A phenanthroimidazole-based fluorescent probe for hypochlorous acid with high selectivity and its bio-imaging in living cells

- A new fluorescent probe 1 based on phenanthroimidazole was synthesized and characterized.
- The photochemical properties of 1 were investigated in different solvent polarity.
- The limit of detection of probe 1 was as low as 1.4 × 10−8 M for OCl−.
- The probe 1 was used as practical probe for imaging of OCl− in living cell.

In this study, a new compound 2-amino-3-[(4-(1H-phenanthro [9,10-d] imidazol-2-yl) phenyl methylene) amino]-2-butenedinitrile (probe 1) as a simple fluorescent probe for hypochlorous acid has been synthesized and characterized. It exhibited high selectivity and sensitivity as hypochlorite sensor in mixed aqueous medium. NMR and mass spectral analysis showed that the probe reacted with the hypochlorite ion through de-diaminomaleonitrile reaction which disrupted the ICT mechanism by breaking the donor and acceptor linkage resulting in a remarkable enhancement of the emission intensity. In addition, the probe worked excellently within a wide pH range of 4 to 10 and the detection limit was found to be 1.4 × 10−2 μM. The cell experiments showed the good cell-membrane permeability of probe, and it could be used to image exogenous HOCl.

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