A NBD-based selective colorimetric and fluorescent chemosensor for Hg2+

A new NBD-based sensor bearing a dipicolylamine derivative, (2-pyridylmethyl)(2-quinolylmethyl)amine (1), was synthesized, and its chromogenic and fluorogenic behaviors toward various metal ions were investigated in methanol solution. Chemosensor 1 selectively detected Hg2+ ions through color change from yellow to colorless. In addition, chemosensor 1 exhibited highly Hg2+-selective ON-OFF fluorescence quenching behavior and was shown to discriminate various competing metal ions, particularly, such as Cu2+, Ag+, and Pb2+. The binding mode of 1-Hg2+ was found to be a 1:2 complex formation, based on Job plot and 1H NMR titration.