Experimental and theoretical studies of 2-Amino-3-methylimidazo[4,5-f] quinoline derivatives: Cooked-food mutagens

摘要

The UV absorption spectra of two potent mutagens, 2-amino-3- methylimidazo[4,5-f]quinoline (IQ) and NO_2-IQ, dissolved in ethanol, were observed at room temperature. General appearance of the two spectra is somewhat different. Theabsorption spectra show five bands in the region above 200 nm. The peak positions of the five bands are similar in the two spectra. The observed bands in the two molecules were assigned using transition energies calculated with time-dependent density functional theory with triple-zeta polarized basis set with the statistical average of orbital potentials exchange-and-correlation functional. The emission spectra of the two molecules dissolved in ethanol were obtained at 77 K. Only fluorescence emission was observed in IQ. No phosphorescence emission of the molecule was observed. Both fluorescence and phosphorescence emissions were observed in NO_2-IQ. These observations were interpreted with the aid of the calculated transition energy spectra. Some lowest vertical ionization energies of the two molecules were also calculated. Thefirst ionization energy of NO_2-IQ is greater than that of IQ by 1.2 eV. Core electron binding energies (CEBEs) of the two molecules were calculated as well. Using CEBE shifts of atoms in the molecules, it was possible to observe the changes of chemical environment when substituent changes.