Long-standing radical species have raised noteworthy concerns in organic functional chemistry and materials. However, there remains a substantial challenge to produce long-standing radicals by light, because of the structural dilemmas between photoproduction and stabilization. Herein, we present a pyrrole and chloride assisted photochromic structure to address this issue. In this well-selected system, production and stabilization of a radical species were simultaneously found accompanied by a photochemical process in chloroform. Theoretical study and mechanism construction indicate that the designed π-system provides a superior spin-delocalization effect and a large steric effect, mostly avoiding possible consumptions and making the radical stable for hours even under an oxygen-saturated condition. Moreover, this radical system can be applied for a visualized and quantitative detection towards peroxides, such as 2,2,6,6-tetramethylpiperidine-1-oxyl, hydrogen peroxide, and ozone. As the detection relies on a radical capturing mechanism, a higher sensing rate was achieved compared to traditional redox techniques for peroxide detection.

中文翻译：

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使用光致变色触发器设计稳定的自由基。

长期存在的自由基种类引起了有机功能化学和材料方面的关注。然而，由于光产生和稳定之间的结构难题，通过光产生长期存在的自由基仍然存在重大挑战。在这里，我们提出了吡咯和氯化物辅助的光致变色结构，以解决这个问题。在这个精心选择的系统中，同时发现了自由基物质的产生和稳定，并伴随着氯仿中的光化学过程。理论研究和机理构建表明，所设计的π系统具有优异的自旋离域作用和较大的空间效应，主要避免了可能的消耗，即使在氧饱和的条件下，自由基仍可稳定数小时。此外，该自由基体系可用于可视化和定量检测过氧化物，例如2,2,6,6-四甲基哌啶-1-氧基，过氧化氢和臭氧。由于检测依赖于自由基捕获机制，因此与用于过氧化物检测的传统氧化还原技术相比，可实现更高的感测率。