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.