A novel OFF-ON-OFF fluorescence probe based on coumarin for Al3+ and F− detection and bioimaging in living cells

A novel fluorescence probe L2 based on coumarin has been designed and synthesized. The probe L2 can be used for relay recognition of metal ions Al 3+ and anion F − in the aqueous HEPES buffer (0.05 M, pH = 7.4), and build a OFF-ON-OFF detection system. The probe showed high selectivity and sensitivity to target ions in the process of relay recognition, and the corresponding detection limit could be as low as 0.014 μM (Al 3+ ) and 0.03 μM (F − ). Besides, the geometry optimizations of probe L2 and [L2 + Al 3+ ] complex were carried out using the Gaussian 16 program based on DFT, and the identification mechanism of the probe was also discussed by the mass spectrometry and theoretical calculations. Moreover, the probe has also been successfully applied to detection of target ions in living cells.