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Photoluminescent Europium Complexes with Oxygen and/or Nitrogen Donating Ligands
Oh, Yunghee,Lee, Chul Ho,Lee, Burm Jong,Shin, Byoung Chul Trans Tech Publications, Ltd. 2005 Key Engineering Materials Vol.277 No.-
<P>The reaction of EuX3 ·nH2O (X=Cl¯ , NO3¯ ), a- pyridoin anion (P) and 2,2¢-dipyridylamine in ethanol solution yields a hydroxo complex, EuP2(OH) 2(H2O) 2, which is characterized by NMR, IR, and elemental analyses. Europium complexes coordinated by nitrogen donating ligands such as 2,2¢-dipyridylamine or 2¢-hydroxypyridine are unstable in solution and are prone to decompose to europium hydroxo complex and pyridinium amine salt. The UV and PL spectra of europium complexes are reported and a decomposition mechanism is proposed.</P>
오영희,최미진 동의대학교 기초과학연구소 2000 基礎科學硏究論文集 Vol.10 No.1
New copper complexes with a ligand, L(L=N.N'-cyclohexane bis(ferrocenylmethylene)amine) which was obtained from ferrocene carboxaldehyde and 1,2-diaminocyclohexane with a mole ratio of 2:1, were prepared and characterized. Those were adapted to asymmetric catalysis. The copper(Ⅱ) complexes do not work in cyclopropanation of styrene and ethyl diazoacetate but copper(Ⅰ) complex catalyzes. The Cu(Ⅰ)LOTf (OTf=trifluorometanesulfonate) shows a good regioselectivity giving high trans to cis ratio of up to 80:20.
장원길,Jihye Shin,Yunghee Oh,Byoung Joon Ahn 한국공업화학회 2008 Journal of Industrial and Engineering Chemistry Vol.14 No.4
In this paper our recent results of the Suzuki reaction using [Pd(NH3)4]2+-modified nanopore silica under solvent-free conditions are described. [Pd(NH3)4]2+-modified nanopore silica was prepared by impregnation using an aqueous solution of [Pd(NH3)4]Cl2 in water or in acetonitrile. The BET surface area, BJH mean pore diameter and pore volume are 138.8 m2/g, 8.7 nm, and 0.34 cm3/g, respectively, and the pore size distribution shows a single peak at around 5 nm in diameter. It has been shown that the Suzuki reaction is performed in excellent yield by using Pd-modified nanopore silica under solvent-free conditions heated at 90–100 8C for 3–5 h. It has been found that aryl bromides can be coupled with aryl boronic acids in excellent yield under solvent-free condition. Phenyl iodide was also coupled with phenyl boronic acids in excellent yield, whereas phenyl chloride gave product in poor yield. And KF, CsF or Bu4NF were also found to be a convenient base additive.
Removal Characteristics of Heavy Metal by Na-P1 Zeolite Synthesized from Coal Fly Ash
Lee Mingyu,Lee Donghwan,Oh Yunghee,Ahn Byoungjoon The Korean Environmental Sciences Society 1997 Environmental sciences Vol.1 No.2
This study was conducted for an efficient utilization of waste fly ash obtained from the power plant. Fly ash was used for synthesizing zeolite. Na-P1 zeolite could be easily synthesized from waste fly ash and showed the potential to remove heavy metal ions. The synthetic zeolite showed good adsorption property for heavy metal much better than raw fly ash and natural zeolites. Na-P1 exhibited the high adsorption efficiency with a maximum value of 260 Pb mg/g and strong affinity for $Pb^{2+}$ ion. The metal ion selectivity of Na-P1 was determined in a decreasing order : $Pb^{2+}>Cd^{2+}>Cu^{2+}>Zn^{2+}>Fe^{3+}$.
Stoichiometric Effects. Correlation of the Rates of Solvolysis of Isopropenyl Chloroformate
Zoon Ha Ryu,Young Ho Lee,Yunghee Oh 대한화학회 2005 Bulletin of the Korean Chemical Society Vol.26 No.11
Solvolysis rates of isopropenyl chloroformate (3) in water, D2O, CH3OD and in aqueous methanol, ethanol, 2,2,2-trifluoroethanol (TFE), acetone, 1,4-dioxane as well as TFE-ethanol at 10 oC are reported. Additional kinetic data for pure water, pure ethanol and 80%(w/w) 2,2,2-trifuoroethanol (T)-water (W) at various temperatures are also reported. These rates show the phenomena of maximum rates in specific solvents (30% (v/v) methanol-water and 20% (v/v) ethanol-water) and, variations in relative rates are small in aqueous alcohols. The kinetic data are analyzed in terms of GW correlations, steric effects, kinetic solvent isotope effects (KSIE), and a third order model based on general base catalysis (GBC). Solvolyses based on predominately stoichiometric solvation effect relative to medium solvation are proceeding in 3 and the results are remarkably similar to those for p-nitrobenzoyl chloride (4) in mechanism and reactivity.
Se Bok Jang,Jong Yul Park,Yunghee Oh Kim,Yang Kim Korean Chemical Society 1993 Bulletin of the Korean Chemical Society Vol.14 No.1
Two crystal structures of dehydrated $Ag_{3.3}Ca_{4.35}-A ({\alpha} = 12.256(2){\AA})$ and of its ethylene sorption complex (${\alpha} = 12.259(2){\AA}$) have been determined by single-crystal X-ray diffraction techniques in the cubic space group Pm3m at 21(l)$^{\circ}$C. Both crystals were dehydrated at 360$^{\circ}$C and $2{\times}10^{-6}$ Torr for 2 days and one crystal was treated with 200 Torr of ethylene at 24(2)$^{\circ}$C. The structures were refined to final error indices, $R_1$=O.065 and $R_2$ = 0.088 with 202 reflections and $R_1$=0.049 and $R_2$ = 0.044 with 259 reflections, respectively, for which I>3${\sigma}$(I). In these structures, all Ag$^+$ and Ca$^{2+}$ ions are located on two and three different threefold axes associated with 6-ring oxygens, respectively. In $Ag_{3.3}Ca_{4.35}-A{\cdot}6.65\;C_2H_4,\;3.3\;Ag^+\;and\;3.35\;Ca^{2+}$ ions are recessed 1.09 ${\AA}$ and 0.21 ${\AA}$, respectively, into the large cavity from the (111) plane at O(3). Each Ag$^+$ and Ca$^{2+}$ ion in the large cavity forms a complex with one $C_2H_4$</TEX molecule. Distances between Ca$^{2+}$ ions and ethylene molecules are longer than those between Ag$^+$ ions and ethylene molecules.