Abstract A simple ratiometric optical method for mercuric ion sensing has been developed using an ensemble of an indicator, such as 7-hydroxy-4-methylcoumarin (7H4MC) and bromothymol blue (BTB), and a receptor, such as N,N-bis(p-methoxybenzyl)-3,6-dioxaoctane-1,8-diamines (bis-pMDODA) and cryptand [2.2.2] (C222), in aqueous solution. The equilibrium between indicator and receptor is perturbed by adding Hg2+ ions (0.8–80 μM), due to the formation of a receptor-metal complex, resulting in a change of the UV/Vis spectra. Both sensitivity and selectivity are explained in terms of association constants between receptor and metal ions and equilibrium constants of the reaction between indicator and receptor. Indicator bromothymol blue has also presented a color variation from light blue to yellow upon coordination of Hg2+ to the receptor, which allows a metal naked-eye detection. The detection limit of the system was found to be about 3 μM and the relative standard deviation for five measurements of 20 μM concentration was 5.6%. BTB/7H4MC arrangement showed a particular selectivity over different interfering cations, suffering only interference from Cu2+ ions for Hg2+ sensing.

中文翻译：

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水溶液中汞（II）离子的酸碱响应探针

摘要 使用指示剂（如 7-羟基-4-甲基香豆素 (7H4MC) 和溴百里酚蓝 (BTB)）和受体（如 N,N-bis (p-甲氧基苄基)-3,6-二氧辛烷-1,8-二胺 (bis-pMDODA) 和穴状配体 [2.2.2] (C222)，在水溶液中。由于受体-金属络合物的形成，指示剂和受体之间的平衡因添加 Hg2+ 离子（0.8-80 μM）而受到干扰，导致 UV/Vis 光谱发生变化。灵敏度和选择性都用受体和金属离子之间的缔合常数以及指示剂和受体之间反应的平衡常数来解释。指示剂溴百里酚蓝在 Hg2+ 与受体协调后也呈现出从浅蓝色到黄色的颜色变化，这允许金属裸眼检测。发现该系统的检测限约为 3 μM，20 μM 浓度的五次测量的相对标准偏差为 5.6%。BTB/7H4MC 排列对不同的干扰阳离子表现出特殊的选择性，仅受到 Cu2+ 离子的干扰，用于 Hg2+ 传感。