A coumarin based azo-phenol ligand as efficient fluorescent “OFF-ON-OFF” chemosensor for sequential detection of Mg2+ and F−: Application in live cell imaging and as molecular logic gate

Abstract A novel coumarin based azo-phenol ligand (H 2 L) has been synthesized and characterized by several spectroscopic techniques. An almost 16 fold enhancement of emission intensity has been observed upon gradual addition of Mg 2+ to H 2 L in DMSO:H 2 O (1:5 v/v) medium while it has no significant effect in emission intensity even in presence of other metal ions. The emission intensity of L-Mg 2+ complex has almost quenched on gradual addition of F − to it. The limit of detection for both Mg 2+ and F − are of 10 −8  M order, hence the newly developed chemosensor is highly efficient in detecting Mg 2+ and F − in very minute levels. The chemosensor can even detect Mg 2+ in the intracellular region of human lung cancer cells (A549 cells).