(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

Theoretical Studies of Structures and13C NMR Chemical Shifts for (3R,4R,5R,7S)-7- (hydroxymethyl)-thiepane-3,4,5-triol

吳育陞(Yun-Sheng Wu)

指導教授 ： 王伯昌

淡江大學/理學院/化學學系碩士班/碩士(2013年)

https://doi.org/10.6846/TKU.2013.00254

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。

關鍵字

理論計算 ； 密度泛函理論 ； 化學位移

並列摘要

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.

並列關鍵字

NMR calculation ； MSTD ； Thiepane

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