Circular Dichroism of Crystals
| Project/Area Number |
14340220
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
機能・物性・材料
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| Research Institution | Ehime University |
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Principal Investigator |
KOSHIMA Hideko Ehime University, Faculty of Engineering, Associate Professor (20304644)
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| Project Period (FY) |
2002 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥15,000,000 (Direct Cost: ¥15,000,000)
Fiscal Year 2003: ¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 2002: ¥12,300,000 (Direct Cost: ¥12,300,000)
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| Keywords | Crystal Optical Activity / Circular Dichroism Spectra / Optical Rotatory Power / Chiral Crystals / Organic Crystals / Birefringence / Chirality / Helical Structure / 光学活性特性 |
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| Research Abstract |
Every chiral organic crystal has inherent optical activity. The sign and the magnitude of the optical activity of an organic crystal should reflect the molecular structure as well as the packing arrangement because the freedom of molecules is severely restricted in the crystal lattice, which is very different from the high mobility of molecules in solution. However, the optical activity of organic crystals has been scarcely measured and therefore never correlated with the crystal structure until the present time. The reason for this is that the measurement of optical activity of a crystal is accompanied with much difficulty due to birefringence being 10^3 times larger birefringence than the gyration tensor, so in this case the latter effect is masked. A few years ago, we first introduced a high accuracy universal polarimeter (HAUP) in chemistry. Recently, we prepared a new version of HAUP in order to measure circular dichroism spectra of crystals. Now the check of performance is in progress.
Herein the rotatory powers of helical-type cocrystal formed between tryptamine and 4-chlorobenzoic acid were determined by the HAUP method. After much trial and error, we could overcome the sample polish problem by using soft Fe_2O_3 polish agent and obtain satisfactorily the rotatory powers of the cocrystal from tryptamine and 4-chlorobenzoic acid. The results revealed that the helically arranged aromatic π electrons as well as the helical ionic and hydrogen bond networks in the crystal contributed to the enhancement of the magnitude of these rotations. This is the the first measurement of the optical activity of organic-organic cocrystal formed from two different achiral molecules.
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Report
(3 results)
Research Products
(23 results)
