title: Modeling and predicting pKa values of mono-hydroxylated polychlorinated biphenyls (HO-PCBs) and polybrominated diphenyl ethers (HO-PBDEs) by local molecular descriptors.
abstract: Hydroxylated polychlorinated biphenyls (HO-PCBs) and polybrominated diphenyl ethers (HO-PBDEs) are attracting considerable concerns because of their multiple endocrine-disrupting effects and wide existence in environment and organisms. The hydroxyl groups enable these chemicals to be ionizable, and dissociation constant, pKa, becomes an important parameter for investigating their environmental behavior and biological activities. In this study, a new pKa prediction model was developed using local molecular descriptors. The dataset contains 21 experimental pKa values of HO-PCBs and HO-PBDEs. The optimized geometries by ab initio HF/6-31G(∗∗) algorithm were used to calculate the site-specific molecular readiness to accept or donate electron charges. The developed model obtained good statistical performance, which significantly outperformed commercial software ACD and SPARC. Mechanism analysis indicates that pKa values increase with the charge-limited donor energy EQocc on hydroxyl oxygen atom and decrease with the energy-limited acceptor charge QEvac on hydroxyl hydrogen atom. The regression model was also applied to calculate pKa values for all 837 mono-hydroxylated PCBs and PBDEs in each class, aiming to provide basic data for the ecological risk assessment of these chemicals.
authors: College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, Jinhua 321004, PR China. Electronic address: yhy@zjnu.cn.
authors: Haiying
authors: H
authors: Yu
authors: UFZ Department of Ecological Chemistry, Helmholtz Centre for Environmental Research, Permoserstr. 15, Leipzig D-04318, Germany; Institution for Organic Chemistry, Technical University Bergakademie Freiberg, Leipzig Str. 29, Freiberg D-09596, Germany.
authors: Dominik
authors: D
authors: Wondrousch
authors: College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, Jinhua 321004, PR China.
authors: Quan
authors: Q
authors: Yuan
authors: College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, Jinhua 321004, PR China.
authors: Hongjun
authors: H
authors: Lin
authors: College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, Jinhua 321004, PR China.
authors: Jianrong
authors: J
authors: Chen
authors: College of Geography and Environmental Sciences, Zhejiang Normal University, Yingbin Avenue 688, Jinhua 321004, PR China.
authors: Huachang
authors: H
authors: Hong
authors: UFZ Department of Ecological Chemistry, Helmholtz Centre for Environmental Research, Permoserstr. 15, Leipzig D-04318, Germany; Institution for Organic Chemistry, Technical University Bergakademie Freiberg, Leipzig Str. 29, Freiberg D-09596, Germany.
authors: Gerrit
authors: G
authors: Schüürmann
mesh_terms: D052244:Endocrine Disruptors / Q000737:chemistry*; D004785:Environmental Pollutants / Q000737:chemistry*; D005544:Forecasting; D055768:Halogenated Diphenyl Ethers / Q000737:chemistry*; D006900:Hydroxylation; D008956:Models, Chemical; D011078:Polychlorinated Biphenyls / Q000737:chemistry*; D018570:Risk Assessment
chemical_list: D052244:Endocrine Disruptors; D004785:Environmental Pollutants; D055768:Halogenated Diphenyl Ethers; D011078:Polychlorinated Biphenyls
keywords: Dissociation constant; HF/6-31G(∗∗); Hydroxylated polybrominated diphenyl ethers; Hydroxylated polychlorinated biphenyls; Local molecular parameters; pK(a)