The molecular properties of nitrobenzanthrone isomers and their mutagenic activities

• Electronic properties of mono-nitrated benzanthrones are investigated theoretically.
• Stability, ionization potentials and electron affinities of isomers are determined.
• DFT methods are employed for calculation of the IR and Raman spectra of isomers.
• Vibrational properties important for characterization of isomers are determined.
• The relationship between vibrational property and mutagenic activity is established.

The mutagenic activity of five mono-substituted nitrobenzanthrones (NBA) has been determined in the Ames assay (Takamura-Enya et al., 2006). In the present study, a theoretical investigation of the electronic properties of all mono-substituted NBA isomers and their relation to mutagenic activity are presented. Equilibrium geometries, vertical ionization potentials (VIP), vertical electron affinities (VEA), relative energies, dipole moments and electronic dipole polarizabilities, and the IR and Raman spectra of NBA isomers calculated by Density Functional Theory (DFT) methods are presented. The position of the nitro group affects the spectral features of the IR and Raman spectra of the NBA isomers. The results show that a good linear relationship exists between the summation of Raman activities (∑ARaman) over all the 3N-6 vibrational modes and the mutagenic activity of the NBA isomers in Salmonella typhimurium strains. The spectroscopic results suggest that the unknown mutagenic activities of 4-NBA, 5-NBA, 6-NBA, 8-NBA and 10-NBA are predicted to follow the order 4-NBA > 10-NBA > 5-NBA > 8-NBA > 6-NBA.