Portable and rapid hydrazine monitoring by a large Stokes shift probe with smartphone-assisted quantification: Its...

Area of Science:

• Chemical Sensing
• Fluorescent Probes
• Environmental Monitoring

Background:

• Hydrazine (N2H4) is a toxic environmental pollutant requiring sensitive detection methods.
• Existing detection methods for hydrazine can be complex or lack selectivity.
• Fluorescent probes offer potential for rapid and selective analyte detection.

Purpose of the Study:

• To design and synthesize a novel phenanthroimidazole-based fluorescent probe for hydrazine detection.
• To investigate the probe's sensing mechanism, selectivity, and response time.
• To evaluate the probe's applicability in real-world environmental and biological samples.

Main Methods:

• Synthesis of a donor-π-acceptor fluorescent probe incorporating benzothiazole and arylidene nitrile units.
• Spectroscopic analysis (fluorescence spectroscopy) to study probe-analyte interactions.
• Selectivity studies against various interfering species (metal ions, anions, amines).
• Mechanistic studies involving nucleophilic addition and ICT process modulation.
• Biocompatibility assessment using cell viability assays.
• Demonstration of vapor-phase detection using TLC kits.
• Analysis of real samples (soil, plant, food) and smartphone-assisted quantification.

Main Results:

• The probe exhibited strong orange fluorescence (ICT-based) that switched to blue upon reaction with hydrazine.
• High selectivity for hydrazine over other species was observed.
• Rapid response time (∼120 s) and a low detection limit (81 nM) were achieved.
• A large Stokes shift (∼188 nm) minimized background interference.
• The sensing mechanism involves nucleophilic addition of hydrazine to the arylidene nitrile unit.
• The probe demonstrated good biocompatibility (>85% cell viability at 200 μM).
• Successful vapor-phase detection and analysis in environmental and food samples were achieved.
• Smartphone-assisted results correlated well with the ninhydrin method.

Conclusions:

• A novel, highly selective, and sensitive fluorescent probe for hydrazine detection was successfully developed.
• The probe's mechanism involves ICT modulation via nucleophilic addition.
• The developed sensing platform is suitable for rapid, portable, and reliable environmental monitoring of hydrazine.
• The probe shows potential for practical applications in diverse sample matrices and vapor-phase sensing.