Benzothiazole-based fluorescence chemosensors for rapid recognition and “turn-off” fluorescence detection of Fe3+ ions in aqueous solution and in living cells

Two new benzothiazole-based fluorescence sensors (sensor 1 and sensor 2) have been successfully synthesized and their structures have been well characterized by 1H NMR, 13C NMR and mass spectrometry. Sensor 1 and sensor 2 displayed a selective fluorescence quenching response towards Fe3+ ions in aqueous solutions with good anti-interference ability. Sensor 1 and sensor 2 exhibited lower detection limits for Fe3+, 8.43 μM for sensor 1 and 5.86 μM for sensor 2, respectively. The Job's plot, mass spectrometry, 1H NMR titration and DFT calculations proved that sensors formed 1:1 complexes with Fe3+ ions. In addition, sensor 1 and Sensor 2 had low cell toxicity and could be used to monitor the existence of Fe3+ ions in living cells.