Synthesis of Yttrium(III)-based Rare-Earth Metal-Organic Framework Nanoplates and Its Applications for Sensing of Fluoride Ions and pH

Abstract High-performance determination of fluoride ion (F-) is an important goal due to the hazards of fluoride to human body. In this study, a rare-earth metal-organic frameworks (RE-MOFs) was successfully designed and prepared with a nanoplates morphology. 4,4,4,4-(Porphine-5,10,15,20-tetrayl) tetrakis (benzoic acid) (called “TCCP”) as the porphyrin-based planar ligand and Y3+ as the metal center were applied to form the Y-TCCP MOF nanoplates (YTMNs) via coordination chelation. Giving the credit to the distinctive host-guest response between YTMNs and F- (or OH-), a multipurpose fluorescence sensor was developed with multiple signal output. F- reacted with YTMNs and light-up the fluorescence of YTMNs under the pH of 6. Thus YTMNs was exploited as a fluorescence nanoprobe for F- detection with high sensitivity and selectivity. In addition, it was found that the alkaline medium (pH > 7) also induced the strong fluorescence of YTMNs. These two phenomena occurred at different pH ranges. Therefore, F- detection and pH sensing were simultaneously realized by YTMNs nanoprobe. More importantly, the paper-based YTMNs strip was prepared for visual sensing of pH. The detection results of YTMNs strip were further analyzed by an Intelligent Identification System for Visual Chip (IISVC) for monitoring of pH with digital output. Additionally, the accuracy of YTMNs nanoprobe was confirmed by determination of F- in natural water and pH in real water.