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.