Wu Ying, Chen Lei, Chen Yong, Liu Yu
College of Chemistry, State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, P. R. China.
ACS Appl Mater Interfaces. 2021 Dec 15;13(49):59126-59131. doi: 10.1021/acsami.1c19076. Epub 2021 Dec 6.
Lanthanide supramolecular assemblies as photoswitches have attracted much attention in the fields of cellular imaging and light-emitting materials. However, the regulation of lanthanide luminescence behavior by redox of metal ions is rare. Herein, we constructed a lanthanide luminescence supramolecular switch, that is, a binary assembly constructed by mono-(6-ethylenediamine-6-deoxy)-β-cyclodextrin (ECD) and ammonium molybdate tetrahydrate ((NH)MoO·4HO, Mo), and further assembled into ternary assemblies with polyoxometalate Na[XWO]·32HO (X-POM, X = Eu and Dy), which was comprehensively characterized by UV-vis, fluorescence, NMR, Fourier transform infrared, dynamic light scattering, scanning electron microscopy, and ζ potential. Thanks to the oxygen-shielding effect of secondary supramolecular assembly, the photoreduction process of Mo (VI) could occur rapidly and efficiently. Due to the high Förster resonance energy transfer (FRET) efficiency of X-POM and Mo (V) in supramolecular assembly, the photoreduction process is accompanied by fluorescence quenching. In addition, the oxidation process of the Mo (V) could be rapidly promoted by heating, which allowed the X-POM fluorescence to recover. Interestingly, ECD-mediated ternary supramolecular assemblies not only tune the lanthanide luminescence but also strongly increase the lanthanide luminescence behavior, leading to the emission of strong narrow red light at D-F, which can be successfully applied to two-dimensional code anticounterfeiting. In this study, a new approach is provided for the construction of lanthanide luminescence supramolecular switches tuned by photoreactive polyoxometalate.
镧系超分子组装体作为光开关在细胞成像和发光材料领域备受关注。然而，通过金属离子的氧化还原调节镧系发光行为的研究却很少见。在此，我们构建了一种镧系发光超分子开关，即由单（6-乙二胺-6-脱氧）-β-环糊精（ECD）和四水合钼酸铵（(NH₄)₂MoO₄·4H₂O，Mo）构建的二元组装体，并进一步与多金属氧酸盐Na₉[XW₁₂O₄₀]·32H₂O（X-POM，X = Eu和Dy）组装成三元组装体，通过紫外可见光谱、荧光光谱、核磁共振、傅里叶变换红外光谱、动态光散射、扫描电子显微镜和ζ电位对其进行了全面表征。得益于二级超分子组装体的氧屏蔽效应，Mo（VI）的光还原过程能够快速有效地发生。由于超分子组装体中X-POM与Mo（V）之间具有较高的Förster共振能量转移（FRET）效率，光还原过程伴随着荧光猝灭。此外，加热可快速促进Mo（V）的氧化过程，使X-POM荧光得以恢复。有趣的是，ECD介导的三元超分子组装体不仅能调节镧系发光，还能显著增强镧系发光行为，在D-F处发射出强而窄的红光，可成功应用于二维码防伪。本研究为构建由光反应性多金属氧酸盐调节的镧系发光超分子开关提供了一种新方法。
