Rhodamine B-based turn-on fluorescent and colorimetric chemosensors for highly sensitive and selective detection of mercury (II) ions

Abstract

Two novel macromolecules based on 2-[3-(2-aminoethylsulfanyl) propylsulfanyl]ethanamine covalently bound to one and two units of rhodamine-B moieties, 1 and 2, were prepared and utilized as fluoroionophores and chromophores for the optical detection of Hg2ions. The sensors were readily prepared by a conventional two-step synthesis. Especially, sensor 1 exhibits high sensitivity and selective OFFON fluorescence enhancement and chromogenic change upon binding to Hg2, which served as a naked-eye indicator by a noticeable color change of the solution (from colorless to pinkred color). 1 is shown to discriminate various competing metal ions, particularly Ag and Cu2, as well as Cd2, Na, Li, K, Ba2, Co2, Ni2, Mg2, Mn2and Al3, with a detection limit of 10 ppb. © 2011 Elsevier B.V. All rights reserved.