Full-color emission of a Eu3+-based mesoporous hybrid material modulated by Zn2+ ions: emission color changes for Zn2+ sensing via an ion exchange approach

Abstract

We reported on the fabrication of a multicolor fluorescent sensor for Zn²⁺ ions based on the Eu complex functionalized mesoporous hybrid material Eu(TTA-MSN)₂L (TTA: 2-thenoyltrifluoroacetone, HL: 4′-(4-carboxy-methyleneoxyphenyl)-2,2′:6′,2′′-terpyridinel). The material was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, and N₂ adsorption measurements. The results revealed that the material preserves mesoscopically ordered structures and exhibited highly uniform pore size distributions. Spectroscopic analyses showed that the mesoporous hybrid material Eu(TTA-MSN)₂L exhibited the characteristic emission of Eu³⁺ ions, reasonably long lifetimes (0.62 ms), and high quantum yields (18.4%). Moreover, the material displayed a highly selective and sensitive function toward Zn²⁺ ions in aqueous solutions. This sensing function could be attributed to the cation exchange of Eu³⁺ in the parent material Eu(TTA-MSN)₂L with Zn²⁺. More importantly, by only modulating the concentration of Zn²⁺ ions in the water solution of Eu(TTA-MSN)₂L, a tunable full-color emission (including white-light emission) can be generated under single-wavelength excitation. To our knowledge, this effort is the first example of a multicolor emissive sensor for Zn²⁺ ions in water solutions based on lanthanide mesoporous hybrid material.