• 분석과학
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• 제12권2호
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• pp.159-165
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• 1999

수용액에서 1,12-diaza-3,4:9,10-dibenzo-5,8-dioxacyclopentadecane(NTOE)가 결합된 merrifield 수지와 1,12,15-triaza-3,4:9,10-dibenzo-5,8-dioxacycloheptadecane(NDOE)가 결합된 merrifield 수지를 이용한 전이금속이온들의 흡착 및 분리특성을 조사하였다. 전이금속이온들의 흡착정도(adsorption degree, E)와 분포비(distribution ratio, D)의 순위는 동일하게 Cu(II)$t_R$)이 흡착정도와 분포비에 의해서 영향을 받았으며, 이러한 흡착 및 분리 실험 결과로부터 혼합금속용액에서 Ag(I)의 분리가능성을 확인할 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제30권11호
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• pp.2691-2696
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• 2009

Effects of representative group II and transition metal ions on the stability of the $poly(dA){\cdot}[poly(dT)]_2$ triplex were investigated by the van’t Hoff plot constructed from a thermal melting curve. The transition, $poly(dA){\cdot}[poly(dT)]_2\;{\rightarrow}\;poly(dA){\cdot}poly(dT)\;+\;poly(dT)$, was non-spontaneous with a positive Gibb’s free energy, endothermic (${\Delta}H^{\circ}$ > 0), and had a favorable entropy change (${\Delta}S^{\circ}$ > 0), as seen from the negative slope and positive y-intercept in the van’t Hoff plot. Therefore, the transition is driven by entropy change. The $Mg^{2+}$ ion was the most effective at stabilization of the triplex, with the effect decreasing in the order of $Mg^{2+}\;>\;Ca^{2+}\;>\;Sr^{2+}\;>\;Ba^{2+}$. A similar stabilization effect was found for the duplex to single strand transition: $poly(dA){\cdot}poly(dT)\;+\;poly(dT)\;→\;poly(dA)\;+\;2poly(dT)$, with a larger positive free energy. The transition metal ions, namely $Ni_{2+},\;Cu_{2+},\;and\;Zn_{2+}$, did not exhibit any effect on triplex stabilization, while showing little effect on duplex stabilization. The different effects on triplex stabilization between group II metal ions and the transition metal ions may be attributed to their difference in binding to DNA; transition metals are known to coordinate with DNA components, including phosphate groups, while group II metal ions conceivably bind DNA via electrostatic interactions. The $Cd_{2+}$ ion was an exception, effectively stabilizing the triplex and melting temperature of the third strand dissociation was higher than that observed in the presence of $Mg_{2+}$, even though it is in the same group with $Zn_{2+}$. The detailed behavior of the $Cd_{2+}$ ion is currently under investigation.

• Bulletin of the Korean Chemical Society
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• 제32권5호
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• pp.1685-1691
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• 2011

The molecular structures of thiacalix[4]biscrown-5 (1) and p-tert-butylthiacalix[4]biscrown-5 (2) and their alkali-metal-ion complexes were optimized using the DFT BLYP/6-31G(d) and mPW1PW91/6-31G(d,p) (hybrid HF-DF) calculations. The total electronic energies, the normal vibrational modes, and the Gibbs free energies of the mono- and di-topic complexes of each host with the sodium and potassium ions were analyzed. The $K^+$-complexes exhibited relatively stronger binding efficiencies than $Na^+$-complexes for both the monoand di-topic complexes of 1 and 2 comparing the efficiencies of the sodium and potassium complexes with an anisole and phenol. The mPW1PW91/6-31G(d,p) calculated distances between the oxygen atoms and the alkali metal ions were reported in the alkali-metal-ion complexes ($1{\cdot}Na^+$, $1{\cdot}2Na^+$, $1{\cdot}K^+$, $1{\cdot}2K^+$, $2{\cdot}Na^+$, $2{\cdot}Na^+$, $2{\cdot}K^+$, $2{\cdot}2K^+$). The BLYP/6-31G(d) calculated IR spectra of the host 1 and its mono-topic alkali-metal-ion complexes are compared.

