Etude Par Photolyse‐Eclair De La Photodegradation Sensibilisee De Spiro (Indoline‐Pyranes) Et De Spiro (Indoline‐Oxazines) Photochromiques

Abstract

The photodegradation and the "colorability" of photochromic spiro (indoline-pyrans) and spiro (indoline-oxazines) have been made by repeated flashes in solution open to the air. The photosensitization proceeds by triplet-triplet energy transfert. For hight ratios photosensitizer/photochrome.(>>loo), the quenching by oxygen has no influence on the "colorability" which like that is optimized. The sensitized photodegradation is very important with a lifetime Vo about 3-5 flashes whereas for the spirooxazines unsensitized V, exceeds several thousands. This study enhances the hypothesis describing the photodegradation process of these molecules mainly via the triplet state.