Origin of Chemiluminescence Accompanying the Reaction of the 9-Cyano-10-methylacridinium Cation with Hydrogen Peroxide

The 9-cyano-10-methylacridinium cation possesses an electrophilic center at the carbon atom in
position (9) susceptible to the addition of anions. The addition of OOH- to this cationin weakly
acidic, neutral, or alkaline mediainitiates processes leading to the formation of electronically
excited 10-methyl-9-acridinone, which deactivates by light emission. The effect of changes in reactant
concentrations and pH on emission decay with time, as well as other features of the accompanying
chemiluminescence, were established. Calculations carried out at the semiempirical and density
functional theory level demonstrated that initial addition of OOH- and subsequent processes lead
either to the elimination of OCNH (in weakly acidic and neutral media) or OCN- (in alkaline media)
and that their exothermicity is sufficiently high to generate electronically excited 10-methyl-9-acridinone. On the other hand, primary addition of OH- to C(9) in alkaline media initiates the
conversion of the cation to the nonexcited 10-methyl-9-acridinone. This relatively rapid process
influences to a substantial extent the intensity of the chemiluminescence. The prospects for the
analytical application of 9-cyano-10-methylacridinium salts are briefly outlined.