银杏内酯分子结构和光谱性质的理论研究

采用密度泛函理论方法详细考察四种银杏内酯分子(银杏内酯A、B、C和J)的结构和光谱性质.研究发现，改变银杏内酯上的取代基，银杏内酯分子骨架具有相对稳定的结构.基于优化得到的稳定结构，我们计算得到了四种银杏内酯分子的红外(Infrared,IR)光谱、拉曼(Raman)光谱和振动圆二色(Vibrational circular dichroism,VCD)光谱性质.我们发现，四种银杏内酯分子的IR光谱图在1100 cm-1有较明显的区别，这些振动峰主要是银杏内酯分子中C-O-C键的伸缩振动峰.在Raman光谱图中，波长在3600cm-1处为银杏内酯分子中羟基的伸缩振动，银杏内酯A、银杏内酯B、银杏内酯C分裂成了两个强度不等的振动峰，而银杏内酯J分子表现为一个宽的振动峰.在VCD光谱图中，我们发现四种银杏内酯分子在3800 cm-1附近有明显的区别.

Theoretical study on molecular structures and spectral properties of ginkgolides

In this work, four ginkgolide molecules (ginkgolides A, B, C and J) were selected as the research objects, and their structures and spectral properties were investigated by density functional theory method. Our results indicated that the molecular skeleton of ginkgolides has a relatively stable structures by changing the substituents on ginkgolides. Based on the optimized structures, we calculated the Infrared (IR), Raman, vibrational circular dichroism (VCD) spectral properties of four ginkgolide molecules. We found that the IR spectra of the four ginkgolide molecules have obvious difference at 1100 cm-1, and this peak is mainly the stretching vibration mode of the C-O-C bond in ginkgolides. For the Raman spectra, the stretching vibration of the hydroxyl group is located at 3200 cm-1, where ginkgolides A, B and C split into two peaks, while ginkgolide J displays a somewhat wide vibrational peak. For the VCD spectra, we found that four ginkgolide molecules are distinctly different around 3800 cm-1.