A highly selective A–π–A “turn-on” fluorescent probe for hypochlorite in tap water

Abstract

A highly selective fluorescent probe (BON) for hypochlorite (ClO⁻) was designed and synthesized. The probe was based on boron-dipyrromethene (BODIPY) dye as the fluorophore and diaminomaleonitrile (DAMN) as the recognition group. Due to the isomerization of CN, BON has almost no fluorescence and produces bright green fluorescence after recognition of ClO⁻. The carbon–nitrogen double bond (CN) connecting DAMN with BODIPY may be oxidized by hypochlorous acid to an aldehyde group. The combined action of the nitro and the aldehyde groups has created a double attraction (A–π–A), which increases the fluorescence intensity by 10 times. BON displayed excellent properties such as high selectivity, an excellent response time (5 min), a low detection limit (LoD = 0.27 μM) and excellent stability. Moreover, BON has been applied for the detection of ClO⁻ in tap water with spiked recoveries in the range of 90.5–93.6%, and BON has been shown to be suitable for the detection of exogenous hypochlorous acid in living cells as well. This means that the probe BON might be a new efficient tool in detecting the roles of hypochlorous acid.