• Journal of the Korean Chemical Society
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• v.26 no.4
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• pp.195-204
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• 1982

Semi-empirical MO calculations, EHT, CNDO/2, MINDO/3, and MNDO met hods, were performed on various geometries of n-butane, n-alkyl radical and tetramethylene diracal (triplet) in order to compare eigenvalue and eigenvector properties with those obtained by STO-3G method. All methods predicted the same relative order of stabilities of various geometries for n-butane; geometrical preferences were found to be dominated by one-electron factor, ${\pi}$-orbital energy changes being more impotant in the semi-empirical methods. The hyperconjugative energy changes accompanying structural changes from $(n-{\sigma}{\ast})_{trans}$ to (n-{\sigma}{\ast})cis were underestimated in the EHT, CNDO/2 and MINDO/3, whereas those were overestimated in the MNDO. The net destabilizing effect of $(n-{\sigma}{\ast})_{trans}$ structure was mainly due to the large internuclear energy involved in the structure. Through-space interaction between $n_1$ and $n_2$ orbitals of diradical caused energy gap narrowing of ${\Delta}E_{sp}$ and ${\Delta}{\varepsilon}={\varepsilon}_0$-${\varepsilon}_{av}$; through-space interaction had opposing effect to that of through-bond interaction. Due to the less severe neglect of differential overlaps in the MNDO, this energy gap narrowing effect appeared amplified in the MNDO. In general orbital properties were found to be reproduced satisfactorily, but eigenvalue properties were not, in all the semi-empirical methods especially when ${\sigma}-{\sigma}{\ast}$ and n-$n-{\sigma}{\ast}$interactions were involved.

• Applied Chemistry for Engineering
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• v.25 no.1
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• pp.14-19
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• 2014

Nanocomposites based on poly(methyl methacrylate) (PMMA)/poly(vinylidene fluoride) (PVDF) and poly(ethylene terephthalate) (PET)/(PVDF) blended with carbon fibers (CF) and carbon nanotube (CNT) were prepared by melt mixing in the twin screw extruder. Morphologies of the PMMA/PVDF/CF/CNT and PET/PVDF/CF/CNT nanocomposites were investigated using SEM. The aggregation of CNT was observed in PMMA/PVDF/CF/CNT nanocomposites while the good dispersion of CNT was shown in PET/PVDF/CF/CNT nanocomposites. In SEM image of PET/PVDF/CF/CNT nanocomposite, the CNT were mainly located at the PET domain of phase-separated PET/PVDF blend due to the ${\pi}-{\pi}$ interaction between the phenyl ring of PET and graphite sheet of the CNT's surface. In addition, a fairly good compatibility between PET/PVDF matrix and CF was shown in the SEM image. In the case of PET/PVDF nanocomposites blended with the co-addition of CF and CNT, the volume electrical resistivity decreased while no change was observed in PMMA/PVDF/CF/CNT composites. The degree of CNT dispersion in morphology results was consistent with the electrical conductivity results. From the DSC results, the crystallization temperature (Tc) of PET/PVDF/CF/CNT nanocomposites increased due to the co-addition of CF and CNTs acting as a nucleating agent. Flexural modulus of PET/PVDF/CF/CNT were sharply enhanced due to increasing the interaction between PET and CF.

• Journal of the Korean Chemical Society
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• v.29 no.1
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• pp.45-51
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• 1985

Rate constants and activation parameters for the methanolysis of t-butyl halide (t-BuCl, t-BuBr, t-BuI) in various MeOH-DMSO mixtures were measured by conductometric method. Taft's solvatochromic parameters, such as polarity-polarizability(SPP's), ${\pi}^{\ast}$, hydrogen bond donor (HBD) acidity, ${\alpha}$, and hydrogen bond acceptor (HBA) basicity, ${\beta}$ of the solvents, were determined by the so called solvatochromic method using five indicators. The variation of methanolysis rate with the solvent composition was discussed on the basis of the activation parameters and the correlation of the rates with the solvatochromic parameters. It is concluded that the polarity-polarizability, HBD acidity and HBA basicity of the mixtures had an effect on the ionization of t-butyl halide cooperatively, also that the specific interaction between the leaving groups and the solvents, such as ion-dipole and hydrogen bond acceptor-donor interaction, is the most important factor of solvent effects on the stabilization of transition states.

