Color prediction of photochromic organic compounds: Theoretical calculations of ground and excited states of spiropyrans, spirooxazines and diarylnaphthopyrans

ab initio and semi-empirical geometry optimization in conjunction with modi fied CS-INDO-CIPSI calculations was performed to predict the lambda(max) of absorption of merocyanines forms of spiro[indoline-naphthoxazine], spiro[i ndoline-naphthopyran] and diarylnaphthopyrans. Thr predicted lambda(max) ar e found in excellent agreement with experimental values providing the geome try used for vertical energies calculation is delocalized, i.e. obtained at the UHF/AM1 and DFT levels.