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KMID : 1059520070510010007
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Journal of the Korean Chemical Society
2007 Volume.51 No. 1 p.7 ~ p.12
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DFT Studies on the Proton Affinities of Oxazole
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Lee Hyun-Mi
Lee Gab-Yong
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Abstract
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The oxazole plays an important role in the binding of lexitropsin to the guanine-cytosine base pair from minor groove of DNA. The geometry optimization is performed with DFT calculations for the two possible conformations of the protonated oxazole. The proton affinities are calculated at B3LYP level of theory with 6-31G* basis set for the optimized geometry. It is found that the proton affinites of the conformations in which the oxazole nitrogen is the protonation center are greater than that of the conformations in which the oxazole oxygen is the protonation center. This result is in good agreement with molecular electrostatic potential (MEP) contour map. The proton affinities are also studied for various substituted oxazoles with the electron-donating and -withdrawing groups to estimate substitutent effect on the proton affinity at the hydrogen bonding site of the oxazoles. it is shown that the electron-donating substituents increase the proton affinity of oxazole, while the electron-withdrawing substituents decrease it.
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KEYWORD
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Oxazole, Proton affinity, Substituent effect, DFT
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