Theoretical study of the molecular properties of dimethylanthracenes as properties for the prediction of their biodegradation and mutagenicity.

There is little information available on methyl derivatives of anthracene and their interaction with the enzymes of bacterial consortia that could be found in petroleum sludge. In this study a theoretical investigation of all dimethylanthracenes (DMA) isomers and their relation to biodegradation are presented. Equilibrium geometries, ionization potentials (IP), electronic affinities (EA), dipole moments and electronic dipole polarizabilities of DMA isomers calculated by Density Functional Theory (DFT) methods are reported. The calculated IP and EA values vary little along the series of isomers. The polarizability values (〈α〉, Δα, and αyy) increase on passing from meso,meso- and α,meso- to β,β-DMA isomers. The computed polarizability values of DMAs can be used as predictors in determining differences in biodegradation rates of DMAs. The summation over Raman activity ∑ARaman over 3N-6 vibrational modes is sensitive to the position of the methyl substituent. The ∑ARaman values of 1-methylanthracene (MA), 2-MA, 2,9-DMA and 9,10-DMA are consistent with observed mutagenic activities in Salmonella Typhimurium strains TA98 and TA100.