In this study, we have designed and synthesized two excited-state proton transfer (ESIPT)-active fluorescent probes (1, 2) that can form nanoscopic self-assembly in pure aqueous medium. The extent of self-assembly was found to be prominent for compound 2 having the hydroxyl unit compared to that witnessed for 1 possessing the amino functional group at the same position. In both cases, the color of the solution changed upon the addition of the CN^– ion. Compound 1 exhibited a superior response toward the CN^– ion with a red-shifted fluorescence maximum, while the addition of CN^– resulted in a blue-shifted λmax for 2 with a relatively poor response. The mechanistic investigations indicated that both the salicylaldimine and hydrazone units participated in the hydrogen bonding interactions with the cyanide ions. Thus, we believe that the differences in response toward the CN^– ion were attributed to both changes in the protonation equilibrium of the compounds along with the extent of aggregation. Given this high sensitivity, we employed this system to analyze cyanide in different natural water samples. The obtained high percentage recovery values (∼100%) and significantly low relative standard deviations (<5%) indicate that semiquantitative analysis of cyanide is achievable using this method. Also, chemically modified paper strips have been designed for rapid, on-location detection as well as quantification of CN^– ions via naked-eye color-changing response.

中文翻译：

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基于 ESIPT 的氰化物双模式传感荧光探针的设计：应用于天然水样的快速现场检测和筛选


在这项研究中，我们设计并合成了两种激发态质子转移（ESIPT）活性荧光探针（1、2），它们可以在纯水介质中形成纳米级自组装。发现与在相同位置具有氨基官能团的化合物 1 相比，具有羟基单元的化合物 2 的自组装程度更为突出。在这两种情况下，添加 CN ^– 离子后溶液的颜色都会发生变化。化合物 1 对 CN ^– 离子表现出优异的响应，荧光最大值红移，而添加 CN ^– 导致 2 的 λmax 蓝移，荧光最大值相对较差。回复。机理研究表明水杨醛亚胺和腙单元都参与了与氰化物离子的氢键相互作用。因此，我们认为对 CN ^– 离子的响应差异归因于化合物质子化平衡的变化以及聚集程度。鉴于这种高灵敏度，我们使用该系统来分析不同天然水样中的氰化物。获得的高百分比回收率值 (∼100%) 和显着低的相对标准偏差 (<5%) 表明使用该方法可以实现氰化物的半定量分析。此外，化学改性纸条设计用于快速、现场检测以及通过肉眼变色响应对 CN ^– 离子进行定量。