Fluorescence sensors for selective detection of Hg²⁺ ion using a water-soluble poly(vinyl alcohol) bearing rhodamine B moieties.

The novel water-soluble poly(vinyl alcohol) with pendant rhodamine B moiety as colorimetric and fluorescene chemosensor for Hg(2+) ions was prepared by grafting poly(vinyl alcohol) using rhodamine B hydrazide and hexamethylenediisocyanate as fluorescent dye and coupling agent, respectively. Because of their good water-solubility, the polymers binding rhodamine B can be used as chemosensors in aqueous media. With the addition of Hg(2+) ions into the aqueous solution, visual color changes and fluorescence enhancements were detected. In addition, we also noticed that other metal ions such as Ag(+), Cd(2+), Co(2+), Cu(2+), K(+), Mg(2+), Ba(2+), Fe(2+), Ni(2+), Pb(2+), Cr(3+), Fe(3+) and Zn(2+) cannot induce obvious changes to the fluorescence spectra of the polymer chemosensors. The combination of water solubility and positive fluorescence response as well as color change are hence particularly promising for the practical utility of the sensors.