• Macromolecular Research
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• v.14 no.3
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• pp.306-311
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• 2006

New unsymmetrical ($\alpha$-Diimine)nickel(II) catalysts having different pendent groups at the ortho positions on aromatic rings were synthesized and subjected to propylene polymerizations with MAO (methylaluminoxane). Structural analyses of the resulting polypropylenes by $^1H\;and\;^{13}C\;NMR$ showed that the ortho substituents on aromatic rings of ($\alpha$-diimine)nickel(II) catalyst affected significantly the polypropylene microstructure. While $C_s$ symmetric catalyst afforded a syndiotactic polypropylene (rr triad content=66%) due to the syndiospecific chain end control, $C_1$ symmetric catalysts produced much less stereoregular polypropylenes (rr triads content <50%), presumably because of collision of the isospecific site control with the syndiospecific chain end control.

• Macromolecular Research
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• v.11 no.6
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• pp.514-517
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• 2003

In the solution polymerizations of methyl methacrylate with (${\alpha}$-diimine)nickel(II)/methylaluminoxane (MAO), we observed effects of the position of two methyl substituents in the ligand on both the activities of the catalysts and the polymer microstructure. ${\alpha}$-Diimine nickel(II) catalysts gave syndiotactic-rich poly(methyl methacrylate) with high molecular weight and narrow molecular weight distribution.

• Journal of Photoscience
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• v.12 no.3
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• pp.135-136
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• 2005

We confirmed that the 1 compound, N,N'-di(p-dimehylaniline)benza1d-1,4-diimine, with two imine bond showed a reversible trans-cis photoisomerization which was recovered to the original state in 8 minutes through the spectroscopic studies.

• Bulletin of the Korean Chemical Society
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• v.16 no.1
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• pp.21-26
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• 1995

Electrochemical reduction of oxygen has been carried out at glassy carbon electrode and carbon ultramicroelectrode, the surface of which is modified with a new Co(Ⅱ)-Schiff base complex, Co(Ⅱ)-3,4-bis(salicylidene diimine)toluene in 1 M KOH solution. The results obtained from cyclic voltammetric and chronoamperometric experiments are consistent with the formation of the reasonably stable superoxide ions as a primary electron transfer reaction product. The exchange rate constant obtained for oxygen reduction is about 0.02 cm/s.

• Polymer(Korea)
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• v.26 no.3
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• pp.410-414
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• 2002

The late transition Pd catalyst of low oxophilicity that has ferrocene -based diimine ligand for stabilization of center metal had been synthesized and applied for the polymerization of methyl methacrylate (MMA). In the presence of triisobutylaluminium (TIBA) for impurity scavenger, the effects of polymerization temperature and [TIBA]/[Pd] mole ratio on the yield and glass transition temperature ($T_g$) of PMMA had been examined. For 40~$50^{\circ}C$ of polymerization temperature and 2000~3000 of [TIBA]/[Pd] mole ratio, higher polymer yields were obtained. It was observed that ($T_g$) of PMMA is almost independent to the polymerization temperature but influenced by the [TIBA]/[Pd] mole ratio. With the examination of($T_g$) of PMMA with the structure of polymer, it had been found that T$_{g}$ of PMMA exhibits a linear relationship with the isotacticity of polymer.r.

• Journal of the Korean Chemical Society
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• v.34 no.6
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• pp.593-599
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• 1990

A series of new, square planar, and mixed-ligand complexes of Ni(Ⅱ), Pd(Ⅱ), and Pt(Ⅱ) have been prepared. From the observation of electronic spectrum for the variation of the ligand substituents, the very intense absorption band in the visible range is by the electronic transition of dithiolene to diimine ligand, HOMO to LUMO. In the various solvent systems the IT band shows the similar behavior to IT transition of mixed-valence dinuclear complexes followed with Hush theory, happens rto dominently by the inner sphere charge transfer transition. The negative solvatochromism represents that the excited-state electric dipole is reduced or reversed by the electronic transition.

• Bulletin of the Korean Chemical Society
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• v.15 no.11
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• pp.980-984
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• 1994

Monomeric rhodium and iridium diimine complexes $Cp^*M(HNRNH)(Cp^*$ = 1,2,3,4,5-pentamethylcyclopentadienyl : (M=lr; R=o-$C_6H_4 (1a), 4,5-(CH_3)_2-C_6H_2-1,2 (1b), 4,5-(Cl)_2-C_6H_2-1,2$ (1c), NCC=CCN-1,2 (1d): M=Rh; R=NCC=CCN-1,2 (1e)) have been synthesized from $[CP^*MCl_2]_2$ and 2 equiv. of diamine in the presence of $NEt_3$. The Crystal structure of 1a was determined by X-ray diffraction method : 1a was crystallized in the monoclinic system, space group $P2_{1/c}$, with lattice constants a=9.543 (1) ${\AA}$, b=16.286 (1) ${\AA}$, c=10.068 (1) ${\AA}$ and ${\beta}$=99.25 (1), with Z= 4. Least-squares refinement of the structure led to R factor of 0.049. The coordination sphere of rhodium and iridium can be described as a 2-legged piano-stool. All complexes are highly colored. Electrochemical studies show that 1d and 1e display quasi-reversible reduction and 1a-1c display irreversible reductions, suggesting that the acceptor orbital might be localized on the diimine ring.

• Proceedings of the Korean Society of Potoscience Conference
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• spring
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• pp.10-10
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• 1995

• Bulletin of the Korean Chemical Society
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• v.15 no.8
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• pp.641-643
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• 1994

Studies of Co(N-N)(3,6-DBSQ)(3,6-DBCat)(N-N=4,7-dimethyl-1 ,10-phenanthroline, 5-chloro-1,10-phenanthroline; DBSQ=di-tert-butylsemiquinonato; DBCat=di-tert-butylcatecholato) have been carried out on the bistability by intramolecular cobalt-quinone electron transfer in solid state. The title complexes dominantly exist as $Co^{III}$(N-N)(3,6-DBSQ)(3,6-DBCat) at room temperature and display a significant bistability on temperature variation. Subtle change in optical spectra and magnetic properties is observed when diimine ligands are changed.

• Journal of the Korean Chemical Society
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• v.18 no.4
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• pp.267-271
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• 1974

The tetradentate schiff base, N,N'-bis(salicylaldehyde)-ethylene diimine has been reacted with a series of Mo(IV), Mo(V), Mo(IV), and Mo(III) oxidation states to form new Complexes; $[MoO_2(C_{16}H_{14}O_2N_2)], (MoO(C_{16}H_{14}O_2N_2)]_2O, (Mo(SCN)(C_{16}H_{14}O_2N_2)]_2O, and (Mo(H_2O)(C_{16}H_{14}O_2N_2)]_2O.$ These complexes have hexa coordinated configurations and the mole ratio of these ions to the ligand was 1:1. These complexes have been identified by visible spectra, infrared specra, T.G.A., D.T.A., and elemental analysis.