In this contribution we build upon our previous work on the MOF [Mg(H₂dhtp)(H₂O)₂]·DMAc (AEMOF-1·DMAc) and its activated dry version AEMOF-1′ which has been shown to exhibit excellent luminescence sensing properties towards water in organic solvents. We demonstrate through combined structural and photophysical studies that the observed changes in the fluorescence properties of AEMOF-1′ upon hydration arise from a structural transformation to the mononuclear complex [Mg(H₂dhtp)(H₂O)₅]·H₂O (H₄dhtp = 2,5-dihydroxyterepthalic acid) (1). In the latter complex, excited state intramolecular proton transfer (ESIPT) is strongly favoured thereby leading to enhanced and red shifted emission in comparison to AEMOF-1·DMAc. Powder X-ray diffraction measurements confirmed that complex 1 is identical to the hydrated form of AEMOF-1·DMAc. As in the case of AEMOF-1′, the dry form of complex 1 (1′) is also an effective sensor for the determination of traces of water in tetrahydrofuran (THF). This work demonstrates that the same chromophore may exhibit very different emission properties when it exists in different chemical environments and that these transformations may be controlled and utilized in water sensing applications.

中文翻译：

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阐明Mg2 +对羟基苯甲酸二甲酯MOF（AEMOF-1'）的水感测机制

在此贡献中，我们基于先前关于MOF [Mg（H ₂ dhtp）（H ₂ O）₂ ]·DMAc（AEMOF- 1 ·DMAc）及其活化的干燥版本AEMOF- 1 '的研究工作，该研究已显示出对有机溶剂中的水具有出色的发光感应性能。我们通过组合的结构和光物理研究证明，水合时AEMOF- 1 '的荧光性质的观察到的变化是由结构转变为单核复合物[Mg（H ₂ dhtp）（H ₂ O）₅ ]·H ₂ O引起的（H ₄dhtp ＝ 2，5-二羟基对苯二甲酸（1）。在后者的复合物中，与AEMOF- 1 ·DMAc相比，强烈支持激发态分子内质子转移（ESIPT），从而导致发射增强和红移。粉末X射线衍射测量证实，配合物1与AEMOF- 1 ·DMAc的水合形式相同。与AEMOF- 1 '一样，复合物1（1'）也是测定四氢呋喃（THF）中痕量水的有效传感器。这项工作表明，当相同的生色团存在于不同的化学环境中时，它可能会表现出非常不同的发射特性，并且这些转化可以在水感测应用中得到控制和利用。