• Proceedings of the PSK Conference
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• 2003.10b
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• pp.202.3-202.3
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• 2003

Two Known compounds, syringaresinol monoglucoside(8), chimaphilin(14), together with three new compounds, (9)[mp. $106{\sim} 111^{\circ}C$, C_{29}H_{44}O_{13}$], (10)[mp. $180{\sim}182^{\circ}C$, $C_{15}H_{20}O_{9}$] and (11)[mp. $100{\sim}105^{\circ}C$, $C_{18}H_{28}O_{8}$] were isolated from the BuOH fractionof Pyrola japonics(Pyrolaceae). The structures of the known compounds were determined by chemical and spectorscopic methods. The assignments of the $^{1}H-$ and $^{13}C-NMP$ spectra of these compounds were carried out by two-dimensional $^1H-^1H-COSY$, NOESY and $^1H-^{13}C$ multiple-bond, multiplequantum spectroscopic correlation techniques. The characterization of the three new compounds is now in progress.

• Bulletin of the Korean Chemical Society
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• v.24 no.2
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• pp.197-204
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• 2003

The intracluster ion-molecule reactions of $Ti^+(H_2O)_n,\;Ti^+(CH_3OCH_3)_n,\;and\;Ti^+(CH_3OD)_n$ complexes produced by the mixing of the laser-vaporized plasma and the pulsed supersonic beam were studied using a reflectron time-of-flight mass spectrometer. The reactions of $Ti^+$ with water clusters were dominated by the dehydrogenation reaction, which produces $TiO^+(H_2O)_n$ clusters. The mass spectra resulting from the reactions of $Ti^+\;with\;CH_3OCH_3$ clusters exhibit a major sequence of $Ti^+(OCH_3)_m(CH_3OCH_3)_n$ cluster ions, which is attributed to the insertion of $Ti^+$ ion into C-O bond of $CH_3OCH_3$ followed by $CH_3$ elimination. The prevalence of $Ti^+(OCH_3)_m(CH_3OD)_n$ ions in the reaction of $Ti^+\;with\;CH_3OD$ clusters suggests that D elimination via O-D bond insertion is the preferred decomposition pathway. In addition, the results indicate that consecutive insertion reactions by the $Ti^+$ ion occur for up to three precursor molecules. Thus, examination of $Ti^+$ insertion into three different molecules establishes the reactivity order: O-H > C-O > C-H. The experiments additionally show that the chemical reactivity of heterocluster ions is greatly influenced by cluster size and argon stagnation pressure. The reaction energetics and formation mechanisms of the observed heterocluster ions are also discussed.

• Bulletin of the Korean Chemical Society
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• v.32 no.1
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• pp.325-328
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• 2011

• Progress in Superconductivity and Cryogenics
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• v.23 no.2
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• pp.14-18
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• 2021

We investigated the structural suitability of GdFeO₃ (GdFO) as a buffer layer for the GdBa₂xCu₃O_7-x (GdBCO) superconducting films. GdFO films with different thicknesses and GdBCO thin films were all prepared by using a pulsed laser deposition technique. The analyses of X-ray diffraction and EXAFS data indicates that the c-axis parameter increases and the Fe-O bond length decreases with the GdFO thickness due to the compressive stain induced by the lattice mismatch between GdFO and STO substrate and as a result, the Debye-Waller factor, an index of disorder in the local structure near the Fe-O bond, increases with the GdFO thickness. However, for the GdBCO/GdFO bilayer structure, the Debye-Waller factor decreases as the GdFO thickness increases indicating a diminished disorder by the structural coupling between GdFO and GdBCO. These results indicate that an appropriate thickness of GdFO is required to be utilized as a magnetic buffer layer for the GdBCO superconducting films.

• Journal of the Korean institute of surface engineering
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• v.29 no.5
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• pp.519-524
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• 1996

We synthesized semiconducting Sn-doped diamondlike carbon films by rf plasma-enhanced chemical vapor deposition using an organotin compound as a dopung gas source. XPS quan-titative analysis for the deposited films after 60 s argon ion etching revealed that Sn concen-tration increased with the partial pressure of the organotin compound in the reactant gas. In C 1s spectra, there was a component due to C-Su bond which had a negative chemical shift. C 1s spectra also indicated that the deposited films were relatively $sp^2$ rich. The chemical shift of the Sn-C bond in Sn $3d_{5/2}$ spectra was about +1.7 eV. The electrical resistivity and the optical transmittance were also investigated.

