An ESIPT-active ɑ-naphtholphthalein-DAMN hydrazone as chromo-fluorogenic tweezers for fast detection of Al3+ ions

ESIPT-based fluorochromes are a type of promising materials for the detection of various chemical/biological species, especially the metal cations. Herein, we elaborately designed a prototypical ESIPT-active ɑ-naphtholphthalein- derived “turn-on” fluorogenic tweezers NPDM for selectively detecting and visualizing Al3+ in biological and environmental samples. NPDM was found to specifically interact with Al3+ with dual emissions, good sensitivity (50 s), large Stokes shifts (140 nm/176 nm) and low detection limit (16.3 nM). Noteworthily, the sensing mechanism of NPDM towards Al3+ involves metal ion-coordination induced fluorescence enhancement (CHEF), ESIPT “turn-on” effect as well as restricted intramolecular rotation (RIR), which has been supported by Job’s plot, HRMS, 1H NMR titrations, as well as detailed DFT calculations. Interestingly, the NPDM-Al3+ ensemble can act as a secondary chromo-fluorogenic tweezers for monitoring F- with a low detection limit down to 34.8 nM level. 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-aided intelligent platform was fabricated to realize the in-field, cost-effective, and faithful detection of Al3+ in real environmental water samples. Significantly, NPDM was successfully employed for imaging the intracellular Al3+ and F- ions in Hela cells without interference from the oxidative stress and it is the first reported smart molecular tweezers capable of determining the Al3+ ions formed during electroporation inside living cells. Furthermore, the strategy developed here is valuable to develop novel practically beneficial luminous molecules and provide intelligent luminescent detection platform for point-of-care sensing of health-related ions species in the prospect.