A fluorescent probe for hydrazine based on a newly developed 1-indanone-fused coumarin scaffold

A 7-diethylaminocoumarin and 1-indanone-fused fluorescent dye (CI) was developed. CI was superior to traditional coumarins in terms of bathochromic shift in absorption and emission maxima (lambda(abs)/lambda(em) = 518/598 nm in ethanol). To illustrate its value, we rational designed a new hydrazine-selective fluorescent probe by the judicious anchoring of CI to malononitrile to form CI-DCV. Upon mixing with hydrazine, the dicyanovinyl group of CI-DCV was converted to the corresponding hydrazone, which inhibited the intramolecular charge transfer within the probe, thereby affording remarkable blue shifts in the absorption and fluorescence spectra. The proposed probe shows high selectivity toward hydrazine over other structural analogs and reductive species and can be applied in hydrazine detection in a variety of samples.