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采用密度泛函理论(DFT)方法和极化连续介质模型(PCM),在B3LYP/6-311++G**水平上对五味子丙素的一个立体异构体的基态几何构型进行了优化;以优化得到的稳定构型为基础,采用含时密度泛函理论(TD-DFT)方法,在相同基组水平进行了电子圆二色谱(ECD)研究,根据计算获得的电子跃迁吸收波长(λ)和电子旋转强度(R)拟合得到了理论ECD谱。理论研究发现:甲醇溶液中,2个苯环之间扭曲形成的二面角∠C(2)-C(1)-C(8)-C(7)约为64°;计算获得的理论ECD谱吸收峰略红移,各谱带形状与实验谱吻合较好。通过对相关跃迁性质的分析发现,理论ECD谱的吸收峰1主要由自于HOMO-2→LUMO和HOMO-2→LUMO+1的电子跃迁贡献;吸收峰2的吸收主要由HOMO→LUMO的电子跃迁贡献。这些结论对深入理解五味子丙素异构体的电子结构和手征光学性质具有一定的科学意义。
The ground state geometries of one stereoisomer of Schisandrin were optimized at the B3LYP / 6-311 ++ G ** level using density functional theory (DFT) and polarized continuum model (PCM) ; Based on the optimized stable configuration, the electronic circular dichroism (ECD) study was carried out on the same basis set using the time-dependent density functional theory (TD-DFT) method. Based on the calculated electron transition absorption wavelength λ) and the electronic rotation strength (R) fitted theoretical ECD spectra. Theoretical studies have found that the dihedral angle ∠C (2) -C (1) -C (8) -C (7) formed by the twisting between two benzene rings in methanol solution is about 64 °. The theoretical ECD Spectrum absorption peak slightly red shift, the shape of each band and experimental spectrum good agreement. Through the analysis of the related transition properties, it is found that the absorption peak 1 of the theoretical ECD spectrum is mainly contributed by the electron transition from HOMO-2 → LUMO and HOMO-2 → LUMO + 1; the absorption peak 2 mainly consists of HOMO → LUMO Jump contribution. These conclusions have certain scientific significance for the further understanding of the electronic structure and the chiral optical properties of the isomers of Schisandra chinensis.