Photooxidative bleaching of chlorophyllin

Chlorophyllin, a water-soluble, copper-containing porphyrin, can be bleache d rapidly in the light or slowly in the dark in a reaction which is oxygen dependent. Both the photo and the dark bleaching reactions are temperature dependent. Cyclic voltammetry measurements show that the copper in the blea ched and non-bleached state remains in the +2 redox state and could be read ily reduced. This would imply that there is no net oxidative change to the copper during the bleaching process. FT-IR absorption spectroscopy showed v ibrations characteristic of a vinyl functionality disappeared upon bleachin g. Aqueous solutions of chlorophyllin were not dialyzable through dialysis tubing of molecular weight cut-off, 6000-8000 molecular weight, indicative of an aggregate chlorophyllin micelle. Analysis of products by high perform ance liquid chromatography showed that the chlorophyllin mixture was more c omplex than originally anticipated and that two components were lost from t he mixture upon photobleaching. One compound that is preferentially lost up on photobleaching has been identified by mass spectral analysis as Cu(II) c hlorin e6.