• Journal of the Korean Chemical Society
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• v.38 no.4
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• pp.283-287
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• 1994

The crystal stucture of bithional surfoxide, $C_{12}H_6Cl_4O_3S$, has been determined from 2295 independent reflections collected on an automated CAD-4 diffractometer with a graphite-monochromated $Mo-K\alpha$ radiation. The crystal belongs to the monoclinic, space group P2$_1$/n, with a unit cell dimensions a = 12.448(4), b = 9.740(1), c = $11.815(2)\AA$, $\beta$ = $100.06^{\circ}$, $\mu$ = 9.02 cm$^{-1}$, Dm = 1.76 g/cm$^3$, Dc = 1.75 g/cm$^3$, F(000) = 744, and Z = 4. The structure was solved by the direct method and refined by the least-squares method. The final R values was 0.037 for 2295 independent reflections. Overall conformation of the molecule is folded with respect to central surfur atom. Comparing with the molecular conformation of bithional, one of phenyl rings was swinged with about $180^{\circ}.$ This conformational change in the molecule results in the existance of intramolecular-hydrogen bond of S-O(3)---H-O(1) type and its steric hindrance between this moiety and the other phenyl ring. The two best planes of the phenyl rings have a maximum deviation of 0.009 $\AA$ for C(1) atom. The dihedral angle between two phenyl rings is $99.22^{\circ}.$ In the crystal structure, the molecules are packed with intermolecular-hydrogen bond of O(3)---H-O(2).

• Korean Journal of Materials Research
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• v.15 no.6
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• pp.375-381
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• 2005

High temperature oxidation behavior of thermal barrier coating (TBC) system (IN738 substrate + NiCoCrAlY or NiAl bond coat with or without Pt + yttria stabilized zirconia) prepared by air plasma spray (APS) process has been studied in order to understand the effect of Pt addition to bond coat on the stability of TBC system. Specimens were oxidized in thermal cycling and isothermal oxidation test at $1100^{\circ}C$. The Pt addition in TBC system with NiCoCrAlY bond coat showed a longer life time compared to that without addition of Pt. Pt addition to TBC system is believed to help the formation of more stable thermally grown oxide, $Al_2O_3$, at the TBC/bond coat interface, leading to a longer lifetime of TBC system.

• Bulletin of the Korean Chemical Society
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• v.33 no.9
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• pp.2976-2980
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• 2012

Nitrile-forming eliminations from (E)-2,4-$(NO_2)_2C_6H_2CH=NOC_6H_4-2-X-4-NO_2$ (1a-e) promoted by $R_3N$ in MeCN have been studied kinetically. The reactions are second-order and exhibit Br$\ddot{o}$nsted ${\beta}$ = 0.83-1.0 and ${\mid}{\beta}_{lg}{\mid}$ = 0.41-0.46. The results have been interpreted in terms of highly E1cb-like transition state with extensive $C_{\beta}$-H bond cleavage and limited $N_{\alpha}$-OAr bond cleavage. Comparison with existing data reveals that the structure of the transition state changes from E2-central to highly E1cb-like either by the change of the ${\beta}$-aryl group from Ph to 2,4-dinitrophenyl under the same condition or by the base-solvent system variation from $EtO^-$-EtOH to $Et_3N$-MeCN for a given substrate (1a-e).

• Bulletin of the Korean Chemical Society
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• v.34 no.7
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• pp.2036-2040
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• 2013

Reactions of 4-nitrophenyl 2-thiophenecarboxylate (1a-e) with $R_2NH/R_2NH{_2}^+$ in 20 mol % DMSO (aq) have been studied kinetically. The $2^{nd}$ order kinetics, ${\beta}_{nuc}$ = 0.88-0.98, and linear Hammett and Yukawa-Tsuno plots observed for these reactions indicate an addition-elimination mechanism in which the $2^{nd}$ step is rate limiting. The ${\beta}_{nuc}$ value increased with a stronger electron-withdrawing 5-thienyl substituent, the Hammett plots are linear except for X = MeO, and Yukawa-Tsuno plots are linear with ${\rho}$ = 0.79-1.32 and r = 0.28-0.93, respectively. The ${\rho}$ value increased and r value decreased with a stronger nucleophile, indicating an increase in the electron density at the C=O bond and a decrease in the resonance demand. These results have been interpreted with enhanced N-C bond formation in the transition state with the reactivity increase.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.3
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• pp.188-192
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• 2000

In this study PZT etching was performed using planar inductively coupled Ar/Cl$_2$/BCI$_3$ plasma. The etch rate of PZT film was 2450 $\AA$/min at Ar(20)/BCl$_3$(80) gas mixing ratio and substrate temperature of 8$0^{\circ}C$. X-ray photoelectron spectroscopy(XPS) analysis for films composition of etched PZT surface was utilized. The chemical bond of PbO is broken by ion bombardment and Cl radical, and the peak of metal Pb in a Pb 4f narrow scan begins to appear upon etching. As increasing additive BCl$_3$content the relative content of oxygen decreases rapidly in contrast with etch rate of PZT thin film. So we though that the etch rate of PZT thin film increased because abundant B and BCl radicals made volatile oxy-compound such as B$_{x}$/O$_{y}$ and/or BClO$_{x}$ bond. We achieved etch profile of about 80$^{\circ}$ at Ar(20)/BCl$_3$(80) gas mixing condition and substrate temperature of 8$0^{\circ}C$TEX>X>.