DFT Study of NMR Shielding Tensors and Thermodynamic Properties on Pyrene and its Derivatives

Emissions from fossil fuel combustion pose a serious threat to public health and =pose the need for animproved monitoring of polycyclic aromatic hydrocarbons (PARS), a major class of persistent organicpollutants. For this purpose the present study reports an investigation of the electronic structure of Pyrene byuse of different chemical models We also made a comparison between different chemical models.Donor — acceptor disubstituted , entropy , enthalpy and Gibbs free-energy vAll be compared too.The isotropic and anisonopic tensor of the pyrene and derivatives structure were calculated with differentchemical models HP/6-3IG, HF/M1-3 l0, BLYP/6-3 ID, BLYP/6-310. , B3LYP/A3 IG, B3LYP.16-3 I 00 and aswell.