• Bulletin of the Korean Chemical Society
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• 제12권2호
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• pp.130-137
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• 1991

The following new cryptand 221 complexes of lanthanides(Ⅲ) and dioxouranium(Ⅵ) nitrate have been synthesized: $(Ln(C_{16}H_{32}N_2O_5)(H_2O)_2(NO_3)_3\ and \((UO_2)_2(C_{16}H_{32}N_2O_5)(H_2O)_4(NO_3)_4$. These complexes have been identified by elemental analysis, moisture titration, conductivity measurements and various spectroscopic techniques. The proton and carbon-13 NMR as well as calorimetric measurements were used to study the interaction of cryptand 221 with La(Ⅲ), Pr(Ⅲ ), Ho(Ⅲ) and $UO_2(Ⅱ)$ ions in nonaqueous solvents. The bands of metal-oxygen atoms, metal-nitrogen atoms and O-U-O in the IR spectra shift upon complexation to lower frequencies, and the vibrational spectra ({\delta}NMN$) of metal-amide complexes in the crystalline state exhibit lattice vibrations below 300 $cm^{-1}$. The NMR spectra of the lanthanides(Ⅲ) and dioxouranium(Ⅵ) nitrate complexes in nonaqueous solvents are quite different, indicating that the ligand exists in different conformation, and also the $^1H$ and $^{13}C-NMR$ studies indicated that the nitrogen atom of the ring has greater affinity to metal ions than does the oxygen atom, and the planalities of the ring are lost by complexation with metal ions. Calorimetric measurements show that cryptand 221 forms more stable complexes with $La^{3+}$ and $Pr^{3+}$ ions than with $UO^{22+}$ ion, and $La^{3+}/Pr^{3+}$ and $UO^{22+}/Pr^{3+}$ selectivity depends on the solvents. These changes on the stabilities are dependent on the basicity of the ligand and the size of the metal ions. The absorption band (230-260 nm) of the complex which arises from the direct interaction of macrocyclic donor atoms with the metal ion is due to n-{\delta}*$ transition and also that (640-675 nm) of $UO^{22+}$-cryptand 221 complex, which arises from interaction between two-dioxouranium(Ⅵ) ions in being out of cavity of the ligand ring is due to d-d* transition.

• 대한전기학회논문지:시스템및제어부문D
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• 제52권5호
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• pp.213-213
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• 2003

We investigated the monolayer behavior at the air-water interface with metal solution, the surface morphologies and the electrical properties such as conductivity, The calculated conductivity values of pure water subphase and its complexes with L $i^{+}$ ions are 5.6$\times$10$^{-l6}$ and 1.9$\times$10$^{-14}$ [S/cm], respectively. And the calculated barrier height D values of pure water subphase and its complexes with Li. ions are 0.70 and 0.66 [eV], respectively. We also attempted to fabricate a crown dendrimer Langmuir-Blodgett (LB) films containing functional end group that could form a complex structure with metal ions. Also, we investigated the surface activity of dendrimer films at air-water interface. In AFM images. the larger domains irregularly shaped structures on the top while the smaller ones were free from such defects. In conclusion, it is demonstrated that the metal ion around dendrimer and polymer included crown function group can contribute to make formation of network structure among crown function group and result in change of electrical properties.s.s.

• Bulletin of the Korean Chemical Society
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• 제25권6호
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• pp.847-851
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• 2004

The complexation characteristics of tetramethyl (1) and tetraethyl esters (2) of p-tert-butylcalix[4]arene with alkali metal cations have been investigated by ab initio calculation. The structures of endo- or exocomplexation of the hosts in cone conformation with alkali metal ions have been optimized using HF/6-31G method followed by B3LYP/6-31G(d) single point calculation. B3LYP/6-31G(d) calculations suggest that exo-complexation efficiencies of sodium ion to the cavity of lower rim of hosts 1 and 2 are 27.1 and 25.8 kcal/mol better than that of potassium ion, respectively. The exo-complexation efficiencies of potassium ion to the cavity of lower rim of hosts 1 and 2 are 33.3 and 31.5 kcal/mol better than the endo-complexation inside the upper rim (four aromatic rings) as expected from the experimental results. B3LYP/6-31G(d) calculation of the ethyl ester 2 shows 29.5 and 30.8 kcal/mol better exo-complexation efficiency for both sodium and potassium ions than the methyl ester 1.

