Unprecedented hydroxyl radical-dependent two-step chemiluminescence production by polyhalogenated quinoid carcinogens and H2O2

Most chemiluminescence (CL) reactions usually generate only one-step CL, which is rarely dependent on the highly reactive and biologically/environmentally important hydroxyl radicals ((OH)-O-center dot). Here, we show that an unprecedented two-step CL can be produced by the carcinogenic tetrachloro-1,4-benzoquinone (also known as p-chloranil) and H2O2, which was found to be well-correlated to and directly dependent on its two-step metal-independent production of (OH)-O-center dot. We proposed that (OH)-O-center dot-dependent formation of quinone-dioxetane and electronically excited carbonyl species might be responsible for this unusual two-step CL production by tetrachloro-1,4-benzoquinone/H2O2. This is a unique report of a previously undefined two-step CL-producing system that is dependent on intrinsically formed (OH)-O-center dot. These findings may have potential applications in detecting and quantifying (OH)-O-center dot and the ubiquitous polyhalogenated aromatic carcinogens, which may have broad biological and environmental implications for future research on these types of important species.