A phenolphthalein-based fluorescent probe for the sequential sensing of Al3+ and F- ions in aqueous medium and live cells

A novel fluorescent probe, phenolphthalein-dialdehyde-(2-pyridyl) hydrazone (L), for sequentially detecting Al3+ and F- in almost 100% aqueous medium was successfully designed and synthesized. The probe offers two binding pockets for Al3+ to form a 1:2 ligand/metal complex, leading to a significant fluorescence enhancement at 465 nm. Further, the in-situ formed L-Al complex acts as a secondary fluorescent chemosensor for F- by quenching the fluorescence of the complex with high selectivity. The detection limit for Al3+ and F- sensing is 228 nM and 0.13 pM, respectively, which are far below the World Health Organization (WHO) acceptable limits (7.41 pM for Al3+ ion and 79 AM for F ) in drinking water. The probe L was successfully applied to the detection of Al3+ and F- in cells using fluorescence microscopy. (C) 2018 Elsevier B.V. All rights reserved.