PHOTOCHROMISM OF SPIRO[INDOLINE-2',3-3H-NAPHTH[2,1-B][1,4]-OXAZINE]

The effect of the piperidine substituent on the spectral and photochro mic properties of spiro(indoline-naphthoxazines) (SINO) in different s olvents is studied. The introduction of this substituent into the naph thoxazine fragment of SINO results in the appearance of fluorescence o f the initial form A of SING at low temperatures. This fluorescence gr adually disappears as the temperature increases. The temperature and c oncentration dependences of the spectral parameters of photoinduced fo rm B of SING make it possible to assume that B molecules aggregate in non-polar solvents. In all solvents studied, form B, unlike the photoi nduced form of the non-substituted spiro naphthoxazine, is stabilized as a bipolar ion with a positive charge on the nitrogen atom of the pi peridine substituent. The increase in the rate of thermal decolorizati on as the medium polarity increases is explained.