A highly sensitive, single selective, fluorescent sensor for Al3+ detection and its application in living cell imaging

A new o-aminophenol-based fluorogenic chemosensor methyl 3,5-bis((E)-(2-hydroxyphenylimino)methyl)-4-hydroxybenzoate 1 have been synthesized by Schiff base condensation of methyl 3,5-diformyl-4-hydroxybenzoate with o-aminophenol, which exhibits high selectivity and sensitivity toward Al3+. Fluorescence titration studies of receptors 1 with different metal cations in CH3OH medium showed highly selective and sensitive towards Al3+ ions even in the presence of other commonly coexisting metal ions. The detection limit of Al3+ ions is at the parts per billion level. Interestingly, the Al(III) complex of 1 offered a large Stokes shift (>120 nm), which can miximize the selfquenching effect. In addition, possible utilization of this receptor as bio-imaging fluorescent probe to detect Al3+ in human cervical HeLa cancer cell lines was also investigated by confocal fluorescence microscopy.