• Bulletin of the Korean Chemical Society
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• v.30 no.7
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• pp.1452-1458
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• 2009

The change in the electronic absorption and emission energy of 7-aminocoumarin derivatives in binary solvent mixtures has been studied. The electronic transition energy along with the Stokes' shift is correlated with the orientation polarizability of the solvent as well as the empirical solvent polarity parameters $E_T$ (30). It is observed that the emission peak shift traces the change of $E_T$ (30) value very closely in binary solvent mixtures. The emission transition more strongly depends on the solvent polarity than the absorption, which indicates the dipole moment gets larger on excitation. From the dependence of the Stokes’ shift of 7-aminocoumarins with the solvent polarity parameters and the ground state dipole moment obtained by the semi-empirical calculations, the excited state dipole moment was estimated. The fluorescence lifetime change of 7-aminocoumarins in binary solvent mixtures was measured and the results are explained in terms of molecular conformation and solvent polarity. The study indicates the empirical solvent polarity $E_T$ (30) is a good measure of microscopic solvent polarity and it probes in general the non-specific solvent interactions.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.641-644
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• 2009

We demonstrated a solvent-assisted soft-lithographic patterning method for producing patterned structure and patterned ordering with lyotropic liquid crystalline polymer (LCP) film. Experimental results showed that the liquid crystalline ordering of lyotropic film could be controlled by shearing effects of the fluidic solvent though the patterned mold channels. In this work, two types of lyotropic LCPs were used to investigate the effects of the alkyl chain length of the lyotropic LCP on producing liquid crystalline ordering through the solvent-assisted fluidic patterning.

• Bulletin of the Korean Chemical Society
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• v.17 no.8
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• pp.682-685
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• 1996

Photothermal properties depend on the characteristics of energy transfer processes in solution. In this study, a time-resolved single beam thermal lens experiment in various solvents is employed to investigate the energy coupling effects which govern the energy transfer processes. Interestingly, it is observed that the behaviour of the photothermal propagation in solution depends on the property of solution and the concentration of solute in a single beam thermal lens configuration. These characteristics lead us to consider the solute-solvent coupling effects as well as the solvent-solvent interactions.

• Textile Coloration and Finishing
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• v.2 no.1
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• pp.21-30
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• 1990

In order to obtain high dye uptake initially, polyethylene terephthalate (PET) filaments were dyed with C.I.Disperse Orange 3 and Red 1 in mixed solvents of tetrachloroethylene acidic solvent, ethyl alcohol and tetrachloroethylene basic solvent, DMF. The dyeing behavior in the mixed solvent of tetrachloroethylene and basic solvent, DMF, the initial uptake of disperse dyes increased rapidly. The shrinkage of PET increased when the solubility parameter values of PET fiber and mixed solvent approached graduately.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.116-117
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• 2006

Increasing the solvent molecular size leads to shrinkage of the polymer chains and increase of the critical overlap concentrations. In addition, the dependency of $R_{g}$ on polymer concentration under normal solvent conditions and solvent molecular size is in good agreement with scaling laws. When the solvent molecular size approaches the ideal end-to-end distance of the polymer chain, an extra aggregation of polymer chains occurs, and the solvent becomes the so-called medium-sized solvent. When the size of solvent molecules is smaller than the medium size, the polymer chains are swollen or partially swollen. However, when the size of solvent molecules is larger than the medium size, the polymer coils shrink and segregate, enwrapped by the large solvent molecules.

• Bulletin of the Korean Chemical Society
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• v.31 no.10
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• pp.2823-2829
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• 2010

We investigated the solvent effects on the relative free energies of binding of $Na^+$ and $Li^+$ ions to 12-crown-4 and ${\Delta}log\;K_s$ (the difference of stability constant of binding) by a Monte Carlo simulation of statistical perturbation theory (SPT) in several solvents. Comparing the relative free energies of binding of $Na^+$ and $Li^+$ ions to 12-crown-4, in $CH_3OH$ of this study with experimental works, there is a good agreement among the studies. We have reported the quantitative free energy polarity (of solvent) relationships (QFPR) of the relationship between the relative free energies and solvent polarity studied on the solvent effects on the relative free energies of binding of $Na^+$ and $Li^+$ ions to 12-crown-4.

