Stanford Series On Magnetic Circular-Dichroism Studies .53. Mcd Spectra Of Some 8-Azapurines

The magnetic circular dichroism spectra of 9-methyl-8-azapurine and of 7-, 8-, and 9-methyl-8-azaadenine have been found to be well resolved; as many as four distinct electronic bands are observable in the 200–350 nm spectral region. CNDO calculations indicate that p ? p* excitations are responsible for almost all of the MCD intensity. A comparison of four different parameterizations shows that a modification of Del Bene and Jaffé's CNDO/S procedure correctly predicts, with one exception, the sign of the observed B-terms and is therefore the most satisfactory method.