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

Abstract

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.