• Korean Journal of Crystallography
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• v.15 no.1
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• pp.35-39
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• 2004

Two new nickel vanadium borophosphate cluster compounds, $(NH_4)_{10}[Ni(H_2O)_5]_4[V_2P_2BO_{12}]_6{\cdot}nH_2O$ (1) and $(NH_4)_{3.5}(C_3H_{12}N_2)_{3.5}[Ni(H_2O)_6]_{1.25}{[Ni(H_2O)_5]_2[V_2P_2BO_{12}]_6{\cdot}nH_2O$ (2) have been synthesized and structurally characterized. Inter-diffusion methods were employed to prepare the compounds. The cluster anion $[(NH_4)\;{\supset}\;V_2P_2BO_{12}]_6$ is used as a building unit in the synthesis of new compounds containing $Ni(H_2O){^{2+}_5}$ in the presence of pyrazine and 1,3-diaminopropane. Compounds contain isolated cluster anions with general composition ${[Ni(H_2O)_5]_n[(NH_4)\;{\supset}\;V_2P_2BO_{12}]_6}^{-(17-2n)}$ (n = 2, 4). Crystal data: $(NH_4)_{10}[Ni(H_2O)_5]_4[V_2P_2BO_{12}]_6{\cdot}nH_2O$, monoclinic, space group C2/m (no. 12), a = 27.538(2) ${\AA}$, b = 20.366(2) ${\AA}$, c = 11.9614(9) ${\AA}$, ${\beta}$ = 112.131(1)$^{\circ}$, Z = 8; $(NH_4)_{3.5}(C_3H_{12}N_2)_b[Ni(H_2O)_6]_{3.5}{[Ni(H_2O)_5]_2[V_2P_2BO_{12}]_6{\cdot}nH_2O$, triclinic, space group P-1 (no. 2), a = 17.7668(9) ${\AA}$, b = 17.881(1) ${\AA}$, c = 20.668(1) ${\AA}$, ${\alpha}$ = 86.729(1)$^{\circ}$, ${\beta}$ \ 65.77(1)$^{\circ}$, ${\gamma}$ = 80.388(1)$^{\circ}$, Z = 2.

• Journal of the Korean Vacuum Society
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• v.18 no.6
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• pp.481-487
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• 2009

To control the diameter size of the carbon nanofilaments (CNFs), SF6 was incorporated in the source gases ($C_2H_2/H_2$) during the initial deposition stage. The source gases and $SF_6$ were manipulated as the cyclic on/off modulation of $C_2H_2/H_2/SF_6$ flow in a thermal chemical vapor deposition system. The characteristics of the CNFs formation on the substrate were investigated according to the different cyclic modulation processes and the substrate temperatures. By $SF_6\;+\;H_2$ flow injection during the cycling etching interval time, the diameter size of CNFs was extremely decreased. The cause for the decrease in the diameter size of the individual CNFs by the cyclic on/off modulation process of $C_2H_2/H_2/SF_6$ flow was discussed in association with the slightly enhanced etching ability by the incorporation of $SF_6$.

• Bulletin of the Korean Chemical Society
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• v.26 no.9
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• pp.1359-1365
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• 2005

