| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 1999: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1998: ¥2,800,000 (Direct Cost: ¥2,800,000)
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| Research Abstract |
Density Functional Study on 1,2-Dimethoxyethane in Aqueous Solution. Conformational behavior of 1,2-dimethoxyethane (DME) in aqueous solution has been attracted in the field of experimental and theoretical structural chemistry for a long time. The conformational stability of DME is known to be strongly affected by solvent environment. In the present study, we have observed the Raman spectra of DME in aqueous solution at various concentrations and have calculated the conformational energies by density functional theory (DFT) via Tomasi's polarizable continuum model (PCM) to understand the conformational stabilization mechanism of DME in aqueous solution. In the gas phase, the TTT conformer is the most stable and the TGG' conformer, as stabilized by an intramolecular 1,5-CH・・・O interaction, is the second. The PCM ealculations show that in aqueous solution the TGT conformer is the most stable and the TGG conformer is the second. The TGG conformer is greatly stabilized in aqueous solution
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because of the dipole moment of this conformer which is much larger than that of the other conformers. The theoretical results are in excellent agreement with the Raman spectroscopic observations. The present study has indicated that the dielectric property of aqueous environment strongly affects the conformational stabilization of DME.
Density Functional Studies on Computational Accuracy in Normal Coordinate Analysis for Basic Molecules. Recently, density functional theory has rapidly developed and has shown that it calculates accurate chemical properties in a practical time. For the purpose of examining calculation accuracy in normal coordinate analysis using the density functional method, vibrational calculations were carried out using fundamental molecular observation wavenumbers which were reported in "Tables of Molecular Vibrational Frequencies" (T. Shimanouchi, 1972). The calculated wavenumbers by B3LYP using large basis sets are in good agreement with the observed wavenumbers at the accuracy of about 5%. As for the compounds involving halogens, calculated wavenumbers tend to deviate considerably to the lower wavenumber side. Less
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