A simple and sensitive fluorescent sensor platform for Al(3+)sensing in aqueous media and monitoring through combined PET and ESIPT mechanisms: practical applications in drinking water and bio-imaging

In this study, a novel hydrazide-based compound, (E)-N '-(5-(benzo[d]thiazol-2-yl)-2-hydroxybenzylidene)furan-2-carbohydrazide (probeBOTH) was designed, characterized and prepared as a fluorogenic "turn-on" sensor for monitoring Al(3+)in near-perfect aqueous media. All emission and absorbance spectral studies were performed in HEPES/DMSO (v/v, 99.95/0.05, pH = 7.0) media at 25 degrees C. The quantum yield of probeBOTHincreases considerably in the presence of Al3+. ProbeBOTHcould sense Al(3+)at a concentration as low as 6.47 nM. ProbeBOTHcould sense Al(3+)with high sensitivity and selectivity, and a quantitative correlation ofR(2)= 0.9887 in the Al(3+)concentration range of 0.0-20.0 equiv. To evaluate the method parameters, a validation study was performed based on different analytical parameters. The formation of complexBOTH-Al3+(2 : 1 stoichiometry) was confirmed by(1)H-NMR titration and MALDI-TOF MS, as well as Job's methods. pH-Dependent and Benesi-Hildebrand plot studies also supported this proposed sensing mechanism. Besides, the binding mechanism of Al(3+)with probeBOTHwas further verified by theoretical studies. Moreover, probeBOTHcould be used for monitoring Al(3+)in living-cells and water samples.