Perylenemonoimide-Based Colorimetric Probe with High Contrast for Naked-Eye Detection of Fluoride Ions

Excessive fluoride ions (F-) in drinking water are harmful to the environment and human health. However, most reported probes of F- can only detect fluorocarbons rather than aqueous F-. Herein, a colorimetric and fluorescent probe (PMI-OH) based on perylenemonoimide is designed and synthesized for the detection of aqueous F-, with high sensitivity, good selectivity, and reversibility. The F- causes deprotonation of PMI-OH, leading to a significant red shift of 222 nm (from 520 to 742 nm) of the absorption band. Upon the addition of fluorocarbons, the fluorescence intensities of PMI-OH show good linearity against the concentrations of F-, realizing the quantitative detection of fluorocarbons with a limit of detection as low as 0.495 μM. Finally, PMI-OH is applied to detect F- in drinking water. The color of PMI-OH solution shows remarkable response from pink to green when the concentrations of F- exceed the upper limit set by the World Health Organization (WHO), realizing rapid and naked-eye detection of aqueous F-.