ELECTRONIC STRUCTURE AND SPECTRA OF ORGANIC MOLECULES .4. PARISER-PARR-POPLE TYPE CALCULATIONS FOR PURINE AND SOME OF ITS 6-SUBSTITUTED DERIVATIVES

The Pariser-Parr-Pople method has been used to calculate the π-electronic structures and spectra of 6-fluoro, 6-hydroxy, 6-methoxy, 6-amino, 6-methylamino, 6-dimethylaminopurine and their parent molecule purine. The purine and adenine (6-aminopurine) absorption spectra (singlet-singlet π→π* type transitions) in particular are discussed in greater detail. The correlation among the absorption bands of the molecules in question and their ground state properties are also discussed. The theoretical results for singlet-singlet transition energies agree fairly well with the experimental data. © 1968 Springer-Verlag.