title: Photoreductive debromination of decabromodiphenyl ethers in the presence of carboxylates under visible light irradiation.
abstract: Polybrominated diphenyl ethers (PBDEs) have aroused global environmental concerns because of their toxicity and ubiquitousness in the biological and environmental systems. It is important to find an efficient method for their decontamination and to understand their chemical transformation in the environment. Here, we report that decabromodiphenyl ether (BDE209) undergoes efficient reductive debromination reactions under visible-light irradiation (≥ 420 nm) in the presence of various carboxylate anions that are common in the environmental media. The debromination reactions occur in a stepwise manner, producing a series of lower brominated PBDE congeners. Solvent-derived radials are observed by spin-trapping electron spin resonance (ESR) experiments during the photoreaction. Further experiments by the UV-vis absorption and isothermal titration calorimetry (ITC), combined with theoretical calculations, reveal a new photochemical debromination pathway based on the halogen binding interaction. According to this pathway, the formation of halogen-binding-based complex between PBDE and carboxylate enables the visible-light absorption and debromination of PBDEs, although neither PBDEs nor carboxylates have visible-light absorption. The halogen-bond-based photochemical debromination could find its application for our better understanding of the transformation process of PBDEs in the environment.
authors: Beijing National Laboratory for Molecular Sciences, Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, China.
authors: Chunyan
authors: C
authors: Sun
authors: Wei
authors: W
authors: Chang
authors: Wanhong
authors: W
authors: Ma
authors: Chuncheng
authors: C
authors: Chen
authors: Jincai
authors: J
authors: Zhao
mesh_terms: D003666:Decontamination / Q000379:methods*; D004785:Environmental Pollutants / Q000737:chemistry*; D055768:Halogenated Diphenyl Ethers / Q000737:chemistry*; D054879:Halogenation; D008027:Light; D055668:Photochemical Processes; D012997:Solvents; D014466:Ultraviolet Rays
chemical_list: D004785:Environmental Pollutants; D055768:Halogenated Diphenyl Ethers; D012997:Solvents; C010902:decabromobiphenyl ether