Redox switchable fluorescent probe selective for either Hg(II) or Cd(II) and Zn(II)
Redox switchable fluorescent probe selective for either Hg(II) or Cd(II) and Zn(II)
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DOI：
10.1021/ja983802r
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发表时间：
1999-06-02
影响因子：
15
通讯作者：
Resch-Genger, U
中科院分区：
文献类型：
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作者：
Hennrich, G;Sonnenschein, H;Resch-Genger, U
在过去的几年中，人们对功能分子的设计和合成给予了相当多的关注，这些功能分子可以用作传感器、可开关和信号转导的分子器件。 1 荧光方法在环境和生物相关重金属阳离子分析检测方面具有巨大潜力，需要开发高选择性和高灵敏度的荧光探针。 2 由于灵敏度原因，由于结合事件而显示荧光增强的探针比在阳离子络合时显示荧光猝灭的探针更受青睐。 3 特别是对于汞 (II) 离子这种广泛认可的荧光猝灭剂，只有很少的系统被描述为将足够的选择性 4 与高信号输出（即荧光增强）相结合。 5对于氧化还原可切换荧光探针系统的设计，我们选择噻二唑/亚氨基硫脲系统作为氧化还原活性构建块。该系统提供了通过可逆氧化还原开关进行外部控制的可能性。氮和硫杂原子对重金属离子的高亲和力使其成为有用的络合单元。 6 一个简单的蒽基充当荧光报告单元。荧光探针系统 1 的氧化形式是通过 Boulton-Katritzki 型重排 7 合成的，其中 3, 4-二苯基-5-氰胺基-1, 2, 4-噻二唑啉 8 与 9-(甲基氨基甲基)-蒽在二恶烷中在碱性条件下反应。生成的 1, 2, 4-噻二唑可被冰醋酸中的锌还原生成 2。使用氯仿中的碘，2 几乎定量地再次转化为系统的氧化形式 1（图 1）。因此，噻二唑1和亚氨基硫脲衍生物2可以被认为是氧化还原可切换系统的两个组成部分。就杂原子的空间特征以及给电子能力而言，两种形式都包含明显不同的结合位点。因此，我们预计 1 和 2 对于所研究的金属阳离子具有不同的选择性。关于系统的
During the past few years considerable attention has been devoted to the design and synthesis of functional molecules that could serve as molecular devices for sensors, switchable and signal transducing. 1 The enormous potential of fluorometric methods for the analytical detection of environmentally and biologically relevant heavy metal cations requires the development of highly selective and highly sensitive fluorescent probes. 2 Due to sensitivity reasons, probes showing fluorescence enhancement as a result of the binding event are to be favored over those which exhibit fluorescence quenching upon cation complexation. 3 Especially for the mercury (II) ion, a widely recognized fluorescence quencher, only very few systems have been described which combine sufficient selectivity4 with a high signal output, ie, fluorescence enhancement. 5For the design of a redox switchable fluorescent probe system we chose the thiadiazole/iminoylthiourea system as a redox active building block. This system offers the possibility of external control via reversible redox switching. The high affinity of nitrogen and sulfur heteroatoms for heavy metal ions makes it a useful complexation unit. 6 A simple anthryl group functions as the fluorescent reporter unit. The oxidized form of the fluorescent probe system 1 was synthesized by a Boulton-Katritzki type of rearrangement, 7 reacting 3, 4-diphenyl-5-cyanimino-1, 2, 4-thiadiazoline8 with 9-(methylaminomethyl)-anthracene in dioxane under alkaline conditions. The resulting 1, 2, 4-thiadiazole could be reduced by zinc in glacial acetic acid to yield 2. Using iodine in chloroform, 2 was reconverted almost quantitatively into the system’s oxidized form 1 again (Figure 1). Hence, the thiadiazole 1 and the iminoylthiourea derivative 2 can be considered as the two components of a redox switchable system. Both forms contain distinctively different binding sites, regarding the steric features as well as the electron-donating capacity of the heteroatoms. Therefore, we expected different selectivities of 1 and 2 for the metal cations studied. Concerning the system’s