A series of new chiral [iminophosphoranyl]ferrocenes, {${\eta}^5-C_5H_4-(PPh_2=N-2,6-R_2-C_6H_3)$}Fe{${\eta}^5-C_5H_3-1-PPh^2-2-CH(Me)NMe_2$} (1: R = Me, $^iPr$), {${\eta}^5{-C_5H_4-(PPh_2=N-2,6-R_2}^1-C_6H_3)$}Fe{${\eta}^5-C_5H_3-1-(PPh_2=N-2,6-R_2-C_6H_3)-2-CH(Me)R_2$} (2: $R^1\;=\;Me,\;^iPr;\;R^2\;=\;NMe_2$, OMe), and $({\eta}^5-C_5H_5)Fe${${\eta}^5-C_5H_4-1-PR_2-2-CH(Me)N=PPh_3$} (3:R = Ph, $C_6H_{11}$) have been prepared from the reaction of [1,1'-diphenylphosphino-2-(N,N-dimethylamino) ethyl]ferrocene with arylazides (1 & 2) and the reaction of phosphine dichlorides ($R_3PCl_{2}$) with [1,1'-diphenylphosphino-2-aminoethyl]ferrocene (3), respectively. They form palladium complexes of the type $[Pd(C_3H_5)(L)]BF_4$ (4-6: L = 1-3), where the ligand (L) adopts an ${\eta}^2-N,N\;(2)\;or\;{\eta}^2$-P,N (3) as expected. In the case of 1, a potential terdentate, an ${\eta}^2$-P,N mode is realized with the exclusion of the –=NAr group from the coordination sphere. Complexes 4-6 were employed as catalysts for allylic alkylation of 1,3-diphenylallyl acetate leading to an almost stoichiometric product yield with modest enantiomeric excess (up to 74% ee). Rh(I)-complexes incorporating 1-3 were also prepared in situ for allylic alkylation of cinnamyl acetate as a probe for both regio- and enantioselectivities of the reaction. The reaction exhibited high regiocontrol in favor of a linear achiral isomer regardless of the ligand employed.

• Journal of the Korean Chemical Society
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• v.55 no.2
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• pp.183-188
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• 2011

The electronic structure and properties of Ni$(C_6H_{4-n}F_n)(CO)_2$ ($C_6H_4$=benzyne, n=1-4) complexes have been investigated using hybrid density functional B3LYP theory. Both aromatic natures and nucleus independent chemical shift (NICS) of the benzyne rings have been analyzed. Among mono-, di-, and tri-fluorinated complexes, 3-F, 3,6-F, and 4-H are the most stable isomers, respectively. NICS values calculated at the several points above the ring centers are consistent with those based on the relative energies of the complexes. The atoms in molecules (AIM) analysis indicates that Ni-C bond distance is well correlated with the electron density of a ring critical point (${\rho}_{rcp}$) in all species.

• Journal of the Korean Chemical Society
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• v.14 no.2
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• pp.193-199
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• 1970

Further validity of the significant structure theory has been tested by calculating the viscosities of binary mixtures-three pairs of $C_6H_6(1)+C_6H_{12}\;(2),\;CCI_4\;(1)+C_6H_6{2}and\l;CCI_4(1)+C_6H_{12}(2)$-and also by calculating the viscosities of n-$C_5H_{12}\;and\;n-C_6H_{14}$ in the pressure range of 1 bar to 4000 bars. The results are quite satisfactory for both cases and provide another evidence for the validity of the significan structure theory.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.6
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• pp.398-403
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• 2001

In this paper, effective ionization coefficient for 6H-SiC is determined. Analytical formulas for the parallel plane breakdown voltage of the 6H-SiC p＋n junction are derived by employing the ionization coefficients. The analytical breakdown voltages show good agreement with the numerical results of Dmitriev＇s［3］and the experimental results of Cree Research［9］over the doping range from 10$^{15}$ cm$^{-3}$ to 10$^{18}$ cm$^{-3}$.

• Bulletin of the Korean Chemical Society
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• v.14 no.1
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• pp.113-117
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• 1993

Good yield synthetic routes for the production of new B-alkyl-dithiaborane clusters are reported. The syntheses of the B-alkyl-dithiaboranes are based on the use of Fischer-type carbene reagents to activate the B-H bonds of dithiaborane for alkyl-addition reactions and are the first examples of transition-mediated reactions of dithiaborane to be reported. Thus, reactions employing arachno-$S_2B_7H_8$- and $(CO)_5M{C(R_1)R_2}$ (M = Cr, W; $R_1 = CH_3,\;C_6H_5;\; R_2 = OCH_3,\;SC_6H_5)$ were found to yield the intermidiate anions I, $[(CO)_5M{C(R_1)R_2S_2B_7H_8}]^-$, which upon protonation gave the corresponding neutral, air-sensitive cluster arachno-4-$RCH_2-6,8-S_2B_7H_8(R=CH_3,\;IIa;\;C_6H_5,\;IIb)$ range from 30 to 35% yield. Complexes IIa and IIb are isoelectronic with arachno-6,8-$S_2B_7H_9$ and, on the basis of the spectroscopic data, are proposed to adopt a similar arachno cage geometry in which an $RCH_2$ units are substituted to 4 position boron atom of the arachno-6,8-$S_2B_7H_9$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.6
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• pp.290-296
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• 2003

