• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1613-1619
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• 2011

A hybrid thermosetting maleimido epoxy compound 4-(N-maleimidophenyl) glycidylether (N-MPGE) containing Co(II), Ni(II) and Cu(II) ions was prepared by curing N-MPGE and tetradentate Schiff base Co(II), Ni(II) and Cu(II) complexes. The curing polymerization reaction of N-MPGE with metal complexes as curing agents was studied. The cured samples were studied for thermal stability, chemical (acid/alkali/solvent) and water absorption resistance and homogeneity of the cured systems. The tetradentate Schiff base, 3-[(Z)-2-piperazin-1-yl-ethylimino]-1,3-dihydro indol-2-one was synthesized by the condensation of Isatin (Indole-2, 3-dione) with 1-(2-aminoethyl)piperazine (AEP). Its complexes with Co(II), Ni(II) and Cu(II) have been synthesized and characterized by microanalysis, conductivity, Uv-Visible, FT-IR, TGA and magnetic susceptibility measurements. The spectral data revealed that the ligand acts as a neutral tetradentate Schiff base and coordinating through the azomethine nitrogen, two piperazine nitrogen atoms and carbonyl oxygen.

• Bulletin of the Korean Chemical Society
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• v.19 no.11
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• pp.1207-1210
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• 1998

The diamagnetic six-coordinate ruthenium polypyridyl complexes have been prepared and assigned. 1H NMR spectral studies were used to unravel the ligand field strength and the basicity on the chemical shift to the particular proton of ligand L in [(tpy)(L)RuⅡ(X)]+/2+ (L=bpy, bqi, dmbpy, phen; X=Cl, CN, N3, NCCD3, NO2, SCN) complexes.

• BMB Reports
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• v.32 no.3
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• pp.279-287
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• 1999

The aromatic hydrocarbon receptor (AhR) is a cytosolic protein that binds the environmental pollutant, dioxin. The liganded AhR translocates into the nucleus where it heterimerizes with a constitutive nuclear protein, AhR nuclear translocator (Arnt). The N-terminal regions of both AhR and Arnt contain basic helix-loop-helix (bHLH) and Per-AhR-Arnt-Sim (PAS) motifs that are required for DNA binding, dimerization, and ligand binding whereas the C-terminal regions of both AhR and Arnt contain transactivation domains. Here, results from the mammalian two-hybrid system indicate that Arnt can make a homodimer but AhR cannot. In the presence of dioxin, the interaction between AhR and Arnt is stronger than that of the Arnt homodimer, suggesting that Arnt prefers to make a heterodimer with the liganded AhR rather than a homodimer. Transfection analyses using the GAL4-driven reporter system suggest that AhR's N-terminal region represses its own transactivation domain, as well as exogenous transactivation domains such as Sp 1 and VP16. Interestingly, the repressed transactivation domains of AhR are activated by ligand-dependent heterodimerization with Arnt. These observations suggest that heterodimerzation with Arnt is necessary not only for DNA binding but also for activation of the repressed transactivation capability of AhR.

• Bulletin of the Korean Chemical Society
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• v.19 no.11
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• pp.1211-1216
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• 1998

Bis(diethyldithiocarbamato)ioxomolybdenum(VI), cis-MoO2(S2CNEt2)2, 1, reacted with chlorotrimethylsilane (Me33SiCl) to give a seven-coordinate, pentagonal bipyramidal complex MoOC12(S2CN]Et2)2, 3, in which the oxo ligand is trans to the chloride ligand and the two chloride ligands are mutually cis. The monooxo molybdenum complex bis(diethyidithiocarbamato)oxomolybdenum(IV), MoO(S2CNEt2)2, 2, reacted with phenyl isocyanate (PhNCO) to give an Mo dimer MO2{μ-N(CONPh)Ph}(μ-NPh)(NPh)2(S2CNEt2)2, 4, which contains an Mo-Mo bond, two diethyldithiocarbamato ligands, two terminal imido (NPh) ligands, and two bridging hnido (NPh) ligands. One of the two bridging NPh ligands seemed to have been attacked by the electrophilic phenyl isocyanate carbon, which suggests that the bridging imido NPh ligand is more nucleophilic than the terminal one. Crystallographic data for 3: monoclinic space group P21/c, a=8.908(l) Å, b=17.509(3) Å, c=12.683(2) Å, β=110.15(1)°, Z=4, R(wR2)=0.0611(0.1385). Crystallographic data for 4-THF: orthorhombic space group P212121, a=17.932(4) Å, b=22.715(5) Å, c=11.802(3) Å, Z=4, R(wR2)=0.0585(0.1286).

• Bulletin of the Korean Chemical Society
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• v.9 no.5
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• pp.292-295
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• 1988

Macrocyclic ligands have been studies as cation carriers in a bulk liquid membrane system. $Cu^{2+}$ has been transported using nitrogen substituted macrocycles as carriers and several transition metal ions($M^{n+}\;=\;Mn^{2+},\;Co^{2+},\;Ni^{2+},\;Cd^{2+},\;Pb^{2+}\;and\;Ag^{+}$) have been transported using $DBN_3O_2,\;DBN_2O_2,\;Me_6N_414C4$ and DA18C6 as carriers in a bulk liquid membrane system. Competitive $Cu^{2+}-M2^+$ transport studies have also been carried out for the same system. In single cation transport experiments, the best macrocyclic ligand for transport is a ligand that gives a moderately stable rather than very stable complex in the extraction. However, when both cations are present in the source phase, the cation which forms the most stable complex with carrier is favored in transport over other cations. Generally, the nitrogen substiituted macrocycles transport $Cu^{2+}$ selectively over $Mn^+$. Ligand structure, equilibrium constant (or stability constant) for complex formation, source phase pH and carrier concentration are also important parameters in transport experiments.

