A simple fluorescein derived colorimetric and fluorescent 'off-on' sensor for the detection of hypochlorite

In this work, we have successfully provided a novel strategy to probe for ClO-. The strategy is based on a specific reaction promoted by ClO-: namely, hypochlorite oxidizes the amino group in probe 1 to an imine. Interestingly, in the presence of ClO-, a colorless solution of probe 1 turned pink with a maximum absorption band at 479 nm, and a 150-fold fluorescence enhancement at 553 nm was found. Probe 1 is highly selective to ClO- among other anions with a detection limit of 0.023 M. The membrane-permeable probe 1 was successfully demonstrated for monitoring ClO- in cultured HeLa cells. Therefore, probe 1 can be used for detection in practical samples. Probe 1 developed herein makes possible the use of organic complexes containing amines for designing fluorescence probes for ClO-.