The role of electronic properties to the mutagenic activity of 1,6- and 3,6-dinitrobenzo[a]pyrene isomers

Physicochemical characterization of environmental mutagens: 3-nitro-6-azabenzo[a]pyrene and its N-oxide derivative

“…Present B3LYP/6-31G* calculations predict for both 1 and 2 a nonplanar equilibrium geometry, owing to the steric hindrance effect between the oxygen atom of the nitro group and the hydrogen atom in peri position. In fact, the typical O-N-C-C dihedral angles are calculated to be 27.8°and 26.2°for 1 and 22.6°and 24.1°for 2, consistent with previous theoretical data for 1-nitronaphthalene [16], 1-nitroanthracene [16], 1-nitrophenanthrene [16], 9-nitrophenanthrene [16], 1-nitropyrene [16], 4-nitropyrene [16], 6-nitrochrysene [16], 1,6-dinitrobenzo[a]pyrene [17], and 3,6-dinitrobenzo[a]pyrene [17], obtained at the B3LYP/6-31G* level. In addition, the distance between the oxygen atom and the hydrogen atom in peri position is computed to be 2.159 and 2.131 Å for 1 and 2.…”

“…However, we note that distortion from planarity of the rings is almost insignificant (within 3°). The C-N and N-O bond lengths of the nitro group here computed at 1.47 and 1.23 Å are in agreement with the corresponding data for nitronaphthalenes [16], nitroanthracene [16], nitrophenanthrene [16], nitropyrenes [16], nitrobenzo[a]pyrenes [18], and dinitrobenzo[a]pyrenes [17] calculated at the same level. For 2, the N-O bond length for the azabenzene nitrogen atom is calculated to be 1.28 Å , which is 0.05 Å longer than the N-O bond lengths for the NO 2 group.…”

“…In this work we adopted the scaling factor reported by Irikura et al [24] for the B3LYP/6-31G* level (0.9594), derived by a leastsquares fitting procedure of experimental and calculated harmonic wavenumber values for a series of 41 common organic compounds. The use of scaling techniques generally reduces the deviation between experimental and calculated data, as demonstrated by the satisfactory results for some PAH derivatives [17,18,[25][26][27][28][29][30][31]. The simulated vibrational spectra were represented by convoluting the calculated wavenumber values with pure Lorentzian band shapes using a full-width at half-maximum of 10 cm -1 , as usually adopted in the literature [32][33][34][35].…”

Contrastive Analysis of the Raman Spectra of Polychlorinated Benzene: Hexachlorobenzene and Benzene

“…The simulations were carried out with the Becke’s three-parameter hybrid method using the Lee-yang-Parr correlation functional (B3LYP) and the LANL2DZ basis set [20]. The B3LYP functional has been employed with success to simulate the Raman spectra of organic pollutants [21]. The Gaussian View was used to input investigated compounds’ data visually.…”

Pharmacophore identification and bioactivity prediction for triaminotriazine derivatives by electron conformational-genetic algorithm QSAR method

“…Geometries and electronic structure for conformers located in this way are optimized with the semi-empirical PM3 method using analytical gradients. Vibrational analysis showed that all the structures are minima in the potential energy surface (no imaginary frequencies) [38]. Heavily populated conformations means those with energies <1.5 kcal/mol above the ground state conformation.…”