• Journal of the Korean Chemical Society
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• v.42 no.1
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• pp.1-8
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• 1998

Molecular electrostatic potential (MEP) of the thiazole, relevant to the binding of lexitroposin that contains thiazole ring to the base pair of minor groove of DNA is obtained from the results of ab initio calculation. The geometry optimization for the two possible conformations of protonated thiazoles is performed with the aid of MNDO and ab initio calculations. The proton affinities are calculated at the 6-31G and 6-31G basis set for the optimized geometry. The proton affinities are also studied for various substituted thiazoles with the electron-donating and electron-withdrawing groups to estimate substituent effect on the proton affinity of thiazoles. It is found that the thiazole with nitrogen atom aligned inward to the DNA minor groove exhibit higher proton affinity and electron-donating substituents increase the proton affinity of thiazoles.ĀȀꃏ?⨀缾ĀȀ會ĀȀ?⨀ꖓĀĀȀ會ĀȀ僐?⨀聥ꖓĀĀȀ會ĀȀ꣐?⨀聐缾ĀȀ會ĀȀÑ?⨀ၑ缾ĀȀ會ĀȀ壑?⨀ꁑ缾ᨀĀꀏ會Āꀏ냑?⨀⡒缾᐀Āꀏ會Āꀏ࣒?⨀끒缾ᰀĀꀏ會Āꀏ惒?⨀ꁩꖓȀĀꀏ會Āꀏ룒?⨀⡪ꖓሀĀꀏ會Āꀏდ?⨀ᤐ돀삺?⨀塨?⨀飣?⨀돐룣?⨀偠잖⨀샣?⨀줏덐탣?⨀젏ꠏܞ
Ȍ蠀
ᥲ⴯

ͧ
Molecua及컲ࡔ
ȏᰗۊऀں
Molecular electrostatic potential (MEP) of the thiazole, relevant to the binding of lexitroposin that contains thiazole ring to the base pair of minor groove of DNA is obtained from the results of ab initio calculation. The geometry optimization for the two possible conformations of protonated thiazoles

• Applied Biological Chemistry
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• v.17 no.2
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• pp.143-148
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• 1974

The interaction of the carcinogenic mycotoxin, Aflatoxin $B_1$, with the electron-donating molecule, benzene, was studied spectrophotometrically. The formation of charge-transfer complex between Aflatoxin $B_1$ and benzene in the presence of zinc chloride was observed and the apparent equilibrium constant of this charge-transfer complex was found to be 0.198 (liter $mole^{-1}$). It is assumed that, as the result of this study, some charge-transfer complexes could be formed between the weak electron-accepting Aflatoxin $B_1$ and strong electron-donating molecules, and the spectral changes occurred in the binding of Aflatoxin $B_1$ with proteins or DNA is attributed to the existence of charge-transfer type interaction.

• Journal of the Korean Chemical Society
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• v.51 no.1
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• pp.7-13
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• 2007

The oxazole plays an important role in the binding of lexitropsin to the guanine-cytosine base pair from minor groove of DNA. The geometry optimization is performed with DFT calculations for the two possible conformations of the protonated oxazole. The proton affinities are calculated at B3LYP level of theory with 6-31G* basis set for the optimized geometry. It is found that the proton affinites of the conformations in which the oxazole nitrogen is the protonation center are greater than that of the conformations in which the oxazole oxygen is the protonation center. This result is in good agreement with molecular electrostatic potential (MEP) contour map. The proton affinities are also studied for various substituted oxazoles with the electron-donating and -withdrawing groups to estimate substitutent effect on the proton affinity at the hydrogen bonding site of the oxazoles. it is shown that the electron-donating substituents increase the proton affinity of oxazole, while the electron-withdrawing substituents decrease it.

