A New ‘Turn-on’ and reversible fluorescent sensor for Al3+ detection and live cell imaging
Herein, we report a new benzothiazole-based azomethine receptor L as reversible fluorescent sensor for the selective detection of Al3+ in buffered aqueous methanol (20 mM HEPES, pH = 6.0, 50% (v/v) CH3OH). The fluorescence enhancement response of L towards Al3+ along with a large blue shift (Δλ= ~157 nm) may be attributed to the formation of L-Al3+ complex, which results in the inhibition of excited state intramolecular proton transfer (ESIPT) and C=N isomerisation as well as the chelation enhanced fluorescence (CHEF).The results of Job’s plot and mass spectroscopic analysis support the stoichiometry of the complex between L and Al3+ ion as 1:1. The proposed complex structure was calculated by applying the DFT method. Furthermore, the applicability of the probe has been tested in BEL-7402 human hepatoma carcinoma cells under fluorescence microscope, where turn-on, intense bluish green fluorescence was observed in the presence of Al3+ ions.