• Journal of the Korean Chemical Society
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• v.68 no.4
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• pp.185-190
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• 2024

Recently, it was reported that the benzobisoxazole (BBO) molecule can be used for independent modulation of the HOMO and LUMO energy levels. In this study, we utilized this interesting property of BBO to quantitatively investigate the substituent effects according the substituents. We designed and proposed four BBO model systems (1BBO, 2BBO, 3BBO and 4BBO) by extending the π-conjugation lengths based on a BBO molecule. Two directions of substitution (x-axis and y-axis) and 15 various substituents were considered. From strong correlation between the LUMO energy levels of x-axis substitution and HOMO energy levels of y-axis substitution calculated from DFT method, it is found that the standardization of substitution effects can be established from BBO model systems. In addition, we demonstrated that the HOMO values of y-axis substituted 3BBO show the best performance to define the order of substituent effects. Our proposed way can be used to expect the substituent effect of any arbitrary substituents and develop the organic sensors and organic light emitting diodes.

• Journal of the Korean Chemical Society
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• v.17 no.3
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• pp.193-197
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• 1973

The correlation of the infrared carbonyl stretching frequency with substituents in benzanilides has been studied. The Hammett-type equation(1) was adopted for this correlation. Substituents in a C-phenyl-ring gave a better correlation with ${\sigma}^{+}$rather than ${\sigma}$, meanwhile, substituents in a N-phenyl-ring gave a better correlation with ${\sigma}$. When substituents are placed on both C-phenyl and N-phenyl ring, they influenced the carbonyl stretching frequency reasonably independently of each other. A conformation of benzanilide which accounts for the above observation has also been discussed.

• Review of KIISC
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• v.3 no.1
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• pp.26-30
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• 1993

본 논문에서는Akl-Meijer가 설계한 랜덤 치환 발생기를 일반화한 알고리즘을 제안한다. Akl과 Meijer는 사이즈가 m인 치환(Permutation)과 0과 m!-1사이의 정수를 일대일 대응시키는 Knuth의 알고리즘을 이용하여, 선형 합동법 Y=X+C mod m! (C는 상수)에서 발생되는 난수와 일대일 대응되는 치환을 발생하는 치환 발생 알고리즘을 설계하였으며, 이를 응용하여, 이진 난수 발생기를 제시하였다. 본 논문에서는 선형 합동법 Y=AX+C mod m!(A, C는 상수)에서 발생되는 난수와 일대일 대응되는 치환 계산과정을 상삼각 행렬(Upper triangular matrix) 의 곱으로 변환하여 고속으로 계산하는 알고리즘을 제시한후, 이 알고리즘의 출력 치환을 n 개 결합하여 치환을 발생하는 랜덤치환 발생기를 설계한다. 또한 이의 암호적인 응용으로, 치환 발생기를 이용한 이진 난수 발생기를 제시한다.

• Journal of the Korean Chemical Society
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• v.30 no.2
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• pp.248-258
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• 1986

The electronic structures and geometries of model substituted oxiranes, and carbonyl ylides containing cyano, methoxy and thiomethoxy substituents were investigated by MNDO-SCF-MO method. Stabilization and geometries caused by substituents, the ease of formation of carbonyl ylides from oxiranes and the reactivities of the cycloaddition of substituted carbonyl ylides were investigated.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.243-246
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• 2008

목질계 바이오매스 가스화 발전에 있어서는 가스화 가스중에 함유되어있는 타르를 가능한 한 가연성 가스로 전환하여 냉가스효율을 향상시키는 것 및 잔유하는 타르는 후단기기에 악영향을 초래할 우려가 있기 때문에 타르를 저감 제거하는 것이 바람직하다. 본 연구에서는 공기 수증기를 사용하여 타르개질 프로세스의 개선을 위해서 타르에서 가스성분으로의 전환에 관한 개질 실험을 실시하여 Wood chip 타르의 열분해 개질 생성물 거동에 대하여 검토하였다. Wood chip 열분해로 생성된 타르의 원소분석 및 $^1H$ NMR분석의 결과로 타르를 치환기를 가지지 않는 방향족, alkyl-기를 가지는 방향족, 산소 함유 방향족, 지방족의 4개로 분류하였다. 개질제에 의해 경질 타르, 중질 타르 모두 감소하였다. 개질 공기는 타르를 연소시키지만 그 속도는 가연성 가스와 경합하고 $900^{\circ}C$에서는 타르의 연소는 나타나지 않았다. alkyl-기를 가지는 방향족은 메탄과 치환기를 가지지 않는 방향족으로 전환되고, 치환기를 가지지 않는 방향족은 수소와 soot로 전환되고, 산소 함유 방향족은 일산화탄소와 치환기를 가지지 않는 방향족으로 전환되는 것을 알았다. 또한, 개질제에 의해alkyl-기를 가지는 방향족, 치환기를 가지지 않는 방향족, 산소 함유방향족 모두가 일산화탄소,이산화탄소로 전환되는 것을 알았다.

