• Bulletin of the Korean Chemical Society
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• v.32 no.9
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• pp.3290-3294
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• 2011

The properties of monomeric and dimeric salen-aluminum complexes, [salen(3,5-$^tBu)_2$Al(OR)], R = $OC_6H_4-p-C_6H_6$ (H1) and R = [salen(3,5-$^tBu$)AlOPh]C$(CH_3)_2$ (H2) (salen = N,N'-bis-(salicylidene)-ethylenediamine) as host layer materials in red phosphorescent organic light-emitting diodes (PhOLEDs) were investigated. H1 and H2 exhibit high thermal stability with decomposition temperature of 330 and $370^{\circ}C$. DSC analyses showed that the complexes form amorphous glasses upon cooling of melt samples with glass transition temperatures of 112 and $172^{\circ}C$. The HOMO (ca. -5.2~-5.3 eV) and LUMO (ca. -2.3~-2.4 eV) levels with a triplet energy of ca. 1.92 eV suggest that H1 and H2 are suitable for a host material for red emitters. The PhOLED devices based on H1 and H2 doped with a red emitter, $Ir(btp)_2$(acac) (btp = bis(2-(2'-benzothienyl)-pyridinato-N,$C^3$; acac = acetylacetonate) were fabricated by vacuum-deposition and solution process, respectively. The device based on vacuum-deposited H1 host displays high device performances in terms of brightness, luminous and quantum efficiencies comparable to those of the device based on a CBP (4,4'-bis(Ncarbazolyl) biphenyl) host while the solution-processed device with H2 host shows poor performance.

• Bulletin of the Korean Chemical Society
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• v.29 no.10
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• pp.1879-1880
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• 2008

• Bulletin of the Korean Chemical Society
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• v.29 no.5
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• pp.969-973
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• 2008

Solvent extraction using a Schiff-base, salen$(NEt_2)_2$, as a chelating agent has been conducted on several water samples to study the determination of trace Cu(II), Mn(II) and Zn(II). Experimental conditions for the formation and extraction of metal complexes were optimized with an aqueous solution similar in composition to the samples. The matrix difference between the sample and standard solutions was approximately matched, and the pH of each sample solution was adjusted to 9.5 with $NaHCO_3/NaOH$ buffer. The concentration of salen$(NEt_2)_2$ was $7.3\;{\times}\;10^{-3}$ mol/L, and the complexes were extracted into MIBK solvent followed by the measurement of AAS absorbance. The potential interference of concomitant ions was investigated, but no interference from alkaline and alkali earth ions was shown in this procedure. The given procedure is precise, as judged from the relative standard deviation of less than 5% for five measured data. The recovery of 93-103% shows that this method is quantitative for such trace metal analysis.

• Bulletin of the Korean Chemical Society
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• v.29 no.9
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• pp.1774-1780
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• 2008

New PVC based polymeric membrane electrodes (PME) and coated glassy carbon electrodes (CGCE) based on synthesized Schiff base complexes of Co(III); [Co(Salen)$(PBu_3)_2$]$ClO_4$, [Co($Me_2$Salen)$(PBu_3)_2$]$ClO_4$, [Co(Salen)$(PBu_3)H_2O$]$ClO_4$; as anion carriers for potentiometric determination of $ClO_4\;^-$were studied. The PME and also CGCE electrodes prepared with [Co(Me2Salen)$(PBu_3)_2$]$ClO_4$ showed excellent response characteristics to perchlorate ions. The electrodes exhibited Nernstian responses to $ClO_4\;^-$ ions over a wide concentration range with low detection limits ($1.0 {\times} 10^{-6}\;mol\;L^{-1}$ for PME and $9.0 {\times} 10^{-7}\;mol\;L^{-1}$ for CGCE). The electrodes possess fast response time, satisfactory reproducibility, appropriate lifetime and, most importantly, good selectivity toward $ClO_4\;^-$ relative to a variety of other common inorganic anions. The potentiometric response of the electrodes is independent of the pH in the pH range 2.5-8.5. The proposed sensors were used in potentiometric determination of perchlorate ions in mineral water and urine samples. The interaction of the ionophore with perchlorate ions was shown by UV/Vis spectroscopy.

