Novel photochromic spirocyclic compounds of thienopyrroline series: 2. Spirooxazines

Photochromic properties of novel spirooxazines of the thienopyrroline series have been studied in comparison with those of an indoline analogue. Solvatochromism of the merocyanine photoisomers has been investigated using the Kamlet–Taft model. It has been found that inversion of the trends in the solvatochromic behavior of the spirooxazines takes place when passing from non-protogenic to protic solvents. Thienopyrroline spirooxazines possess relatively poor fatigue resistance. The origin of the processes causing their photodegradation has been studied.