PLS和PM3算法对缺氧沉积物中卤代芳烃还原脱卤QSPR研究

Research on application of PLS and PM3 algorithms in QSPR to reductive dehalogenation of selected halogenated aromatic hydrocarbons in anoxic sediment

运用HamiltonianPM3算法,计算了36种卤代芳烃化合物的26个量子化学参数,在此基础上通过偏最小二乘法得到了卤代芳烃化合物在缺氧沉积物中还原脱卤速率的QSPR模型.该模型可用于解释卤代芳烃化合物还原脱卤的机理.结果表明,卤代芳烃化合物中整个分子的最负的原子净电荷(q-)、键序最小的碳卤键中碳原子的单中心项电子-核吸引能(ENC)、该碳-卤键上碳原子的净电荷(qC)、分子最低未占据轨道能(Elumo)值越大,该卤代芳烃化合物还原脱卤的速率常数越小;而前线轨道间隙能(ΔE)、键序最小的碳卤键中碳原子的单中心项电子-电子推斥能(EEC)、相对分子质量(Mr)、整个分子的最正的原子净电荷(q+)、平均分子极化率(α)值越大,该卤代芳烃化合物还原脱卤的速率常数越大.

A quantitative structureproperty relationship (QSPR) model was developed for reductive dehalogenation rate constants of 36 halogenated aromatic hydrocarbons in anoxic sediment by means of partial least squares method and 26 quantum chemical descriptors computed by PM3 Hamiltonian. The model can be used to explain the dehalogenation mechanism. Among the 26 quantum chemical descriptors, there are 9 quantum chemical descriptors relating with the reductive dehalogenation rate of the halogenated aromatic hydrocarbons significantly, including the most negative atomic charges on an atom of the molecule (q-), the difference of frontline orbital energy (ΔE), electronnuclear attraction energy of the onecenter term for the carbon atoms (ENC) of the weakest carbonhalogen bond, electronelectron repulsion energy of the onecenter term for the carbon atoms (EEC) of the weakest carbonhalogen bond, the net atomic charges on the carbon atom of the weakest carbonhalogen bond (qC), molecular weight (Mr), energy of the lowest unoccupied molecular orbital (Elumo), the most positive net atomic charges on an atom of the molecule (q+),average molecular polarizability (α). q-, ENC, qC and Elumo correlate with the reductive dehalogenation rate negatively, while the others act positively.