几种香豆素衍生物核磁共振谱的理论研究

在B3LYP / 6-311G(d，p)水平下对六种香豆素衍生物的结构进行了优化，并通过振动分析验证了其稳定性。利用GIAO方法在B3LYP/6-311G(d，p)水平下研究了香豆素衍生物的NMR谱。研究表明，六个化合物结构共平面性较好，具有较大共轭体系；不同的取代基和取代基的不同位置对几种香豆素衍生物的NMR都有不同的影响。苯环上的氢原子被其他基团取代后，其α-C原子和邻位碳原子的δ值变化明显，而间位碳原子δ值几乎没有变化。取代基的电负性对α-C原子δ值的影响具有一定规律性，而共轭效应对苯环碳原子的影响则更为复杂。最后，为了说明理论计算值与实验值之间的相关性，给出了六种衍生物化学位移值的理论与实验值相关图，并进行线性回归。结果表明，六种香豆素衍生物的化学位移理论与实验值之间的相关性非常好。

Theoretical Study on 13C Nuclear Magnetic Resonance Spectra of Several Coumarin Derivatives

The structure of the six kinds of coumarin derivatives has been optimized at the level of B3LYP/6-311G (d, p), under which the stability has been verified by means of Vibration analysis. Moreover, NMR Spectra of the coumarin derivatives compounds have been studied at the level of B3LYP/6-311G (d, p) by GIAO method. The results showed that the structure of the six compounds, a larger conjugated system, had good planarity. Different Substituents and different positions of substituents all have different influences on NMR of the several coumarin derivatives. In general, after the hydrogen atom on the benzene ring is substituted by other groups, the δ value of the α-C atom next to the substituent changes obviously, the δ value of the Ortho carbon atoms have great change too, but the δ value of the meta carbon atom have almost no change. The effect of electronegativity of substituents on α-C atoms presents obvious regularity, while the influence of conjugate effect on carbon atoms of benzene ring is more complex. Finally, in order to show the correlation between theoretical calculation and experimental values, we showed the correlation diagram of the chemical shift values of the six kinds of derivatives, and carried on the linear regression. Results showed that the correlation between the chemical shift theory and the experimental value of the six kinds of the Coumarin derivatives was very good.