A “Two-in-One” Pyrrolopyrrole Cyanine Fluorescent Probe for Discriminative Detection of Hydrazine and Hydrogen Sulfide in Real Samples

Abstract

Hydrazine (N 2 H 4 ) and hydrogen sulfide (H 2 S) play important roles in industrial, agricultural and pharmaceutical fields. However, their high toxicity and carcinogenic effects as environmental pollutants could not be neglected when the concentration was higher than the threshold limit value. It is urgent and challenging to develop a highly sensitive method for determining N 2 H 4 and H 2 S to assess environmental risks and protect human health. In this work, by utilizing "Two-in-One" strategy of pyrrolopyrrole cyanine (PPCy) core as both recognition group and fluorophore, an efficient dual-responsive fluorescent probe to simultaneously monitor N 2 H 4 and H 2 S with high sensitivity was designed and synthesized. PPCy as an electronaccepting unit and triphenylamine (TPA) as an electron-donating unit were linked by phenyl bridge. The resulting D-A-D type probe (PPCy-Ph-BF2) was non-fluorescent. The merits of PPCy-Ph-BF2 included excellent selectivity, rapid response, low limit of detection (2.38 nM for N 2 H 4 and 0.64 nM for H 2 S), visually colorimetric change and discriminative fluorescence "Turn On" dual signals. The sensing mechanism revealed that when the probe encountered with N 2 H 4 or H 2 S featuring distinct nucleophilic abilities, different additional nucleophilic reaction to break PPCy core produced diverse reaction compounds. Moreover, the probe was successfully employed to quantitative detection of N 2 H 4 and H 2 S solution or their gas by combination of a smartphone-based Color APP with polyamide thin film or sponge-based platform, meeting the requirements of the household use. The release of H 2 S gas from garlic and detection of N 2 H 4 in soil were clearly shown by fluorescence "Turn on" with naked eyes. Good recovery in real samples (water, soil, red wine, beer, flour, and corn flour) showcased its broad potential for multiple applications. This work provides a new approach to dual detection of N 2 H 4 and H 2 S in environmental monitoring and food freshness detection more conveniently.