1999 Fiscal Year Final Research Report Summary
STUDY OF STRUCTURAL CHANGE ACCOMPANIED WITH PHASE TRANSITION AT LOW TEMPERATURES IN ORGANIC CRYSTALS
| Project/Area Number |
09640609
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical chemistry
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| Research Institution | OKAYAMA UNIVERSITY |
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Principal Investigator |
KASHINO Setsuo Okayama University, Faculty of Science, Professor, 理学部, 教授 (70032810)
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| Co-Investigator(Kenkyū-buntansha) |
KUBOZONO Yoshihiro Okayama University, Graduate School of Natural Science and Technology, Research Associate, 大学院・自然科学研究科, 助手 (80221935)
ISHIDA Hiroyuki Okayama University, Faculty of Science, Associate Professor, 理学部, 助教授 (70193331)
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| Project Period (FY) |
1997 – 1999
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| Keywords | organic crystals / phase transition / structural change / low temperature X-ray diffraction / hydrogen bond / intermolecular interactions |
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| Research Abstract |
The present study was aimed at determining the structures of organic crystals composed of molecules having functional groups with hydrogen-bonding ability and carbonyl groups with strong dipole moment by single-crystal X-ray diffraction method at room and low temperatures to get structural information toward the crystal design which can never be obtained by conventional room temperature experiments. 1 Crystal structures of ammonium hydrogen succinate and potassium hydrogen trans-glutaconate monohydrate were studied at the temperatures above and below the second order phase transition. Change in the crystal symmetry by the phase transition was not observed for both crystals. Difference in the temperature dependence above and below the phase transition was observed for hydrogen-bonding distances in the former crystals, while in the latter crystals no significant change was observed for the O...O distances of very short hydrogen bonds. It has been elucidated that the short hydrogen bonds
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take the single-minimum potential with the minimum at the inversion centers. 2 A short non-symmetric O-H...O hydrogen bond has been found in the crystals of ammonium hydrogen tartronate. No significant change was observed for the O...O distance of this hydrogen bond from room temperature to 20 K. it has been confirmed that the H atom involved in the hydrogen bond is bonded to a specified O atom. 3 The structure of thermochromic crystals of a charge-transfer (CT) complex of N-salicylindene-2-aminopyridine has been determined at room temperature and 80 K. A contribution of the keto form was observed even at 80 K for the molecular structure. It has been shown that weak intermolecular CT interactions modify the potential energy curve of an intramolecular hydrogen-bond system. 4 Crystal structure of the tannin geraniin heptahydrate, CィイD241ィエD2HィイD228ィエD2OィイD227ィエD2.7HィイD22ィエD2O has been determined at room temperature and 120 K. The molecular conformation and a complex system of 30 different hydrogen bonds have been elucidated. 5 Structural study at room temperature : The structure of a new methanol-water solvate of N-(1-adamantyl)acetamide has been established. It has been found that 2-pyridone forms intermolecular complexes through hydrogen-bonds with di-carboxylic acids and that the molecular composition of the complexes and the scheme of the hydrogen bonds in the crystals depend on whether the molecular of a di-carboxylic acids has a center of symmetry or no symmetry. Less
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Research Products
(12 results)
