ESIPT-based fluorochromes are promising materials for the detection of various chemical and biological species, particularly metal cations. Herein, we have meticulously designed a prototypical ESIPT-based α-naphtholphthalein-derived "turn-on" fluorogenic tweezer, NPDM, for the selective detection and visualization of Al3⁺ in biological and environmental samples. NPDM was found to specifically interact with Al3⁺, exhibiting dual emissions, high sensitivity (50 s), large Stokes shifts (140 and 176 nm), and a low detection limit of 16.3 nM. Notably, the sensing mechanism of NPDM for Al3⁺ involves metal ion-coordination-induced fluorescence enhancement (CHEF), ESIPT "turn-on" effect as well as restricted intramolecular rotation (RIR). This mechanism is supported by Job's plot, high-resolution mass spectrometry (HRMS), proton nuclear magnetic resonance (¹H NMR) titrations, and density functional (DFT) calculations. Interestingly, the NPDM-Al3+ ensemble can function as a secondary chromo-fluorogenic tweezer for monitoring fluoride ions (F-) with a low detection limit of 34.8 nM. Thus, an advanced molecular memory device was constructed based on the fluorescence "off-on-off" strategy and its excellent sensing properties. Moreover, a portable, smartphone-assisted intelligent platform has been developed to facilitate in-field, cost-effective, and accurate detection of Al3⁺ in real environmental water samples. Significantly, NPDM was successfully employed to image intracellular Al3⁺ and F⁻ ions in HeLa cells without interference from oxidative stress. This represents the first reported smart molecular tweezer capable of detecting Al3⁺ ions generated during electroporation within living cells. Furthermore, the strategy developed here is valuable for the creation of novel, practically beneficial luminescent molecules and offers an advanced luminescent detection platform for point-of-care sensing of health-related ionic species.
Keywords: Al3+; Cell imaging; ESIPT; fluorochromogenic tweezer; portable detection.
© 2025 Wiley‐VCH GmbH.