• Analytical Science and Technology
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• v.11 no.4
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• pp.231-234
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• 1998

Separation factor for $^6Li$ and $^7Li$ has been determined using ion exchange resin having 1,7,13-trioxa-4,10,16-triazacyclooctadecane ($N_3O_3$) as an anchor group. The ion exchange capacity of the $N_3O_3$ ion exchanger was 2.0 meq/g dry resin. The lighter isotope, $^6Li$, is concentrated in the fluid phase, while the heavier isotope, $^7Li$, is enriched in the resin phase. By column chromatography [0.3 cm(I.D)${\times}$30 cm (height)] using 3.0 M ammonium chloride solution as an eluent, single separation factor, ${\alpha}$, 1.018, i.e. $(^7Li/^6Li)_{resin}/(^7Li/^6Li)_{fluid}$ was obtained by the Glueckauf theory from the elution curve and isotope ratios.

• Journal of the Korean Chemical Society
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• v.36 no.5
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• pp.621-626
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• 1992

The effects of $Ca^{2+}$ ion on the charge transfer(CT) interaction of $4-(C_9H_{19})C_6H_4O(CH_2CH_2O)_{40} [NP-(EO)_{40}]$ with iodine in aqueous solution were investigated by UV-visible spectrophotometer. Maximum absorption wavelengths to the CT interaction were in the vicinity of 390 nm, and by the addition of $Ca^{2+}$ ion shifted toward 370 nm. Above CMC, the intensity of the CT interaction by the addition of $Ca^{2+}$ ion were increased and then decreased. The increase in the intensity of CT band were attributed to the increase of the donor-acceptor overlap with iodine caused by the compactness of micelle in the presence of $Ca^{2+}$ ion. These phenomena suggest that the linear oxyethylene(EO) chains, relatively free to assume various configuration in aqueous solution, could form a pseudo-crown ether structures capable of forming complexes with $Ca^{2+}$ ion.

• Journal of the Korean Chemical Society
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• v.38 no.3
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• pp.254-259
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• 1994

Five new crown ethers containing methyl groups were synthesized. 2,3,4,5: 9,10,11,12-Dibenzo-8,8-dimethyl-15,18,1-trioxacycloeicosane, 2,3,4,5: 9,10,11,12-dibenzo-8,8-dimethyl-15,18,21,1-tetraoxacyclotricosane, 2,3,4,5 : 9,10,11,12-dibenzo-8,8-dimethyl-15,18,21,24,1-pentaoxacyclohexacosane, 2,3,4,5 : 9,10,11,12 : 22,23,24,25 : 29,30,31,32-tetrabenzo-8,8,28,28-tetramethyl-15,18,21,35,38,1-hexaoxacyclotetracontane and 2,3,4,5 : 9,10,11,12 : 25,26,27,28:32,33,34,35-tetrabenzo-8,8,31,31-tetramethyl-15,18,21,24,38,41,44,1-octaoxacyclohexatetracontane were synthesized by reaction of 4,4'-isopropylidenediphenol with di-, tri-and tetraethyleneglycol ditosylate in the presence of MOH(M = Na, K). Di-, tri- and tetraethyleneglycol ditosylate were synthesized by reaction of p-toluenesulfonylchloride with diethyleneglycol, triethyleneglycol and tetraethyleneglycol in the presence of NaOH.

• Journal of the Korean Chemical Society
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• v.46 no.5
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• pp.412-429
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• 2002

Chiral separation of gemifloxacin, an quinolone antibacterial agent, using (+)-(18-crown-6)-tetracar-boxylic acid $(18C6H_4)$ as a chiral selector was performed by capillary electrophoresis (CE). Direct analysis of quinolone antibacterial agent in body fluid is beneficial in terms of fast analysis time, multicomponent analysis. However, high con-centration of sodium ion in body fluid can prevent gemifloxacin from interacting with $18C6H_4$ since sodium ion has high affinity with $18C6H_4$ due to the strong charge interaction. Ethylenediaminetetraacetic acid (EDTA), as a chelating ligand, was added in the running buffer in order to reduce the interaction between sodium ion and the chiral selector. Increased separation efficiency and reduced migration time were observed while sodium ion exists in the sample solution at the concentration up to 150 mM.

• Journal of the Korean Chemical Society
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• v.37 no.1
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• pp.36-42
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• 1993

In the presence of $Ca^{2+}$ ion, the charge transfer (CT) interaction of nonionic surfactants, $nonylphenol-(ethylene oxide)_n\;[NP-(EO)_n; n = 11, 40, 100]$ with iodine in aqueous solution were investigated by UV-visible spectrophotometer. The characteristics of spectra depended on the concentration of $Ca^{2+}$ ion and the number of EO unit. Above CMC, the intensity of the CT band by the addition of $Ca^{2+}$ ion for the $NP-(EO)_{11}$ and $NP-(EO)_{40}$ increased and then decreased, while for the $NP-(EO)_{100}$ continuously increased. The increase in the intensity of CT band were attributed to the compactness of micelle in the presence of $Ca^{2+}$ ion. These phenomena may be explained by the fact that the linear ethylene oxide (EO) chain, to be free configuration in aqueous solution, could form a pseudo-crown ether structures capable of forming complexes with $Ca^{2+}$ ion.

