A cell-compatible phenolphthalein-aminophenol scaffold for Al³⁺sensing assisted by CHEF phenomenon

Monitoring of excess Al³⁺ and its selective detection in biological and environmental samples are important tasks for researcher due to its harmful effects. Herein, we present a phenolphthalein-aminophenol derived sensor (PFAP) for the selective fluorescent response of Al³⁺ in an "OFF-ON" mode over a pool of analytes including eighteen cations with striking greenish emission. It has a prominent limit of detection (LOD) value (1.5 µM), fast response time (10 s) for Al³⁺ detection. The complexation properties of PFAP with Al³⁺ ions were clarified by UV–vis, ¹H & ¹³C NMR, HRMS, and FTIR spectroscopic experiments. The recognition mechanism of PFAP for Al³⁺working with chelation enhanced fluorescence (CHEF) and is verified with two model compounds PF and PFAN in the light of UV–vis, PL, TRPL, and NMR experiment. To check its applicability, easily prepared test paper and TLC strip of PFAP was produced for rapid and selective onsite detection of Al³⁺ ions. Bio-imaging application of PFAP in human lung cancer cell lines A549 demonstrated excellent results with negligible cytotoxicity and as an excellent marker to detect traces of Al³⁺ ion in a time-dependent as well as concentration-dependent manner. Actual sample analysis for Al³⁺ with the probe PFAP produces fruitful result.