A Colorimetric and Fluorescent Probe Based on Rhodamine B for Detection of Fe³⁺ and Cu²⁺ Ions

Development of optical probe for the detections of Fe³⁺ and Cu²⁺ is one of the most active and interesting research directions in analytical chemistry because of their vital roles in the environment protection and human health. Herein, a turn on optical rhodamine B-based probe (probe 1) with the significant changes in color and fluorescence has been prepared. The color of this probe solution changed from colorless to amaranth in the presence of Fe³⁺ and to pink in the presence of Cu²⁺, which is promising for the qualitative recognition of Fe³⁺ and Cu²⁺. More importantly, probe 1 could be used for the quantitative analysis of Fe³⁺ and Cu²⁺ by fluorescence enhancement. The detection limits for Fe³⁺ and Cu²⁺ reached 8.1 × 10^-8 M and 4.8 × 10^-7 M, respectively. Furthermore, it was found that this probe can also be used for fluorescence imaging of Fe³⁺ and Cu²⁺ in living cells.