• Journal of the Korean Chemical Society
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• v.37 no.10
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• pp.855-860
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• 1993

In the presence of SDS(sodium dodecyl sulfate), effect of $Ca^{2+}$on the interaction of NP-40EO[nonylphenol-(ethylene oxide)40] with iodine in aqueous solution were investigated by UV-visible spectrophotometer. In the presence of SDS, the intensity of interaction peaks were decreased and markedly increased by the addition of $Ca^{2+}$. Decrease of interaction peaks is caused by decrease of EO number to be interact with iodine per unit surface area of mixed micelle to the insertion of SDS and increase is attributed to the compactness of micelle in the presence of $Ca^{2+}$. These phenomena may be explained by the fact that the linear EO (ethylene oxide) chains, to be free in aqueous solution, could form a pseudo-crown ether structures of forming with $Ca^{2+}$ion.

• Journal of the Korean Chemical Society
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• v.40 no.8
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• pp.557-564
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• 1996

FAB CAD MS/MS(Fast Atom Bombardment Collision Activated Dissociation Mass Spectrometry/Mass Spectrometry) was used to study different degree of bond stability according to the linkage positions of alkali cationized $(Na^+, Li^+, K^+, NH_4^+)$ stereoisomeric and synthetic oligosaccharides. The alkali metal cations were much more stable, requiring over -40 eV of collision energy vs. only -10 eV for the protonated forms. Of the cations, the potassium cationized trisaccharides were more stable than the others. They would not yield fragment ions under the conditions of collision available in triple quadrupole. Other cationized species exhibited decreasing stability in the series $Nap^+>Li^+>NH_4^+$ using 0.8 mTorr argon pressure in the collision cell. Metal cations of the oligosaccharides maintained charge principally on the amino sugar as shown by shift of all the fragment ions containing the amino sugar. The reason for the higher stability of the metal cationized form is the formation of crown ether-like bond around metal cations, N-acetyl group on GlcNAc and oxygens on fucose moiety. Depending on the metal sizes and the conformation of linkage-isomeric region, cationized species gave linkage dependent fragment patterns and exhibited stability in the series 1-6 > 1-4 > 1-3 linkage.

• Journal of the Korean Chemical Society
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• v.32 no.1
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• pp.53-59
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• 1988

Recently, the formation of the complexes between macrocyclic polyethers and alkali metal salts have been determined by several methods. It has been suggested that the specificity of the complexation be due to the nature of the surrounding solvent molecules. The formation constant values ($K_f$) of $K^+$ are shown to be the largest among the other alkali metal cations because the ionic diameter of $K^+$ is approximately the same with the hole size of 18-crown-6. In this study the formation constants of the 1 : 1 complexes of 18-crown-6 with potassium p-substituted phenoxide are calculated by the conductance measurement in organic solvents. As a result, the $K_f$ value series among organic solvents are given in the order of $CH_3$OH > DMF > DMSO. It seems that the donor number of the solvent is a main factor in the formation of the complex between $K^+$ metal ion and 18-crown-6 molecules. At the same time, the formation constants increase with increasing the electron-withdrawing power of substituents because the phenoxide ion is stabilized by the charge dispersion.

• Journal of the Korean Chemical Society
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• v.32 no.5
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• pp.443-451
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• 1988

New crown ether dye-Ⅰ and dye-Ⅱ having an azo group(-N=N-) were synthesized from monobenzo-15-crown-5 and dibenzo-18-crown-6. These dyes showed ${\lambda}_{max}$ of 377 and 383nm respectively. The complexes of alkali metal ions ($Na^+$, $K^+$, $Cs^+$) with dye ligands showed band shift (390~400nm) and intensity increased. For a given anion, the extraction constants are in the order of $K^+$ < $Cs^+$ < $Na^+$ for dye-Ⅰ and $Cs^+$ < $Na^+$ < $K^+$ for dye-Ⅱ. These results show that the selectivity of crown ethers toward the alkali metal ions is dependant on the charge density of cation and the size of crown ether cavity. For a given cation, the order of the extraction constant is $Cl^-$ < $Br^-$ < $I^-$ < picrate. This order coincides with the degree of anion solvation effect.

• Journal of the Korean Chemical Society
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• v.41 no.7
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• pp.337-342
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• 1997

Acryloylmethylbenzo-15-crown-5 was prepared from the reaction of 4'-hydroxymethylbenzo-15-crown-5 with acryloyl chloride. And, poly(acryloylmethylbenzo-15-crown-5) [poly(AMB15C5)] was synthesized by radical polymerization using AIBN as initiator in benzene. Coated wire lead(II) ion-selective electrodes ($Pb^{2+}$-CWISEs) using either poly(AMB15C5) or B15C5 as neutral carrier were prepared, respectively. $Pb^{2+}$-CWISEs gave linear responses with slopes of 28$\pm$ 1mV per decade within the concentration range of $10^{-5} M{\sim}10^{-1}$ M, respectively. Also, the detection limits were $10^{-6}$ M and response times were either 3 or 5 min. for B15C5 and poly(AMB15C5), respectively. $Pb^{2+}$-CWISE base on B15C5 was rather unstable than poly(AMB15C5)'s due to solubility of the B15C5 in water. The selectivity coefficients of a variety of interfering ions such as $Mg^{2+},\; Ca^{2+},\; Co^{2+},\; Ni^{2+},\; Cu^{2+},\; Zn^{2+}$ and $Cd^{2+}$ were small ($10^{-4}{\sim}10^{-5}$), while those of $Na^+$ and $K^+$ were large (0.1∼0.01). In addition, the electrode responses depended upon the pH of test solution and the composition of the membrane. In the range pH 3∼6 of test solution, potentials of Pb2+-CWISEs were hardly changed. The optimal contents of B15C5 and poly(AMB15C5) were 7.7 wt% and 13.1 wt%, respectively.