Excitation dependent emissive multi stimuli responsive ESIPT organic luminogen for monitoring sea food freshness

Excited state intramolecular proton transfer (ESIPT) organic luminophores with excitation wavelength-dependent color tunability have drawn significant attention due to their exceptional photoluminescent properties in solution and solid state. A novel salicylaldehyde-based Schiff's base molecule, (E)-N'-(3,5-dibromo-2-hydroxybenzylidene)benzohydrazide (BHN) exhibited stimuli (excitation wavelength and pH) induced changes in fluorescence properties which was utilised for applications like trace level water sensing in organic solvents (THF, acetone and DMF), detection and quantification of biogenic amines and anticounterfeiting. In the solution state, BHN rendered a ratiometric detection and quantification of ammonia, diethylamine and trimethylamine, which is further supported by DFT studies. The photoluminescent response of BHN towards various biogenic amines was later utilised to monitor shrimp freshness. The investigation carried out highlights the potential versatility of ESIPT hydrazones, which renders multi stimuli responsive behaviour that can be utilised for water sensing, anticounterfeiting and the detection and quantification of biogenic amines.