• Molecules and Cells
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• v.38 no.9
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• pp.765-772
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• 2015

Saussurea lappa has been reported to possess anti-atopic properties. In this study, we have confirmed the S. lappa's anti-atopic properties in Nc/Nga mice and investigated the candidate gene related with its properties using microarray. We determined the target gene using real time PCR in in vitro experiment. S. lappa showed the significant reduction in atoptic dermatitis (AD) score and immunoglobulin E compared with the AD induced Nc/Nga mice. In the results of microarray using back skin obtained from animals, we found that S. lappa's properties are closely associated with cytokine-cytokine receptor interaction and the JAK-STAT signaling pathway. Consistent with the microarray data, real-time RT-PCR confirmed these modulation at the mRNA level in skin tissues from S. lappa-treated mice. Among these genes, PI3Kca and $IL20R{\beta}$ were significantly downregulated by S. lappa treatment in Nc/Nga mouse model. In in vitro experiment using HaCaT cells, we found that the S. lappa components, including alantolactone, caryophyllene, costic acid, costunolide and dehydrocostus lactone significantly decreased the expression of PI3Kca but not $IL20R{\beta}$ in vitro. Therefore, our study suggests that PI3Kca-related signaling is closely related with the protective effects of S. lappa against the development of atopic-dermatitis.

• Journal of the Korean Chemical Society
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• v.19 no.4
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• pp.233-239
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• 1975

The configuration of two oxime groups in cis-2-butenedialdioxime, unsymmetrical compound conjugated by three double bonds, is determined by a NMR study on the effects of the solvent, temperature and concentration; it is certain that, in solutions of usual conditions, the configuration exists as only "syn-syn". And the relative strengths of the hydrogen bond between these oxime groups and several solvents are compared and somc effects of the temperature and concentration are also considered. The several models of hydrogen bond between oxime and solvents are proposed; especially it is to be noted here that the hydrogen bond in pyridine solvent is not resulted from the interaction between a lone electron pair on nitrogen atom of pyridine and the hydroxyl proton of oxime, but the result of $\pi$-complex formed between the $\pi$-orbital of pyridine and the hydroxyl proton of the solute.

• Bulletin of the Korean Chemical Society
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• v.23 no.9
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• pp.1315-1327
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• 2002

The model compounds, 8-methoxypsoralen-CH2O(CH2)n-adenine (MOPCH2OCnAd, n=2, 3, 5, 6, 8, and 10) in which 5 position of 8-methoxypsoralen (8-MOP) is linked by various lengths of polymethylene bridge to N9 of adenine. UV absorption spectra are identical with the sum of MOPCH2OC3 and adenine absorption spectra. Solvent effects on the UV absorption and fluorescence emission spectra indicate that the lowest excited singlet state is the $(\pi${\rightarrow}$\pi*)$ state. The spectral characteristics of the fluorescence of MOPCH2OCnAd are strongly dependent upon the nature of the solvents. The fluorescence emission spectra in aprotic solvents are broad and structureless due to the excimer formation through the folded conformation accelerated by hydrophobic ${\pi}-{\pi}$ stacking interaction. Increasing polarity of the protic solvents leads to higher population of unfolded conformation stabilized through favorable solvation and H-bonding, and consequently to an increase in the fluorescence intensity, fluorescence lifetime, and a shift of fluorescence maximum to longer wavelengths. The decay characteristics of the fluorescence in polar protic solvents shows two exponential decays with the lifetimes of 0.6-0.8 and 1.6-1.9 ns in 5% ethanol/water, while MOPCH2OC3 shows 0.5 and 1.7 ns fluorescence lifetimes. The long-lived component of fluorescence can be attributed to the relaxed species (i.e., the species for which the solvent reorientation (or relaxation) has occurred), while the short-lived components can be associated with the unrelaxed, or only partially relaxed, species.

• Bulletin of the Korean Chemical Society
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• v.33 no.4
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• pp.1259-1263
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• 2012

Two metal compounds, $[Co(phen)_2(H_2O)_2]{\cdot}2H_2SIP{\cdot}2H_2O$ 1 and $[Ni(phen)_3]{\cdot}2H_2SIP{\cdot}3H_2O$ 2, have been obtained by incorporating 1,10-phenanthroline (phen) and 5-sulfoisophthalic acid monosodium salt ($NaH_2SIP$) ligands under hydrothermal conditions. Meanwhile, the two compounds were characterized by element analysis, IR, XRD, TG-DTA and single-crystal X-ray diffraction. Both 1 and 2 present 3D supramolecular structures via O-H${\cdots}$O hydrogen bond interactions. Luminescent properties for 1 and 2 were also studied. The compound 1 has two fluorescence emission peaks centered at 398 nm attributed to the intraligand emission from the SIP ligand and at 438 nm assigned to the combined interaction of intraligand ${\pi}^*-{\pi}$ transitions of the phen ligand and ligand-to-metal-charge-transfer (LMCT) transitions (${\lambda}_{ex}$ = 233 nm). The compound 2 shows one emission band centered at 423 nm with a shoulder peak at 434 nm which may be originated from the intraligand ${\pi}^*-{\pi}$ transitions of the phen ligand (${\lambda}_{ex}$ = 266 nm).

