• 한국세라믹학회지
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• 제25권5호
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• pp.473-478
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• 1988

In order to obtain the high purity $\beta$-SiC powder that possesses the excellent sinterability and is close to the spherical shape, the carbon black was mixed into the composition of Si(OC2H5)4-H2O-NH3-C2H5OH which the monodispersed spherical fine particles is formed the hydrolysis of Ethylsilicate and the mixture was carbonized under an argon atmosphere. Particle shpae, size and the yield of $\beta$-SiC powder were investigated according to the molar ratio of carbon/alkoxide and variations of reaction temperature and reaction time. The results of this study are as follow ; 1) The yield of $\beta$-SiC gained from the reaction for one hour at 150$0^{\circ}C$ almost got near 100% and the particle size of $\beta$-SiC from the reaction for 15 hrs at 150$0^{\circ}C$ was 0.2${\mu}{\textrm}{m}$ on the average and close to the spherical shape agglomerate state. 2) When the molar ratio carbon/alkoxide is over 3.1 and the reaction occurs at 145$0^{\circ}C$ for 5hrs, the carbon content has not an effect on the kind of crystal of product.

• 한국세라믹학회지
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• 제28권9호
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• pp.730-738
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• 1991

Machinable ceramics containing ${\beta}$-spodumene crystal was fabricated by melting method using domestic pyrophyllite. Raw materials were batched by molar ratio of 8:2, 7:3, 6:4, and 5:5 for fluorophlogopite and ${\beta}$-spodumene. These compounds were melted at 1450$^{\circ}C$ for 1 hr and formed in graphite mold. Base glasses were heat-treated according to 2-step schedule which was determined from DTA, XRD analysis and SEM observation. Fabricated machinable ceramics have excellent themal, chemical properties and machinability.

• 약학회지
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• 제35권5호
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• pp.427-431
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• 1991

A flavonoidal glycoside was isolated from the whole plant of Hydrocotyle japonica(Um belliferae) and identified as quercetin-3-O-$\beta$-D-galactoside quercetin-3-O-$\beta$-D-(hyperoside) (C$_{21}H_{20}O_{12}$.1/3 $H_2O$, yellow needle crystal, m.p. $249~250^{\circ}$, $[\alpha]^{28}_D^{\circ}$$-65.94^{\circ}$ in pyridine) by physicochemical properties and spectroscopic evidences(UV, IR, NMR and Mass etc., in comparison with authentic sample.

• 대한화학회지
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• 제19권2호
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• pp.85-91
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• 1975

피페리디노티오세미카르바지드의 결정구조가 X-선을 이용한 단결정 해석에 의하여 해명되었다. 공간군은 $P2_1/c$이며 단위세포는 4분자를 포함하고 있고, 단위세포는 4분자를 포함하고 있고, 세포상수는 $a=14.68{\pm}0.04,\;b=4.59{\pm}0.02,\;c=12.92{\pm}0.04{\AA},\;{\beta}=109.4{\pm}0.2^{\circ}$이다. 3차원적인 회절반점의 강도는 목측에 의하여 얻었다. 결정구조는 패터슨 함수의 해석으로 밝혔고, 원자좌표치는 최소자승법으로 정밀화하였으며 378개의 독립적인 회절반점에 대한 최종 R값은 0.14이었다. 수소결합에는 $N-H{\cdot}{\cdot}{\cdot}S$ 형과 $N-H{\ldots}N$형의 두종류가 있다. $N-H{\ldots}S$형의 길이는 3.28 및 $3.39{\AA}$이고, $N-H{\ldots}N$형의 길이는 $3.03{\AA}$이다. 수소결합외의 분자들을 연결하는 힘은 van der Wasls힘이다.

• 통합자연과학논문집
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• 제9권2호
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• pp.94-102
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• 2016

The crystal structure of the potential active 6-ethoxy-3-phenyl-5a,9a-dihydro-3H-chromen[4,3-c][1,2]oxazole-3a(4H)-carbonitrile ($C_{19}H_{15}N_2O_3$) has been determined from single crystal X-ray diffraction technique. The title compound crystallizes in the monoclinic space group C2/c with unit cell dimension a= 29.3026(9) ${\AA}$, b= 6.7695(2) ${\AA}$ and c= 19.7597(6) ${\AA}$ [${\alpha}= 90^{\circ}$, ${\beta}= 125.709(10)^{\circ}$ and ${\gamma}= 90^{\circ}$]. Single crystals suitable for X-ray diffraction were obtained by slow evaporation method, the isoxazole and six membered pyran rings adopts envelope conformation. The crystal packing of the molecules is stabilized by the weak $C-H{\ldots}N$ hydrogen bond interaction.

• 통합자연과학논문집
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• 제9권2호
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• pp.103-112
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• 2016

The crystal structure of the potential active Methyl 8-bromo-3-phenyl-5a,9a-dihydro-3H-chromen [4,3-c][1,2] isoxazole-3a(4H)-carboxylate ($C_{18}H_{15}BrNO_4$) has been determined from single crystal X-ray diffraction technique. The title compound crystallizes in the triclinic space group Pī with unit cell dimension a=8.3129 (3) ${\AA}$, b=9.5847 (4) ${\AA}$ and c=11.1463(4) ${\AA}$ [${\alpha}=98.457(3)^{\circ}$, ${\beta}=102.806(2)^{\circ}$ and ${\gamma}=105.033(5)^{\circ}$]. Single crystals suitable for X-ray diffraction were obtained by slow evaporation method, the isoxazole and six membered pyran rings adopts envelope conformation. In the crystal, molecules are linked via pairs of inter molecular $C-H{\ldots}O$ hydrogen bonds to form dimmers.

