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

Abstract

A Rhodamine-based dual chemosensor L1 for simultaneously detecting Fe³⁺ and Cu²⁺ was designed and synthesized. The spectroscopic properties of L1 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 L1 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 L1 and the concentration of Fe³⁺, as well as the UV-Vis absorption intensities of L1 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 L1 with Fe³⁺ and ESI-MS for L1 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.