基于密度泛函方法的梓醇红外光谱的预测

梓醇是一种具有特殊药理活性的环烯醚萜苷类化合物。采用密度泛函(DFT)B3LYP/6-311G**方法对梓醇分子的几何构型进行全优化，得到其几何构型参数，进一步计算得到梓醇的红外振动光谱，振动频率校正因子为0.96。对计算得到的振动频率进行归属和解析并与实验测定得到的梓醇IR光谱特征峰比较，发现理论计算出的IR光谱与实验测定IR特征峰位具有很好的一致性，说明所采用的DFT方法能够用于梓醇分子几何构型的优化，预测难以得到标准对照品的环烯醚萜苷类化合物的IR光谱数据。

Theoretical Study on Infrared Vibration Spectrum of Catalpol by DFT

The catalpol, which can be isolated from the Chinese traditional herbs Rehmannia glutinosa as an effective and active ingredient, is an iridoid glycoside with many pharmacological functions. The molecular structure and the infrared (IR) spectrum of catalpol were calculated using density-functional theory (B3LYP) at 6-311G** level, and the theoretical frequency was scaled by 0.96. The vibrational modes of IR spectrum were assigned and compared with that of the experimental data. The calculated IR spectral features from DFT are in good agreement with the experimental ones. The results indicate that DFT is an useful method for the structure optimization and IR spectrum calculation of the iridoid compounds, which can be isolated from natural resources and often with difficulty. The theoretical calculation results of IR spectrum can provide useful information for the prediction of the theoretical property and investigation of the structure-activity relationship of the iridoid compounds.