title: Rate constants of hydroxyl radical oxidation of polychlorinated biphenyls in the gas phase: A single-descriptor based QSAR and DFT study.
abstract: The second-order rate constants (k) of hydroxyl radical (·OH) with polychlorinated biphenyls (PCBs) in the gas phase are of scientific and regulatory importance for assessing their global distribution and fate in the atmosphere. Due to the limited number of measured k values, there is a need to model the k values for unknown PCBs congeners. In the present study, we developed a quantitative structure-activity relationship (QSAR) model with quantum chemical descriptors using a sequential approach, including correlation analysis, principal component analysis, multi-linear regression, validation, and estimation of applicability domain. The result indicates that the single descriptor, polarizability (α), plays an important role in determining the reactivity with a global standardized function of lnk = -0.054 × α ‒ 19.49 at 298 K. In order to validate the QSAR predicted k values and expand the current k value database for PCBs congeners, an independent method, density functional theory (DFT), was employed to calculate the kinetics and thermodynamics of the gas-phase ·OH oxidation of 2,4',5-trichlorobiphenyl (PCB31), 2,2',4,4'-tetrachlorobiphenyl (PCB47), 2,3,4,5,6-pentachlorobiphenyl (PCB116), 3,3',4,4',5,5'-hexachlorobiphenyl (PCB169), and 2,3,3',4,5,5',6-heptachlorobiphenyl (PCB192) at 298 K at B3LYP/6-311++G**//B3LYP/6-31 + G** level of theory. The QSAR predicted and DFT calculated k values for ·OH oxidation of these PCB congeners exhibit excellent agreement with the experimental k values, indicating the robustness and predictive power of the single-descriptor based QSAR model we developed.
authors.affiliation: Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha, 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha, 410083, China.
authors.forename: Zhihui
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha, 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha, 410083, China.
authors.forename: Shuang
authors.initials: S
authors.lastname: Luo
authors.affiliation: Department of Civil, Environmental and Geodetic Engineering, The Ohio State University, Columbus, OH, 43210, USA.
authors.forename: Zongsu
authors.initials: Z
authors.lastname: Wei
authors.affiliation: Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha, 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha, 410083, China.
authors.forename: Tiantian
authors.initials: T
authors.lastname: Ye
authors.affiliation: Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Spinney
authors.affiliation: Indiana University-Purdue University Fort Wayne, Fort Wayne, Indiana, 46805, USA.
authors.forename: Dong
authors.initials: D
authors.lastname: Chen
authors.affiliation: Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha, 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha, 410083, China. Electronic address: xiao.53@csu.edu.cn.
authors.forename: Ruiyang
authors.initials: R
authors.lastname: Xiao
mesh_terms: D001272:Atmosphere / Q000737:chemistry; D017665:Hydroxyl Radical; D007700:Kinetics; D008956:Models, Chemical; D010084:Oxidation-Reduction; D011078:Polychlorinated Biphenyls / Q000032:analysis / Q000737:chemistry*; D021281:Quantitative Structure-Activity Relationship
chemical_list: C015550:2,4',5-trichlorobiphenyl; D017665:Hydroxyl Radical; C034559:2,3,4,5,3',4',5'-heptachlorobiphenyl; C035976:2,4,2',4'-tetrachlorobiphenyl; D011078:Polychlorinated Biphenyls; C027309:3,4,5,3',4',5'-hexachlorobiphenyl
keywords: DFT; Hydroxyl radical; PCBs; Polarizability; Single–descriptor based QSAR