A coumarin-based fluorescent probe CHA functionalized with a 2-hydrazone pyridine unit displayed different photophysical responses to Au, Cu and Hg. It exhibited ratiometric fluorescent response to Au, whereas remarkable fluorescence “turn-off” response to Cu/Hg in aqueous solution. Au and Cu respectively induced clear blue-shift and red-shift in the absorption maximum, while Hg had little impact on the absorption spectrum. The results of NMR, Job's titration and competition assay reveal that CHA was hydrolyzed to aldehyde under catalysis of Au, while it formed complex with Cu and Hg. The ratio of fluorescence intensities I/I of CHA exhibited linear relationship to Au concentration in the range of 0.5–5.0 μM with a detection limit of 0.02 μM. The fluorescence intensity at 540 nm was in linearly correlative with Cu/Hg concentration. Therefore, CHA could be used for detection of Au, Cu/Hg in different channels as well as visual differentiation of exogenous Au and Cu/Hg in living HeLa cells.

中文翻译：

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使用基于香豆素的探针对 Au(III) 进行比率荧光检测，并对 Cu(II)/Hg(II) 进行荧光“关闭”识别

用 2-腙吡啶单元功能化的基于香豆素的荧光探针 CHA 对金、铜和汞表现出不同的光物理响应。它对 Au 表现出比率荧光响应，而对水溶液中的 Cu/Hg 表现出显着的荧光“关闭”响应。 Au和Cu分别在吸收最大值处引起明显的蓝移和红移，而Hg对吸收光谱影响不大。 NMR、乔布滴定和竞争分析结果表明CHA在Au的催化下水解成醛，同时与Cu和Hg形成络合物。 CHA 的荧光强度比值 I/I 在 0.5~5.0 μM 范围内与 Au 浓度呈线性关系，检测限为 0.02 μM。 540 nm处的荧光强度与Cu/Hg浓度呈线性相关。因此，CHA可用于检测不同通道中的Au、Cu/Hg以及活HeLa细胞中外源Au和Cu/Hg的视觉区分。