• 한국환경과학회지
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• 제5권2호
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• pp.211-220
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• 1996

두 개의 황과 셀렌의 주개원자를 포함한 새로운 thia 및 diselena 크라운에데르 화합물을 합성하였다. 그리고 이 화합들을 중성운반체로 하고 PVC-가소제 (STPB)를 포함한 Hg(ll) 선택성 전극을 제작하였다. 이 전극들을 이용하여 여러 이온들의 전기화학적 선택성, 중성운반체의 종류 및 농도와 선택막의 매질에 대한 효과 그리고 실험용액의 pH변화에 대한 전극의 선택적 감응성들의 영향을 각각 검토하였다. 1,10-diselena-18-crown-6-PVC-STPB의 중성운반체의 막전극은 $10^{-2}$-10- M $Hg^{2+}$ 이온의 농도범위에서 ${28.2}\pm{0.6}$의 Nernstian 기울기를 갖는 좋은 선형적 감응성을 갖는다. 그리고 이 전극은 pH 2.5~6.0 범 위에서 알칼리토 금속, 몇가지 중금속 및 희토류 금속 이온에 대하여 좋은 선택성을 갖는다. 특히 이 전극은 수용액 중에서.$1^-$ 이온으로 Hg^{2-}$ 이온을 전위차 적정할 수 있는 센서로서 응용할 수 있다.

• Bulletin of the Korean Chemical Society
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• 제23권5호
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• pp.688-692
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• 2002

The aminomethylation of phenols with para-substituents by the Mannich reaction has successfully been accomplished to produce the Mannich bases 2-6. The compounds 7-8 have also been synthesized in order to identify the effect of the side arms and t he macrocycle in the complex formation. Protonation constants and stability constants of the double armed diaza-18-crown-6 ethers 2-7 with metal ions have been determined by potentiometric method at 25 $^{\circ}C$ in 95 % methanol solution. Under a basic condition (pH > 8.0), the double-armed crown ethers 2-6 revealed stronger interaction with divalent metal ions than the simple diazacrown ether 1. The stability constants with these metal ions were Co 2+ < Ni2+ < Cu2+ > Zn 2+ in increasing order, which are in accordance with the order of the Williams-Irving series. The stability constants with alkali earth metal ions were Ca 2+ < Sr 2+ < Ba 2+ in increasing order, which may be explained by the concept of size effect. It is noteworthy that the hosts 2-6, which have phenolic side arms and a macrocycle, bind stronger with metal ions than the hosts 1 and 7. On the other hand, the host 8, which has phenolic side arms with a pyperazine ring,provided comparable stability constants to those with the host 3. These facts demonstrate that phenolic side arms play a more important role than the azacrown ether ring in the process of making a complex with metal ions especially in a basic condition. In particular, the log KML values for complexation of divalent metal ions with the hosts 2-6 had the sequence, i.e., 2 (R=OCH3) < 3 (R=CH3) < 4 (R=H) < 5 (R=Cl) < 6 (R=CF3). The stability constants of the hosts 5 and 6 containing an electron-withdrawing group are larger than those of the hosts 2 and 3 containing an electron-donating group. This substituent effect is attributed to the solvent effect in which the aryl oxide with an electron-donating group has a tendency to be tied strongly with protic solvents.

• Bulletin of the Korean Chemical Society
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• 제27권5호
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• pp.713-717
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• 2006

$S_2O$-donor macrocyclic isomers incorporating a xylyl group in o- ($L^1$), m- ($L^2$) and p-positions ($L^3$) extract no metal ions except silver(I) from aqueous to chloroform phase. And the magnitudes of %Ex for silver(I) are in the order of $L^1$ > $L^2$ > $L^3$. Taking this result into account, $L^1$-$L^3$ were utilized as membrane active components to prepare potentiometric silver(I)-selective electrodes. The proposed macrocycles-based electrodes E1 ($L^1$), E2 ($L^2$) and E3 ($L^3$) exhibited comparable results which show considerable selectivity toward silver(I) over alkali, alkali earth and other transition metal ions. Comparative NMR study on $L^1$-$L^3$ and their complexes with silver(I) in solution was also accomplished. In addition, a unique sandwich-type complex $[Ag(L^1)_2]CIO_4$ was prepared from the assembly reaction of $L^1$ with $AgClO_4$ and structurally characterized by an X-ray diffraction analysis.

