Facile Preparation of a Rhodamine B Derivative-Based Fluorescent Probe for Visual Detection of Iron Ions

Iron ions play an important role in our lives. Excessive or lack of iron ion intake leads to many diseases. At the same time, the water environment is easily polluted by these metal ions with the acceleration of industrialization. Therefore, the detection of iron ions in the water environment and the human body is particularly important. In this paper, we prepared a RhB-EDA fluorescent probe by condensing rhodamine B (RhB) with ethylenediamine (EDA) for high recognition of Fe³⁺. A RhB-EDA molecule itself is colorless and has no fluorescence emission in an alcohol solution. When Fe³⁺ was added, the lactam ring structure of the fluorescent probe opened, and the UV and fluorescence spectra changed. At the same time, the color of the mixed solution gradually deepened toward pink. Therefore, dual spectral detection and naked-eye observation of Fe³⁺ were realized. In addition, with the decrease of the pH value and the prolongation of chelating time, the ultraviolet absorbance and fluorescence emission intensity were enhanced and the color of the mixed solution deepened. The RhD-EDA fluorescent probe is simple and accurate and provides good technical support for the detection of Fe³⁺.