Sensing performance enhancement via chelating effect: A novel fluorescent film chemosensor for copper ions

A novel fluorescent Cu(II) sensing film was developed by covalently attaching dansyl (5-dimethylamino-1-naphthalenesulfonyl) moieties onto glass slide surface based on self-assembled monolayer technique. Fluorescence measurements showed the emission of the dansyl-functionalized film was selectively quenched by Cu(II) ions and slightly influenced by the presence of other similar divalent metal ions (Pb(II), Zn(II), Ni(II), Co(II), etc.). In addition, the sensitivity of the film towards Cu(II) was increased as expected since more binding sites, the diethylenetriamine moieties, were incorporated into the spacer. It was also found that the presence of organic anions like acetate, citrate, and tartrate, etc. could enhance the quenching efficiency of Cu(II) compared with inorganic anions such as chloride, sulfate, and nitrate. This observation was explained by considering the spacer screening effect as discovered previously. Moreover, the response of the film toward Cu(II) is fully reversible which makes it attractive for sensing application.