A novel bola-amphiphilic-phenolphthalein sensor for switchable fluorescent detection of Hg2+/Cu2+ and GSH in real water samples.

This study presents the design, synthesis, and evaluation of TSC-PP-TSC, a novel phenolphthalein-based fluorescent sensor produced via a straightforward synthetic route. The sensor demonstrates a quantum yield of 0.114 and exhibits highly selective and sensitive "turn-off" fluorescence towards Hg2+ and Cu2+ ions in a 0.01/99.9 ethanol/water solution. Selectivity for these ions was further confirmed in water/ethanol (v/v: 9.9/0.1) and tap water. Upon binding with Hg2⁺ or Cu2⁺, the sensor forms a 2:1 metal-to-ligand complex, resulting in the dispersion of probe aggregates. The limits of detection (LODs) were determined to be 117 nM for Hg2+ and 1.56 μM for Cu2+. Furthermore, the reversible interaction with I⁻ ions and glutathione (GSH) enabled the construction of a sophisticated four-input OR-INHIBIT logic gate. Notably, the TSC-PP-TSC-Cu2⁺ complex also showed promise as a "turn-on" fluorescent sensor for GSH detection in water and the LOD was 1.80 µM, leveraging the reversibility of the complex formation.