A rapid on-site fluorescence sensing platform for malachite green in an aqueous phase based on lanthanide-functionalized MOF.

The residue of malachite green (MG) in water has serious toxic effects on the human body, so it is very important to establish a highly sensitive and convenient method for MG detection. In this study, a novel double-emission lanthanide MOF fluorescence probe (Eu-Zn-MOF) was designed for monitoring MG in water by post-synthetic modification (PSM) to Zn-MOF synthesized by a simple hydrothermal method. Eu-Zn-MOF exhibits excellent photoluminescence properties, making it suitable as a ratiometric fluorescence sensor (I/I) for the sensitive detection of MG. MG effectively quenches the luminescence of Eu at 615 nm, while the luminescence of the Zn-MOF frame at 410 nm remains unaltered. The fluorescence sensing platform had a relatively wide linear range (0-30 µM), low detection limit (9.8 nM), high sensitivity, and rapid response time (within 1 min). At the same time, the recovery of actual samples was 90.2-107.0%, and the relative standard deviation (RSD) was ≤ 3.82%. Simultaneously, by combining the smartphone color recognition APP with RGB analysis, a portable smartphone auxiliary sensing platform was established to realize the visual detection of MG. This method provides a novel strategy for real-time monitoring of pollutants in the environment.