• Bulletin of the Korean Chemical Society
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• v.7 no.2
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• pp.145-147
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• 1986

Dichlororhodium(Ⅲ) complexes of a flexible quadridentate ligand, N,N'-dimethylethylenediamine-N,N'-diacetic acid (dmedda), have been prepared. Both cis-${\alpha}$ and cis-${\beta}$ isomers have been yielded in the $K[Rh(dmedda)Cl_2]$ complexes, which were characterized with elemental analyses, electronic absorption and proton nuclear magnetic resonance spectroscopic data.

• Archives of Pharmacal Research
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• v.21 no.4
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• pp.452-457
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• 1998

Three compounds, 5-(acetoxymethyl)-5-(hydroxymethyl)-3-tetradecyl-2,5-dihydro-2-furanone (3), 5-(acetoxymethyl)-5-(hydroxymethyl)-3,3-dihexyltetrahydro-2-furanone (4) and 5-(acetoxymethyl)-5-(hydroxymethyl)-3,3-dioctyltetrahydro-2-furanone (5), were designed and synthesized as surrogates of the ultrapotent DAG analogue, 5-(acetoxymethyl)-5-(hydroxymethyl) 3-[(Z)-tetradecylideneltetrahydro-2-furanone (1), a compound that showed high affinity for PKC-$\alpha$ ($K_1$=35 nM) in a competition binding assay with [$^3H$-20]phorbol-12,13-dibutyrate (PDBU). In an attempt to overcome the problem of generating geometrical E- and Z- isomers, as encountered with 1, the double bond was moved to an endocyclic location as in 3, or an additional alkyl chain was appended to C3 to give the corresponding 3,3-dialkyl saturated lactones (4 and 5). The lactone was constructed from glycidyl-4-methoxyphenyl ether in 5 steps. The target compounds showed reduced binding affinities for PKC-.alpha. with $K_{i}$ values of 192 nM (3), 4,829 nM (4), and 2,812 nM (5), respectively. These results indicate that constrained DAG analogues having a tetrahydro-2-furanone template are effectively discriminated by PKC-(X in terms of the direction of the long alkyl chain connected to the 3-position.n.

• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2523-2528
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• 2014

In the present study, at first, azo Schiff base ligand of (N,N'-bis(5-phenylazosalicylaldehyde)-ethylenediamine) ($H_2L$) has been synthesized by condensation reaction of 5-phenylazosalicylaldehyde and ethylenediamine in 2:1 molar ratio, respectively. Then, its cobalt complex (CoL) was synthesized by reaction of $Co(OAc)_2{\cdot}4H_2O$ with ligand ($H_2L$) in 1:1 molar ratio in ethanol solvent. This ligand and its cobalt complex containing azo functional groups were characterized using elemental analysis, $^1H$-NMR, UV-vis and IR spectroscopies. Subsequently, the interaction between native calf thymus deoxyribonucleic acid (ct-DNA) and CoL complex was investigated in 10 mM Tris/HCl buffer solution, pH = 7 using UV-vis absorption, thermal denaturation technique and viscosity measurements. From spectrophotometric titration experiments, the binding constant of CoL complex with ct-DNA was found to be $(2.4{\pm}0.2){\times}10^4M^{-1}$. The thermodynamic parameters were calculated by van't Hoff equation.The enthalpy and entropy changes were $5753.94{\pm}172.66kcal/mol$ and $43.93{\pm}1.18cal/mol{\cdot}K$ at $25^{\circ}C$, respectively. Thermal denaturation experiments represent the increasing of melting temperature of ct-DNA (about $0.93^{\circ}C$) due to binding of CoL complex. The results indicate that the process is entropy-driven and suggest that hydrophobic interactions are the main driving force for the complex formation.

• Molecules and Cells
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• v.26 no.5
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• pp.486-489
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• 2008

Curcumin (diferuloylmethane), a pigment derived from turmeric, has anti-oxidant and anti-inflammatory activities. Accumulating evidence points to a biochemical link between increased oxidative stress and reduced bone density. Osteoclast formation was evaluated in co-cultures of bone marrow stromal cells (BMSC) and whole bone marrow cells (BMC). Expression of receptor activator of nuclear factor-${\kappa}B$ ligand (RANKL) was analyzed at the mRNA and protein levels. Exposure to curcumin led to dose-dependent suppression of osteoclastogenesis in the co-culture system, and to reduced expression of RANKL in $IL-1{\alpha}$-stimulated BMSCs. Addition of RANKL abolished the inhibition of osteoclastogenesis by curcumin, whereas the addition of prostaglandin $E_2$ ($PGE_2$) did not. The decreased osteoclastogenesis induced by curcumin may reduce bone loss and be of potential benefit in preventing and/or attenuating osteoporosis.

• Journal of the Korean Society of Industry Convergence
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• v.3 no.1
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• pp.77-82
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• 2000

The stereoselective ligand exchange reaction of trans-$[Co(SS-epm)Cl_2]^+$ and racemic propane-1,2-diamine (rac-pn) produces the complex that is identified as $[CO(N)_6]^{3+}$ type of $[Co(SS-epm)(pn)]^{3+}$ by absorption spectrum. It is conceivable that the reaction mechanism involves substitution and isomerization. The calculated and experimentally determined ratios of the complexed enantiomeric substrates at equilibrium were as follows: $[Co(SS-epm)(pn)]^{3+}$,calcd 32 % / 68 %, exptl 19 % / 81 % R-pn / S-pn. It has been shown that the employment of molecular mechanics calculations as a predictive tool may lead to the design of chiral complexes that may be applied to the separation of racemic mixtures of simple bidentate ligands.