Synthesis of a Novel Fluorescent Sensor Bearing Dansyl Fluorophores for the Highly Selective Detection of Mercury (II) Ions

A new macromolecule possessing two dansyl moieties and based on 2-[4-(2-aminoethylthio)butylthio]ethanamine was prepared as a fluorescent sensor and its mercury sensing properties toward various transition metal, alkali, and alkali earth ions were investigated. The designed compound exhibited pronounced Hg(2+)-selective ON-OFF type fluorescence switching upon binding. The new compound provided highly selective sensing to Hg(2+) in acetonitrile-water solvent mixtures with a detection limit of 2.49 x 10(-7) M or 50 ppb. The molecular modeling results indicated that ions-recognition of the sensor originated from a self assembly process of the reagent and Hg(2+) to form a helical wrapping structure with the favorable electrostatic interactions of Hg(2+) coordinated with sulfur, oxygen, nitrogen atoms and aromatic moieties.