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

Abstract

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. (»100), the quenching by oxygen has no influence on the “colorability” which like that is optimized. The sensitized photodegradation is very important with a lifetime V o about 3‐5 flashes whereas for the spirooxazines unsensitized V o exceeds several thousands. This study enhances the hypothesis describing the photodegradation process of these molecules mainly via the triplet state.