Highly selective and sensitive fluorescence detection of Zn2+ and Cd2+ ions by using an acridine sensor

Fluorescence spectroscopy investigations of the new acridine derivative bis(N, N-dimethylaminemethylene) acridine (3) show remarkable selectivity and sensitivity towards Zn2+ and Cd2+ ions in methanol and for the latter even in water. Through the chelation of the metal ions the present PET effect is quenched, significantly enhancing the emission intensity of the fluorophore. In solution, the bonding situation is studied by fluorescence and NMR spectroscopy, as well as ESI-TOF mass-spectrometry measurements. The solid state environment is investigated by X-ray diffraction and computational calculations. Here, we can show the complexation of the zinc and cadmium ions by the methylene bridged amine receptors as well as by the nitrogen atom of the acridine system.