Chemiluminescence upon Photooxidation of 4,4"-Diazidodiphenyl with Molecular Oxygen

It was found that irradiation of the solution of 4,4"-diazidodiphenyl in ethyl alcohol with UV-light at a wavelength longer than 280 nm in the presence of dissolved oxygen resulted in appearance of post-luminescence. The luminescence intensity increases with increasing the oxygen concentration; the luminescence virtually disappears after purging the solution with argon. The observed emission of light was attributed to chemiluminescence of the products of photooxidation of 4,4"-diazidodiphenyl. The rate dependence of the afterglow shows two maxima. The first is observed immediately after cessation of the UV irradiation of the solution and its transfer to a photometric cell. The intensity of the corresponding chemiluminescence decreases by an exponential law with _e= 5 s. The second maximum appears after a certain time interval after the first one. Addition of a triplet sensitizer (Michler's ketone) to the reaction mixture results in quenching of the chemiluminescence from the photooxidation products, whereas the addition of substances that stabilize electrophilic species in the singlet state leads to an increase in the chemiluminescence intensity. It was suggested that the chemiluminescence resulted from reactions involving the singlet nitrene adduct with oxygen.