• Bulletin of the Korean Chemical Society
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• 제28권3호
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• pp.391-396
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• 2007

The three-dimensional structure of an inorganic crystal, CaMoO4 (space group I 41/a, a = 5.198(69) A and c = 11.458(41) A), was determined by electron crystallography utilizing a high voltage electron microscope. An initial structure of CaMoO4 was determined with 3-D electron diffraction patterns. This structure was refined by crystallographic image processing of high resolution TEM images. X-ray crystallography of the same material was performed to evaluate the accuracy of the TEM structure determination. The cell parameters of CaMoO4 determined by electron crystallography coincide with the X-ray crystallography result to within 0.033-0.040 A, while the atomic coordinates were determined to within 0.072 A.

• Applied Microscopy
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• 제47권3호
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• pp.160-164
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• 2017

Electron crystallography has been used as the one of powerful tool for studying the structure of biological macromolecules at high resolution which is sufficient to provide details of intramolecular and intermolecular interactions at near-atomic level. Previously it commonly uses two-dimensional crystals that are periodic arrangement of biological molecules, however recent studies reported a novel technical approach to electron crystallography of three-dimensional crystals, called micro electron-diffraction (MicroED) which involves placing the irregular and small sized protein crystals in a transmission electron microscope to determine the atomic structure. In here, we review the advances in electron crystallography techniques with several recent studies. Furthermore, we discuss the future direction of this structural approach.

• Bulletin of the Korean Chemical Society
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• 제23권7호
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• pp.1042-1044
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• 2002

• Bulletin of the Korean Chemical Society
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• 제23권11호
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• pp.1545-1547
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• 2002

A new insecticide, bistrifluron acts as an inhibitor of insect development and interferes with the cuticle formation of insects. Since it shows low acute oral and dermal toxicities, it can be one of potent insecticides. Based on X-ray crystallography, NMR spectroscopy and molecular modeling, the structural studies of bistrifluron have been carried out.

• Natural Product Sciences
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• 제9권1호
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• pp.28-30
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• 2003

A sesquiterpene lactone, 1-O-acetyl-4R,6S-britannilactone (1) which has a new stereochemistry was isolated from the flowers of Inula britannica L. var.chinensis (Rupr.) Reg. Its stereostructure was determined by a x-ray crystallography.

• Bulletin of the Korean Chemical Society
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• 제22권10호
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• pp.1101-1104
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• 2001

• Applied Microscopy
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• 제36권spc1호
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• pp.1-7
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• 2006

The three-dimensional structure of an inorganic crystal, $SmZn_{0.67}Sb_2$ (space group $P4/nmm,\;a=4.30(3){\AA}\;and\;c= 10.27(1){\AA}$), was refined by electron crystallography utilizing high voltage electron microscopy (HVEM). Effects of instrumental resolution, image quality, beam damage and specimen tilting on the structure refinement have been evaluated. The instrumental resolution and image quality were the most important factors on the final results in the structure refinement, while the beam damage and specimen tilting effects could be experimentally minimized or controlled. The average phase errors $({\Phi}_{res})$ for the [001], [100] and [110] HVEM images of $SmZn_{0.67}Sb_2$ were $10.1^{\circ},\;9.6^{\circ}\;and\;6.8^{\circ}$, respectively. The atomic coordinates of $SmZn_{0.67}Sb_2$ were consistent within $0.0013{\AA}{\sim}0.0088{\AA}$, compared to the X-ray crystallography data for the same sample.

• Journal of Applied Biological Chemistry
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• 제43권1호
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• pp.37-43
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• 2000

1,3,2-Dioxaphosphorinanes are suitable compounds for studying the stereochemistry of substitution at phosphorus. Cis- and trans-5-hydroxymethl-5-methyl-2-thiono-2ethoxy-1,3,2-dioxaphosphorinane were prepared, and their structures and stereochemistry unambiguously assigned by NMR and X-ray crystallography with acetoxy and 3,5-dinitrobenzoyloxy derivatives, respectively. Trans isomer gave $^{31}P$ NMR signal at higher field than cis isomer, and the ring proton Spectrum of cis isomer showed characteristic pattern for identifying its geometry. In X-ray crystallography they adopted a chair conformation with the ethoxy groups in the axial positions, and the sulfide groups in the equatorial positions. A flattening of the ring around the phosphorus center was noted, the POC bond angles were about $120^{\circ}$, and the C-O bonds in the ring were significantly longer than the C-O bond for the ethoxy group or the C-O bond for hydroxyl group.

• 한국결정학회지
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• 제19권1호
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• pp.1-6
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• 2008

Dilithio-o-carborane과 dipenyl disulfide를 반응(反應)하여 a phenyl thiolated o-carborane compound가 얻어 졌으며 X-ray crystallography로 밝혀진 이 compound의 구조(構造)와 ab initio 및 density functional theory로 계산(計算)한 이 compound의 구조문(構造間)에 conformational similarity가 있음을 확인(確認)하였다.

• 한국결정학회지
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• 제13권2호
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• pp.73-81
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• 2002

Triclinic system에는 2개의 point group들 1,(equation omitted), 그리고 monoclinic system에는 3개의 point groups, 2, m, 2/m 가 있는데/sup 1)/ point group들 1, 2, m은 polar point group이고 이 중의 1, 2는 enantiomorphous point group이며 point group들 (equation omitted)와 2/m은 centric point group으로 Laue group이라 일컬어진다./sup 2-4)/ 본 해설문에서는 point group들 1, (equation omitted)에서 나오는 2개의 space group들과 point group들 2, m, 2/m에서 유도되는 13개의 space group들의 좌표들을 유도하였다 . Monoclinic system에서는 unique axis b 만을 다루었고, 그리고 space group No. 14은 3가지로 해석하였으며 나머지는 standard space group만을 다루었다. 모든 space group diagram은 “International Tables for Crystallography, Volume A edited by Theo Hahn, Third revised edition published for The International Union of Crystallography by Kluwer Academic Publishers, 1992”에 기재되어 있다.