• Bulletin of the Korean Chemical Society
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• v.33 no.7
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• pp.2439-2442
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• 2012

In order to explore the effects of the solvent on the formation rate of polyynes, we investigated the absorption spectra of polyynes obtained by laser ablation of a graphite target in different solvents at 1064 nm. Polyynes so produced were confirmed by the Raman band around $2200cm^{-1}$ which corresponds to the carbon triple bonds. The production of polyynes by laser ablation turned out to be significantly affected by the ratio of the hydrogen and carbon atoms in the solvent molecule. No clear correlations were observed in the formation of polyynes for other properties of the solvent such bond dissociation energy, thermal conductivity, and total mass of hydrogen atoms per volume of solvent.

• Bulletin of the Korean Chemical Society
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• v.16 no.11
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• pp.1104-1108
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• 1995

A measure of stabilities (-ΔHo) and resonance delocalization (-Δq(Cα+)) for some carbocations has been estimated using the semiempirical AM1 method. The stability (-ΔHo) of carbocations can be correlated with the sensitivity (m) of localized cations to the solvent ionizing power scale Y, whereas the extent of resonance delocalization (-Δq(Cα+)) can be correlated with the sensitivity (h) of delocalized cations to the solvent ionizing power scale Ⅰ. It has been shown that two solvent ionizing power scales Y and I have in general opposite signs so that effects of electrostatic solvation are opposite for the localized and delocalized cationic charges. The use of two different solvent scales for a substrate with delocalizable cationic charge is not only prerequisite to the proper correlation of solvolysis rates but also is justified.

• Korean Journal of Human Ecology
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• v.1 no.2
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• pp.89-99
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• 1998

This study was carried out to investigate some antioxidative effects of stewed pumpkin juice (SPJ) and the SPJs added with ginger (SPJ-G), onion (SPJ-O), jujube (SPJ-J) or boxthorn (SPJ-B), respectively, on the lipid oxidation of soybean oil (S) and mackerel pike boiled ground (MPBG). Antioxidative substances of SPJ were extracted by using the two solvent layers of n-hexane:acetone (1:1)(H) and methanol:water (7:3)M. The antioxidative effects of the extracts were observed by the peroxide value (P.O.V.) and thiobabituric acid (T.B.A.) value. The P.O.V. and T.B.A. value of two solvent extracts of S and MPBG showed significantly lower than those of S and MPBG. The SPJ showed very distingnished antioxidative effects. It was considered that melanoidine extracted by using methanol:water (7:3) solvent as well as carotenoid extracted by using n-hexane:acetone (1:1) solvent had an antioxidative effect. During storage, T.B.A. value of MPBG significantly increased, while that of MPBG-SPJ significantly decreased more than that of MPBG. T.B.A. value of MPBG-SPJs decreased much than that of MPBG-SPJ, SPJ-O, SPJ-G, SPJ-J and SPJ-B, in order of abundance, showed higher level of antioxidative effects than SPJ. (Korean J Human Ecology 1(2):89∼99, 1998)

• Analytical Science and Technology
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• v.17 no.4
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• pp.295-301
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• 2004

In this study, static and dynamic solvent extractions are compared for more efficient extraction of polychlorinated dibenzofurans (PCDFs) from fly ash. Static solvent extraction rather than dynamic extraction showed a higher recovery of PCDFs, which was adsorbed strongly with fly ash. The effects of parameters, such as temperature, toluene-isopropyl alcohol mixture, static and dynamic time flow rate, and solvent volume on the extraction were investigated and the variations in average recoveries of PCDFs were explained. In both extractions, temperature was an effective parameter because the higher temperature gave the higher recoveries. In dynamic solvent extraction, dynamic time was more effective than flow rate and solvent volume for the extraction of PCDFs from fly ash. Multi-layer column chromatography on neutral and acidic silica gel with n-hexane was used for cleaning up the extracts. The quantification of the PCDFs extracted was performed using HPLC-UV.