• Bulletin of the Korean Chemical Society
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• 제27권5호
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• pp.747-750
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• 2006

Research on tripodal complexes has grown in recent decades and has been subject of numerous reports.1-11 The reasons for this interest include their relevance to model functions of metalloenzymes1-3 and their potential applications in catalysis.13-17 The ligand system used most in this category has been tren, the tripodal tetraamine N(CH2CH2NH2)3, and its derivatives.4 The bz3tren is a versatile tetradentate ligand, known to form stable complexes not only with transition metals5-11 including Cu2+, Zn2+ and Co2+ but also anion species.12 However, only few results on the d10 metal complexes with bz3tren have been reported by us10 and others.6,7 As a part of on going efforts, we therefore focus our attention to extend other d10 system that includes heavy metal ions.

• 한국재료학회지
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• 제33권4호
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• pp.135-141
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• 2023

The volatilization of alkali ions in (K,Na)NbO₃ (KNN) ceramics was inhibited by doping them with alkaline earth metal ions. In addition, the grain growth behavior changed significantly as the sintering duration (t_s) increased. At 1,100 ℃, the volatilization of alkali ions in KNN ceramics was more suppressed when doped with alkaline earth metal ions with smaller ionic size. A Ca²⁺-doped KNN specimen with the least alkali ion volatilization exhibited a microstructure in which grain growth was completely suppressed, even under long-term sintering for t_s = 30 h. The grain growth in Sr²⁺-doped and Ba²⁺-doped KNN specimens was suppressed until t_s = 10 h. However, at t_s = 30 h, a heterogeneous microstructure with abnormal grains and small-sized matrix grains was observed. The size and number of abnormal grains and size distribution of matrix grains were considerably different between the Sr²⁺-doped and Ba²⁺-doped specimens. This microstructural diversity in KNN ceramics could be explained in terms of the crystal growth driving force required for two-dimensional nucleation, which was directly related to the number of vacancies in the material.

• Bulletin of the Korean Chemical Society
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• 제33권7호
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• pp.2299-2304
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• 2012

Two new metal(II) complexes, $[Mn(dpa)(phen)(H_2O)_2]_n$ (1) ($H_2dpa$ = dephenic acid, phen = 1,10-phenanthroline) and $[Ni_2(nda)(phen)_2(H_2O)_6](nda)(H_2O)$ (2) ($H_2nda$ = 2,6-naphthalenedicarboxylic acid) have been synthesized and characterized by elemental analysis, infrared spectroscopy, thermogravimetric analysis, and single crystal X-ray diffraction. In complex 1, Mn(II) ion is six-coordinated, and Mn(II) ions are bridged by dpa ligands into 1D chains. While, the complex 2 is dimer and two Ni(II) ions are bridged by one nda ligand cooperated with the terminal ligand phen. In each complex, the dicarboxylate ligand is coordinated to metal(II) ions as a bis-monodentate.

• Bulletin of the Korean Chemical Society
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• 제32권9호
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• pp.3223-3228
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• 2011

To quantify the presence of mercuric ions in aqueous solution, double-stranded DNA (dsDNA) of poly(dT) was employed using a light switch compound, $Ru(phen)_2(dppz)^{2+}$ (1) which is reported to intercalate into dsDNA of a right-handed B-form. Addition of mercuric ions induced the dehybridization of poly(dT)${\cdot}$poly(dA) duplexes to form a hairpin structure of poly(dT) at room temperature and the metal-to-ligand charge transfer emission derived from the intercalation of 1 was reduced due to the dehybridization of dsDNA. As the concentration of $Hg^{2+}$ was increased, the emission of 1 progressively decreased. This label-free emission method had a detection limit of 0.2 nM. Other metal ions, such as $K^+$, $Ag^+$, $Ca^{2+}$, $Mg^{2+}$, $Zn^{2+}$, $Mn^{2+}$, $Co^{2+}$, $Ni^{2+}$, $Cu^{2+}$, $Cd^{2+}$, $Cr^{3+}$, $Fe^{3+}$, had no significant effect on reducing emission. This emission method can differentiate matched and mismatched poly(dT) sequences based on the emission intensity of dsDNA.