西安交通大学林健团队报道了溶解再结晶：一种使用颜色可调发光金属有机框架进行Th4+荧光检测的新机制。相关研究成果发表在2024年7月22日出版的《德国应用化学》。

钍是地壳中主要的锕系元素，由于其放射性，对环境和健康构成重大风险。在开采和加工独居石中的稀土元素（REEs）时，这些风险尤为明显，因为稀土元素中含有大量的钍。目前钍的仪器分析方法具有高精度，但需要费力的样品制备和昂贵的仪器，使其不适合现场分析。

该文中，研究人员提出了一类基于镧系元素的颜色可调发光金属有机框架（Ln-MOF）作为Th⁴⁺阳离子的荧光传感器。利用异双金属Eu³⁺/Tb³⁺掺杂策略，Eu_xTb_1-x-BDC-OH的发光颜色可以从红色、橙色和绿色精细调节。更有趣的是，Th⁴⁺的较高路易斯酸度有助于Eu_xTb_1-x-BDC-OH通过溶解-再结晶机制转化为UiO型Th-MOF。

该过程导致特征Ln³⁺发射的逐渐减少和基于蓝色配体的荧光的出现，从而随着Th⁴⁺浓度的增加而产生选择性荧光反应，并实现Th⁴⁺阳离子的可见检测。此外，还制造了一种定制的便携式光电器件，可以直接将发光颜色转换为红绿蓝（RGB）值。该设备能够轻松量化Th⁴⁺浓度，无需复杂的仪器。

附：英文原文

Title: Dissolution-Recrystallization: A Novel Mechanism for Fluorochromic Detection of Th4+ Using Color-Tunable Luminescent Metal-Organic Frameworks

Author: Yunyi Cui, Huangjie Lu, Huiliang Hou, Yaoyao Bai, Junpu Yang, Yarui Li, Jie Qiu, Shuao Wang, Jian Lin

Issue&Volume: 2024-07-22

Abstract: Thorium, a predominant actinide in the Earth's crust, presents significant environmental and health risks due to its radioactive nature. These risks are particularly pronounced during the mining and processing of monazite for rare earth elements (REEs), which contain substantial thorium concentrations. Current instrumental analysis methods for thorium, offer high accuracy but require laborious sample preparation and expensive instruments, making them unsuitable for on-site analysis. Herein, we present a class of color-tunable luminescent lanthanide-based metal-organic frameworks (Ln-MOFs) as fluorochromic sensors for Th4+ cations. Utilizing a heterobimetallic Eu3+/Tb3+ doping strategy, the luminescence colors of EuxTb1–x-BDC-OH can be finely tuned from red, to orange, and to green. More intriguingly, the higher Lewis acidity of Th4+ facilitates the transformation of EuxTb1–x-BDC-OH into a UiO-type Th-MOF via a dissolution-recrystallization mechanism. This process results in a gradual reduction of characteristic Ln3+ emissions and the emergence of blue color ligand-based fluorescence, thereby leading to selective fluorochromic responses with increasing Th4+ concentrations and enabling visible detection of Th4+ cations. Additionally, a custom-built portable optoelectronic device was fabricated, which directly converts luminescence colors into red-green-blue (RGB) values. This device enables easy quantification of Th4+ concentrations without the need for complex instrumentation.

DOI: 10.1002/anie.202410453

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202410453