• Journal of Photoscience
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• v.8 no.1
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• pp.33-37
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• 2001

Picosecond absorption spectroscopy has been employed in the study of the solvent dynamics of 1, 2, 4, 5-tetracyanobenzene/biphenyl derivative radical ion pairs, and the resulting rates of radical ion pair separation are faster in acetonitrile than in dichloromethane. In an effort to account quantitatively for such solvent effect on the rate of radical ion pair separation, an equation for the rate of radical ion pair separation is introduced, in which the rate depends exponentially on the electrostatic interaction energy in the radical ion pair. In our analysis of the types of electrostatic interaction energy based on the conducting spheres in dielectric continuum was chosen, and the rate equation employing this electrostatic energy provided information on the distance on the distance of radical ion pair separation and solvation energy of the radical ion pair, thereby providing quantitative explanation for the observed solvent effect on the rate of radical ion pair sepaaration.

• Mass Spectrometry Letters
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• v.1 no.1
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• pp.9-12
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• 2010

Trimethylboroxine (TMB) is a six-membered ring compound containing Lewis acidic boron and Lewis basic oxygen atoms that can bind halide anion and alkali metal cation, respectively. We employed Fourier transform ion cyclotron resonance spectroscopy to study the gas-phase binding of $LiBrLi^+$ and $F^-(KF)_2$ to TMB. TMB forms association complexes with both $LiBrLi^+$ and $F^-(KF)_2$ at room temperature, providing direct evidence for the ditopic binding. Interestingly, the $TMB{\cdot}F^-(KF)_2$ anion complex is formed 33 times faster than the $TMB{\cdot}Li^+BrLi$ cation complex. To gain insight into the ditopic binding of an ion pair, we examined the structures and energetics of $TMB{\cdot}Li^+$, $TMB{\cdot}F^-$, $TMB{\cdot}LiF$ (the contact ion pair), and $Li^+{\cdot}TMB{\cdot}F^-$ (the separated ion pair) using Hartree-Fock and density functional theory. Theory suggests that $F^-$ binds more strongly to TMB than $Li^+$ and the contact ion-pair binding ($TMB{\cdot}LiF$) is more stable than the separated ion-pair binding ($Li^+{\cdot}TMB{\cdot}F^-$).

• Bulletin of the Korean Chemical Society
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• v.9 no.4
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• pp.209-212
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• 1988

The hydrophobic interaction leading to the formation of ion-pair between $MB^+$ and $TPB^-$ was investigated spectroscopically by varying the medium with the addition of 1,A-dioxane or urea. Beyond 0.01 mole fraction of 1,A-dioxane in water or above 2.0M urea the ion-pair appeared to be completely dissociated into individual ions. The ion-pair was not observed in common organic solvents and the absorption maxima of $MB^+$ were correlated relatively well with the ${\pi}^{\ast}$-scale.

• Archives of Pharmacal Research
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• v.13 no.2
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• pp.174-179
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• 1990

Second derivative (D2) spectrometry using ion-pair extraction technique was development for the determination of total glycyrrhetic acid (GA) in Glycyrrhizae Radix, Glycyr-rhizin (G) obtained from Glycyrrhizae Radix was hydrolyzed into GA in 2 N-HCI and methanol (1:1) and extracted from aqueous phase in the form of an ion-pair complex with tetrapentylammonium bromide (TPA) as a counter ion. Maximum D2 amplitude (Z value) was obtained when 1000-fold or greater molar ratio of TPA was used at pH 11. Reaction an effective extraction solvent of the ion-pair complex. The linearity of standard curve of ion-pair GA was obtained in the range of 4.120 $\mu$g/ml as GA. Assayed contents of GA in dry powder by D2 UV spectrometry and HPLC method were 5.31 $\pm$ 0.04% and 5.20 $\pm$ 0.008%, respectively.

• YAKHAK HOEJI
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• v.35 no.3
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• pp.182-189
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• 1991

Systematic study on the extraction of ion pair by the use of picric acid (PCA) as an ion pair forming reagent to the aliphatic amines has not be done by spectrophotometric method. The extraction of ion pair by the use of PCA and 23 kinds of the aliphatic amines was examined. The procedure is as follows; Elving's buffer solution (pH 1.3~10, ionic strength 0.5) each amine solution, and PCA solution were taken into a test tube. The mixture was shaken mechanically with chlorform. The organic phase was filtered through a filter paper to remove water droplets. The absorbance was examined at $\lambda_{max}$ against a reagent blank. Primary and secondary whose carbon number were more than 7 or 6, respectively, are extractable as ion pairs with PCA, while tertiary amines and quaternary ammonium salts are also extractable without the correlation of carbon number. It was considered that the ion pair extraction of primary and secondary amines was affected by the number of carbon of amines, but its extraction of tertiary amines or quaternary ammonium salts was affected by kind of aliphatic amines rather than pKa values or carbon number of amines.

