Design of a sustainable light-up flavonol probe for dual-ratiometric fluorescent sensing and visual differentiating...

Ammonia (NH₃) and hydrazine (N₂H₄) present potential risks to human health, food and environmental safety. A sustainable flavonol-based probe, quercetin pentaacetate (QPA, weak blue emission 417 nm), was fabricated for dual-ratiometric fluorescent sensing and visual differentiating NH₃ and N₂H₄. Excited state intramolecular proton transfer-on products with green (487 nm) and yellow (543 nm) emissions occurred as meeting with NH₃ and N₂H₄, respectively, for their different nucleophilicities. Such a promising response offered a great opportunity of QPA to discriminatively detect NH₃ and N₂H₄ with large Stokes shifts (>122 nm), high sensitivity (limit of detection: 35.4 μM and 0.70 ppm for NH₃ solution and gas; 0.26 μM for N₂H₄ solution), excellent accuracy (spiked recoveries from 98.6 % to 105 %), and superior selectivity. Importantly, QPA was utilized for monitoring NH₃ vapor in fish spoilage procedures and detecting N₂H₄ in water samples for food and environmental safety evaluation.