Photoinduced chemiluminescence in salicylaldehyde hydrazone solution

摘要

Simultaneously with the chemiluminescent reaction of salicylaldehyde hydrazone (G) oxidation by hypochlorite, the competing chemiluminescent reaction of G with the hydroxide ion occurs in alkaline media. The former reaction is accompanied by green chemiluminescence, whereas the latter, with blue chemiluminescence. The estimation of the rate constant for the bimolecular reaction G + OH- gives the value similar to 2 x 10(5) l mol(-1) s(-1). The necessary condition for appearance of chemiluminescence upon interaction of G with OH- is the preliminary illumination of the solution of G with light at a wavelength of 400-540 mm, which is accompanied by the formation of an acoplanar quinonoid isomer of G interacting with the hydroxide ion. The height of the energetic barrier for transition of G molecules from the "illuminated" to the "dark" state is similar to 18 kcal mol(-1).