• Bulletin of the Korean Chemical Society
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• v.21 no.1
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• pp.9-22
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• 2000

Optical-optical double resonance experiments have been used to identify and characterize five ion-pair states and several of the bound and repulsive valence states of ClF. This report provides a description of these experiments for $^{35}CIF$ and $^{37}CIF$, and a summary of the current knowledge of the valence and ion-pair states. The important role of perturbations among the rovibronic levels of the bound valence states and their utilization in the double resonance technique is discussed. The ion-pair states of the same symmetry, ${\Omega}$=$0^+$ (E and f) and 1( $\beta$ and G) interact very strongly and the spectroscopy of these states is anomalous and, hence, interesting. Comparison is made to some recent ab initio calculations for ClF. One possible explanation of the irregular vibrational energy levels and rotational constants of the ion-pair states of $O^+$ and 1 symmetry is a crossing of the diabatic potentials of these states. Some currently unresolved questions about ClF spectroscopy are posed for future work. Where appropriate, analogy is made between the electronic states of ClF and the corresponding valence and ion-pair states of $Cl_2.$.

• Journal of the Korean Chemical Society
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• v.14 no.1
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• pp.13-18
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• 1970

非水溶液 Ethylenediamine 中에서 水銀電極의 標準電位 및 水銀鹽化物, $HgCl_2,\;HgBr_2,\;HgI_2$의 Ion-Pair 形成恒數를, Hg電極/$HgX_2$ 또는 $HgX_2$+NaX//亞鉛아마르감 參照電極과 같은 Cell의 構成으로서 電位差法에 依하여 測定하였다.

• Bulletin of the Korean Chemical Society
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• v.6 no.3
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• pp.149-152
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• 1985

Spectrophotometric and spectrofluorimetric methods of analysis were conducted in dilute aqueous solutions of methylene blue and tetraphenylborate. The formation of double ion-pair was confirmed and its overall formation constant, ${\Delta}H^{\circ}$, and ${\Delta}S^{\circ}$ were obtained. The irradiation with wavelengths over visible region resulted in bleaching the mixed solution. The bleaching reaction was also proceeded at $55^{\circ}C$. The reactions of the double ion-pair were briefly discussed.

• Journal of Pharmaceutical Investigation
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• v.4 no.1_2
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• pp.46-54
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• 1974

A new spectrophotemetric method was estalished for the determination of oleic acid. This method is based on the 1,2-dichloroe-thane extraction of the ion-pair formed between methylene blue and oleic acid. But the absorbance of an ion-pair in the 1,2-dichloroe-thane layer was variable with the temperature, the ion-pair was extracted back into a diluted hydrochloric acid solution. The maximum absorbance of the acid extract observed at $660m{\mu}$ and a lineal relationship was observed from the initial amount over the range of $50-800{\gamma}/ml$ of oleic acid in the aqueous phase. The composition ratio of the ion-pair formed between methylene blue and oleic acid was determined to be 2 : 1 by both the mole ratio and continuous variation methods.

• Polymer(Korea)
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• v.24 no.6
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• pp.802-809
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• 2000

Counterion-specific helix formation and ion-selective transport of alkali metal chlorides (LiCl, NaCl, KCl, CsCl) were investigated for a poly(L-glutamic acid)(PLGA)/poly (vinyl alcohol)(PVA) blend membrane immersed in aqueous ethanol. The counterion specificity for helix formation of PLG alkali metal salts in the membrane was Li>Na>K>Cs. This specificity is ascribed to a contact ion-pair formation between the PLG carboxyl anion and the bound counterion, which depends on the energy balance between the electrostatic interaction and the desolvation. In aqueous ethanol, an appreciable ion-selectivity was observed for the permeability coefficient, i.e. Li$^{+}{\cdot}$Cl$^{-}$) formation between counterion and coion, and the latter to a specific interaction of diffusing counterions with polymer charges.