QSPR/QSAR models for prediction of the physico-chemical properties and biological activity of polychlorinated diphenyl ethers (PCDEs)

Polychlorinated diphenyl ethers (PCDEs) are a group of important persistent organic pollutants. In the present study, geometrical optimization and electrostatic potential calculations have been performed for all 209 PCDE congeners at the HF/6-31G* level of theory. A number of statistically-based parameters have been obtained. Linear relationships between gas-chromatographic relative retention time (RRT), n-octanol/water partition coefficient (log KOW), 298 K supercooled liquid vapour pressures (log pL), aqueous solubilities (log Sw,L) and the immunotoxicity values (log ED50) of PCDEs and the structural descriptors have been established by multiple linear regression method. The result shows that the quantities derived from electrostatic potential Vs,min,∑Vs+,Vs,av-,Π,σtot2,σ+2,ν, and Nv+, together with the number of the chlorine atoms on the two phenyl rings (NClNCl) can be well used to express the quantitative structure–property (activity) relationships of PCDEs. Good predictive capabilities have also been demonstrated by leave-group(1/5)-out cross-validation and external test set. Based on these equations, the predicted values have been presented for those PCDE congeners whose experimentally determined physico-chemical properties are unavailable.