Design of a Eu3+-post-synthetic modified MOF ratiometric fluorescent probe for recyclable recognition of light green SF

Abstract

Light green SF (LGSF), a pervasive dye posing a grave risk to human health, urgently demands the creation of a straightforward, swift, sensitive, intuitive, and recyclable detection method. In this research endeavor, we have innovatively designed a Eu³⁺@MOF-1 ratiometric fluorescent (RF) probe, utilizing a post-synthetic modification (PSM) approach, for the efficient detection of LGSF in lake water and green-colored beverages. This probe exhibits distinctive fluorescence emission properties, characterized by dual emission peaks at 443 nm and 614 nm. In the presence of LGSF, the emission intensity at 443 nm remains constant, functioning as an internal reference, while the emission intensity at 614 nm decreases progressively. This shift is attributed to the principle of fluorescence resonance energy transfer (FRET), where LGSF effectively quenches the fluorescence of Eu³⁺@MOF-1 at 614 nm, thereby enabling RF detection of LGSF. Notably, the luminescence color of Eu³⁺@MOF-1 undergoes a significant change from red to blue upon LGSF addition, which is readily observable by the naked eye. A thorough analysis of the fluorescence quenching mechanism of LGSF on Eu³⁺@MOF-1 has been conducted. Furthermore, the Eu³⁺@MOF-1 RF probe exhibits robustness, enduring five testing cycles with a clear transition from red to blue in each iteration, underscoring its high stability and reproducibility. Experimental findings reveal that the Eu³⁺@MOF-1 RF probe exhibits remarkable specificity, sensitivity, and exceptional regeneration capabilities for LGSF detection. This RF probe offers a potent tool for monitoring water pollution and identifying illicit additions of LGSF in yellow-green beverages, highlighting its broad spectrum of application prospects.