Comparison of photochromic behaviour between spiroxazines and spiropyrans: theoretical calculations of ground and excited states

MOPAC/AM1 and CNDO/S calculations have been performed on a spiro[indoline-naphthoxazine], a spiro[indoline-naphthopyran] and their open merocyanine(s) form. The energies were fully optimized and the bond orders, charge distribution and energies of both ground and excited states evaluated. The theroretical absorption spectra were calculated and found in good agreement with the experimental ones.