We report here a water-soluble metal cation sensor system based on the as-prepared or reduced form of an expanded porphyrin, texaphyrin. Upon metal complexation, a change in the redox state of the ligand occurs that is accompanied by a color change from red to green. Although long employed for synthesis in organic media, we have now found that this complexation-driven redox behavior may be used to achieve the naked eye detectable colorimetric sensing of several number of less-common metal ions in aqueous media. Exposure to In(III), Hg(II), Cd(II), Mn(II), Bi(III), Co(II), and Pb(II) cations leads to a colorimetric response within 10 min. This process is selective for Hg(II) under conditions of competitive analysis. Furthermore, among the subset of response-producing cations, In(III) proved unique in giving rise to a ratiometric change in the ligand-based fluorescence features, including an overall increase in intensity. The cation selectivity observed in aqueous media stands in contrast to what is seen in organic solvents, where a wide range of texaphyrin metal complexes may be prepared. The formation of metal cation complexes under the present aqueous conditions was confirmed by reversed phase high-performance liquid chromatography, ultra-violet-visible absorption and fluorescence spectroscopies, and high-resolution mass spectrometry.

中文翻译：

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还原型泰克萨菲林：水溶液中重金属的比率光学传感器

我们在此报告了一种基于已制备或还原形式的膨胀卟啉（泰克萨菲林）的水溶性金属阳离子传感器系统。金属络合时，配体的氧化还原态发生变化，并伴随着颜色从红色变为绿色。尽管长期用于有机介质中的合成，但我们现在发现这种络合驱动的氧化还原行为可用于实现水介质中几种不常见金属离子的肉眼可检测比色传感。暴露于 In(III)、Hg(II)、Cd(II)、Mn(II)、Bi(III)、Co(II) 和 Pb(II) 阳离子会在 10 分钟内产生比色响应。该过程在竞争分析条件下对 Hg(II) 具有选择性。此外，在产生响应的阳离子子集中，In(III) 被证明在引起基于配体的荧光特征的比率变化方面是独特的，包括强度的整体增加。在水性介质中观察到的阳离子选择性与在有机溶剂中观察到的阳离子选择性相反，有机溶剂中可以制备多种泰克萨菲林金属配合物。通过反相高效液相色谱、紫外可见吸收和荧光光谱以及高分辨率质谱证实了在当前水性条件下金属阳离子络合物的形成。