• Nuclear Engineering and Technology
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• v.5 no.4
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• pp.321-333
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• 1973

The rates and activation parameters for the halide exchange reactions of substituted benzenesulfonylbromides (R-C$_{6}$H$_4$SO$_2$Br, R=p-MeO, p-$CH_3$, p-H, p-NO$_2$) in dry acetone at two temperatures were determined. It was found that the nucleophilicity order of Cl->I-$\geq$Br- for strong electron withdrawing-, and mild electron donating group, and of I-$\geq$Cl->Br- for strong electron donating group, Hammett plots showed slightly convoked characteristics which is similar to the plots of substituted benzenesulfonylchlorides, but contrary to the concaved nature for the halide exchange reactions of substituted benzyl chlorides. The rate of halogen exchange between benzenesulfonylbromide and lithium bromide decreased in the order of solvent : ($CH_3$)$_2$CO>$CH_3$CN》MeOH. The rates and activation parameters were also compared with those already known in the substituted benzenesulfonylchlorides. Theses were explained in terms of the structural properties of the transition state, and discussed the reaction mechanisms.s.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.4
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• pp.359-365
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• 2022

The development of efficient electron donor (or hole-transporting) molecules that can be used in various optoelectronic device fields is highly demanded. In this work, a novel class of triptycene-based three-dimensional (3D) triphenylamine (TI-TPA) derivatives with different end substituents was designed and prepared for transparent electron donor materials. Owing to the rigid 3D triptycene framework, the obtained TI-TPA derivatives had an amorphous morphology with high thermal decomposition temperature. The oxidation potential of these TI-TPA derivatives decreased as the electron donating strength of the end substituent increased. Among TI-TPA derivatives, TI-TPA-OMe exhibited the highest HOMO level (-5.31 eV) which is similar to that of Spiro-OMeTAD (-5.22 eV). In addition, TI-TPA-OMe was found to form a strong charge transfer complex with the triptycene-based acceptor TI-BQ, leading to a new absorption band at around 640 nm. These results can be applied for developing efficient electron donor materials that can mimic the advantages of the spiro-linked structure and TPA units of Spiro-OMeTAD.

• Bulletin of the Korean Chemical Society
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• v.27 no.3
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• pp.399-402
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• 2006

Porous organic-inorganic hybrids have been prepared from tetraethylorthosilicate (TEOS) and organosilane precursors by sol-gel method. Two organosilanes, 3-(2,4-dinitrophenylamino)propyltriethoxysilane (DNPTES) and N-[[(2-nitrophenyl)methoxy]carbonyl]-3-triethoxysilylpropylamine (NPTES) were used to incorporate electron-accepting (di)nitrophenyl groups into the hybrids. The hybrids were characterized by FT-IR spectroscopy and elemental analysis, and their pore characteristics were studied by nitrogen sorption porosimetry. Surface area of the hybrids ranged from 563 to 770 $m^2$/g, pore volume, 0.23-0.30 $cm^3$/g, and porosity, 35-41%. It was demonstrated by UV-vis spectroscopy that aniline, ethylenediamine, and 1-aminonaphthalene could be removed from their hexane solutions in the presence of the hybrid powders. The removal of amines is attributable to donor-acceptor interaction between the electron-donating amines and electron-accepting (di)nitrophenyl moiety.

• Bulletin of the Korean Chemical Society
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• v.23 no.9
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• pp.1309-1338
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• 2002

The fluorescence and photoisomerization quantum yields of trans-1-(9-anthryl)-2-(4-pyridyl)ethene (t-4-APyE), 1-(10-methyl-9-anthryl)-2-(4-pyridyl)ethene (t-4-MeAPyE), and 1-(10-chloro-9-anthryl)-2-(4- pyridyl)ethene (t-4-ClAPyE) were measured in cyclohexane, acetonitrile, and methanol at room temperature.Polar solvents result in the drastic reduction of fluorescence quantum yield and increase of photoisomerization quantum yield for all three compounds. These results are probably due to the stabilization of intramolecular charge transfer (ICT) excited state in polar solvent. The higher contribution of ICT in the presence of more electron-donating methyl substituent, manifested by largest positive fluorescence solvatochromism, indicates that the pyridine ring acts as an electron acceptor. Protonation or methylation makes pyridine ring stronger electron acceptor and causes long-wavelength ground state charge transfer absorption band and complete quenching of fluorescence. The fluorescence from t-4-APyE derivatives can be switched off responding external stimuli viz. medium polarity, protonation, or methylation.