• Bulletin of the Korean Chemical Society
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• 제32권11호
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• pp.3959-3962
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• 2011

A simple propargylamide-fuctionalized chemodosimeter was prepared for the ratiometric fluorescence detection of mercuric ions in HEPES buffer. The chemodosimeter exhibited $Hg^{2+}$-induced propargyl amide-tooxazole transformation, with a significant accompanying ratiometric change in fluorescence. It afforded high selectivity for mercuric ion detection without any competitive inhibition by common alkali, alkaline earth, or other transition metal ions. The probe showed a $17{\times}10^{-6}M$ detection limit for $Hg^{2+}$ ions and potential applicability for detecting aqueous $Hg^{2+}$ 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.

• 자원환경지질
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• 제31권5호
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• pp.365-374
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• 1998

Economic U- and Th-bearing pegmatite deposits occur in the Kyemyeongsan Formation, and are spatially closely associated with the Carboniferous alkali granite. The pegmatite is lithochemically alkaline and peralumious, and consists mainly of potassic feldspar and quartz with allanite and U- and Th-bearing minerals. Paragenetic stages of mineralization in the pegmatite are divided as follows: early silicate mineralization, main rare metal mineralization, and late silicate mineralization. Thorite, euxenite, fergusonite and uranpyrochlore are the predominant U- and Th-bearing minerals. Both the enrichments of Nb, Y, Th, U, and Ta and the depletions of Hf, Ba, and Rb in the pegmatite were resulted from magmatic differentiation. The increases of Na and Ca in uranpyrochlore, of Th and U in fergusonite, of Si, Th, U and Pb in thorite, and of Nb and Y in euxenite were possibly resulted from both later internal fractionation and hydrothermal alteration. The variation of chemical composition in a mineral species reflects the different pysico-chemical conditions during the crystallization.

• 대한화학회지
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• 제19권3호
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• pp.193-197
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• 1975

無煙炭의 燃燒에 있어서 $SO_2 가스의 發生을 抑制하기 위하여 小量의 알칼리 혹은 알칼리 土金屬의 水酸化物을 添加 시키는 것이 效果的이라는 것을 알았다. 그것은 燃燒時에 無煙炭中의 黃分의 大部分이 黃化物 혹은 黃酸鹽의 形態로 炭分中에 固着되기 때문이라고 생각된다. $1000^{\circ}C$로 加熱할 때는 添加劑를 가한 無煙炭中의 黃分의 약 20%가 SO_2$ 가스로 發生한다.

• 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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• 제29권5호
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• pp.969-973
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• 2008

Solvent extraction using a Schiff-base, salen$(NEt_2)_2$, as a chelating agent has been conducted on several water samples to study the determination of trace Cu(II), Mn(II) and Zn(II). Experimental conditions for the formation and extraction of metal complexes were optimized with an aqueous solution similar in composition to the samples. The matrix difference between the sample and standard solutions was approximately matched, and the pH of each sample solution was adjusted to 9.5 with $NaHCO_3/NaOH$ buffer. The concentration of salen$(NEt_2)_2$ was $7.3\;{\times}\;10^{-3}$ mol/L, and the complexes were extracted into MIBK solvent followed by the measurement of AAS absorbance. The potential interference of concomitant ions was investigated, but no interference from alkaline and alkali earth ions was shown in this procedure. The given procedure is precise, as judged from the relative standard deviation of less than 5% for five measured data. The recovery of 93-103% shows that this method is quantitative for such trace metal analysis.

• Bulletin of the Korean Chemical Society
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• 제26권6호
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• pp.882-886
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• 2005

Copper(II) ion-selective PVC membrane electrode based on 2-mercaptobenzoxazole as a new ionophore and o-nitrophenyl octyl ether (o-NPOE) as plasticizer is proposed. This electrode revealed good selectivity for $Cu^{2+}$ over a wide variety of other metal ions. Effects of experimental parameters such as membrane composition, nature and amount of plasticizer, and concentration of internal solution on the potential response of $Cu^{2+}$ sensor were investigated. The electrode exhibits good response for $Cu^{2+}$ in a wide linear range of 5.0 ${\times}$ 10−.6-1.6 ${\times}$ $10^{-2}$ mol/L with a slope of 29.2 ${\pm}$ 2.0 mV/decade. The response time of the sensor is less than 10 s, and the detection limit is 2.0 ${\times}$ $10^{-6}$ mol/L. The electrode response was stable in pH range of 4-6. The lifetime of the electrode was about 2 months. The electrode revealed comparatively good selectivities with respect to many alkali, alkaline earth, and transition metal ions.