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运用量子化学方法计算水溶液中一些含氮小分子化合物和醇、酚、羧酸的pKa值。采取从头计算的Hartree-Fock法和6- 31G(d,p)基组,以及aug-cc-pVDZ基组,密度泛函理论的B3LYP法6-31G(d,p)基组,分别优化分子和离子的气相几何结构,采用极化连续介质模型模拟溶质和溶剂分子间的相互作用,不同方法和基组计算结果差别不大,18个化合物的均方根误差均为1．03,预测值与实验值的相关系数均为0．98,一致性较好。证明HF／6-31G(d,p)法和模型计算或预测含有相同官能团的小分子的pKa数值很合理,能够为研究药物分子体系的构效关系提供精确的pKa参数。
Quantum chemical method was used to calculate the pKa values of some nitrogen-containing compounds and alcohols, phenols and carboxylic acids in aqueous solution. The ab initio Hartree-Fock method and the 6-31G (d, p) basis set and B3LYP method 6-31G (d, p) basis set of the aug-cc-pVDZ basis set and density functional theory And the gas phase geometry, the polarization continuum model was used to simulate the interaction between solute and solvent molecules. The calculated results of different methods and groups were not different. The root mean square errors of 18 compounds were 1.03, and the predicted values The correlation coefficient with the experimental value is 0.98, the consistency is better. It is proved that the pKa value of HF / 6-31G (d, p) method and model for calculating or predicting small molecules containing the same functional groups is reasonable and can provide accurate pKa parameters for studying the structure-activity relationship of drug molecule systems.