• Bulletin of the Korean Chemical Society
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• 제23권11호
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• pp.1527-1530
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• 2002

1,12-diazacyclodocosane-2,11-dione was first isolated from a plant Phyllanthus niruri Linn. Its structure has been determined by means of spectroscopy methods and X-ray crystallography. Two peptide groups in the big ring (lactam) are the main factors influencing intermolecular contacts. The hydrogen-bond interaction of these hydrophilic groups is observed in the crystal structure. Meanwhile, C-H···O hydrogen bonds in molecules contribute to the formation of the whole crystal. These two kinds of hydrogen-bond form six- member rings among molecules. This compound crystallizes in the triclinic space group P-1 with a= 9.588(1) $\AA$, b= $9.850(1)\AA$, c = $11.810(1)\AA$, $\alpha=$ 68.18(1)$^{\circ}C$ , $\beta=$ 84.98(1), $\gamma$ = 86.03(1)$^{\circ}C$ , V = $1030.66(17)\AA3$ , Z = 2. A disorder of five-member carbon chain in the whole ring is observed in the title compound. The bond angle 105.8(4) is determined for a extreme configuration C(14)-C(15)-C(16), and 117.7(10) for another extreme configuration C(14')-C(15')-C(16'). In this crystal, two molecules are tied each other by short intermolecular hydrogen bonds, the oxygen atom being tied by hydrogen bond to nitrogen atom of another two molecules. The NMR and IR spectral data coincides to the structure of the compound.

• Archives of Pharmacal Research
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• 제2권2호
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• pp.99-110
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• 1979

The crystal structure of sulfapyridine, $C_{11}H_{11}N_{3}O_{2}S$, has been determined by X-ray diffraction method. The compound crystallizees in the monoclinic space group C2/c with a = 12, 80(4), b= 11.72(4), $c= 15.36(5){\AA}, {\beta}= 94(3)^{\circ}$and Z = 8. A total of 1133 observed reflections were collected by the Weissenberg method with CuKaradiation. Structure was solved by the heavy atom method and refined by isostropic block-diagonal least-squares method to the R value of 0.14. The nitrogen in the pyridine ring of sulfapyridine is associated with an extra-annular hydrogen. The C (benzene ring) S-N-C (pyridine ring) group adopts the gauche form with a fonformational angle of $71^{\circ}$. The benzene ring are inclined at angle of $84^{\circ}.to the pyridine ring plane. Sulfapyridine shows three different hydrogen bonding in the crystal. They are two N-H...O hydrogen bonds with the distance of 2.90 and 2.98${\AA}$ respectively, and on N-H...N with the distance of 3.06 ${\AA}$.

• 통합자연과학논문집
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• 제6권4호
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• pp.197-204
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• 2013

The crystal structure of the potential active 4,6-dimethyl-9-phenyl-8,12-dioxa-4,6-diazatetracyclo [8.8.0.02,7.013,18] octadeca-2(7),13,15,17-tetraene-3,5,11-trione 2-ethoxyphenyl (2E)-but-2-enoate ($C_{22}H_{18}N_2O_5$) has been determined from single crystal X-ray diffraction data. In the title compound crystallizes in the monoclinic space group $P_12_1/c_1$ with unit cell dimension a=15.2039(8), b=12.3888(6) and c= 9.8162(5) [alpha & $gamma=90^{\circ}$ beta=98.113(2)]. In the structure fused pyrone and pyran rings each adopt a sofa/envelop conformation. The crystal structure is stabilized by intramolecular C-H... O hydrogen bond interaction.

• 대한화학회지
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• 제63권1호
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• pp.29-36
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• 2019

A potentially tetradentate Schiff base ligand, 2-((2-((pyridin-2-ylmethylene)amino)ethyl)amino)ethan-1-ol (PMAE), and its cadmium(II) complex, [$Cd(PMAE)I_2$] (1), were prepared and characterized by elemental analysis, FT-IR, Raman, $^1H$ and $^{13}C$ NMR spectroscopies and single-crystal X-ray diffraction. In the crystal structure of 1, the cadmium atom has a slightly distorted square-pyramidal geometry and a $CdN_3I_2$ environment in which the PMAE acts as an $N_3$-donor. In the crystal packing of the complex, the alcohol and amine groups of the coordinated ligands participate in hydrogen bonding with iodide ions and form $R^2{_2}(14)$ and $R^2{_2}(8)$ hydrogen bond motifs, respectively. In addition to the hydrogen bonds, the crystal network is stabilized by ${\pi}-{\pi}$ stacking interactions between pyridine rings. The thermodynamic stability of the isolated ligand and its cadmium complex along with their charge distribution patterns were studied by DFT and NBO analysis.