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Quantitative structure–property relationship (QSPR) modeling is a powerful approach for predicting environmental behavior of organic pollutants with their structure descriptors. This study reports an optimal QSPR model for estimating logarithmic soil sorption coefficients (log K_OC) of polycyclic aromatic hydrocarbons (PAHs). Quantum chemical descriptors computed using density functional theory at the B3LYP/6-31G(d) level and partial least squares (PLS) analysis with an optimizing procedure were used to generate QSPR models for log K_OC of PAHs. The correlation coefficient of the optimal model was 0.993, and the results of a cross-validation test () showed this optimal model had high fitting precision and good predicting ability. The log K_OC values predicted by the optimal model are very close to those observed. The PLS analysis indicated that PAHs with larger electronic spatial extent tend to more easily adsorb and accumulate in soils and sediments, whereas those with higher molecular total energy and larger energy gap between the lowest unoccupied and the highest occupied molecular orbital adsorb and accumulate in soils and sediments less readily.

Occurrence of electron transfer was studied for different combinations of polycyclic aromatic hydrocarbons (PAHs) and DNA bases as electron donors or acceptors and free radicals only as electron acceptors. Geometries of all the molecules and radicals were optimized in aqueous medium employing the polarizable continuum model. Single electron transfer (SET) and sequential proton loss electron transfer mechanisms were investigated employing Gibbs free energies of the appropriate neutral, anionic and cationic species. Barrier energies involved in these phenomena were calculated using the Marcus theory. The SET barrier energies were found to be linearly correlated with $\mathrm{\Delta }E=$ (Electron affinities of acceptors – Ionization potentials of donors). SET barrier energies from the DNA bases to the PAHs follow the order Cy $>$ Th $\approx$ Ad $>$ Gu, whereas SET barrier energies from the PAHs to the DNA bases follow the order Gu $>$ Ad $>$ Th $\approx$ Cy. Thus, guanine, among the DNA bases, is the best electron donor to the PAHs and worst electron acceptor from the same.