DABCO EFFECT ON THE PHOTODEGRADATION OF PHOTOCHROMIC COMPOUNDS IN SPIRO[INDOLINE-PYRAN] AND SPIRO[INDOLINE-OXAZINE] SERIES

Photochromic compounds are involved in secondary oxidative reactions o f photodegradation leading to the loss of their properties. The analyt ical studies of this process in toluene solution of both photochromic molecules, i.e. the 1,3-dihydro- methylspiro[2H-indole-2,2'-[3H]naphth [2,1-b]pyran] and the ro[2H-indole-2,3'-[3H]-naphth[2,1-b][1,4]oxazine ], have allowed us, by identification of the main photoproducts, to pr opose same mechanisms for the oxidative degradation processes which oc cured by radical structures or singlet oxygen. In order to prove the i mplication of this last species in the degradation process, we have te sted the effect of a singlet oxygen quencher with experimental spectro photometric apparatus: the 1,4-diazabicyclo[2,2,2]octan (DABCO) which exhibits an important increase of the fatigue resistance of photochrom ic compounds. This quantitative aspect of the DABCO effect has been co mpleted by a qualitative degradation approach concerning a comparative analytical study by gas chromatography between degradation of photoch romic compounds with and without DABCO. In those conditions we have ob served a significant change in the chromatographic profiles.