Jia Fei-yun, Su Yu, Ran Ming, Zhu Jiang, Zhang Bo
Guang Pu Xue Yu Guang Pu Fen Xi. 2016 Jan;36(1):60-3.
Infrared spectroscopy is an important source of information for the identification of the compounds structure and it is great significant for biological activity research of natural and organic drug molecules. With the theoretical calculation method is more reasonable and calculation accuracy continues to improve, Theoretical calculate advantage is more obvious in the infrared spectrum simulation and vibration modes attributable identified. And it has important reference value for experimental study of infrared spectral analysis. Using density functional theory, geometry optimizations and frequencies calculation of 7-Hydroxycoumarin were performed at the level of B3LYP/6-311G(d, p), the stable structure and all vibration modes of 7-Hydroxycoumarin were attained. The results show that the infrared absorption peak of 7-hydroxycoumarin is mainly distributed in the several regions in wave number of 3 700-3 500, 3 150-3 000, 1 750-1 400, 1 400-1 000, 1 000-50 cm(-1). In addition to the vibration in a wave number range of 3 700-3 500, 3 150-3 000 cm(-1) is relatively independent, and were attributed to OH stretching vibration and benzene ring CH stretching vibration, the other several vibration regions are more complex, the different degree of spectral peaks is composed of multiple vibration modes. Finally, based on the theoretical analysis of the vibration mode, the vibration modes of 7-Hydroxycoumarin molecule were assigned, and in order to discuss the reliability of theoretical calculation method, the correlation diagram of the main absorption peak of 7-hydroxyl group was drawn from the theoretical value of X axis and the experimental value of Y axis, the correlation between experimental IR data and calculated IR data of 7-Hydroxycoumarin was analyzed through the linear regression method. Results show that they have good correlation, correlation coefficient values "r" equals 0.998 5, and the theory calculation of 7-Hydroxycoumarin IR by density functional theory at the base set level is reliable.
红外光谱是鉴定化合物结构的重要信息来源，对天然和有机药物分子的生物活性研究具有重要意义。随着理论计算方法越来越合理且计算精度不断提高，理论计算在红外光谱模拟及归属振动模式方面的优势愈发明显，对红外光谱分析的实验研究具有重要参考价值。采用密度泛函理论，在B3LYP/6 - 311G(d, p)水平上对7 - 羟基香豆素进行几何优化和频率计算，得到了7 - 羟基香豆素的稳定结构和所有振动模式。结果表明，7 - 羟基香豆素的红外吸收峰主要分布在波数3700 - 3500、3150 - 3000、1750 - 1400、1400 - 1000、1000 - 50 cm⁻¹的几个区域。除了波数范围在3700 - 3500、3150 - 3000 cm⁻¹的振动相对独立，分别归属于OH伸缩振动和苯环CH伸缩振动外，其他几个振动区域较为复杂，不同程度的光谱峰由多种振动模式组成。最后，基于振动模式的理论分析对7 - 羟基香豆素分子的振动模式进行了归属，为探讨理论计算方法的可靠性，以X轴理论值和Y轴实验值绘制了7 - 羟基主要吸收峰的相关图，通过线性回归方法分析了7 - 羟基香豆素实验红外数据与计算红外数据之间的相关性。结果表明它们具有良好的相关性，相关系数“r”值等于0.9985，基于基组水平的密度泛函理论对7 - 羟基香豆素红外光谱的理论计算是可靠的。
