Xie Jing, Wu Ting, Wang Xiaoling, Yu Chengfeng, Huang Wei, Wu Dayu
Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, Advanced Catalysis & Green Manufacturing Collaborative Innovation Center, School of Petrochemical Engineering, Changzhou University, Changzhou, Jiangsu 213164, P. R. China.
Inorg Chem. 2020 Oct 19;59(20):15460-15466. doi: 10.1021/acs.inorgchem.0c02488. Epub 2020 Sep 29.
Photochromism is an important strategy for realizing reversible light-controllable fluorescence switching. In spite of several reports on fluorescence switching via a photochromic process, the success of photochromic multimetallic complexes reversibly showing fluorescence switching in the solid or crystalline state has been limited for their application importance. Here, we report a photoswitchable near-infrared (NIR) fluorescence based on photochromism in the azo-label 3d/4f heterometal-organic rhomboids, (Ln = Eu (), Yb (), and Er ()), in the crystalline state. An individual metallorhomboid contains up to four azobenzene fragments, which is prepared via the three-component assembly of a -azobenzene-grafted multifunctional ligand, and 3d and 4f metal ions. The photoisomerization quantum yields of complexes can be retained or even higher when compared to the free ligand due to the modification of electronic structure. The impressive crystalline-state NIR luminescence is observed for the complexes of azo-ZnYb () and azo-ZnEr () at room temperature. Intriguingly, the switchable NIR luminescence can be effectively regulated by photochromism in the crystalline state. These features endow the self-assembly of the 3d/4f metallorhomboid with synergetic multifunctional behavior between photochromism and NIR luminescence.
光致变色是实现可逆光控荧光开关的重要策略。尽管有几篇关于通过光致变色过程实现荧光开关的报道，但对于光致变色多金属配合物在固态或晶态下可逆地显示荧光开关，其应用重要性方面的成功案例有限。在此，我们报道了一种基于偶氮标记的3d/4f异金属有机菱形化合物（Ln = Eu（）、Yb（）和Er（））在晶态下光致变色的可光开关近红外（NIR）荧光。单个金属菱形化合物包含多达四个偶氮苯片段，它是通过一种接枝了偶氮苯的多功能配体与3d和4f金属离子的三组分组装制备而成。由于电子结构的改变，配合物的光异构化量子产率与游离配体相比能够保持甚至更高。在室温下，偶氮 - ZnYb（）和偶氮 - ZnEr（）配合物表现出令人印象深刻的晶态近红外发光。有趣的是，晶态下的光致变色能够有效地调节可开关近红外发光。这些特性赋予了3d/4f金属菱形化合物的自组装在光致变色和近红外发光之间协同的多功能行为。
