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    题名: (3R,4R,5R,7S)-7-(hydroxymethyl)-thiepane-3,4,5-triol的結構與13C化學位移之理論計算研究
    其它题名: Theoretical studies of structures and 13C NMR chemical shifts for (3r,4r,5r,7s)-7-(hydroxymethyl)-thiepane-3,4,5-triol
    作者: 吳育陞;Wu, Yun-Sheng
    贡献者: 淡江大學化學學系碩士班
    王伯昌;Wang, Bo-Cheng
    关键词: 理論計算;密度泛函理論;化學位移;NMR calculation;MSTD;Thiepane
    日期: 2013
    上传时间: 2014-01-23 13:46:48 (UTC+8)
    摘要: 在本論文研究中，我們選擇了DFT/B3LYP/6-311++G(d,p)計算方法來進行(3R,4R,5R,7S)-7-(hydroxymethyl)thiepane-3,4,5-triol的結構最佳化計算，並接著使用此計算方法來進行計算波茲曼分佈貢獻，計算結果顯示TCS2、TCS5及TCS6這三個構形為(3R,4R,5R,7S)-7-(hydroxymethyl)-thiepane-3,4,5-triol七種異構物中最主要的分佈。在(3R,4R,5R,7S)-7-(hydroxymethyl)thiepane-3,4,5-triol 13C NMR化學位移理論計算方面挑選了GIAO/DFT/B3LYP、GIAO/DFT/OPBE、GIAO/DFT/mPW1PW91 andGIAO/HF等四種計算方法並搭配6-311++G(d,p)、6-311+G(2d.p)、cc-pVDZ及cc-pVTZ四種基底函數來做計算。
    TC2 ,TC5,TC6三個構形的13C NMR化學位移計算結果與實驗值相當接近，與實驗值相比較的結果可以得到相當低的MAE及RMS值。DFT/OPBE/6-311+G(2d.p)是(3R,4R,5R,7S)-7-(hydroxymethyl)thiepane-3,4,5-triol 13C NMR化學位移理論計算最適用的方法，在混合構形的計算結果MAE值為1.9 ppm，RMS值為2.4 ppm。
    In this study, the optimized structures, relative Gibbs free energy, and Boltzman weighting factor of (3R,4R,5R,7S)-7-(hydroxymethyl)thiepane-3,4,5-triolconformers were obtained by using DFT/B3LYP/
    6-311++G(d,p) method. Among these conformers, we selected the TC2, TC5, TC6 to be the major contribution conformers because they exhibited a quite low total energy compared with other conformers. For the NMR calculation, the GIAO/DFT/B3LYP, GIAO/DFT/OPBE, GIAO/DFT/mPW1PW91 and GIAO/HF single point calculation with 6-311++G(d,p),6-311+G(2d.p),cc-pVDZ and cc-pVTZ basis set of (3R,4R,5R,7S)-7-(hydroxymethyl)thiepane-3,4,5-triol were conducted to generate their 13C NMR chemical shifts.TC2,TC5,TC6 calculation result was very closed correlation with experimental, it was generated lower MAE and RMS value.
    A good calculation method and basis set choice to evaluate the theoretical chemical shifts for these conformers is DFT/OPBE/6-311+G(2d.p), the MAE value is 1.9 ppm
    RMS value is 2.4 ppm.
    显示于类别:[化學學系暨研究所] 學位論文

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