LCI Pariser-Parr-Pople calculations of π-electron systems in nitrogen-heterocyclic molecules. Correlation with spectral data

Abstract

Limited configuration interaction Pariser-Parr-Pople calculations were performed for 19 nitrogen heterocyclic aromatic molecules. After optimizing the semiempirical parameters for six “test” molecules, calculations were performed for the remaining thirteen molecules. Strong correlations were made with experimentally observed ionization potentials, singlet-singlet transition energies, polarizations and oscillator strengths as well as ground state molecular geometries for cases where these observations have been made. These correlations indicate spectral features which should be carefully examined experimentally to determine the effect of nitrogen substitution in aromatic hydrocarbon molecules.