Preparation of a versatile fluorescence sensor for co-detecting ions in aqueous solution

A multifunctional fluorescence sensor is an important analytical method for detecting water quality. Herein, PCBH-FS, a fluorescence sensor, is first constructed by dispersing a new compound PCBH in THF-H₂O (fw 60%, v/v). PCBH-FS exhibits a distinct red-shifted emission from 405 to 475 nm and a "turn-on" fluorescence response to Fe³⁺ and Al³⁺ in the pH range of 5-9, and PCBH-FS exhibits a good fluorescence response to H⁺ in the pH range from 1 to 5. The Al³⁺-PCBH system can be used for F^- detection, while the Al³⁺-PCBH and Fe³⁺-PCBH systems can be used for sequential AcO^- detection in THF/H₂O mixed media. The binding ratio and the possible sensing mechanism between cations and PCBH molecules are discussed clearly. The LOD of the PCBH-FS reaches 0.44 µM, 0.36 µM, 2.02 µM, and 1.45 µM for detecting Fe³⁺, Al³⁺, F^-, and AcO^- in turn. The sensor provides a simple "on-off" & fluorescent-shift co-detection strategy for sequential detection of multiple ions in aqueous solutions.