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CHEMILUMINESCENCE IN PORPHYRIN-CATALYZEl 

 DECOMPOSITION OF PEROXIDES^ 



Henry Linschitz 



Department of Chemistry 



Brandeis University 

 Walt ham, Massachusetts 



The thermal decomposition of peroxides, catalyzed by heavy metal 

 ions (12), is a reaction of great chemical interest and biochemical 

 relevance. Via appropriate enzymes, this reaction of course plays a 

 key biochemical role in peroxide and oxygen metabolism. In the case 

 of certain metallo-porphyrins in vitro, the reaction is of further interest 

 in that the catalysis is often accompanied by chemiluminescence. A 

 study of the process may therefore be helpful in establishing possible 

 mechanisms of bioliuuinescence. 



The chemiluminescence of porphyrins in the presence of peroxides 

 was discovered by Helberger (5, 6) , who observed a red emission when 

 magnesium phthalocyanine was added to hot tetralin. Further work 

 showed that tetralin hydroperoxide (THP) , present as impurity in 

 the solvent, is required for the luminescence, and that the emission 

 is accompanied by the breakdown of both the peroxide and the 

 metallo-porphyrin. In our own work, we have established that the 

 chemiluminescence spectrum corresponds to the fluorescence of the 

 original metallo-porphyrin. Thus, some of the energy released in the 

 exergonic peioxide breakdown may be used for electronic excitation 

 of the catalyst. 



Among the metallo-porphyrins and related compounds which show 

 the reaction is chlorophyll itself (11) . The process thus becomes still 

 more intriguing in connection with its possible bearing on the photo- 

 synthesis problem. The catalyzed breakdown of THP results mainly 



' This work was supported by grants from the U. S. Atomic Energy Commission 

 to Syracuse L'niversity (Contract No. AT (.'K)-I)-820) and to Brandeis University 

 (Contract No. ,\T (30-I)-2003). The experimental studies siniimarized briefly in 

 this paper were canied out in collaboration with Drs. E. W. Abrahamson, 

 D. R. Cross, and Mrs. M. K. Schumni. It is a pleasure to acknowledge their 

 contributions. .\ detailed joint report will appear elsewhere. 



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