• Journal of Microbiology and Biotechnology
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• v.3 no.3
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• pp.161-167
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• 1993

Immobilized metal ion affinity chromatography (IMAC) was used to separate various types of recombinant hirudins from the culture broth. The wild type hirudin exhibited a retention in Cu(II)-chelated affinity chromatgoraphy since it contained a single exposed histidine at position 51. To obtain a stronger retention on an IDA-Cu(II) column, the hirudin variants were genetically engineered to contain one or two histidine (s) more than the wild type. While the affinity of the variants for IDA-Cu(II) ligand increased in comparison to that of the wild type, the antithrombin activities reduced to a certain degree. Cu(II), Ni(II) and Zn(II) ions were applied separately to the metal chelate column to investigate ligand specificity with respect to protein retention. As a result, the Cu(II) chelated chromatography gave the best resolution for all the hirudins tested and appeared to be the only IMAC that could be used generally for the purification of hirudins with a decreasing pH gradient.

• Textile Coloration and Finishing
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• v.8 no.6
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• pp.40-46
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• 1996

In order to investigate a practical application of fibrous absorbents to transition metals such as copper, nickel, cobalt, chrome, and iron, amidoximated fiber as a particular class of solid chelate agents were prepared from acrylic fibers treatment with hydroxylamine. The adsorption mechanisms of metal ions onto amidoximated acrylic fibers and their complexes were studied. Amidoximation of acrylic fiber with hydroxylamine is found to be first-order reaction, followed by the disappearance of infrared adsorption peaks due to nitrile groups of acrylic fibers. The uptake of metal ions onto amidoximated acrylic fiber is increased with temperature raising and the adsorption is also depended on pH of the soiutions. About 70% of metal ions can be recovered from aqueous solutions of Ni(II), Co(II), Cr(III), and Fe(II) on the concentration below 5x 10$^$^{-4}$ in the range of pH 2.1~10.0. Transition metals are adsorbed to form complex with amidoxime group by the ligand sites such as C=N, NH, NO, NHOH.OH.

• Journal of the Korean Chemical Society
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• v.57 no.5
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• pp.574-590
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• 2013

A new solid complexes of Ti(IV), Y(III) and Ce(IV) have been synthesized with ofloxacin. The formulae and structure of the complexes have been proposed in the light of analytical, spectral ($^1H$ NMR, IR and UV-Visible), magnetic, molar conductivities and thermal studies. The complexes are soluble in DMSO-$d_6$ and DMF. The measured molar conductance values indicate that, the three complexes are electrolyte in nature. The results support the formation of the complexes and indicated that ofloxacin reacts as a bidentate ligand chelate to the metal ion through the pyridone oxygen and one carboxylato oxygen. The kinetic parameters of thermogravimetric and its differential have been evaluated by using Coats Redfern (CR) and Horowitz-Metzeger (HM) methods. The thermodynamic data reflect the thermal stability for all complexes. The metal- ligand binding of the Ti(IV), Y(III) and Ce(IV) complexes is predicted using density funcational theory at the B3LYP-CEP-31G level of theory and total energy, dipole moment estimation of different Ti(IV), Y(III) and Ce(IV) ofloxacin structures. The biological activities of the ofloxacin, inorganic salts and their metal complexes were assayed against different bacterial species.

• Journal of the Korean Chemical Society
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• v.32 no.3
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• pp.211-226
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• 1988

Liquid chromatographic behavior of several metal ions in dithiocarbamate(DTC) chelates were investigated by reversed phase high performance liquid chromatography on Novapak $C_{18}$ and ${\mu}$-Bondapak $C_{18}$ columns. The optimum conditions for the separation of DTC-metal chelate were examined with respect to the pH, shaking time, flow rate, extraction solvent, and mobile phase strength. The metal ions in mixtures at trace level, chelated with some dithiocarbamate derivatives were separated successfully on Novapak $C_{18}$ column using acetonitrile/methanol/water or acetonitril/water mixtures as mobile phases. It was found that all DTC metal chelates studied were eluted in an acceptable range of capacity factor values ($0{\leqq}log\;k'{\leqq}1$). Although several foreign metal ions were coexisted, high recovery and good precision were attained ; 97.0-106.7 % for the recovery and 0.98-3.41% for the coefficient of variation. Under the optimum analytical conditions, trace metal ions in the composite water samples were determined sucessfully with in relative error of about {\pm}$6.7 %.

