• Bulletin of the Korean Chemical Society
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• 제26권4호
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• pp.641-644
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• 2005

Nucleophilic addition reactions of benzylamines $(XC_6H_4CH_2NH_2)\;to\;{\beta}$-cyanostilbenes ($YC_6H_4CH=C(CN)C_6H_4$Y’) have been studied in acetonitrile at 30.0 oC. A greater degree of N-$C_{\alpha}$ bond formation (larger ${\beta}_X$) is obtained with a stronger electron-withdrawing substituent in either ${\alpha}-\;(\delta\sigma_Y\;{\gt}\;0)\;or\;{\beta}-ring\;(\delta\sigma_{Y'}\;{\gt}$ 0). A stronger charge development is observed in the TS on $C_{\beta}\;(\rho_{Y'}$= 1.06 for X=Y=H) rather than on $C_{\alpha}\;(\rho_{Y}$ = 0.62 for X=Y’H) indicating the lag in the resonance development into the activating group (CN) on $C_{\beta}$ in the transition state. Similarly, the magnitude of $\rho$$_{XY'}$(−0.72) is greater than $\rho_{XY}$ (−0.66) due to a stronger interaction of the nucleophile with $\beta$-ring than $\alpha$-ring. The positive sign of $\rho_{YY'}$correctly reflects $\pi$ bond cleavage between the two rings in the TS. Relatively large kinetic isotope effects ($k_H/k_D\;{\geq}$ 2.0) involving deuterated nucleophiles ($XC_6H_4CH_2ND_2$) suggest a four-membered cyclic TS in which concurrent N-C$_{\alpha}$ and H(D)-C$_{\beta}$ bond formation occurs.

• 한국결정성장학회지
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• 제20권2호
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• pp.101-105
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• 2010

플라즈마 에쳐 내에 사용되는 실리콘 전극과 링 부품은 사용 중에 강한 플라즈마와 접촉하면서 주기적인 가열과 냉각 과정을 거친다. 이 때 부품의 표면에서는 열 응력으로 인하여 PSB라고 하는 띠 형상의 결함이 생성되며 이로 인하여 그 수명을 다하게 된다. 원료인 실리콘 잉곳의 관점에서 그 수명에 미치는 인자를 살펴보았다. 잉곳의 등급, 즉 S/F와 S/A에 따라 불순물과 결함의 농도를 GDMS와 ${\mu}$-PCD로 평가하여 잉곳의 어떤 요소들에 의하여 수명이 결정되는가를 분석하였다. 그 결과, {001} 면상에서 관찰되는 <110> 방향의 면 결함들이 PSB와 연결될 가능성이 있음을 제안하였다.

• 한국패류학회지
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• 제21권1호
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• pp.57-64
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• 2005

Samples of Corbicula japonica Prime of Jujin estuary in Gochang were collected from July 2000 to September 2001. Age of C. japonica was determined from the rings on the shell. The relationship between shell length and ring radius in each ring group was expressed as a regression line. Therefore, there is a correspondence in each ring formation. Based on the monthly variation of the marginal index (MI') of the shell, it is assumed that the ring of this species was formed once a year during the period of February and March. The relationship between shell length (SL; mm) and total weight (TW; g) was expressed by the following equation: TW = 1.0942 ${\times}10^{-4}SL^{3.3217}$ ($r^2$ = 0.9905). Shell length (SL) and shell height (SH; mm) was highly correlated with shell height as the following equation: SH = 0.9174 SL - 0.9935 ($r^2$ = 0.9885). The shell length (SL) - shell width (SW) relation was also expressed by the following equation; SW = 0.5925 SL - 1.1706 ($r^2$ = 0.9726). Growth curves for shell length and total weight fitted to the von Bertalanffy's growth curve were expressed as: $$SL_t = 46.4861[1-e^{-0.3383(t+0.0958)}]$$, $$TW_t = 34.54[1-e^{-0.3383(t+0.0958)}]^3.3217$$.

