Turn-on fluorescent chemosensor based on an amino acid for Pb(II) and Hg(II) ions in aqueous solutions and role of tryptophan for sensing.

This communication presents a fluorescent chemosensor for detecting Pb(II) and Hg(II) in aqueous solutions. The sensor showed a turn-on response to Pb(II) by an enhancement of emission intensity at 380 nm and to Hg(II) by an enhancement of emission intensities at 380 and 475 nm. We have first characterized a unique function of tryptophan as a ligand as well as a quencher for recognition and fluorescent change by a metal binding event.