Fluorescent Rhodamine Sensors for Mercury, Iron, and Copper Ion Detection in Water: Mechanisms and Applications

Fluorescent rhodamine sensors (FRS) have emerged as highly effective tools for detecting metal ions. These sensors coordinate with metal ions with specific donor atoms in the rhodamine structure, which led to the significant changes in fluorescence properties such as quenching or enhancement, of rhodamine. This paper explores the sensing mechanisms behind the detection of mercury (Hg²⁺), iron (Fe²⁺/Fe³⁺), and copper (Cu²⁺) in water. The metal ions often interact with the thiol, amine, and carboxyl groups of FRS which results in alterations to the electrons and produces measurable spectroscopic changes. The ability of these sensors provides real-time, sensitive, and selective detection of metals for monitoring water quality in industrial, environmental, and biomedical applications. Additionally, the novelty of this research lies in the development of FRS based multi-metal detection systems that allow simultaneous analysis of multiple ions viz., Hg²⁺, Fe²⁺, Fe³⁺, and Cu²⁺. This feature advocates the utility of FRS in complex water samples. The characterization of FRS includes NMR, Mass, and FTIR techniques, while the evaluation of sensing efficacy of FRS for metal ions involves spectroscopic and imaging methods. The integration of these sensors into portable devices and smart monitoring systems opens new avenues for real-time metal monitoring and metal pollution control. This paper highlights the current advancements, challenges, and prospects of FRS and emphasises their role in ensuring safer water and environmental sustainability.