title: Elucidating triplet-sensitized photolysis mechanisms of sulfadiazine and metal ions effects by quantum chemical calculations.
abstract: Sulfadiazine (SDZ) mainly proceeds triplet-sensitized photolysis with dissolved organic matter (DOM) in the aquatic environment. However, the mechanisms underlying the triplet-sensitized photolysis of SDZ with DOM have not been fully worked out. In this study, we investigated the mechanisms of triplet-sensitized photolysis of SDZ(0) (neutral form) and SDZ(-) (anionic form) with four DOM analogues, i.e., fluorenone (FL), thioxanthone (TX), 2-acetonaphthone (2-AN), and 4-benzoylbenzoic acid (CBBP), and three metal ions (i.e., Mg(2+), Ca(2+), and Zn(2+)) effects using quantum chemical calculations. Results indicated that the triplet-sensitized photolysis mechanism of SDZ(0) with FL, TX, and 2-AN was hydrogen transfer, and with CBBP was electron transfer along with proton transfer (for complex SDZ(0)-CBBP2) and hydrogen transfer (for complex SDZ(0)-CBBP1). The triplet-sensitized photolysis mechanisms of SDZ(-) with FL, TX, and CBBP was electron transfer along with proton transfer, and with 2-AN was hydrogen transfer. The triplet-sensitized photolysis product of both SDZ(0) and SDZ(-) was a sulfur dioxide extrusion product (4-(2-iminopyrimidine-1(2H)-yl)aniline), but the formation routs of the products for SDZ(0) and SDZ(-) were different. In addition, effects of the metal ions on the triplet-sensitized photolysis of SDZ(0) and SDZ(-) were different. The metal ions promoted the triplet-sensitized photolysis of SDZ(0), but inhibited the triplet-sensitized photolysis of SDZ(-).
authors.affiliation: State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China.
authors.forename: Se
authors.initials: S
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China.
authors.forename: Xuedan
authors.initials: X
authors.lastname: Song
authors.affiliation: State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China. Electronic address: haoce@dlut.edu.cn.
authors.forename: Ce
authors.initials: C
authors.lastname: Hao
authors.affiliation: State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China.
authors.forename: Zhanxian
authors.initials: Z
authors.lastname: Gao
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China.
authors.forename: Jingwen
authors.initials: J
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China.
authors.forename: Jieshan
authors.initials: J
authors.lastname: Qiu
mesh_terms: D001577:Benzophenones / Q000737:chemistry; D002118:Calcium / Q000737:chemistry; D005449:Fluorenes / Q000737:chemistry; D008274:Magnesium / Q000737:chemistry; D009281:Naphthalenes / Q000737:chemistry; D010782:Photolysis; D013411:Sulfadiazine / Q000737:chemistry* / Q000528:radiation effects; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000528:radiation effects; D015032:Zinc / Q000737:chemistry
chemical_list: D001577:Benzophenones; D005449:Fluorenes; D009281:Naphthalenes; D014874:Water Pollutants, Chemical; D013411:Sulfadiazine; C058818:4-benzoylbenzoic acid; D008274:Magnesium; D015032:Zinc; D002118:Calcium
keywords: DFT; Mechanism; Metal ions; Sulfadiazine; Triplet-sensitized photolysis