회지
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• 제39권5호
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• pp.421-426
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• 1995

2-Hydroxyethyl methacrylate(HEMA)와 ethylene glycol dimethacrylate(EDGMA)로부터 수용액중에서 친수성 3차원 메타아크릴레이트 고분자 망상의 수화겔을 제조하여 NMR 분석법에 의해 그 친수성 메타아크릴레이트와 물 사이의 상호작용에 대하여 연구하였다. 적은 양의 물을 함유하고 있는 수화겔의 스핀-격자 이완시간$(T_1)$을 측정한 결과 물 양성자 주위의 다른 두 환경에 따른 $T_{1a}$와 $T_{2b}$가 나타났다. Poly(2-hydrocyethyl methacrylate)[p(HEMA)]-$(10{\%}\; H_2O)$ 수화겔에 대한 $T_{1a}$와 $T_{1b}$가 각각 $16.4{\times}10^{-3}\; sec$와 $58.2{\times}10^{-3}\;sec$이고, 가교된 EGDMA-p(HEMA)- $(10{\%}\; H_2O)$ 수화겔에 대한 $T_{1a}$와 $T_{2b}$가 각각 $13.2{\times}10^{-3}\; sec$와 $23.1{\times}10^{-3}\; sec$이었다. 또한 수화겔들에 대해 스핀-스핀 이완시간$(T_2)$를 측정한 결과 $p(HEMA)-(H_2O)_n$ 및 가교된 $EDGMA-p(HEMA)-(H_2O)_n$의 계에 $(T_2)$값은 물 함량이 증가함에 따라 증가하였다. $(T_2)$값들은 $(T_1)$의 값들보다 약 10배 작게 나타나고 스핀이완원리와 일치하였다.

• 한국미생물·생명공학회지
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• 제33권2호
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• pp.123-129
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• 2005

참비름(Amaranthus lividus)의 에탄올 추출물이 6종의 분리 병원성 미생물에 대해 항 미생물 활성을 나타내었으며 silicagel column chromatography에서는 8개의 fraction중에서 7번째가 6개의 분리 미생물에 대해 clear zone을 형성하여 가장 높은 항균력을 나타내었고 특히 A. sobria CLFM1 은 31mm, S. spp.는 33mm로 가장 큰 clear zone을 형성하였다. 활성물질의 순도를 확인하고자 methanol에 용해시킨 시료를 n-hexane : Ethyl acetate(1:1, v/v)용매계로 TLC를 전개시킨 결과 Rf 13.3의 위치에서 단일 spot를 나타내어 활성물질이 대단히 정제되어 있었으며, HPLC로 확인 결과 retention time 3.36에 single peak를 나타내 단일 물질임을 확인할 수 있었다. 분리된 활성물질을 GC-MS(m/z)로 분석한 결과 m/z 222에서 base peak로 나타났으며 이 spectrum으로 NIST library 검색을 실시 한 결과, $C_{12}H_{14}O_4$의 diethyl phtalate로 시사되었다. C-NMR과 1H-NMR을 실시한 결과 참비름에서 분리한 물질은 구조식 C12H14O6인 diethyl phtalate로 동정되었다. 참비름(Amaranthus lividus)의 에탄올 추출물이 6종의 분리 병원성 미생물에 대해 항 미생물 활성을 나타내었으며 silicagel column chromatography에서는 8개의 fraction중에서 7번째가 6개의 분리 미생물에 대해 clear zone을 형성하여 가장 높은 항균력을 나타내었고 특히 A. sobria CLFM1은 31 mm, S. spp.는 33 mm로 가장 큰 clear zone을 형성하였다. 활성물질의 순도를 확인하고자 methanol에 용해시킨 시료를 n-hexane : Ethyl acetate(1:1, v/v)용매계로 TLC를 전개시킨 결과 Rf 13.3의 위치에서 단일 spot를 나타내어 활성물질이 대단히 정제되어 있었으며, HPLC로 확인 결과 retention time 3.36에 single peak를 나타내 단일 물질임을 확인할 수 있었다. 분리된 활성물질을 GC-MS(m/z)로 분석한 결과 m/z 222에서 base peak로 나타났으며 이 spectrum으로 NIST library 검색을 실시 한 결과, $C_{12}H_{14}O_4$의 diethyl phtalate로 시사되었다. C-NMR과 1H-NMR을 실시한 결과 참비름에서 분리한 물질은 구조식 $C_{12}H_{14}O_6$인 diethyl phtalate로 동정되었다.

• Bulletin of the Korean Chemical Society
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• 제17권11호
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• pp.1052-1056
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• 1996

The effects of β-CD, Me-β-CD, and biphenyl capped β-CD on 1H NMR spectra of mandelic acid 1, α-methylbenzylamine 2 and 2-phenylpropionic acid 3 were investigated. Enantiomeric recognition was observed for mandelic acid 1 by all the hosts used, for α-methylbenzylamine 2 by β-CD and Me-β-CD, and for 2-phenylpropionic acid 3 by Me-β-CD. In the presence of biphenyl-capped β-CD, ο-, m-, and p-protons of the phenyl groups of the guests are discriminated due to ring current of the capped biphenyl group. The splitting pattern of the phenyl protons indicates that the phenyl group of the guests is inserted into the β-CD cavity from the secondary hydroxyl side and positioned in close proximity to the capped biphenyl ring. The magnitude of the upfield shifts of H3 and H5 protons of β-CD upon binding of guests 1-3 is similar to that caused by ephedrine or pseudoephedrine, suggesting that the substitution at benzylic carbon atom has little effect on the depth of the insertion of the phenyl group into the β-CD cavity and stability of the inclusion complexes.

