四种姜黄素类似物核磁共振谱的理论研究

在B3LYP/6-31G(d, p)水平下优化了四种姜黄素类似物的几何构型，并通过振动分析验证了其构型稳定性。在B3LYP/6-311G(d, p)水平下计算了该类化合物的核磁共振谱，研究结果表明：四种化合物主体结构共平面性较好，为一较大共轭体系。由于羟基及甲氧基的引入，使Compound-B/C/D中C₃，C₄以及Compound-A/D中C₅均具有较大δ值，Compound-A中C₄和C₆的δ值相对较小，C₃的δ值相对较大。而在羰基与碳碳双键所形成的共轭羰基化合物中，羰基C₁₃的δ值(183 ppm)相对于乙醛中的δ值(201ppm)有所减小，C_{11, 15}(α碳)的δ值(122 ppm)相对减小，而C_{9, 17}(β碳)的δ值(145 ppm)相对增大。最后，通过线性回归方法，利用相关系数值r研究了1H NMR δ值的实验和理论计算值的相关性，结果表明相关性较好，实验值和理论值基本吻合。

Theoretical Study on Nuclear Magnetic Resonance Spectra of the Four Kinds of Curcumin Analogues

The structure of four kinds of curcumin analogues was optimized at the level of B3LYP/6-31G(d,p), under which the stability was verified by means of vibration analysis. Moreover, NMR spectra of curcumin analogues compounds were studied at the level of B3LYP/6-311G(d,p) by GIAO method. The results show that the structure of four kinds of compounds, a larger conjugated system, has good planarity. Because of introducing hydroxyl and methoxy, the compound-B/C/D-C₃, C₄ and compoud-A and compound-D-C₅ have greater δ value. δ value of compound-A-C₄. C₆ is relatively smaller, and δ value of C₃ is relatively larger. In the conjugated carbonyl compounds, compared with the acetaldehyde δ value (201 ppm), carbonyl C₁₃ δ value(183 ppm) decreases relatively, C_{11, 15}(α-carbon) δ value(122 ppm) decreases relatively, and C_9,17(β-carbon) δ value(145 ppm) increases relatively. Finally, the correlation between experimental δ value and theoretical δ value of the 1H NMR was analyzed through the linear regression method. Results show that they have good correlation, and the experimental values coincide with the theoretical values.