Selective sensing of copper and mercury ions with pyrene-functionalized fluorescent film sensor containing a hydrophilic spacer

A fluorescent film sensor for Cu(II) and Hg(II) ions was designed and prepared by chemical attaching pyrene moieties on an epoxy-terminated surface via a long flexible and hydrophilic spacer. The chemical attachment of pyrene moieties on the surface was verified by contact angle, XPS, and fluorescence characterization. The fluorescence responses of the present film to a series of metal ions in aqueous solution indicate that this film sensor is sensitive to both copper and mercury ions. Presence of other metal ions, including Ni(II), Fe(III), Pb(II), Mg(II), Ba(II), Zn(II), La(II) and Eu(II), has little effect upon the fluorescence emission of the film. The sensitivity of the present film sensor is quite high toward both Cu(II) and Hg(II) ions in the form of inorganic salts as revealed by the large KSV values. Moreover, the presence of organic anions produces little influence on the sensitivity of the film sensor toward metal ions, suggesting the introduction of the hydrophilic spacer weakens the spacer layer screening effect in aqueous solution. The novel fluorescent film sensor may have potentials as Cu(II) and Hg(II) sensors to probe natural environments.