基于密度泛函理论的左旋延胡索乙素的红外、拉曼光谱研究

研究了左旋延胡索乙素的红外光谱(IR)、固体常规拉曼光谱(NRS)以及以新型Ag/Cu纳米材料为基底的表面增强拉曼光谱(SERS)。以密度泛函理论(DFT)，B3LYP/6-311+G(d,p)基组对其红外光谱和拉曼光谱进行了计算，给出了对应的光谱振动图，并利用Gauss view 5.0可视化软件对其峰位进行了全面归属。左旋延胡索乙素在3 300～2 500和1 800～600 cm-1波数范围内有明显的红外和拉曼峰，在左旋延胡索乙素的SERS中，Ag/Cu纳米基底利用SnCl₂和PVP作为结构导向剂，采用循环浸泡的方法，最终生成分散较好的银纳米颗粒，实现了很好的增强效应，分子获得了信号较强的选择性增强散射峰，其中1 500～1 400和1 000～700 cm-1波数范围内的增强效应最明显，经分析，该分子的亚甲基与银纳米表面吸附，苯环与银衬底夹角接近90°。左旋延胡索乙素的红外、拉曼光谱的理论计算和实验结果基本一致，存在一定差异的原因可能是因为分子之间的作用力等因素。可视化软件直观形象展示出了该分子的结构特征和分子基团振动情况，对其振动峰位的归属提供了重要的依据。左旋延胡索乙素是一种重要的中药试剂，包含于多种养心安神类药物当中，该研究为左旋延胡索乙素的快速、特征、痕量监测提供了依据，也为中枢抑制性镇痛药物的生物作用研究提供了重要参考。

IR and Raman Spectra Studies of Rotundine Based on DFT

Infrared spectroscopy (IR), the normal Raman spectroscopy (NRS) and the surface enhanced Raman spectroscopy (SERS) in new Ag/Cu nanomaterial of Rotundine were studied in the present paper. The IR and the NRS of Rotundine were calculated by the density functional theory (DFT) using B3LYP/6-311+G(d,p), then the spectral intensity graph of Rotundine were given. The vibrational peaks were assigned comprehensively by the visualization software of Gauss view 5.0. Rotundine has obvious infrared and Raman vibrational peak in the wave number range of 3 300～2500 and 1 800～600 cm-1. SnCl₂ and PVP was used as capping agent for the silver nanoparticles in SERS of Rotundine. Finally, by using the method of cyclic immersion well dispersed silver nanoparticles was obtained and achieved good enhancement effect. This molecule acquired strong selective enhancement vibration peak, In the wave number ranges of 1 500～1 400 and 1 000～700 cm-1 the enhancement effect is most obvious. After analyzed, the methylene of this molecule is adsorbed on the silver nanoparticles surface and the angle between the benzene ring and the silver substrate is close to 90°. The theoretically calculated spectra of Rotundine are consistent with the obtained experimental spectra. There are some differences may be due to the interaction forces between molecules and so on. The visualization software displayed the structure characteristics and molecular group vibration of this molecular visually and provided important basis for assigning the vibrational peaks. Rotundine is an important traditional Chinese medicine agent contained in many kinds of sedative drugs. The study provides a strong basis for the rapid, feature and trace identification of Rotundine and also supplies important reference for the biological role of central inhibition of analgesic drugs.