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采用傅里叶红外光谱仪(FT-IR)和振动圆二色谱仪(VCD),在氘代溶剂(CDCl3和DMSO-d6)中检测槐果碱的IR和VCD光谱.运用密度泛函算法(DFT),分别在极化连续介质模型(PCM)以及显示溶剂模型和隐式溶剂模型的结合模型(Explicit+PCM)中模拟优化,得到槐果碱的两种构象异构体:C/D-cis和C/D-trans.在B3LYP/6-311+G(d,p)水平上计算这两种构象异构体的理论IR和VCD光谱,并与相应的实验光谱进行对比.玻尔兹曼分布显示,在不同溶液状态下,C/D-cis和C/D-trans均以一定比例共存.其中,在Explicit+PCM-CDCl3模型中模拟优化后的计算结果与相应的实验结果(CDCl3溶剂中检测的IR和VCD光谱)吻合度最高,从而确定了槐果碱分子的绝对构型和构象分布.
IR and VCD spectra of sophocarpine were measured in deuterated solvents (CDCl3 and DMSO-d6) by Fourier transform infrared spectroscopy (FT-IR) and vibrational circular dichroism spectroscopy (VCD) ) Were simulated and optimized in the polarization continuum medium model (PCM) and the combined model (Explicit + PCM) of the display solvent model and the implicit solvent model respectively to obtain two conformational isomers of sophocarpine: C / D-cis And C / D-trans. Theoretical IR and VCD spectra of these two conformers were calculated at the B3LYP / 6-311 + G (d, p) level and compared with the corresponding experimental spectra. The results show that C / D-cis and C / D-trans all coexist in a certain proportion under different solution conditions. Among them, the results of simulation and optimization in Explicit + PCM-CDCl3 model are consistent with the corresponding experimental results In the detection of IR and VCD spectra) the highest degree of coincidence, so as to determine the absolute configuration and conformational distribution of sophocarpine molecules.