• Journal of the Korean Chemical Society
• /
• v.28 no.6
• /
• pp.355-360
• /
• 1984

A new absorption spectrum observed from dilute aqueous solutions of methylene blue$(MB^+)$ and tetraphenylborate(TPB$^-$) ions was investigated by spectrophotometry. The species responsible for the spectrum can be a charge-transfer complex formed between the two, univalent, and poorly hydrated ions in order to minimize the disturbance to the water structure. However, as the absorption band of MB$^+$ is split into two bands with exciton splitting of about 2,000 cm$^{-1}$, the formation of double ion-pair, (MB-TPB)$_2$ appears to be more favorable than the charge transfer complex.

• Archives of Pharmacal Research
• /
• v.19 no.6
• /
• pp.435-440
• /
• 1996

The effect of benzalkonium chloride on skin permeability of partially modified antisense phosphorothioate oligonucleotides (PS-ODN), which are designed as scar formation inhibitor, was investigated using Franz Diffusion Cell. When the concentration ratio of PS-ODN-quarternary ammonium salt complex is more than 1:100, the apparent partition coefficient (APC) of each complex was increased in the following order; tetraphenyl phosphonium chloride (TPP) < cetyltrimethyl ammonium bromide(CTAB) < benzalkonium chloride (BZ). The permeability of PS-ODN through the rat skin increased in the presence of BZ. The fluxs of PS-ODN with BZ were increased by addition of Pluronic F 68 or Triton X-100 to phosphate buffered saline (PBS), respectively. When the mole ratio of PS-ODN to BZ is 1:10, the fluxs penetrated of PS-ODN with BZ was greatest. The increase of the permeability in the presence of BZ might be due to the formation of lipophilic ion-pair complex between PS-ODN and BZ. By regulation of mole ratio of PS-ODN to BZ, the development of topical dosage forms using PS-ODN as scar formation inhibitor will be possible with minimal systemic exposure.

• Journal of the Korean Chemical Society
• /
• v.37 no.9
• /
• pp.793-799
• /
• 1993

Ion-pair model was predominated over ion-interaction model in the retention mechanism of analytes when tetramethylammonium bromide (TMAB) was used as a counter-ion in the investigation of aromatic sulfonic acids on the reversed-phase liquid chromatography by $C_{18}$ column as a stationary phase. The capacity factors of analytes were influenced by the type and concentration of counter-ions, concentrations of methanol and co-anion, types and position of functional group, and the pH mobile phase. Components of analyte mixture could be separated under the optimum conditions by this method.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.8
• /
• pp.2722-2726
• /
• 2011

Plasticized poly(vinyl chloride), PVCs, with different membrane compositions tested for use in the construction of an ion-selective sensor for the determination dibucaine. A prepared membrane with dioctyl phthalate-PVC and ion-pair of N-(1-naphthyl)ethylenediamine dihydrochloride-tetraphenyl borate had a good potential to acts as a potentiometric sensor for the analysis of dibucaine. A linear relationship was obtained between potential and logC varying between $1.0{\times}10^{-6}$ and $1.0{\times}10^{-2}$ M dibucaine with a good repeatability and reproducibility. The sensor was applied for the determination of the drug in pharmaceuticals and biological fluids such as plasma and urine samples with satisfactory results. The drug electrode has also been used to study the interaction of bovine serum albumin (BSA) with dibucaine. The saturated quantities of dibucaine binding were 13.04, 5.30 and 9.70 mol/mol in 0.01, 0.02 and 0.1% of protein, respectively.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.9
• /
• pp.2571-2574
• /
• 2010

We investigate the mechanism of $S_NAr$ fluorination reactions under the influence of protic solvents and ions. We find that counterion or protic solvent alone retards the $S_NAr$ reactions, but together they may promote the reaction. In this mechanism, the protic solvent acts on the counterion as a Lewis base, and the nucleophile reacts as an ion pair. We also show that an anion (mesylate) may exhibit catalytic effects, suggesting the role of ionic liquids for accelerating the $S_NAr$ reactions.

