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采用量子化学密度泛函理论在B3LYP/6-31+G**水平上对白芷中的5种香豆素类化合物分子几何构型进行全优化;用含时密度泛函理论在相同水平对上述化合物分子进行电子吸收光谱研究。为模拟真实条件,采用PCM模型,以甲醇为溶剂,计算其对分子电子结构和光谱性质的影响。计算结果表明:标题化合物分子母环发生共轭形成大π键,为刚性的平面分子结构。分子△E_(gap)随着共轭体系的减少而增大;蛇床子素共轭体系最小,△E_(gap)最大;8,甲氧基异欧前胡素2个取代基氧原子与母环存在p-π共轭,共轭体系最大,△E_(gap)最小;佛手柑内酯、异欧前胡素、欧前胡素分子共轭体系类似,△E_(gap)相近。计算所得的标题化合物理论紫外吸收图谱均存在3个吸收峰。甲醇溶液使标题化合物分子△E_(gap)减小,吸收光谱λ_(max)红移;研究还发现,甲醇溶剂改变了部分λ_(max)的主要电子跃迁来源轨道。
Quantum chemical density functional theory at the B3LYP / 6-31 + G ** levels of Angelica in the five kinds of coumarins molecular geometry optimization; using time-dependent density functional theory at the same level of the above Compound molecules were studied by electron absorption spectroscopy. In order to simulate the real conditions, the PCM model was used and the influence of molecular weight on the electronic structure and spectral properties was calculated using methanol as solvent. The calculated results show that the title compound molecular conjugate forms a large π bond and is a rigid planar molecular structure. The △ △ gap of the molecule increases with the decrease of the conjugate system; the osmanthrin conjugate system is the smallest with the largest △ E gap; 8, the two substituent oxygen atoms of isoimperatorin and the parent The conjugates of p-π have the largest conjugate system and the smallest △ E-gap. The conjugates of bergapin, isoimperatorin and imperatorin have similar △ E gap. The calculated theoretical absorption spectrum of the title compound showed three absorption peaks. The methanol solution reduced the △ E gap of the title compound and the red shift of the absorption spectrum λ max. The study also found that the methanol solvent changed some λ max of the main electronic transition source orbitals.