中文摘要：

传统的化学发光通常只会产生一次化学发光,并且极少专一依赖于高反应活性的羟基自由基（OH）。致癌性四氯苯醌（TCBQ）与H2O2反应能产生一种非同寻常的两次化学发光,其产生与2次OH形成存在良好相关性,且前者直接依赖于后者。研究推测在TCBQ与H2O2的反应过程中,生成了某种依赖于OH形成的新型醌-1,2-二氧杂环丁烷中间体以及激发态的多羰基物质,正是它们导致了该体系的化学发光。这些发现将有助于检测和定量OH以及多卤代芳烃类致癌物。

英文摘要：

Tetrachloro-1,4-benzoquinone （TCBQ） is one of the major genotoxic and carcinogenic quinoid metabolites of the widely used wood preservative pentachlorophenol. We found previously that TCBQ and H2O2 could produce hydroxyl radicals （＊OH） independent of transition metal ions. However, the underlying molecular mechanism is still unclear. Here we show that an unusual two-step chemiluminescence （CL） can be produced by TCBQ and H2O2. The two-step CL produced by TCBQ/H2O2 was found to be well correlated to and dependent on its two-step production of ＊OH： markedly quenched by the classic ＊OH scavengers, but enhanced further by classic Fenton reagent, which is known to produce extra ＊OH. The initial reaction intermediate of TCBQ/H2O2 were found to be trichlorohydroxy-1,4-benzoquinone, and the major final products were identified as 2,5-dichloro-3,6-dihydroxy-1,4- benzoquonine, and the ring-opening 2,3-dichloromaleic acid and CO2 by complementary applications of multiple analytical methods such as HPLC-MS, GC-MS, ion chromatography （IC） and total organic carbon （TOC）. Based on these data, we proposed that ＊OH-dependent formation of quinone-dioxetane and electronically excited carbonyl species might be responsible for this unusual two-step CL production by TCBQ and H2O2. These findings may have potential applications in detecting and quantifying ＊OH and the ubiquitous polyhalogenated aromatic carcinogens, which may have broad biological and environmental implications for future research on these types of important species.