Photochromic and thermochromic spiranes 33. Synthesis of a new indolinonaphthoxazino- bisspiropyran and investigation of its photochromic characteristics

A new unsymmetrical bisspiropyran was synthesized on the basis of 2,4-dihydroxyisophthalic aldehyde with naphthoxazinone and indoline fragments in the structure. The structure of the obtained compound was proved by the data from H-1 NMR and IR spectroscopy and X-ray crystallographic analysis. The photochromic characteristics of the obtained compound were investigated. It was established by means of the data from B3LYP/6-31G** quantum-chemical calculations that irradiation of a solution of the obtained biphotochrome with unfiltered light leads to opening of both pyran fragments. This is the first corroborated example of the twofold cleavage of C-spiro-O bonds for compounds of this class.