A Schiff base dual mode“Turn-On” fluorescent probe for selective detection of HClO/ClO− in buffer

Hypochlorous acid (HClO) and sodium hypochlorite (NaClO) are widely present in living organisms and the environment and are closely associated with health or disease in living organisms. Therefore, it is necessary to develop new materials and methods that can detect HClO/ClO − quickly, easily and sensitively. Based on the oxidative property of hypochlorite on the amine bond of diaminomaleonitrile Schiff bases, we have designed and synthesized a ‘Turn-ON’ fluorescent/colourimetric dual-mode probe with high selectivity for HClO/ClO − . In the detection system (DMF: water=1:1, v/v), the addition of HClO/ClO − to the probe was accompanied by a gradual change in the colour of the solution from pink to colourless, with a concomitant 97-fold enhancement of fluorescence intensity at 522 nm (Tun-On), a Stokes shift of 96 nm and a detection limit of 250 nM. A novel HClO/ClO − sensing mechanism in which the imine bond of the probe is oxidized to a carboxyl group by HClO/ClO − was demonstrated by high-resolution mass spectrometry and 1 H NMR spectroscopy. In addition, the probe was applied to the spiked recovery detection of HClO/ClO − in real water samples and the imaging of hypochlorite in cells.