Toward an Understanding of the Chemiluminescence Accompanying the Reaction of 9-Carboxy-10-methylacridinium Phenyl Ester with Hydrogen Peroxide

The reaction between 9-carboxy-10-methylacridinium phenyl ester (CMAPE) and hydrogen peroxide leading to the formation of electronically excited 10-methyl-9-acridinone has been examined at the semiempirical PM3 level of theory. The reaction mechanisms proposed in the literature were verified and the details of the rather complicated processes leading to the emission of light (chemiluminescence) explained by these theoretical studies. Particular reaction steps were characterized at the thermodynamic and kinetic levels. The influence of the solvent was studied by means of the PM3-COSMO method (aqueous medium). The bottleneck steps determining the kinetics of the overall process were identified. Structural modifications of CMAPE that could improve its analytical usefulness were indicated on the basis of theoretical considerations.