• Current Applied Physics
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• v.18 no.11
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• pp.1458-1464
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• 2018

An improved method for the preparation of g-$C_3N_4$ is described. Currently, heating (> $400^{\circ}C$) of urea is the common method used for preparing the g-$C_3N_4$. We have found that sonication of melamine in $HNO_3$ solution, followed by washing with anhydrous ethanol, not only reduce the crystallite size of g-$C_3N_4$ but also facilitate intriguing electronic structure and photoluminescence (PL) properties. Moreover, loading of metal (Pt and Ag) nanoparticles, by applying the borohydride reduction method, has resulted in multicolor-emission from g-$C_3N_4$. With the help of PL spectra and local electronic structure study, at C K-edge, N K-edge, Pt L-edge and Ag K-edge by X-ray absorption spectroscopy (XAS), a precise mechanism of tunable luminescence is established. The PL mechanism ascribes the amendments in the transitions, via defect and/or metal states assimilation, between the ${\pi}^*$ states of tris-triazine ring of g-$C_3N_4$ and lone pair states of nitride. It is evidenced that interaction between the C/N 2p and metal 4d/5d orbitals of Ag/Pt has manifested a net detraction in the ${\delta}^*{\rightarrow}LP$ transitions and enhancement in the ${\pi}^*{\rightarrow}LP$ and ${\pi}^*{\rightarrow}{\pi}$ transitions, leading to broad PL spectra from g-$C_3N_4$ organic semiconductor compound.

• Journal of Global Scholars of Marketing Science
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• v.17 no.3
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• pp.61-81
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• 2007

Recently, use of foreign models and foreign language in advertising is a general trend in Korea even though the effect has not been well-known..Most of the previous research shows rather an opposite effect claiming marketing communication is more effective when higher congruity between marketing communication and consumer's cultural values are achieved. However, the introduction of global culture due to the expansion of new media such as Internet or cable television makes the congruity not the best choice of marketing strategy. In addition, use of highly attractive models in advertising to increase the effect of advertising is general. However, recent studies show that targeted women audience tend to compare themselves to the highly attractive models and do experience negative sentiment. Bower (2001) proved the difference between 'comparer' and 'noncomparer' when women face highly attractive models. The results show that a comparer who has an intention to compare highly attractive model (HAM) with herself has a significantly negative effect on model expertise, product argument, product evaluation and buying intention. Therefore, HAM is not always a good choice and model attractiveness plays a role in the processing other cues or changing the advertising effect from result of processing other cues. The purpose of this study is to investigate the effect of the use of foreign language on the advertising response of the audience with regard of the model attractiveness. For the empirical study, the virtual advertising using foreign models (HAM, NAM), brand names and slogans(Korean, English) were used as stimuli. The respondents of each stimulus were 75('HAM-Korean'), 75('NAM-Korean'), 66('HAM-English') and 66 ('NAM-English') respectively. To establish the effect of marketing communication, the attitude for media(AM), the attitude for product(AP), targetedness(TD), overall quality(OQ), and purchase intention(PI) with 7 point likert scale were measured. The manipulation was verified to check the difference between HAM attractiveness assessment (m=3.27) and NAM attractiveness assessment (m=5.12). The mean difference was statiscally significant (p<.05). As a result, all consequences were significantly changed with model attractiveness, and overall quality evaluation(OQ) were significantly changed with language. The interaction effect from model attractiveness and language was significant on attitude toward the product(AP) and purchase intention(PI). To analyze the difference, the mean values and standard deviation of consequences were compared. The result was more positive when model attractiveness was high for all consequences. For language effect, the assessment was more positive when English was used for OQ. Considering model attractiveness and language simultaneously, HAM-Korean was more positive for AP and PI, and NAM-English was more positive for AP and PI. In other words, the interaction effect was confirmed by model attractiveness and language. As mentioned above, use of foreign models and foreign language in advertising was explained by cultural match up hypothesis (Leclerc et al. 1994) which claimed that culture of origin effect. In other words, in advertising, use of same cultural language with the foreign model could make positive assessment for OQ. But this effect was moderated by model attractiveness. When the model attractiveness was low, the use of English makes PI high because of the effect of foreign language which supported the cultural match up hypothesis. When the model attractiveness was low, the use of Korean made AP and PI high because the effect of foreign language was diluted. It was a general notion that the visual cues got processed before (Holbrook and Moore, 1981; Sholl et al, 1995) compared to linguistic cues. Therefore, when consumers were faced HAM, so much perception was already consumed at processing visual cues making their native language of Korean to strongly and positively connected with the advertising concept. On the contrary, when consumers were faced with NAM, less perception was consumed compared to HAM, making English to accompany cultural halo effect which affected more positively. Therefore, when foreign models were employed in advertising, the language must be carefully selected according to the level of model attractiveness.

• Bulletin of the Korean Chemical Society
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• v.27 no.10
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• pp.1685-1688
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• 2006