A Rhodamine-based Dual Chemosensor for the Simultaneous Detection of Fe3+ and Cu2+

A Rhodamine-based dual chemosensor LI for simultaneously detecting Fe3+ and Cu2+ was designed and synthesized. The spectroscopic properties of LI were analyzed, and its recognition mechanism was speculated. We found that the addition of Fe3+ induced a great fluorescence enhancement, while Cu2+ induced a strong UV-Vis absorption enhancement. The results revealed that LI was highly selective for recognizing Fe3+ and Cu2+ in UV-Vis spectroscopy in CH3OH-H2O (1/1, v/v, pH 7.2) with the interference of other metal ions. A good linear relationship between the fluorescence intensities of LI and the concentration of Fe3+, as well as the UV-Vis absorption intensities of LI and the concentration of Cu2+ was observed, respectively. The detection limit was 9.2 × 10−8 M (5.5 μg/L) for Fe3+ and 3.8 × 10−8 M (2.4 μg/L) for Cu2+, respectively. The detection capacity for targeted metal ions of Fe3+ and Cu2+ were studied, which are less than 5 min. Job's plot method for LI with Fe3+ and ESI-MS for LI with Cu2+ indicated a 1:1 stoichiometry in the complex. The results may provide an effective strategy for the design of new dual chemosensors for the rapid detection of targeted metal ions.