• Bulletin of the Korean Chemical Society
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• 제32권5호
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• pp.1599-1603
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• 2011

Novel chemosensors based on 2-(2'-hydroxyphenyl)quinoline were prepared and evaluated for sensing metal cations. The photophysical properties of chemosensors 1-3 were examined and their ion-selectivity was evaluated by measuring their fluorescent emission responses to alkali, alkaline earth, and transition metal ions. Chemosensors 1, 2 and 3 show ratiometric and enhanced fluorescence changes with transitional metals that are efficient fluorescence quenchers, especially 3 has a high binding constant with $Hg^{+2}$ in $CH_3CN$.

• Bulletin of the Korean Chemical Society
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• 제29권3호
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• pp.567-570
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• 2008

A new pyrene appended diaza-18-crown-6 ether derivative 1 has been prepared and its fluoroionophoric properties toward transition metal ions were investigated. Compound 1 exhibited a high Hg2+-selectivity over other transition metal ions as well as alkali and alkaline earth metal ions in aqueous acetonitrile solution. The ratiometric analysis of the monomer and excimer emissions of pyrene successfully signals the presence of Hg2+ ions. The detection limit for Hg2+ ions was found to be 3.1 ´ 10-6 M in 50% aqueous acetonitrile solution at pH 8.1. Competition experiments also suggest that the compound could be utilized as a selective and sensitive fluorescent chemosensor for the analysis of micromolar Hg2+ ions in physiological and environmental samples.

• 한국세라믹학회지
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• 제45권7호
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• pp.375-379
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• 2008

Redox behavior was observed in alkali alkaline earth silicate PDP (Plasma Display Panel) glass melts doped with sulfate and sulfide by square wave voltammetry (SWV). According to voltammograms produced at a temperature range of 1100 to $1400^{\circ}C$ and frequency range of 5 to 1000 Hz, both melts showed the same behavior in which there is one reduction peak at low frequency but another peak at an increase of frequency. Based on the frequency dependence of the peak current, self diffusivity of $S^{4+}$ was determined. Based on the temperature dependence of the peak potential, standard enthalpy (${\Delta}H^0$) and standard entropy (${\Delta}S^0$) for the reduction of $S^{4+}$ to $S^0$ were calculated.

• Bulletin of the Korean Chemical Society
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• 제29권3호
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• pp.620-622
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• 2008

A new thiacalix[4]arene diamide (TCAm) has been prepared and its electrochemical property and complexation behavior toward various metal ions have been investigated by voltammetry. p-tert-Butylthiacalix[4]arene diamide (TCAm) exhibited selectivity toward Sr2+ ion over alkali, alkaline earth and transition metal ions while conventional calix[4]arene diamides showed selective binding property with Ca2+ ion. This is probably due to the bigger size of thiacalix[4]arene than those of calix[4]arene.

• 분석과학
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• 제18권6호
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• pp.491-494
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• 2005

The main component governing selectivity in ion-selective electrodes and optodes is the ionophore. For this reason, a member of natural products that possess selective ion-binding properties have long been sought after. By applying this principle, the performance of cyclosporin used as neutral carriers for calcium selective polymeric membrane electrode was investigated. The calcium ion-selective electrode based on cyclosporin gave a good Nernstian response of 26.6 mV per decade for calcium ion in the activity range $1{\times}10^{-6}M$ to $1{\times}10^{-2}M$. The optimized calcium ion-selective electrode displayed very comparable selectivity for $Ca^{2+}$ ion against alkali and alkaline earth metal ions, $Na^{2+}$, and $Mg^{2+}$ in particular.

