A novel pyrene-based film: Preparation, optical properties and sensitive detection of organic copper(II) salts

A novel fluorescent sensing film for organic copper(II) salts was developed by covalently attaching pyrene moieties onto glass slide surfaces via a long flexible spacer. Fluorescence measurements demonstrated that the emission of the film was efficiently quenched by organic copper(II) salts, including copper acetate, cupric tartrate and cupric citrate. Presence of any of other divalent metal acetates, such as Ni(Ac)2, Co(Ac)2, Pb(Ac)2, Cd(Ac)2 and Zn(Ac)2, has little effect upon the emission of the film. The quenching efficiency of Cu(Ac)2, however, was reduced moderately in the presence of these similar divalent metal acetates. The interference of these salts to the sensing of organic copper(II) salts was attributed to the competition of the complexation sites in the spacer, which may be one of the reasons that enhance the enrichment of Cu(II) into the spacer layer. The detection limit of the film to Cu(Ac)2 is 0.26 μM, which is much lower than those reported earlier. The quenching by copper acetate of the emission of the film is static in nature due to complexation of the spacers to the metal ions. Furthermore, the sensing process is fully reversible.