ABSTRACT Methods for optical detection of inorganic cyanide based on the single molecule sensor with high selectivity and sensitivity have attracted increasing interest recently due to the high toxicity of cyanide ions. In this work, a visual sensor (S1) containing both imidazole NH and azo-phenolic OH was synthesised and characterised. The spectral experimental data indicated that protic aqueous solution facilitated enhancing the selectivity of cyanide ions with the nanomolar-level detection limit in semi-aqueous solution. The visual sensing mechanism arising from the deprotonation of azo-phenolic OH and the enhancement of intramolecular charge transfer could be clearly demonstrated by titration experiments of 1H NMR, HR MS and energy changes between the HOMO−LUMO band gaps. Furthermore, the reversibility and reusability of S1 upon alternating addition of CN− and H+ were studied. Graphical Abstract A visual sensor incorporated by imidazole NH and azo-phenolic OH was developed to detect inorganic CN− via reversible proton transfer based on the deprotonation/protonation of azo-phenolic OH/O− in aqueous solution.

中文翻译：

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基于偶氮酚羟基去质子化的无机氰化物视觉传感的可控可逆质子转移

摘要 由于氰化物离子的高毒性，基于具有高选择性和灵敏度的单分子传感器光学检测无机氰化物的方法最近引起了越来越多的关注。在这项工作中，合成并表征了含有咪唑 NH 和偶氮酚 OH 的视觉传感器 (S1)。光谱实验数据表明，质子水溶液有利于提高氰化物离子的选择性，在半水溶液中具有纳摩尔级的检测限。通过 1H NMR、HR MS 和 HOMO-LUMO 带隙之间的能量变化的滴定实验可以清楚地证明偶氮酚 OH 的去质子化和分子内电荷转移的增强所产生的视觉传感机制。此外，研究了交替添加 CN- 和 H+ 后 S1 的可逆性和可重用性。图形摘要开发了一种由咪唑 NH 和偶氮酚 OH 结合的视觉传感器，基于水溶液中偶氮酚 OH/O- 的去质子化/质子化，通过可逆质子转移检测无机 CN-。