• Bulletin of the Korean Chemical Society
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• 제19권2호
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• pp.207-211
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• 1998

Potentiometric characteristics of DOS plasticized PVC-based membranes containing upper-rim calix[4]crown neutral carrier to various metal cations and protonated alkylamines have been examined. Although the calix[4]crown-based membrane electrodes exhibited substantial emf responses to alkali and alkaline earth metal cations, their high detection limits (- log[Cs+]=4.5) and sub-Nernstian response slopes (48 mV/pCs+) to the most selective cation, cesium, indicate that the metal cation complexing ability of calix[4]crown is much weaker than that of macrocyclic crown ethers. However, the calix[4]crown-based membrane electrodes exhibited near-Nernstian response slopes (56 mV/decade for hexylNH3+) with low detection limits (log[hexylNH3+]= - 6.7) to most alkylammonium ions compared to those of blank (DOS plasticized PVC membrane with no ionophore) or crown ether-based membranes. While the selectivity patterns of blank and crown ether-based membranes are determined primarily by the lipophilicity of alkylammonium ions, the membranes doped with calix[4]crown ionophore could effectively discriminate the steric shapes of nonpolar alkyl groups of alkylammonium ions.

• 대한화학회지
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• 제13권2호
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• pp.137-140
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• 1969

This investigation was made to evaluate the corrosion inhibiting effects of urotropine for mild steel in HCl. 1) Formaldehyde produced by the decomposition of urotropine also showed positive inhibiting effects. 2) In the presence of the ions, such as $Cu^+$, $Cu^{++}$, $Fe^{+++}$, $SO_3^=$, $SO_4^=$, $NO_2^-$, $NO_3^-$, $Cr_2O_7^=$, the inhibiting capacity of the urotropine was decreased. Alkali and alkaline-earth metal ions had no effects but the halogen ions improved it. 3) From measurements of polarization curves, it was assumed that the anode reaction was more retarded by the urotropine and the halogen.

• Bulletin of the Korean Chemical Society
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• 제22권12호
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• pp.1345-1349
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• 2001

New quadruply-bridged calix[6]arenes (I-V) have been studied as cesium selective ionophores in poly(vinyl chloride) (PVC) membrane electrodes. PVC membranes were prepared with dioctyl sebacate (DOS) or 2-nitrophenyl octyl ether (o-NPOE) as the sol vent mediator and potassium tetrakis(p-chlorophenyl)borate as the lipophilic salt additive. These ionophores produced electrodes with near-Nernstian slope. The selectivity coefficients for cesium ion with respect to alkali, alkaline earth and ammonium ions have been determined. The lowest detection limit (logaCs+ = -6.3) and the higher selectivity coefficient (logkpotCs+,Rb+ = -2.1 by SSM, -2.3 by FIM for calix[6]arene I) for Cs+ have been obtained for membranes containing quadruply-bridged calix[6]arenes (I, Ⅱ, Ⅲ), which have no para t-butyl substituents on the bridging benzene ring.

• 방사성폐기물학회지
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• 제19권2호
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• pp.255-266
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• 2021

Solid-state mechanochemical reduction combined with subsequent melting consolidation was suggested as a technical option for the oxide reduction in pyroprocessing. Ni ingot was produced from NiO as a starting material through this technique while Li metal was used as a reducing agent. To determine the technical feasibility of this approach for pyroprocessing, which handles spent nuclear fuels, thermodynamic calculations of the phase stabilities of various metal oxides of U and other fission elements were made when several alkaline and alkali-earth metals were used as reducing agents. This technique is expected to be beneficial, not only for oxide reduction but also for other unit processes involved in pyroprocessing.

• 대한화학회지
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• 제27권2호
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• pp.127-132
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• 1983

톨루엔의 동종간 주고 받기 반응에 대한 ZSM-5 촉매의 활성은 양이온의 종류, 이온교환을 그리고 반응온도에 좌우된다. 활성은 알카리금속, 알카리토금속, 수소, 희토류 금속 이온이 교환되는 순서로 증가하며 이온 교환도가 증가함에 따라 감소한다. 이온 교환된 ZSM-5 촉매중에서 Cs-ZSM-5만이 p-크실렌에 대해 우세한 선택성을 나타내는데 p-크실렌에 대한 선택성은 세슘이온 교환율이 증가할 수록 반응온도가 감소 할수록 증가한다. 이러한 현상은 ZSM-5의 세공 교차점에 있는 세슘이온이 부분적으로 세공을 막아주는 형상 선택성으로 해석된다.