Use of fluorogenic Al3+- Quinolinyl-azo-naphtholato complex for the determination of F− in aqueous medium by visible light excitation and application on ground water fluoride analysis
Quinolinyl-azo-naphthol (HL) is a selective turn-on chemosensor to Al3+ in presence of other ions and the excitation at visible light (537 nm) shows 750 fold enhancement of emission at 612 nm. The limit of detection (LOD) is 0.69 nM (3 method), which is far below the WHO recommended value of Al3+ in drinking water (7.41 µM). The composition of the isolated complex [AlL2]+ is supported by ESI-MS spectral data and Job’s plot. Upon addition of aqueous F- to [AlL2]+ solution the emission intensity is quenched and LOD of F- is 0.63 nM. HL is thus instrumental for the designing of potable kits for the detection of fluoride contamination in drinking water. The probe undergoes azo-hydrazo tautomerization and also exhibits an INHIBIT logic gate with Al3+ and F− as chemical inputs by monitoring the emission mode at 612 nm.