Pyridyl-substituted triarylmethyl radicals exhibited cation-responsive turn-on fluorescence when additional pyridyl rings were incorporated at an appropriate position; the mechanism of fluorescence enhancement is examined. Reduced quenching by internal and external heavy atom effects is proposed as a unique property of fluorescent radicals, which can be utilized in different environments to conventional closed-shell fluorescent molecules.

中文翻译：

---

阳离子响应的开启荧光，吡啶基取代的三芳基甲基自由基不具有重原子效应

当在合适的位置引入另外的吡啶基环时，吡啶基取代的三芳基甲基自由基显示出阳离子响应的开启荧光。检查了荧光增强的机理。提出通过内部和外部重原子效应减少淬灭是荧光自由基的独特性质，可以与常规的闭壳荧光分子在不同的环境中使用。