• Bulletin of the Korean Chemical Society
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• v.20 no.6
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• pp.701-704
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• 1999

Metallophthalocyanines [PcM, Pc: phthalocyanine, M: Fe 2+ , Co 2+ ] were reacted with α-isocyanonaphthalene( α-in) and α-isocyanoanthracene (α-ia) to form monomeric complexes. The synthesis and coordination behaviour of the isocyanides as a ligand (L) are discussed. All the products were characterized by spectroscopic methods and instrumental analysis. The electrical conductivities of these complexes, which were not treated with dopant, were attributed to the metal-ligand electron delocalization in the PcML2 complexes. The complexes have an enlarged macrocycle where the π-electron back donating ability of PcM is stronger than the σ-electron coordinating ability of the isonitrile ligands. Their electrical conductivities were measured as σRT = 2.1×10 -9 ~3×10 -10 S/cm. Also thermal stability was investigated in this study.

• Korean Journal of Food Science and Technology
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• v.45 no.5
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• pp.657-660
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• 2013

The effects of roasting temperature and time on the antioxidant activities of Cassia tora L. were investigated. In comparison with raw seeds (7.15 mg TAE/g), roasted seeds contained a significantly higher total polyphenol content (p<0.05). However, seeds roasted at a higher temperature ($250^{\circ}C$) for 10 min showed a significantly lower total polyphenol content (2.30 mg TAE/g; p<0.05). The electron donating abilities of Cassia tora L. seeds increased with an increase in roasting time; further, seeds roasted for 5 min at lower temperatures showed higher electron donating abilities (80.61% at $175^{\circ}C$; 80.75% at $200^{\circ}C$) than did seeds roasted for 5 min at higher temperatures (76.26% at $225^{\circ}C$; 77.35% at $250^{\circ}C$). Seeds roasted at lower temperatures showed adequate L values, regardless of roasting time; by contrast, seeds roasted for 10 min at higher temperatures, showed markedly lower L values. Our results indicate that roasting temperature and time must be controlled to produce high-quality Cassia tora L. products.

• Journal of the East Asian Society of Dietary Life
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• v.21 no.5
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• pp.713-722
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• 2011

This study was conducted to monitor the quality characteristics of Acai (Euterpe oleracea Mart.) ethanolic extracts by a response surface methodology. The independent variables in the extraction experiments were ethanol concentration (0~100%), extraction temperature ($35{\sim}95^{\circ}C$), and ratio of solvent to sample (10~30 mL/g). The coefficients of determinations ($R^2$) were 0.9596 (p<0.01), 0.9356 (p<0.01), and 0.8842 (p<0.05) for total polyphenol, total flavonoid, and electron donating ability, respectively. The electron donating ability and nitrite scavenging effect improved with an increase in ethanol concentration as opposed to extraction temperature. Anthocyanin content with extraction conditions was 74.421~291.841 mg/L and the coefficient of determinations ($R^2$) was 0.9792 (p<0.01). ORAC (oxygen radical absorbance capacity) with extraction conditions was 137.73~562.94 ${\mu}moles$ TE/g and increased with an increase in ethanol concentration and a decrease in the ratio of solvent to sample content. Estimated conditions for maximum extraction including yield, total polyphenol, total flavonoid, electron donating ability, anthocyanin content, and ORAC were 28~58% for ethanol concentration, $60{\sim}68^{\circ}C$ for extraction temperature, and 10~12 mL/g for ratio of solvent to sample.