A ratiometric fluorescent probe with large Stokes shift and emission shift for sensing hydrazine in living organisms

As a highly toxic reagent, hydrazine (N₂H₄) is notorious to human beings and the environment. To simply and conveniently detect N₂H₄ in environmental and biological systems, a ratiometric fluorescent probe MA-N₂H₄ was developed with excellent sensitivity and selectivity. Probe MA-N₂H₄ was readily prepared based on a naphthalene as the fluorescent scaffold and an indanedione group as the responsive moiety for N₂H₄. This probe displayed a red-emitting fluorescence at 670 nm with a large Stokes shift (200 nm). After treatment with N₂H₄, a significant blue-shifted emission at 440 nm could be observerd, which led to an extremely large emission wavelength shift (230 nm). The fluorescent intensity ratio (I₄₄₀/I₆₇₀) of probe MA-N₂H₄ was rapidly and significantly increased (273-fold) within 18 min. The detection limit for N₂H₄ was 0.5 µM. In addition, the probe was successfully employed for tracking N₂H₄ in living cells and zebrafish through a ratiometric manner.