Self-Catalyzing Chemiluminescence of Luminol-Diazonium Ion and Its Application for Catalyst-Free Hydrogen Peroxide...

We report the unique self-catalyzing chemiluminescence (CL) of luminol-diazonium ion (N₂⁺-luminol) and its analytical potential. Visual CL emission was initially observed when N₂⁺-luminol was subjected to alkaline aqueous H₂O₂ without the aid of any catalysts. Further experimental investigations found peroxidase-like activity of N₂⁺-luminol on the cleavage of H₂O₂ into OH^• radical. Together with other experimental evidence, the CL mechanism is suggested as the activation of N₂⁺-luminol and its dediazotization product 3-hydroxyl luminol by OH^• radical into corresponding intermediate radicals, and then further oxidation to excited-state 3-N₂⁺-phthalic acid and 3-hydroxyphthalic acid, which finally produce 415 nm CL. The self-catalyzing CL of N₂⁺-luminol provides us an opportunity to achieve the attractive catalyst-free CL detection of H₂O₂. Experiments demonstrated the 10^-8 M level detection sensitivity to H₂O₂ as well as to glucose or uric acid if presubjected to glucose oxidase or uricase. With the exampled determination of serum glucose and uric acid, N₂⁺-luminol shows its analytical potential for other analytes linking the production or consumption of H₂O₂. Under physiological condition, N₂⁺-luminol exhibits highly selective and sensitive CL toward ¹O₂ among the common reactive oxygen species. This capacity supports the significant application of N₂⁺-luminol for detecting ¹O₂ in live animals. By imaging the arthritis in LEW rats, N₂⁺-luminol CL is demonstrated as a potential tool for mapping the inflammation-relevant biological events in a live body.