A new fluorescent probe for detection of hydrazine and extremely acidic pH in different modes

Toxic hydrazine poses a huge threat to living organisms and our environment. Extremely acidic pH is also harmful to various ecosystems. Here, a coumarin-based dye called CMM has been synthesized for the ratiometric detection of hydrazine (F504 nm/F560 nm). CMM could detect gaseous hydrazine in the environment and endogenous hydrazine in live cells. Furthermore, the fluorescence at 563 nm of CMM was stable from pH 10.0 to 2.0, whereas increased greatly from pH 2.0 to 1.2. Thus, the probe could also detect extremely acidic pH with great fluorescence enhancement. The pKa value was determined to be as low as 1.41. We anticipate that the probe could provide a good candidate for detection of toxic hydrazine and extremely acidic pH.