title: IR and Raman spectra of nitroanthracene isomers: substitional effects based on density functional theory study.
abstract: Structure, IR and Raman spectra of 1-, 2- and 9-nitroanthracene isomers (1-NA, 2-NA and 9-NA) were calculated and analyzed through density functional theory computations using the B3LYP functional with the 6-311+G** basis set. Steric and π-conjugative effects determine the characteristic ONCC dihedral angles, which vary from 0° (2-NA) to 28-29° (1-NA) and 59° (9-NA), influencing the relative order of stability along the series 9-NA<1-NA<2-NA. The spectral regions at wavenumber values>3000 cm(-1) and <1000 cm(-1) little depend on the substituent position. The Raman and IR intensity values of the characteristic symmetric nitro group stretching transition, appearing between 1310 and 1345 cm(-1), are rather sensitive to the position of the substituent, decreasing regularly on passing from the planar to the NO2-rotated isomers (9-NA<1-NA<2-NA). In the medium-energy spectral region (1000-1700 cm(-1)), the number and the relative position of the strongest Raman bands are of potential utility to discriminate the NA isomers. Structural and spectroscopic results suggest that the unknown mutagenic activity of 1-NA is expected to be between that of 9-NA and 2-NA.
authors.affiliation: Research Centre for Analysis, Monitoring and Minimization Methods of Environmental Risk, Department of Chemistry, University of Catania, viale A. Doria 6, Catania 95125, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Alparone
authors.forename: Vito
authors.initials: V
authors.lastname: Librando
mesh_terms: D000873:Anthracenes / Q000737:chemistry*; D007536:Isomerism; D008958:Models, Molecular; D011789:Quantum Theory; D013055:Spectrophotometry, Infrared; D013059:Spectrum Analysis, Raman
chemical_list: D000873:Anthracenes; C050590:2-nitroanthracene; C035016:9-nitroanthracene