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运用量子化学密度函数理论B3LYP/ 6 31G 方法计算了石杉碱甲的电子结构和红外光谱 ,得到了与实验结果的谱图特征基本一致的红外振动光谱 .通过对振动模式的分析 ,指认了 1 0 2个振动模式中分离得比较完全的 45个振动模式 ,结果表明其吡啶酮CO伸缩振动的红外活性最强 ,吡啶酮NH键的伸缩振动的频率最高 .涉及可形成氢键的石杉碱甲氨基氢及吡啶酮内酰胺氢的红外振动吸收的理论值与实验值差异较大 ,其原因是在晶体中存在分子间氢键 ,这不仅改变了这些氢在空间的取向 ,而且也改变了键的力学性质 ,导致红外振动吸收频率发生改变
The electronic structure and infrared spectra of huperzine A were calculated by using the B3LYP / 6 31G method of quantum chemical density function, and the infrared vibration spectra were obtained which were basically the same as those of the experimental results.According to the analysis of vibration modes, 1 The results showed that the CO stretching vibration of pyridone had the strongest IR activity and the NH stretching vibration of pyridone had the highest frequency.Related to the formation of hydrogen bond of huperzine The theoretical values of the infrared vibrational absorption of methylamino hydrogen and pyridone lactams are quite different from the experimental values due to the existence of intermolecular hydrogen bonds in the crystal which not only changes the orientation of these hydrogen in space but also changes The mechanical properties of the bond change the frequency of infrared vibration absorption