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应用Materials Studio4.2计算38个含氮化合物的结构参数,对其碱性做QSAR研究。使用遗传函数算法(genetic function approximation,GFA),从前线分子轨道能量、偶极矩、部分电荷、分子表面积、分子体积等30个反映分子微观特征和溶剂化效应的结构参数中,筛选出主要的结构参数,建立出含氮化合物碱性-结构参数定量关系方程。所建方程的关联系数r~2=0.951,交叉相关系数CV-r~2=0.930,并且应用方程估算测试样本的碱性,其预测值与实验值基本一致,表明建立的QSAR方程具有较好的拟合度和较强的预测能力。分析QSAR方程各参数对含氮化合碱性影响表明,分子的最高占据轨道能量(HOMO)、偶极矩、氮原子上的电荷以及表示溶剂化效应的参数,是影响碱性的主要结构因素。HOMO能量反映分子供电子能力,能量越高,越易供给电子,碱性越强。分子偶极矩越大、氮原子上的负电荷越多,都使碱性增强。方程中引入电介质能量,说明溶剂化效应对含氮化合物碱性有一定的影响;电介质能量越大,溶质一溶剂的相互作用可能降低溶质分子的稳定性,使含氮化合物的碱性增强。
Materials Studio4.2 was used to calculate the structural parameters of 38 nitrogen-containing compounds and their QSARs were studied for their alkalinity. Using genetic function approximation (GFA), 30 structural parameters that reflect the molecular micro-characteristics and solvation effects of molecular frontier molecular orbital energy, dipole moment, partial charge, molecular surface area and molecular volume were screened out, Structure parameters, the establishment of nitrogen-containing compounds basic-structure parameters quantitative relationship equation. The correlation coefficient r2 = 0.951 and the cross-correlation coefficient CV-r2 = 0.930, and the basicity of the test sample is estimated by using the equation. The predicted value is basically consistent with the experimental value, indicating that the established QSAR equation has a good performance The degree of fit and strong predictive ability. The analysis of the influence of various parameters of the QSAR equation on the basicity of the nitrogenous compounds shows that the HOMO, the dipole moment, the charge on the nitrogen atom and the parameters representing the solvation effect are the main structural elements that influence the basicity. HOMO energy reflects the ability of molecules to supply electrons. The higher the energy is, the easier it is to supply electrons. The more alkaline the ions are. The larger the dipole moment of molecule, the more the negative charge on the nitrogen atom, all make alkaline increase. The introduction of dielectric energy into the equation indicates that the solvating effect has a certain influence on the basicity of the nitrogen-containing compounds. The larger the dielectric energy, the solute-solvent interaction may reduce the stability of the solute molecules and enhance the basicity of the nitrogen-containing compounds.