PH04 Advances in Analysis and Measurements
Exhibit Hall
8:00 AM - Thursday
(PH006) Density Function Theory calculation of thermodynamic properties and molecular orbitals of polybrominated diphenyl ethers.
Zeng, X1, Freeman, P1, Vasil'ev, Y1, Barofsky, D1, Simonich, S1, 1 Oregon State University, Corvallis, OR, USA
ABSTRACT- As flame retardants, polybrominated diphenyl ethers (PBDE) have been widely used and are becoming an increasing concern for environmental scientists. There is significantly less information on PBDE properties than on their chlorinated analogues. In the current study, the geometries and energies, as well as molecular orbitals, of isomers of 38 synthesized PBDE congeners have been computed on the B3LYP/6-31GD//B3LYP/6-31GD level using the computer program Gaussian 03. Calculation results show that, with increasing number of bromine atoms, PBDE congeners become more electronegative and gain higher electron affinities. The thermodynamic properties (heat capacity, entropy and Gibbs energy of formation) of these PBDE congeners in the gas state (at 298.15K and 101.325Kpa) have also been calculated on the same level. The absolute entropy and Gibbs energy from the output of theoretical calculation are combined with experimental data to derive the formation entropy and Gibbs energy of PBDEs. Computational studies also have been performed to find the correlation between the energies of virtual molecular orbital eigenvalues and possible electron capture energies on Gas Chromatography Electron Capture Mass Spectrometry (GC/EC-MS).
Key words: Molecular properties, polybrominated diphenyl ether