title: Thermodynamics and photochemical properties of alpha, beta, and gamma-hexabromocyclododecanes: a theoretical study.
abstract: The thermodynamics and photochemical properties of -alpha, +beta, and -gamma-hexabromocyclododecanes (HBCDs) have been investigated by density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations. The optimized geometries of HBCDs are in agreement with recently published X-ray crystallographic data. The thermodynamic properties of three HBCDs indicate that alpha-HBCD is the most stable one. The TD-DFT calculations obtain the UV absorption spectra of the three HBCDs and provide a detailed assignment of the UV spectral features. Inspections of the frontier molecular orbitals reveal the n-->sigma* nature of the lowest-lying transition and predict the photodegradation and photostereoisomerization trends of HBCDs under the UV illumination with wavelengths shorter than 240 nm.
authors.affiliation: Research Center of Environmental Engineering and Management, Graduate School at Shenzhen, Tsinghua University, Shenzhen, China. zhao.yaying@sz.tsinghua.edu.cn
authors.forename: Ya-Ying
authors.initials: YY
authors.lastname: Zhao
authors.forename: Xi-Hui
authors.initials: XH
authors.lastname: Zhang
authors.forename: O S Samuel
authors.initials: OS
authors.lastname: Sojinu
mesh_terms: D006842:Hydrocarbons, Brominated / Q000737:chemistry* / Q000528:radiation effects; D008956:Models, Chemical; D055668:Photochemical Processes; D010782:Photolysis; D013237:Stereoisomerism; D013816:Thermodynamics
chemical_list: D006842:Hydrocarbons, Brominated; C089796:hexabromocyclododecane