A new colorimetric and turn-on fluorescent chemosensor for Al3+ in aqueous medium and its application in live-cell imaging

A new simple Schiff-base ligand 2-Hydroxy-1-naphthaldehyde-(2-pyridyl) hydrazone (HL) was synthesized and characterized as a fluorescent probe. In aqueous solution containing 10% ethanol (Hexamethylenetetramine-HCl buffer, pH5.3), HL selectively binds Al 3+ to form a 1:1 ligand/metal complex, resulting in a color change from colorless to yellow–green and a significant fluorescence enhancement at 454   nm. The addition of EDTA quenches fluorescence of the HL·Al 3+ complex, indicating that HL serves as a reversible chemosensor for Al 3+ . Under the optimum conditions, the dynamic range of the system was found to be linear up to 4.0   ×   10 −6   M Al 3+ ions with a limit of detection of 36.6   nM. The probe is very effective for detection of intracellular Al 3+ through fluorescence microscopic imaging.