• Bulletin of the Korean Chemical Society
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• v.18 no.10
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• pp.1061-1066
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• 1997

The complexes M(CO)4-1,2-(PPh2)2-1,2-C2B10H10 (M=Cr 2a, Mo 2b, W 2c) have been prepared in good yields from readily available bis-diphenylphosphino-o-carboranyl ligand, closo-1,2-(PPh2)2-1,2-C2B10H10 (1), by direct reaction with Group Ⅵ metal carbonyls. The infrared spectra of the complexes indicate that there is an octahedral disposition of chelate bis-diphenylphosphino-o-carboranyl ligand around the metal atom. The crystal structure of 2a was determined by X-ray diffraction. Complex 2a crystallizes in the monoclinic space group P21/n with cell parameters a = 12.2360(7), b = 17.156(1), c = 16.2040(6) Å, V = 3354.1(3) Å3, and Z =4. Of the reflections measured a total of 2514 unique reflections with F2 > 3σ(F2) was used during subsequent structure refinement. Refinement converged to R1 = 0.066 and R2 = 0.071. Structural studies showed that the chromium atom had a slightly distorted pseudo-octahedral configuration about the metal center with two phosphine groups of o-carborane occupying the equatorial plane cis-orientation to each other. These metal carbonyl complexes are rapidly converted to the corresponding metal carbene complexes, [(CO)3M=C(OCH3)(CH3)]-1,2-(PPh2)2-1,2-C2B10H10 (M= Cr 3a, Mo 3b, W 3c), via alkylation with methyllithium followed by O-methylation with CF3SO3CH3.

• Analytical Science and Technology
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• v.5 no.1
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• pp.63-71
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• 1992

Liquid chromatographic behavior of Pd(II), Ni(II) and Co(III) in N-Alkylisonitrosoacetylacetone imine(HIAA-NR) chelates was investigated by reversed phase high perfomance liquid chromatography. The optimum conditions for the separation of IAA-NR-metal chelates were examined respect to the flow rate and mobile phase strength. The metal-N-Alkylisonitrosoacetylacetone imine chelates in solution were successfully separated on Novapak $C_{18}$ column using acetonitrile/water mixture as mobile phase. The elution order of chelates is methyl>ethyl>propyl>butyl as N-alkyl group for ligand is varied. It was found that all IAA-NR-metal chelates were eluted in an acceptable range of capacity factor value($0{\leq}log\;k^{\prime}{\leq}1$). The dependence of log k' on the volume fraction of water in the binary mobile phase was examined. Also, the dependence of k' on the liquid-liquid extraction distribution ratio(Dc) in acetonitrile-water-alkane extraction system was investigated for IAA-NR-metal chelate. Both kinds of dependence are linear, which suggests that the retention of the electroneutral metal chelates on Novapak $C_{18}$ column is largely due to the hydrophobic effect.

• Journal of the Korean Chemical Society
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• v.36 no.5
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• pp.652-660
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• 1992

The polyamine resins were synthesized by reacting amines such as diethylenetriamine(dien), triethylenetetramine(trien), tetraethylenepentamine(tetren), and pentaethylenehexamine(penten). Stepwise dissociation constants of amines, enthalpy and free energy of metal chelate were determined. Formation constants $(log k_1) of metal chelates were in order of Cu(Ⅱ) > Ni(Ⅱ) > Cd(Ⅱ) > Zn(Ⅱ) > Co(Ⅱ) and tendency of stabilities were proportional to nitrogen numbers of ligand such as dien < trien < tetren > penten. Elutional selectivites of metal ions on resin were agreed to formation constants of metal chelates. {\Delta}H and {\Delta}G were calculated by Van't Hoff equation. Stability constants (log k1) of metalic complexes were in order Cu(Ⅱ) > Ni(Ⅱ) > Cd(Ⅱ) > Zn(Ⅱ) > Co(Ⅱ), and tendency of stabilities were {\circledP}_L-Dien < {\circledP}_L-Trien < {\circledP}_L-Tetren < {\circledP}_L-Penten. The elutional selectivities of metal ions were agreed to stability constants of metal chelates.

