精确计算化学键解离能的ONIOM-G3B3方法及其在抗氧化剂研究中的应用

通过对179个有机化合物C—H, N—H, O—H键离解能的理论计算, 系统评估了高精度组合从头算方法(ONIOM-G3B3)和密度泛函理论方法(B3LYP)在预测键离解能上的可靠性. 研究发现ONIOM-G3B3方法可以准确预测各类有机化合物的键解离能, 精度达到5.9 kJ/mol. 运用ONIOM-G3B3方法成功预测了两类重要的天然抗氧化剂维生素E族和茶多酚族的键解离能, 并进一步讨论了抗氧化活性、自由基清除机理及其构效关系.

Accurate Calculation of Bond Dissociation Enthalpy of ONIOM-G3B3 and the Application to Study of Natural Antioxidant

Composite ab initio method (ONIOM-G3B3) and density functional theory (B3LYP) were evaluated against 179 experimental C—H, O—H and N—H bond dissociation enthalpies of diverse organic molecules to verify their performance. It was found that the ONIOM-G3B3 predictions were in good agreement with the experimental values for these three types of bond dissociation enthalpies, and the accuracy was about 5.9 kJ/mol. Finally, armed with this powerful tool two interesting classes of natural antioxidants including vitamin E and catechins in tea were studied. Discussions were made about the antioxidant activity, radical scavenge mechanism and structure-activity relationships.