Theoretical study of 1,3,4,6,7,9,9b-heptaazaphenalene and its ten derivatives

Density functional theory has been used to study the geometries, electronic structures, harmonic vibrational frequencies, and high-energy density material properties of 1,3,4,6,7,9,9b-heptaazaphenalene and its 10 derivatives (2,5,8-triR-1,3,4,6,7,9,9b-heptaazaphenalene, R = NH2, OH, N-3, NO2, F, Cl, Br, -Cequivalent toN, -CH= CH2, and -Cequivalent toCH) at the B3LYP/aug-cc-pVDZ level of theory. Geometry studies show that all of the compounds have a highly symmetric structure with a planar and rigid heteroring. Calculation results confirm that there exists considerable conjugation over the parent ring, which is an advantage to the stabilities of these compounds. Substituent effects on the geometry, electronic structure, conjugation, HOMO, and LUMO of the parent ring are discussed in detail. Vibrational frequency studies indicate that the parent ring has a characteristic frequency and the substitution of all of the substituents makes it shift to a lower wavenumber. Moreover, our study shows that some of our discussed compounds may be potential candidates for high-energy density materials (HEDMs).