Effect of diphenylamine on photodissociation of aryl azides

The charge-transfer complexes of aromatic azides with diphenylamine (DPA) were studied. Irradiation of 4-nitrophenyl azide in the presence of DPA was found not to give rise to the dissociation of the azido group in the azide radical anionvia intracomplex electron transfer. The photodissociation slows down due to both the static (the formation of a photostable complex with diphenylamine) and dynamic quenching. When 4-azidoacetophenone is irradiated in the presence of DPA, the amine-sensitized decomposition of azide and the photodecomposition of the azide—DPA complex occur along with the direct photolysis of azide, which results in acceleration of the photodissociation due to an increase in the efficiency of the light absorption by the reaction system. A possible sensitization of photodecomposition of aromatic azidesvia an electron transfer mechanism by irradiation of the azide-donor complex is shown.