• 한국어류학회지
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• 제18권4호
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• pp.355-362
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• 2006

본 연구에서는 2003년 4월부터 2004년 3월까지 우리나라 동해안 강원도 양양군 현남면 남애리 연안에서 어획된 참가자미의 연령과 성장에 관하여 조사하였다. 연령형질로서는 이석을 사용하였고, 윤문형성시기는 3~5월로 산란시기와 일치하였으며, 연간 1회 형성되어 윤문을 연륜으로 간주하였다. 비선형 회귀방법으로부터 추정한 참가자미의 von Bertalanffy 성장식은 암컷이 $L_t=37.2$ ($1-e^{-0.131\;(t+2.008)}$)이었고, 수컷은 $L_t=28.3$ ($1-e^{-0.177\;(t+2.135)}$)으로, 암수간에 성장의 차이가 있었다.

• Bulletin of the Korean Chemical Society
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• 제28권12호
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• pp.2209-2213
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• 2007

Ginseng has long been used as a traditional medicine in Asian countries including Korea and China. In recent years, it has been reported that the biological activities of ginseng are due to its active components, ginsenosides. Ginsenosides are represented by triterpenes of the dammarane type. Ginsenoside Re consists of two glucose rings, one rhamnose ring, and the triterpene ring. In the present study ginsenoside Re has been isolated from the Korean ginseng (Panax ginseng) and the tertiary structure has been determined using NMR spectroscopy. Flexibilities around each linkages described by seven torsion angles were considered. The structures of ginsenoside Re obtained by NMR spectroscopy show the rigidity around the glucopyranosyl ring II and alkene side chain. The dihedral angles of φ5, φ6, φ7 are about 150o, 50o and 45o, respectively. In addition, flexibility exists around rhamnopyranosyl and glucopyronosyl moiety. The linkage around the rhamnopyranosyl and glucopyranosyl ring I, are divided into three groups. This flexibility seems to play important role in regulation of the hydrophobic surface exposed to the solvent. Because of the growing need for the structural determination of ginsenoside, this result can help to understand their well-accepted pharmacological effects of ginsenoside Re.

• Bulletin of the Korean Chemical Society
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• 제34권12호
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• pp.3681-3689
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• 2013

This study explored a direct SET-photochemical strategy to construct a new family of thioene conjugated-naphthalamide fluorophore based lariat-crown ethers which show strong binding properties towards heavy metal ions. Irradiations of designed nitrogen branched (trimethylsilyl)methylthio-terminated polyethylenoxy-tethered naphthalimides in acidic methanol solutions have led to highly efficient photocyclization reactions to generate naphthalamide based lariat type thiadiazacrown ethers directly in chemo- and regio-selective manners which undergo very facile secondary dehydration reactions during separation processes to produce their corresponding amidoenethio ether cyclic products tethered with electron donating diethyleneoxy- and diethyenethio-side arm chains. Fluorescence and metal cation binding properties of the lariat type enamidothio products were examined. The photocyclized amidoenethio products, thioene conjugated naphthalamide fluorophore containing lariat-thiadiazacrowns exhibited strong fluorescence emissions in region of 330-450 nm along with intramolecular exciplex emissions in region of 450-560 nm with their maxima at 508 nm. Divalent cation $Hg^{2+}$ and $Pb^{2+}$ showed strong binding to sulfur atom(s) in side arm chain and atoms in enethiadiazacrown ether rings which led to significant enhancement of fluorescence from its chromophore singlet excited state and concomitant quenching of exciplex emission. The dual fluorescence emission responses towards divalent cations might provide a new guide for design and development of fluorescence sensors for detecting those metals.

• 한국결정학회지
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• 제5권1호
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• pp.14-19
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• 1994

