Analytical Sciences

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

Tao LAN,*1,*2,*3 Feng-He WANG,*1,*2 Xing-Jun XI,*3 Chun-Wen CHENG,*1,*2,*4 Wu LEI,*4 Ming-Zhu XIA,*4 and Feng-Yun WANG*4

*1 Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, School of Environment, Nanjing Normal University, Nanjing 210023, PR China
*2 Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, School of Geography Science, Nanjing 210023, PR China
*3 China National Institute of Standardization, Beijing 100191, PR China
*4 Industrial Chemical Institute, Nanjing University of Science and Technology, Nanjing 210094, PR China

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.

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