RESUMEN
In this manuscript, readily available cephalosporin's drugs cefuroxime axetil (L1) cefpdoxime proxetil (L2), and cefditoren pivoxil (L3) possess dihydrothiazine ring as signaling unit, and -NH groups as the binding site were used for the sensing of fluoride (F-) ions. In the presence of F-, the drug selectively portrayed a naked-eye detectable color change from colorless. The binding constant of 1:1 stoichiometric complex of L1, L2, and L3 with F- was found to be 2.36 × 104 M-1, 2.44 × 103 M-1 and 1.02 × 104 M-1 respectively. The lowest detection limit (LOD) of F- was found to be 11 µM (209 ppb) with drug L1 and L2. The binding mechanism of the drug with F- was studied by 1H and 19F nuclear magnetic resonance (NMR) spectral titration, electrospray ionization mass spectra (ESI-MS) analysis, and density functional theory (DFT) studies. The presence of F- was monitored in various spiked water and Colgate toothpaste samples. Overall, cephalosporin's drug demonstrates a promising potential for the detection of F- ions in the semi-aqueous phase.