ESIPT performance bis-Schiff base for multifunctional detection of Pb2+, Mg2+ and Al3+ ions through "turn-on" response and its biological application

Benzothiazole, hydrazine/ammonia and salicylaldehyde were selected as basic unit for constructing of bis-Schiff base molecules with excited state intramolecular proton transfer (ESIPT) property. Herein, "turn-on" fluorescent performance and highly sensitive multifunctional fluorescence probes were developed to stably and efficiently detect Pb2+, Mg2+ and Al3+ in biological and environmental samples. Among them, BF-SJ could distinguish Pb2+ and Mg2+ ions under different pH conditions, while BF-SO could separate Pb2+ and Al3+ by different emission wavelength. More important, target ions could be distinguished by naked eyes with color change of solution under sun light and ultraviolet lamp. The LOD values of BF-SJ and BF-SO for Pb2+/Mg2+ and Pb2+/Al3+ were as low as 31.23 mu M, 25.95 mu M, 59.57 mu M and 1.38 mu M, respectively. Ideally, they showed low cytotoxicity and were successfully used for imaging of exogenous Pb2+/Mg2+ and Pb2+/Al3+ in HeLa cells. Also, BF-SJ exhibited satisfactory performance in detection of Mg2+ in seawater and test paper experiment.