QSPR/QSAR models for prediction of the physicochemical properties and biological activity of polybrominated diphenyl ethers

Polybrominated diphenyl ethers (PBDEs) are a group of important persistent organic pollutants. In the present study, geometrical optimization and electrostatic potential calculations have been performed for all 209 PBDE 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/air partition coefficient (lg K_OA), 298 K supercooled liquid vapour pressures (lg p_L), Henry's law constant (lg H) and Ah receptor binding affinity (-lg RBA) of PBDEs and the structural descriptors have been established by multiple regression method. The result shows that the quantities derived from electrostatic potential V_{s, max}, V_{s, min}, Π, ∑ V_s⁺, over(V_s^-, -), ν, σ_tot², and N_v^-, together with the molecular volume (V_mc) can be well used to express the quantitative structure-property relationships of PBDEs, which proves the general applicability of this parameter set to a great extent. Good predictive capabilities have also been demonstrated. Based on these equations, the predicted values have been presented for those PBDE congeners whose experimentally determined physicochemical properties are unavailable. The QSAR model for the Ah receptor binding affinity is relatively poor, which can be ascribed to the complexity of factors which affect biological activity and the limitations of the present parameter set in describing steric characters of the molecule.