The heteroepitaxial growth of crystalline 3C-SiC on 6H-SiC substrates using high purity silane ($SiH_4$) and prophane ($C_3H^8$) was carried out by thermal chemical vapor deposition, and growth characteristics were investigated in this study. In case that the flow ratio of C/Si and flow rate of $H_2$ were 4.0 and 5.0 slm, respectively, the growth rate of epilayers was about 1.8 $\mu$m/h at growth temperature of $1200^{\circ}C$. The Nomarski surface morphology, X-ray diffraction, Raman spectroscopy, and photoluninescence of grown epilayers were measured to investigate the crystallinity. In this study, the high quality of crystalline 3C-SiC heteropitaxial layers was observed at growth temperature of above $1150^{\circ}C$.

• Journal of Plant Biotechnology
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• v.33 no.1
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• pp.65-73
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• 2006

Regulatory mechanism for endogenous levels of castasterone (CS) and its biosynthetic precursors in shoots of maize was investigated by the use of enzyme solution prepared from the plant tissue. When [$^2H_0$]- and [$^2H_6$]-CS was used as substrates, [$^2H_0$]-26-norCS and [$^2H_3$]-28-norCS were identified as products, indicating that [$^2H_0$]- and [$^2H_6$]-CS are differently metabolized into [$^2H_0$]-26-norCS and [$^2H_3$]-28-norCS by C-26 and C-28 demethylation, respectively. This suggests that both C-26 and C-28 demethylation can be involved in CS catabolism. In fact that C-28 demethylation only occurred when isotope labeled substrate was used, however, C-26 demethylation is thought be a natural reaction occurred in the maize shoots. When 6-deoxoteasterone (6-deoxoTE) was used, 6-deoxo-26-norTE and 3-dehydro-6-deoxo-26-norTE as well as 6-deoxo-3-dehydroTE and 6-deoxotyphasterol (6-deoxoTY) were identified as enzyme products. When 6-deoxoTY was added, 6-deoxo-26-norTY as well as 6-deoxo-3-dehydroTE and 6-deoxoTE was identified as products. These indicate that C-26 demethylation of 6-deoxoTE, 6-deoxo-3-dehydroTE and 6-deoxoTY as well as a reversible C-3 epimerization from 6-deoxoTE to 6-deoxoTY intermediated by 6-deoxo-3-dehydroTE are operative in the maize shoots, demonstrating that endogenous levels of biosynthetic precursors of CS are also controlled by C-26 demethylation. Therefore, it is thought that C-26 demethylation is an important and a common deactivation process which functions to maintain steady state levels of endogenous brassinosteroids in the maize shoots.

• Toxicological Research
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• v.16 no.3
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• pp.179-185
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• 2000

Zinc is known to generate reactive oxygen species (ROS) including superoxide anion and hydrogen peroxide ($H_2O_2$), which eventually contribute to cytotoxicity in a variety of cell types. Here in, we demonstrated that zinc decreased the viability of C6 glial cells in a time and dose-dependent manner, which was revealed as apoptosis characterized by ladder-pattern fragmentation of genomic DNA. chromatin condensation and DNA fragmentation in Hoechst dye staining. Zinc-induced apoptosis of C6 glial cells was prevented by the addition of catalase and antioxidants including reduced glutathione (GSH), N-acetyl-L-cysteine (NAC) and pyrrolidinedithiocarbamate (PDTC). Wefurther confirmed that zinc decreased intrac-ellular levels of GSH and generated $H_2O_2$in C6 glial cells. Moreover, antioxidants also decreased the generation of zinc-induced $H_2O_2$ in C6 glial cells. These data indicated that zinc-induced the apoptotic death of C6 glial cells via generation of reactive oxygen species such as $H_2O_2$.