Fluorescence ‘turn-on’ sensor for F− derived from vitamin B6 cofactor

A novel vitamin B6 Schiff base analog (L) was synthesized by combining vitamin B6 cofactor pyridoxal with 2-aminophenol. Receptor L displays a color change detectable by the naked-eye from yellow to red in the presence of fluoride and acetate due to the formation of hydrogen bonding host–guest complexes in 1 : 1 stoichiometry. Importantly, receptor L showed fluoride-selective ‘turn-on’ fluorescent response with a detection limit (3σ) of 7.39 × 10−8 M.