Quantitative structure–property relationships for direct photolysis of polybrominated diphenyl ethers

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Using semiempirical quantum chemical descriptors, by partial least squares (PLS) regression, quantitative structure–property relationships (QSPRs) were established for direct photolysis quantum yields ( Φ) and rate constants ( k) of polybrominated diphenyl ether congeners dissolved in water/methanol and methanol solutions, respectively, and irradiated by artificial ultraviolet A light. Q cum 2 , a parameter indicating robustness and predictive abilities of PLS models, for the significant QSPR models is larger than 0.702. The gap of frontier molecular orbital energies ( E LUMO– E HOMO) and the most positive Mulliken atomic charges on a hydrogen atom ( q H + ) are two main molecular structural factors governing the log Φ values. log Φ increases with increasing E LUMO– E HOMO and q H + values. log k is mainly related to bromination degree and pattern which can be characterized by molecular weight ( Mw), average molecular polarizability ( α), and average Mulliken atomic charges on bromine atoms ( q Br). log k increases with bromination degree ( Mw, α) and q Br.