Application of quantum chemical descriptors into quantitative structure-property relationship models for prediction of the photolysis half-life of PCBs in water

Quantitative structure-property relationship (QSPR) models were developed for prediction of photolysis half-life (t1/2) of polychlorinated biphenyls (PCBs) in water under ultraviolet (UV) radiation. Quantum chemical descriptors computed by the PM3 Hamiltonian software were used as independent variables. The cross-validated Qcum2 value for the optimal QSPR model is 0.966, indicating good prediction capability for lg t1/2 values of PCBs in water. The QSPR results show that the largest negative atomic charge on a carbon atom (QC−) and the standard heat of formation (ΔHf) have a dominant effect on t1/2 values of PCBs. Higher QC− values or lower ΔHf values of the PCBs leads to higher lg t1/2 values. In addition, the lg t1/2 values of PCBs increase with the increase in the energy of the highest occupied molecular orbital values. Increasing the largest positive atomic charge on a chlorine atom and the most positive net atomic charge on a hydrogen atom in PCBs leads to the decrease of lg t1/2 values.