摘要
在密度泛函(DFT)理论6-31G水平下,运用不同泛函方法对黄芩素分子结构进行几何优化,并在B3LYP/6-311++G**水平下对几何优化后的分子结构模型进行1H NMR计算。通过各模型的1H核磁计算值变化趋势辅助确定实验谱中H的化学位移,并以与实验值最吻合的分子模型作为直接空间法解析黄芩素晶体结构的初始模型,通过蒙特卡洛/模拟退火全局搜索及Rietveld精修技术精修,表征黄芩素晶体结构,结果为:单斜晶系,P21/c空间群,晶胞参数a=0.787 351 nm、b=1.333 318 nm、c=1.165 971 nm、β=100.150°,Z=4。
Geometry optimization calculations were performed with different functional methods in density functional theory （DFT） at level 6 -31G, and then ~H NMR calculations were performed with B3LYP/6 -311 ＋ ＋ G level. The chemical shifts in the experi- mental ~ H NMR spectra were identified according to the changing trend of calculated ~ H NMR chemical shifts of baicalein, and the ini- tial structure unit for crystal structure solution was determined by comparing the experimental with the calculated 1H NMR spectra. The crystal structure of baicalein was determined directly from powder X-ray diffraction data using direct space approach and refined using Rietveld refinement techniques, and the result showed that the crystal structure of bacalein is monolinic, P21/c space group with cell parameters a of 0.787 351 nm, b of 1.333 318 rim, c of 1. 165 971 nm,/3 of 100. 150,and Z of 4.
出处
《四川大学学报（工程科学版）》
EI
CAS
CSCD
北大核心
2012年第6期171-174,共4页
Journal of Sichuan University (Engineering Science Edition)
关键词
晶体结构
粉末衍射
核磁氢谱
黄芩素
crystal structure
powder X-ray diffraction
i H NMR
bacalein
