• Bulletin of the Korean Chemical Society
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• v.25 no.6
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• pp.819-822
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• 2004

Protonation constants of calix[4]-cyclen-benzo-crown-6, L in 1X$10^{-2}$ M $Bu_4NCF_3SO_3$ in 40% $CH_2Cl_2/CH_3OH$ at $25^{\circ}C$ determined by potentiometric titration are log $K_1$ = 10.91, log $K_2$ = 10.30, log $K_3$ = 6.24 and log $K_4$ = 2.55. Stability constants for the receptor L complexes with Cu(II) and Zn(II) in 1X$10^{-2}$ M $Bu_4NCF_3SO_3$ in 40% $CH_2Cl_2/CH_3OH$ at $25^{\circ}C$ were determined by UV-VIS spectrometric titration. Stability constants of the CuL and ZnL complexes as log $\beta$ are 4.37 and 3.45, respectively. Stabilization energies for protonations of receptor L, derived from ab initio Hartree-Fock method with 6-31G basis set, are ${\Delta}E_1$ = -290.1, ${\Delta}E_2$ = -205.0, ${\Delta}E_3$ = -124.9 and ${\Delta}E_4$ = -26.9 kcal/mol and complexation energy of ZnL complex is -370.3 kcal/mol.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.192-192
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• 2011

Hyperthermal ion scattering experiments were conducted with low kinetic energy (<35 eV) cesium ion beams to analyze the UV-photolyzed water-ice films. Neutral molecules (X) on the surface were detected as cesium-molecule ion clusters ($CsX^+$) which were formed through a Reactive Ion Scattering (RIS) process. Ionic species on the surface were desorbed from the surface via a low energy sputtering (LES) process, and were analyzed [1]. Using these methods, the thermal stability of hydronium ion ($H_3O^+$) that was produced by UV light was examined. As the thermal stability of $H_3O^+$ is related with the reaction, $H_3O^+$ + OH + $e^-$ (or $OH^-$) ${\rightarrow}$ $2H_2O$, which is similar or same with the reverse reaction of the auto-ionization of water, the result from this work would be helpful to understand the auto-ionization of $H_2O$ in water-ice that has not been well-understood yet. However, as $H_3O^+$ was not detected through a LES method, the titration experiment of $H_3O^+$ with methylamine ($CH_3NH_2$, MA), MA + $H_3O^+\;{\rightarrow}\;MAH^+$ + $H_2O$, was conducted. In this case, the presence of $MAH^+$ indicates that of $H_3O^+$ in the ice. Thus the pristine ice was photolyzed with UV light for a few minutes and this photolyzed ice was remained at the certain temperature for minutes without UV light. Then MA was adsorbed on that surface so that the population of $H_3O^+$ was found. From the calibration experiments, the relation of $MAH^+$ and $H_3O^+$ was found, so that the thermal stability of $H_3O^+$ can be investigated [2].

• Bulletin of the Korean Chemical Society
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• v.31 no.2
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• pp.435-441
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• 2010

We report the preparation and characterization of a new and water soluble complex of palladium(II) with 1,10- phenanthroline and butyldithiocarbamate ligands. This compound has been studied through spectroscopic techniques, $^1H$ NMR, IR, electronic spectra and elemental analysis and conductivity measurements. The complex shows 50% cytotoxic concentration ($Ic_{50}$) value against chronic myelogenous leukemia cell line, K562, much lower than that of cisplatin. Thus the mode of binding of this complex to calf thymus DNA have been extensively investigated by isothermal titration UV-visible spectrophotometry, fluorescence, gel filteration and other methods. UV-visible studies show that the complex exhibits cooperative binding with DNA and remarkably denatures the DNA at extremely low concentration ($~13\;{\mu}M$). Fluorescence studies indicate that the complex intercalate into DNA. Gel filtration studies suggest that the binding of Pd(II) complex with DNA is strong enough that it does not readily break. In these interaction studies, several thermodynamic and binding parameters are also determined which may reflect the mechanism of action of this type of compound with DNA.

• Bulletin of the Korean Chemical Society
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• v.27 no.10
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• pp.1577-1580
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• 2006

The article reports the synthesis and enantiomeric recognition of a new chiral azophenolic pyridino-18-crown-6 ether, (S,S)-6, possessing diphenyl groups as chiral barriers. The association constants for the enantiomeric recognition of chiral primary amines (7-12) using chiral azophenolic pyridino-18-crown-6 ether, (S,S)-6, were determined by UV-visible titration method in acetonitrile at $25{^{\circ}C}$.

• Bulletin of the Korean Chemical Society
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• v.35 no.7
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• pp.2025-2028
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• 2014

Anion receptor 1 based on acylhydrazone has been designed and synthesized. UV-vis and $^1H$ NMR titration showed that receptor 1 is selective receptor for dihydrogen phosphate ($H_2PO_4{^-}$). Dihydrogen phosphate was complexed by the receptor 1 via at least 4 hydrogen bonding interactions, contributing from two amide N-Hs and two imine C-Hs. In addition, nitrogen in the aromatic ring could make 2 additional hydrogen bondings with OH groups in the dihydrogen phosphate. However, the receptor 1 could make only 4 hydrogen bonds with halides. Therefore, receptor 1 could bind anions through hydrogen bonds with a selectivity in the order of $H_2PO_4{^-}$ > $Br^-$ > $Cl^-$ in highly polar solvent such as DMSO.

