Structure of a new photochromic indoline spiropyran

Conclusions An x-ray diffraction structural study was carried out for the photochromic spirpyran 1,3,3-trimethyl-5-nitrospiro(indoline-2,2-[2H-1]-benzopyran). The C_spiro-O bond in the spiropyran is longer than the normal value but shorter than in the isomeric spiropyran with the nitro group in the benzopyran fragment, which is characterized by a higher quantum yield.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 191–194, January, 1985.