The results presented in Fig. 2B are somewhat surprising as the photodegradation of MC is a well known problem that limits application of SP in reversible, self-regenerated sensing devices.
It is generally accepted that interaction of MC form with singlet and triplet oxygen leads to photodecomposition of MC [27]. Therefore, by putting together a pair of the films containing the photochromic compound within an air-tight environment, Matsushima et al.were able to significantly reduce the photodegradation of fulgimides
[28].
Interestingly, this approach did not provide any improvement
in photofatigue of spiropyrans.