• Bulletin of the Korean Chemical Society
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• v.30 no.12
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• pp.3025-3030
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• 2009

Novel poly(aspartic acid) derivatives conjugated with $\gamma$-amino butyric acid, GABA, moieties, and their amphiphilic analogs were synthesized and characterized. The chemical structures of these polymers were confirmed by FT-IR and $^1H$ NMR spectroscopy. Their physicochemical properties in aqueous media were characterized by electrophonetic light scattering spectrophotometry (ELS), acid-base titration, and UV-spectroscopy. In addition, the in vitro cell activity of the GABA-conjugated polymer was examined. These results indicated that GABA-conjugated poly(aspartic acid) derivatives showed cell-growth activity and nanoparticle formation of a suitable size within aqueous media. These polymers have potential application in the cosmetic and pharmaceutical fields.

• Bulletin of the Korean Chemical Society
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• v.22 no.2
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• pp.145-148
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• 2001

The interaction between tetradecyl trimethyl ammonium bromide (TTAB) with bovine ${\alpha}-lactalbumin$ has been investigated at pH = 9 and at $37^{\circ}C$ by isothermal titration calorimetry, equilibrium dialysis and UV-Vis spectrophotometry methods. The binding data from unusual Scatchard plot have been analyzed in terms of the Hill equation for three sets of binding sites. The calorimetric data show that TTAB interacts endothermically with ${\alpha}-lactalbumin$ and causes protein unfolding below 2 mM concentration of TTAB, which is confirmed by spectrophotometric data. The unfolding of the protein would be mainly due to occupation of the second set of binding sites.

• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2523-2528
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• 2014

In the present study, at first, azo Schiff base ligand of (N,N'-bis(5-phenylazosalicylaldehyde)-ethylenediamine) ($H_2L$) has been synthesized by condensation reaction of 5-phenylazosalicylaldehyde and ethylenediamine in 2:1 molar ratio, respectively. Then, its cobalt complex (CoL) was synthesized by reaction of $Co(OAc)_2{\cdot}4H_2O$ with ligand ($H_2L$) in 1:1 molar ratio in ethanol solvent. This ligand and its cobalt complex containing azo functional groups were characterized using elemental analysis, $^1H$-NMR, UV-vis and IR spectroscopies. Subsequently, the interaction between native calf thymus deoxyribonucleic acid (ct-DNA) and CoL complex was investigated in 10 mM Tris/HCl buffer solution, pH = 7 using UV-vis absorption, thermal denaturation technique and viscosity measurements. From spectrophotometric titration experiments, the binding constant of CoL complex with ct-DNA was found to be $(2.4{\pm}0.2){\times}10^4M^{-1}$. The thermodynamic parameters were calculated by van't Hoff equation.The enthalpy and entropy changes were $5753.94{\pm}172.66kcal/mol$ and $43.93{\pm}1.18cal/mol{\cdot}K$ at $25^{\circ}C$, respectively. Thermal denaturation experiments represent the increasing of melting temperature of ct-DNA (about $0.93^{\circ}C$) due to binding of CoL complex. The results indicate that the process is entropy-driven and suggest that hydrophobic interactions are the main driving force for the complex formation.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.39 no.2
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• pp.149-158
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• 2013

L-ascorbic acid, the representative antioxidants, has a great effect on skin whitening, collagen synthesis, and anti-aging, but has low oxidative stability during storage. Therefore, in this study, thermal and oxidation properties of L-ascorbic acid under various storage conditions (powder, aqueous phase, changes of temperature, UV-irradiation, and inflow of external air etc.) were investigated. And the storage stability of ingredient was validated in the double-spaced pouch by analysing oxidation properties under each storage conditions (powder phase and blended with essence). In oder to analyze the thermal properties, TGA, DSC, and FT-IR analysis were carried out and UV-visible spectrophotometer & redox titration were used in parallel for oxidation property analyses. From the result of experiment, L-ascorbic acid was oxidized fast when it contained lots of metallic ion, hydroxy ion in aqueous solution under high temperature, UV-irradiation & inflow external air, whereas it was not oxidized for a long time when it was stored as pure powder although it has same condition as heating up, UV-irradiation & inflow external air. Based on this result, retention period of cosmetics which is using L-ascorbic acid, less stable material in oxidation can be innovatively increased when using double-spaced pouch that is designed and produced for separating storage of active ingredients.

• Journal of the Korean Chemical Society
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• v.23 no.5
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• pp.320-324
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• 1979

Purple membrane from Halobacterium halobium was incorporated into 7.5% polyacrylamide gels. Absorption and circular dichroic spectra of purple membrane incorporated with gels were obtained at various pH. The spectra of these gels measured at pH 7.0 were essentially identical with those obtained in the aqueous suspension of purple membrane. Acid titration of the gels showed the transition to a form absorbing at 605nm $(bR_{605}^{acid}$) at pH 2.6, and to a second form at 565nm $(bR_{565}^{acid})$ at pH 0.8. Dark-adapted gels showed an isosbestic point for each transition whereas light-adapted gels did not. Visible CD spectra of $bR_{570}^{LA},\;bR_{305}^{acid}\;and\;bR_{565}^{acid}$ all showed the typical bilobed pattern. CD spectra measured at UV wavelength region were also independent of the variation of pH in terms of molar ellipticity and spectral shape. The protonated species $bR_{605}^{acid}$ may be one of the intermediates formed during the normal photochemical cycle of purple membrane. Most probably, the species $bR_{605}^{acid}$ is considered to be $O^{640}$ in the cycle.