Theoretical study of the formation of dinitro-pyrenes from mononitro-pyrenes initiated by OH radicals

Nitrated polycyclic aromatic hydrocarbons are more mutagenic and carcinogenic than parent PAHs. The formation mechanism of dinitro-pyrenes initiated by OH from mononitro-pyrenes was conducted by quantum chemical calculations. The products are 1,2-, 1,7-, 2,4-, 2,5- and 2,7- dinitropyrenes. Water molecules can decrease the Gibbs activation barriers of water loss step of NO2-OH-nitropyrene. By canonical variational transition state theory with small curvature tunneling correction, the calculated overall rate constants for 1-, 2- and 4-nitropyrene are 8.13 × 10−13 cm3 molecule−1 s−1, 8.90 × 10−13 cm3 molecule−1 s−1 and 1.50 × 10−12 cm3 molecule−1 s−1 at 298 K and 1 atm, respectively.