Semi-empirical Self-consistent Field Calculations of Heteroaromatic Compounds of Biological Interest. II. The π-Electronic Structure of Riboflavin

Abstract

The Pariser-Parr-Pople SCF calculation has been carried out with the aid of the variable β-core method for the investigation of the π-electronic structure of riboflavin. Comparison between the experimental and theoretical results on the transition energy and intensity, and the direction of transition moment of π-π bands in the electronic spectra is presented, together with the π-electron densities and free valences of the lowest singlet and triplet excited states which have been calculated with the aid of configuration interaction method. It has been found that the π-electron distribution of the photo-excited state is in parallel with the experimental facts suggesting a photo-induced change of basicity and a direct hydrogen-transfer in anaerobic photobleaching reaction.