Quinoline Hydrazine Schiff Base Ligand for the Selective Detection of Silver Ions and Its Real Time Applications

In this study, a triphenylamine aldehyde and quinoline hydrazine Schiff base probe, N , N ‐diphenyl‐4‐((2‐(quinolin‐2‐yl)hydrazineylidene)methyl)aniline ( TPA‐QH ) synthesized by using a simple condensation reaction. The probe TPA‐QH was structurally characterized by using FTIR, NMR ( 1 H and 13 C), and mass analysis. The probe TPA‐QH shows a characteristic absorbance band at 383 nm and an emission band at 470 nm in MeOH:H 2 O (8:2, v/v). Probe TPA‐QH exhibits a selective red‐shifted absorbance band to 422 nm and red‐shifted enhanced emission at 494 nm upon the interaction with Ag + ions in MeOH:H 2 O (8:2, v/v). Further, the Job's plot and BH plot analysis show that probe TPA‐QH can form a 2:1 stoichiometry complex with an association constant of 1.42 × 10 6 M −1 with Ag + ions. In addition, the TPA‐QH can detect Ag + ions down to 17.6 nM with not much interference from other common interfering ions. The FTIR, NMR, and ESI‐mass analysis studied the binding mechanism of TPA‐QH with Ag + ions. Further, the experimental spectral change of TPA‐QH and its Ag + complex was investigated using DFT and TD‐TDFT calculations. The probe TPA‐QH was applied to detect Ag + ions in different water samples using the developed spectrofluorometric methods.