• Journal of the Korean Chemical Society
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• v.34 no.1
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• pp.85-90
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• 1990

The inertness of eight-coordinate tetrakis(picolinato)tungsten(IV) complex has been investigated by spectroscopic method in nonpolar solvent at 60$^{\circ}C$, 75$^{\circ}C$, 90$^{\circ}C$, 120$^{\circ}C$, and reflux condition. Until 2 days, showed the inertness whether existance of oxygen or not. After 2 days, showed the oxidation of W(IV) complex much more rapidly than substitution, which had $k_{obs}(sec^{-1}) {\varpropto} 1/[ligand]^2$. On sealing the sample under Ar gas, showed the inertness until 50 days, which had $k_{obs}(sec^{-1}) = 8.8{\times} 10^{-7}$. The$^1H$-NMR peak of $H_6$ in complex was diminished, otherwise that of free ligand was grown up. This result indicated that this complex was very inert.

• Applied Chemistry for Engineering
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• v.3 no.3
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• pp.407-411
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• 1992

The effects of phase transfer catalyst was studied on the substitution of CO ligand of $Mo(CO)_6$ [M=Cr, Mo, W] with two electron-pairs donating ligands, 2, 2'-bipyridine and 2, 2'-biquinoline. The change of product yield, $M(CO)_4(L)_2$, was discussed according to reaction time, mole composition of $M(CO)_6$, and type of ligand.

• Journal of the Korean Chemical Society
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• v.52 no.5
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• pp.476-481
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• 2008

• Journal of the Korean Chemical Society
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• v.17 no.3
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• pp.174-181
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• 1973

Dichlorodiacetatotitanium(IV) dissolves in alcohols with chemical reaction. Such solvolytic reaction of $TiCl_2(OAc)_2$with various alcohols has been studied by means of solution NMR spectroscopy and chemical analysis of the isolated products. The reaction of $TiCl_2(OAc)_2$ with primary alcohols has shown to be a quantitative two-step ligand substitution process as shown in the following: $TiCl_2(OAc)_2+ROH{\to}TiCl_2(OAc)_2(OR)+AcOH$ $TiCl_2(OAc)_2(OR)+ROH{\to}TiCl_2(OAc)_2+AcOH$The molecular form initially soluble in organic solvents has been found to be the monosubstituted species $TiCl_2(OAc)(OR)$. Alcoholysis with t-butyl alcohol has shown remarkable differences. When the mole ratio of t-butyl alcohol to $TiCl_2(OAc)_2$ is less than 1/2, the following reaction is dominant. $TiCl_2(OAc)_2+t-ButOH{\to}TiCl_2(OAc)_2+t-ButCl$However, at higher mole ratio another substitution process resembling the first step reaction with primary alcohols is competitively accompanied. The reaction with t-butyl alcohol also differs from that with primary alcohols in that only one either of the two chloro-or acetato-ligands in $TiCl_2(OAc)_2$ is subjected to substitution.

• Applied Chemistry for Engineering
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• v.30 no.3
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• pp.308-312
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• 2019

Amphiphilic gold nanoparticles were synthesized by the functionalization of gold nanoparticles with hydrophilic and hydrophobic ligands on their surfaces, which can be applied to many disciplines such as biology, photonics, electronics, and so on. The ratio of hydrophilic and hydrophobic ligands plays an important role in such applications since the ratio is closely related to physiochemical properties of the nanoparticles. In this paper, the effect of temperature during the ligand exchange reaction on the ratio of ligands on the gold nanoparticle surface was investigated. Hydrophilic ligands have higher affinity to the nanoparticle surface with an increase of the temperature. Furthermore, the amphiphilic nanoparticles at a higher temperature were more soluble in an aqueous solution even with a lower hydrophilicity of the nanoparticle surface.

• Journal of the Korean Chemical Society
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• v.30 no.2
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• pp.181-187
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• 1986

It is shown that the substitutive ligand on the photochemical substitution reactions of $trans-Cr^{Ⅲ}N_4XY$ complexes is predicted by considering the total stabilization energy of the hypothetical primary intermediates resulting from the loss of one ligand. The total stabilization energy and one electron energy level of d-orbital are calculated within the framework of angular overlap model. According to the calculated results, the intermediates with larger total stabilization energy are, as expected, more easily produced. Consequently, the relative values of the total stabilization energy are used to decide which of the ligands in $trans-Cr^{Ⅲ}N_4XY$ complexes is preferentially labilized on the lowest energy d-d irradiation. The prediction for the leaving ligand on the photoaquation of $trans-Cr^{Ⅲ}N_4XY$ complexes is consistent.

• Journal of the Korean Chemical Society
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• v.51 no.6
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• pp.499-505
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• 2007

Monomeric complexes of nickel(II) having terdentate bis(imino)aryl ligands (N,C,N-pincer) are reported. New complexes (2,6-(ArN=CH)2C6H3)NiBr (Ar=2,6-dimethylphenyl (1), 2,6-diisopropylphenyl (2)) have been synthesized through oxidative addition of 1,3-(ArN=CH)2C6H3Br (bis(N-Ar)-2-bromoisophthalaldimine: Ar=Ph-2,6-Me2, Ph-2,6-iPr2) to Ni(COD)2 (COD=1,5-cyclooctadiene), in high yields. The development of a synthetic route to ligands and nickel complexes is outlined. The complexes were characterized by IR, 1H-NMR and elemental analysis. Full characterization of complexes 1 and 2 is discussed. An investigation into the catalytic activity of the complexes in ethylene polymerization was performed, resulting in no formation of polyethylenes but producing a small amount of oily oligomers. Preliminary results indicate that the pincer complexes were found to be inactive as catalysts in ethylene polymerization.

• Journal of the Korean Chemical Society
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• v.42 no.2
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• pp.184-189
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• 1998

Tris(pentafluorophenyl)indium acetonitrile complexes have been prepared from the reaction of Indium trihalides (halogen=Cl, Br) and bis(pentafluorophenyl)cadmium in acetonitrile, and characterized by elementary analysis, $^13C{^1H}-,\; ^1H-\;and\; ^{19}F-NMR$ spectroscopy and mass spectrometry. The Indium (III) compounds were formed stable 1:1 adducts with acetonitrile. $In(C_6F_5)_3{\cdot}DMAP$ has been prepared from the ligand exchange reaction of In$(C_6F_5)_3 {\cdot} CH_3CN$ with DMAP in $CH_2Cl_2 {\cdot} DMAP$ has higher donating character and replaced the $CH_3CN$ through the ligand transfer reaction.

• Journal of the Korean Chemical Society
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• v.24 no.1
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• pp.15-19
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• 1980

CNDO/2, EHT molecular orbital methods are used to investigate the electronic structure and reactivity of glycinato, glycine ester ligands. The results show that bidentate glycinato has a more stable structure, Gly-I with a $105.9^{\circ}$dihedral angle between ${\Delta}O_4C_3C_2$ and ${\Delta}C_3C_2N_1$ than Gly-Ⅱ. The electron inductive effects in the alkyl group substituted glycine ester ligands can also be derived from the calculation. According to the electron density, qN of ligands on the basis of CNDO/2 MO calculations, it is concluded that the stabilities are in the order of glycinato > Gly-Et-ester > Gly-i-Pr-ester > Gly-Me-ester.

• Journal of Life Science
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• v.14 no.1
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• pp.14-16
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• 2004

Various ligands function as regulators in the allosteric control of tryptophan synthase. Effects of the monovalent cations and glycerophosphate on the mutant tryptophan synthases were examined in the presence of L-serine. The results showed that these compounds might play roles in the allosteric control of the proteins.