A multi-functional picolinohydrazide-based chemosensor for colorimetric detection of iron and dual responsive detection of hypochlorite.

A novel effective chemosensor HPHN, (E)-6-hydroxy-N'-((2-hydroxynaphthalen-1-yl)methylene) picolinohydrazide, was synthesized. HPHN sensed Fe3+/2+ with the changes of color from yellow to orange without obvious inhibition from other cations. In addition, HPHN could detect ClO- by both the color change from yellow to colorless and the fluorescence quenching. The binding modes of HPHN with Fe3+/2+ and ClO- were determined to be 1:1 with Job plot and ESI-mass analysis. HPHN displayed low detection limits of 0.29 μM for Fe3+ and 0.77 μM for Fe2+. For ClO-, the detection limit was 6.20 μM by colorimetric method and 3.99 μM by fluorescent one, respectively. Moreover, HPHN can be employed to quantify Fe3+ and ClO- in environmental samples and apply to cell imaging for ClO-.