• Journal of the Korean Applied Science and Technology
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• v.38 no.1
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• pp.19-28
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• 2021

Corrosion is the degradation of metals by reaction with the environment. It is difficult to completely remove. Corrosion proceeds rapidly after the protective barrier is destroyed, and several reactions occur that alter the composition and properties of the metal surface and local environments, such as diffusion of metal cations into the matrix, the formation of oxides, and local pH changes. The study of corrosion of steel and iron is of theoretical and practical interest and is receiving considerable attention. Acid solutions, which are widely used in industrial pickling, acid descaling, cleaning and acidification of oil wells, require the use of corrosion inhibitors to suppress corrosion attacks on metallic materials. Physical removal of rust requires expensive special equipment, and chemical removal of it can cause corrosion or shorten the life of the metal. In this study, an eco-friendly rust cleaner was developed using cosmetics and food materials by applying the concept of perm reducing agent and chelate, and applied to remove rust from industrial and hot water pipes and various industrial devices. As a result, it was found that rust cleaners remove rust more effectively and safely compared to conventional treatment methods. At the same time, the rust removal efficiency was 1.75 to 2.5 times better for industrial piping and 1.56 to 2.2 times better for boiler hot water than conventional methods.

• Journal of Life Science
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• v.20 no.7
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• pp.1041-1046
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• 2010

Phytoextraction is a technique which uses plants to clean up metal-contaminated soils. Recently, various chelating agents were introduced into this technique to increase the bioavailability of metals in soils. Even though the technique is an economic and environment-friendly method, this cannot be applied in highly metal-contaminated areas because plants will not normally grow in such conditions. Therefore, this research focuses on identifying chelating agents which are biodegradable and applicable to highly metal-contaminated areas. Alunimum (Al) as a target metal and cysteine (Cys), histidine (His), citrate, malate, oxalate, succinate, and ethylenediamine (EDA) as biodegradable chelating agents were selected. Ethylenediamine tetraacetic acid (EDTA) was used as a comparative standard. Plants were grown on agar media containing various chelating agents with Al to analyze the effect on plant growth. His slightly diminished the inhibitory effect of Al on root growth of plants, whereas, Cys, citrate, malate, oxalate, and succinate did not show significant effects. Both EDTA and EDA strongly diminished the inhibitory effect of Al on root growth. The effect of EDA is correlated with decreased Al uptake into the plants. In conclusion, as a biodegradable chelating agent, EDA is a good candidate for highly Al-contaminated areas.

• Current Research on Agriculture and Life Sciences
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• v.32 no.3
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• pp.155-158
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• 2014

Phytoextraction is a technique that uses plants to remediate metal-contaminated soils. However, this technique cannot be applied in highly metal-contaminated areas, as plants cannot normally grow under such conditions. Therefore, this study investigated the introduction of various biodegradable chelating agents to increase the bioavailability of metals in highly metal-contaminated areas. Mercury (Hg) was selected as the target metal, while cysteine (Cys), histidine (His), malate, succinate, oxalate, citrate, and ethylenediamine (EDA) were used as biodegradable chelating agents. Plants were grown on agar media containing various chelating agents and Hg to analyze the effect on plant root growth. Cys and EDA were both found to diminish the inhibitory effect of Hg on plant root growth, whereas His, citrate, and ethylenediamine tetraacetic acid (EDTA) did not show any significant effects, and malate, succinate, and oxalate even promoted the inhibitory effect of Hg on plant root growth. Thus, Cys and EDA would seem to be promising biodegradable chelating agents for highly Hg-contaminated areas.