• Journal of the Korean Chemical Society
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• v.50 no.3
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• pp.183-189
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• 2006

A series of substituted styryl 4-methoxy-1-naphthyl ketones [(2E)-1-(4-methoxy-1-naphthyl)-3-phenyl-2-propen-1-ones] were synthesized using facile method of microwave assisted condensation reaction. The yield of chalcones is more than 90%. They are characterized by their physical constants, micro analysis, infrared (KBr, 4000-400 cm？1) and NMR both 1H and 13C spectral data. From infrared spectra, the s-cis and s-trans stretching vibrations of carbonyl group, from NMR spectra the ethylenic proton and carbon chemical shifts (ppm) are assigned. These spectral data are correlated with various Hammett substituent constants. From the results of statistical analysis the effect of substituents on CO, ？ and ？ proton and carbons are explained.

• Journal of the Korean Chemical Society
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• v.44 no.3
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• pp.184-189
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• 2000

ab initio molecular orbitaI calculation is performed to estimate the substituent effects for meta-substituted pyridines. Electrostatic potentials are obtained from ab initio wavefunctions of the optimized structures for the meta-substituted pyridines. Electrostatic potenhals are shown to be minimum at nitrogen atom of pyridines. The potenttial minima are good correlated with the substituent constants, ${\sigma}_m$ and with the ${\Delta}pK_a$, respectively. It is found that the electrostatic potential minima can be used as a useful measure of substituent effects.

• Journal of the Korean Chemical Society
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• v.43 no.4
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• pp.378-383
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• 1999

Ab initio calculation is performed to estimate the substituent effects for Para-substituted pyridines. Electrostatic potentials are obtained from ab initio molecular orbital wavefunctions of optimized structures for substituted pyridines. Electrostatic potentials are computed to be minimum at nitrogen atom of pyridines. The potential minima are good correlated with the substituent constants, ${\sigma}_p$ and with the ${\Delta}pKa$. It is shown that the electrostatic potential minima can be used as a measure of substituent effects.

• Applied Biological Chemistry
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• v.42 no.3
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• pp.252-255
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• 1999

Inhibition activities$(pI_{50})$ of chalcone derivatives as substrate with farnesyl protein transferase(FPTase) were determined in vitro. The structure activity relationships(SAR) between the activity and physicochemical parameters of X & Y-substituents on the phenyl groups were analyzed by Free-Wilson and Hansch method. X-substituents on the benzoyl group have the more important role to inhibition activity than Y-substituents on the styryl group. Among them, none substituent, 8 showed the highest FPTase inhibition activity$(pI_{50}=4.30)$. Particularly, the SAR equation could be formulated, showing a parabolic relationship between the activity and hydrophobicity(logP) where the optimal value$({\Sigma}logP)_{opt}$ was 3.915. And also the activity depends on the steric effect(Es > 0) with X-substituent and the resonance effect(R < 0) with electron donating Y-substituents. Based on the results of SAR analyses, the interactions between substrates and receptor, FPTase, could be assumed.

• Journal of the Korean Chemical Society
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• v.26 no.5
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• pp.333-339
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• 1982

Substituent effects of substrate and leaving group for the reaction of substituted ${\beta}$-phenylethyl arenesulfonates with pyridine were determined conductometrically in acetonitrile at 50∼70$^{\circ}$C. The substituent effect in substrate is not so significant than expected, but still the electron donating substituent shows the slight acceleration to give a small negative ${\rho}$ value and Hammett plots show slight curvature on the acting substituents, even though it is not so remarkable than that of benzyl system. These results represent a little bit the favorable bond breaking at the transition state by the electron donating substituents. The effects of leaving group in the arenesulfonates in which the rate constants are decreased by electron donating substituents, while electron withdrawing groups presented the reverse effects. Hammett ${\rho}$ value is significantly smaller than that of p-nitrobenzyl arenesulfonates and thus, the mechanism should be closer to tight $S_N2$ one. Especially 2,5-dichlorobenzenesulfonate was more accelerated than expected at the additivity of substituents. This facts showed that dichlorobenzenesulfonate anion is more stabilized by the great electron withdrawing substituents at transition state.