• Applied Chemistry for Engineering
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• v.26 no.2
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• pp.132-137
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• 2015

BEA-zeolite was modified by alkaline solution to introduce mesoporosity in the crystals and the homogeneous chiral Co(III) salen was immobilized in the mesopores. The dinuclear chiral Co(salen)-$GaCl_3$ catalyst immobilized on mesoporous BEA-zeolite showed high activity for the regioselective ring opening of terminal epoxides by carboxylic acids. Various chiral monoester derivatives could be synthesized with moderate enantioselectivity (47~69 ee%) from racemic epoxides through above reaction. When the chiral (S)-ECH was used as a reactant, it was efficiently resolved by carboxylic acid with a high enantioselectivity in the presence of heterogenized chiral salen catalyst, and the ring opened product afforded optically pure monoester epoxide (R)-GB (up to 98 ee%) through the ring closing in the basic solution by elimination of HCl. The heterogeneous catalyst could be fabricated easily, and the catalytic activity was retained for several times reuse without any further regeneration step.

• Macromolecular Research
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• v.8 no.1
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• pp.1-5
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• 2000

The valiclity of the simple mathematical model for facilitated transport in a solid state membrane developed previously has been examined againsts the carrier concentration and membrane thick-ness. Membranes are prepared with copolymer of styrene and 4-vinylpyridine as a matrix and Co(salen) as a carrier. 4-Vinylpyridine is incorporated to provide the coordination site for Co(salen) carrier. Oxygen permeability through the facilitated transport membrane is linearly increased with the square of its thick-ness, as predicted by the mathematical model. However, the oxygen permeability does not increase linearly with the carrier concentration. This seems to be due to the deactivation of the carrier by dimerization at high carrier concentrations as well as the reduced chain mobility by coordination of bulky Co(salen) carrier.

• Bulletin of the Korean Chemical Society
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• v.30 no.2
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• pp.389-396
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• 2009

MFI structural zeolite (ZSM-5 or Sililcalite) was treated with HF solution to introduce mesoporous channels in the microporous crystals. Inner mesopore size could be controlled from 2.5 to 3.5 nm by changing the concentration of HF solution. The pore structure of HF-treated MFI zeolite was studied by instrumental analysis. The active Co (III) salen complex monomers were successfully anchored non-covalently on the surfaces of mesoporous MFI-type zeolite. These heterogeneous catalysts could be applied in asymmetric ring opening of terminal epoxides by phenol derivatives. It showed very high enantioselectivity and yield up to 95% in the catalytic synthesis of optically active $\alpha$-aryloxy alcohol compounds.

• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.829-834
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• 2010

Ligand variation was carried out on a cobalt(III) complex of Salen-type ligand comprised of 1,2-cyclohexenediamine and salicylaldehyde bearing a methyl substituent on 3-position and -[$CMe(CH_2CH_2CH_2N^+Bu_3)_2$] on 5-position, which is a highly active catalyst for $CO_2$/propylene oxide copolymerization. Replacement of the methyl substituent with bulky isopropyl group resulted in alteration of the binding mode, consequently lowering turnover frequency significantly. Replacement with an ethyl group preserved binding mode and activity. Replacement of the tributylammonium unit with trihexylammonium or trioctylammonium, or replacement of 1,2-cyclohexenediamino unit with -$NC(Me)_2CH_2N$- decreased activity, even though the binding mode was unaltered.

• Journal of the Korean Chemical Society
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• v.57 no.4
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• pp.525-528
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• 2013

• Journal of the Korean Chemical Society
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• v.52 no.6
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• pp.727-733
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• 2008