• Bulletin of the Korean Chemical Society
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• 제27권6호
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• pp.893-898
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• 2006

Novel bis- and tris-crown ethers were synthesized from 1-aza and diaza-crown ethers with 2-acryloyloxy-methyl crown ethers through Michael addition. The synthesized bis- and tris-crown ethers were characterized by their elemental analyses, $^1H$-NMR, $^{13}C$-NMR, mass spectra, IR spectra, respectively. The complexation behavior of the bis- and tris-crown ethers with $Li^+$, $Na^+$, $Na^+$, $Rb^+$, $Cs^+$ was examined by $^1H$-NMR, FAB mass, and UV spectrometry.

• 한국자기공명학회논문지
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• 제21권4호
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• pp.126-130
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• 2017

In the developed NMR hyperpolarization techniques, Parahydrogen-Induced Polarization (PHIP) technique is widely utilized to overcome the low sensitivity of the NMR/MRI. Parahydrogen generator is essential to produce high spin order of parahydrogen molecule. Commercial parahydrogen generator is well developed with user-friendly systems. However, it has drawbacks of long preparation time (~ 2h including cooling down time of 1h) and high cost (~ 200 million won) for the commercial setup. We designed a simple and portable parahydrogen generating system with low cost (~ 2 million won), which produce polarization in less than 1 min. With the designed parahydrogen generator, we successfully performed the PHIP with Wilkinson's catalyst on styrene. This study will broaden the parahydrogen based polarization transfer study on many researchers by providing the simple portable and low cost parahydrogen generator.

• 한국자기공명학회논문지
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• 제4권2호
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• pp.125-132
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• 2000

The detailed $^1$H and $^{13}$ C NMR assignments of a novel sucrose isovaleryl ester isolated from the seed of Euphorbia Lathyris L., were achieved by one-and two-dimensional techniques. The new sucrose ester was characterized as an $\alpha$-D-glucopyranoside, 3,4,6-tris-O-(3-methyl-1-oxobutyl)-$\beta$-D-fructofuranosyl, 2,6-bis(3-methylbutanoate); sucrose 4,7,8,11,12-pentaisovalerate by MS and NMR experiments.

• 공업화학
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• 제10권6호
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• pp.876-880
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• 1999

이온성과 비이온성계면활성제의 혼합 미셀 용액의 자기확산계수는 NMR FT-PGSE법으로 측정하였다. 또한 프로톤 NMR 피크의 폭을 관찰하였다. 연구된 계는 $C_{12}EO_5/SDS/D_2O$, $C_{12}EO_5/DTAC/D_2O$ 및 $C_{12}EO_8/SDS/D_2O$의 혼합계이다. 모든 시료에서 솔벤트와 계면활성제의 몰비는 일정하고 계면활성제의 혼합비는 다양하게 실험을 하였다. $C_{12}EO_5$ 계에서 계면활성제의 자기확산계수는 이온성계면활성제의 혼합비가 약 25%일 때 최소치를 나타내었다. 비이온성계면활성제가 이온성계면활성제로 치환됨에 따라서 자기확산계수가 감소하는 것은 미셀간의 반발력이 증가하기 때문이다. 이온성계면활성제의 높은 분율에서 자기확산계수가 증가하는 것은 미셀의 크기가 감소하기 때문이다. $C_{12}EO_8$ 계에서 계면활성제의 혼합비의 효과는 분자의 기하학적 구조와 큰 관능기의 면적 때문에 거의 없다. 프로톤 NMR 피크와 자기확산계수는 상호 밀접한 관계를 나타내고 알킬 사슬의 메틸렌 시그날의 넓혀짐 현상은 자기확산계수가 작을 때 나타난다.

• 한국자기공명학회논문지
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• 제7권1호
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• pp.37-45
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• 2003

Human CD99 is a ubiquitous 32-kDa transmembrane protein encoded by mic2 gene. Recently it has been reported that expression of a splice variant of CD99 transmembrane protein (Type I and Type II) increases invasive ability of human breast cancer cells. To understand structural basis for cellular functions of CD99 Type II, we have initiated studies on hCD99$\^$TMcytoI/ using circular dichroism (CD) and multi-dimensional NMR spectroscopy. CD spectrum of hCD99$\^$TMytoI/ in the presence of 200mM DPC and CHAPS displayed an existence ${\alpha}$-helical conformation, showing that it could form an ${\alpha}$-helix under membrane environments. In addition, we have found that the cytoplasmic domain of CD99 would form symmetric dimmer in the presence of transmembrane domain. Although it has been rarely figured out the correlation between structure and functional mechanism of hCD99$\^$TMcytoI/, the dimerization or oligomerization would play an important role in its biological function.