ELECTRONIC STRUCTURES AND SPECTRA OF SOME NATURAL PRODUCTS OF THEORETICAL INTEREST .I. MOLECULAR ORBITAL STUDIES OF ANTHOCYANIDINS

Anthocyanidins are naturally occurring plant pigments. The HMO, ω-SCF with ω = 0·5 and 1·4 and Pariser-Parr-Pople semiempirical SCF ASMO CI have been employed to study the electronic properties of these compounds. In general, the results from the different methods show at least semi-quantitative consistency with repect to predictions for spectra, charge densities, and geometry of the molecules. The colors of the anthocyanidin flower pigments are explained by the PPP method in excellent agreement with the experimental data. In addition, the theoretical π-dipole moments and the directions of the transition moments have been obtained by the PPP method. © 1968.