Dual-Emitting EY@Zr-MOF Composite as Self-Calibrating Luminescent Sensor for Selective Detection of Inorganic Ions and Nitroaromatics

A dual-emitting dye@MOF composite has been synthesized by incorporating a fluorescent dye eosin Y (EY) within a UiO-type zirconium-based metal–organic framework (Zr-MOF) through a synthetic encapsulation method. The Zr-MOF prevents the aggregation of EY molecules and keeps EY molecules stably included after synthesis. As expected, an energy transfer from Zr-MOF to EY molecules occurred because of the good overlap between the emission of Zr-MOF and the absorption of EY. As a result, the obtained EY@Zr-MOF composite features a weak blue emission at 446 nm and a strong yellow emission at 553 nm. By using the relative height of the two emission peaks replacing absolute peak height as detecting signals, EY@Zr-MOF composite acts as a self-calibrating luminescent sensor for selectively detecting Fe3+, Cr2O72–, and 2-nitrophenol. Furthermore, the observed fluorescence responses of the composite toward analyte are highly stable and reversible after recycling experiments. To the best of our knowledge, this is the first example of a dye@MOF-implicated self-calibrating sensor for Fe3+, Cr2O72–, and 2-nitrophenol detection.