• Proceedings of the PSK Conference
• /
• 2002.10a
• /
• pp.313.2-313.2
• /
• 2002

Environmentally benign protein staining method in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) using both an acidic dye, zincon (ZC) and a basic dye. ethyl violet (EV) is described. It is based on a counter ion-dye staining technique that employs oppositely charged two dyes to form an ion-pair complex. The selective binding of the free dye molecules to proteins in an acidic solution produces bluish violet colored bands. It is a rapid procedure, involving only fixin and staining steps that are completed in 45 min. (omitted)

• Electrical & Electronic Materials
• /
• v.7 no.2
• /
• pp.100-106
• /
• 1994

A bilayer film consisting of a layer of a-Se$_{75}$ Ge$_{25}$ with a surface layer of silver -100[.angs.] thick and a monolayer film of a-Se$_{75}$ Ge$_{25}$ are irradiated with 9[keV] Ga$^{+}$ ion beam. The Ga$^{+}$ ion (10$^{16}$ [ions/cm$^{2}$] exposed a-Se$_{75}$ Ge$_{25}$ and Ag/a-Se$_{75}$ Ge$_{25}$ thin films show an increase in optical absorption, and the absorption edge on irradiation with shifts toward longer wavelength. The shift toward longer wavelength called a "darkening effect" is observed also in film exposure to optical radiation(4.5*10$^{20}$ [photons/cm$^{2}$]). The 0.3[eV] edge shift for ion irradiation films is about twice to that obtained on irradiation with photons. These large changes are primarily due to structural changes, which lead to high etch selectivity and high sensitivity.

• Analytical Science and Technology
• /
• v.10 no.4
• /
• pp.231-239
• /
• 1997

We developed a procedure that can effectively separate and determine tertiary amines and quaternary ammonium salts in some samples with reverse phase ion-pair high performance chromatography, employing indirect spectrophotometric detection method. Detection and ion-pairing reagents used in this study were benzyl trimethylammonium chloride (BTMACl) and sodium dodecyl sulfate(DDSANa), respectively. Eluting the electrolyte solutions of some commercial electrolytic capacitors with a MeOH(40):water(60) eluent (pH 8.5 adjusted with NH4Cl-NH3 buffer) containing 0.010M DDSANa and 0.004 M BTMACl through Supelco LC-18 or ${\mu}$-Bondapak phenyl column, amines and ammonium salts contained in the sample were successfully separated and determined. Varying the composition, especially the content of quaternary ammonium salts, of electrolyte solutions based on this analysis. we could prepare the low impedance(0.08~0.13) electrolytic capacitors with excellent electrical properties and it was a confirmation that the analysis is favorable.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.9
• /
• pp.2483-2487
• /
• 2010

Pseudo-first-order rate constants ($k_{obsd}$) were measured spectrophotometrically for nucleophilic substitution reactions of 4-nitrophenyl picolinate (6) with alkali metal ethoxides (EtOM, $M^+\;=\;K^+$, $Na^+$ and $Li^+$) in anhydrous ethanol at $25.0{\pm}0.1^{\circ}C$. The plot of $k_{obsd}$ vs. [EtOM] exhibits upward curvature regardless of the nature of $M^+$ ions. However, the plot for the reaction of 6 with EtOK is linear with significantly decreased $k_{obsd}$ values when 18-crown-6-ether (18C6, a complexing agent for $K^+$ ion) is added in the reaction medium. Dissection of $k_{obsd}$ into $k_{EtO^-}$ and $k_{EtOM}$ (i.e., the second-order rate constant for the reaction with dissociated $EtO^-$ and ion-paired EtOM, respectively) has revealed that ion-paired EtOM is 3~17 times more reactive than dissociated $EtO^-$. The reaction has been proposed to proceed through a 5-membered cyclic transition state, in which $M^+$ ion increases the electrophilicity of the reaction site. Interestingly, $Na^+$ ion exhibits the largest catalytic effect. The presence of a nitrogen atom in the pyridine moiety of 6 has been suggested to be responsible for the high $Na^+$ ion selectivity.

• Bulletin of the Korean Chemical Society
• /
• v.22 no.7
• /
• pp.669-672
• /
• 2001

Pseudo-first-order rate constants have been measured spectrophotometrically for the title reactions. The plot of kobs vs the concentration of alkali metal ethoxides is linear for the reactions performed in the presence of complexing age nt, 18-crown-6 ether, but curved upwardly for the corresponding reactions performed in the absence of the complexing agent, indicating that the alkali metal ions studied in this study behave as a catalyst. The catalytic effect was found to increase in the order Li+ << K+ ${\leq}$ Na+. Second-order rate constants were determined for the reactions with dissociated free ethoxide (kEtO-) and with ion paired alkali metal ethoxides (kEtO-M+ ) from ion pairing treatments. The magnitude of catalytic effect (kEtO-M+/kEtO-) was found to be 2.3, 9.5 and 8.7 for the reaction of 8-(5-nitroquinolyl) 2-furoate, while 1.4, 3.6 and 4.2 for that of 4-nitrophenyl 2-furoate, indicating that the catalytic effect is larger in the reaction of the former substrate than in that of the latter one. The larger catalytic effect was attributed to two possible complexing sites with alkali metal ions in the former substrate.