트리풀르오로메칠트리페닐 1,2,4-트리오키소란(C21H15F3O3)은 삼사정계인 공간군 P1으로 a=10.477(1), b=11.056(1), c=9.917(3)A, a=104.7(1), B=122.7(1), r=63.9(1)°, Z=2, V=867.9(3) A3, Dc=1.43 g/cm3, λ(Mo BCn)=0.71069 A, μ=0.0116 cm-1, F(000)=384, 그리고 I ) 1.0 o(I) 인 1713 개의 관측 된 회절점에 대한 R 값은 0.067 였다. 직접법에 의하여 구조를 풀었으며 전행열-최소자숭법에 의하여 정밀화하였고 C-H결합길이는 0.96 A 에 고정하였다. 106.6°의 두 사이각을 갖는 페닐고리(2)와 고리(3)는 트리오키소란분자평면의 위쪽에 있으나 CF3기와 페닐고리(1)은 아래쪽으로 있다. 트리오키소란 꼬리는 봉투모양의 구조를 갖고 있으며 그의 두 탄소 원자(C(2)와 C(3))는 탄소원자의 내각에 거의 비슷한 각으로 치환기들과 연결되어 있다. 분자들은 van der Waals 힘에 의하여 결합되었고 가장 가까운 거리는 0(2) 와 F(2)(-x, 1+y,1-z) 사이의 3.256 A 이다.

• 한국결정학회지
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• 제15권1호
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• pp.1-4
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• 2004

上記 題目의 化合物, $C_{18}H_{20}O_5S$은 한 對非稱 單位內에 한 個의 分子를 가지고 對稱中心室間群 $P\={1}$로 結晶化 되었다. sulfonate 群內ml S 原子는 O와 C 原子들로 이루워진 四面體 環境을 維特하고 있으며, S-O 二重結合 平均 길이는 1.420(2) ${\AA}$이며 S-O 單一結合 길이는 1.598(2) ${\AA}$이고 S-C 結合 길이는 1.742(3) ${\AA}$이다. C(7)-S-O(3)-C(8) 의 비틀림 角은 100.3(2)$^{\circ}$이며, 두 個의 six-membered rings의 二面角은 42.73(20)$^{\circ}$이다.

• Bulletin of the Korean Chemical Society
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• 제35권3호
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• pp.875-880
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• 2014

Adsorption of 4,4'-bis(mercaptomethyl)biphenyl (44BMBP) on silver nanoparticles has been investigated by surface-enhanced Raman scattering (SERS) spectroscopy. In addition, the Raman spectra of 44BMBP in solid state and in basic condition have been obtained for comparative study to elicit the characteristics of adsorption. The observed Raman and SERS spectra were analyzed comparing with the normal modes and vibrational frequencies from density functional theory (DFT) calculations performed for the feasible structures of 44BMBP molecule. On the basis of excellent agreement between the calculated and the experimental results, the molecule is found to have both the cis- and trans-forms for the mercaptomethyl groups in the solid state as well as in the basic condition. In contrast, the molecule is found to be chemisorbed on the silver surface by forming two Ag-S linkages only in the cis-form but not in the trans-form due to the steric interruption, which indicates the parallel orientation of molecules on the surface. Particularly, the spectral features in the SERS spectra such as the absence of the C-H stretching band and enhancement for the out-of-plane skeletal modes are confirmatory for the parallel geometry through ${\pi}$ interaction between the phenyl rings and the metal surface, based on the electromagnetic surface selection rule.

• Korean Chemical Engineering Research
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• 제46권2호
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• pp.301-309
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• 2008

본 연구에서는 레졸수지 합성에서 부가반응 실험변수인 F/P 몰비, 촉매 wt% 및 반응온도가 페놀치환체에 미치는 영향을 2단 실험계획법을 사용하여 실험하고 실험 결과를 삼원변량분석법(ANOVA, SPSS)을 사용하여 해석하였다. 페놀치환체는 반응시간 300분에서 F/P 몰비가 높을수록, 반응온도가 낮을수록, 촉매량이 적을수록 증가하는 경향을 보였고 ortho 지향성이 있음을 확인하였다. 레졸형 페놀수지의 합성에서 페놀계 치환체의 해리반응과 메틸렌글리콜 형태의 포름알데하이드의 분율을 고려하는 Zavitsas류의 속도론 모델을 단순화시킨 기초반응 모델을 제시하고 Zavitsas류의 속도론 모델과 비교하였다. 기초반응 모델은 평균적으로 2.79%의 오차를 보였으며 Zavitsas류 모델의 오차인 3.27%와 비슷한 값을 보이는 것을 확인하였다. 따라서 본 논문에서 제시한 기초반응 모델은 레졸합성의 부가반응 속도론 연구에 적용 가능하다고 판단된다.