A pyridine naphthalene conjugate: ESIPT based molecular chemosensor for Al3+ ions and sequential detection of H2PO4- and applications in milk, water samples and bio-imaging

A fluorescent probe (HL) with an "off-on-off" feature was created to identify Al3+ ions in aqueous solutions. The probe can identify Al3+ ions while other metal ions are present, and it is made to be straightforward to use. The probe was built utilizing a Schiff-base chemosensor, 1-[(pyridin-2-ylimino)] naphthalene-2-ol (HL), and a variety of spectroscopic methods were employed to describe it. Probe HL's sensing ability was assessed in a 1:1 volumetric ratio THF/H2O medium, and to establish the binding with Al3+ ions, several spectroscopic methods such as 1H NMR titration analysis, ESI-MS technique including DFT analysis were used. The probe HL showed notable alterations in fluorescence emission spectra during the detection of Al3+ and H2PO4- in the presence of other competing ions. The value of the association constant and the detection limit for Al3+ and H2PO4- were found to be 8.51×104 M-1 and 5.5×102 M-1, respectively. Besides, its applications as tests using milk and water samples successfully identified Al3+ ions in the presence of the probe HL. Additionally, probe HL was successfully examined in E.Coli pathogen for the sensing of Al3+ and H2PO4- ions