Electronic Structure and Circular Dichroism of Natural Alboatisins Isolated from Aerial Parts of Isodon Albopilosus: DFT and TDDFT Study |
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| Authors: | Gao-zhang Gou Bo Zhou Ling Shi Shao-ming Chi Xian-lan Chen Wei Liu |
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| Affiliation: | 1.School of Science, Honghe University, Mengzi 661199, China;Key Laboratory of Natural Pharmaceutical and Chemical Biology of Yunnan Province, Mengzi 661199, China2.School of Science, Honghe University, Mengzi 661199, China3.College of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming 650500, China |
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| Abstract: | The stable conformations of a series of bioactive molecules, (?)-alboatisins A?C, are identified via Monte Carlo searching with the MMFF94 molecular mechanics force field. Then, the optical rotation (OR) values, vibrational circular dichroism (VCD), and electronic circular dichroism (ECD) spectra were calculated using the gradient-corrected density functional theory method. The vibrational and transition modes of molecular chirality were explored in terms of their microscopic origin. The calculated specific rotations are in agreement with the experimental values. From the OR analysis, it was concluded that optical rotation values areregulated by hydroxyl substitution. Vibrations occurring on the chiral skeleton may cause strong absorption in VCD spectra; VCD spectra are thus the spectral response to deformation vibrations on the chiral carbon skeleton. The lowest-energy negative Cotton effect is caused by σ→π* transition. Frontier molecular orbital analysis showed that strong ECD absorptions are produced when the dominant transition on the chiral skeleton is asymmetric; ECD spectra show the result of transitions lacking asymmetry on the chiral skeleton. |
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| Keywords: | Alboatisin Optical activity Density functional theory Circular dichroism Cotton effect |
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