Rhodamine Based Chemosensors for Metal ions Detection: An Overview.

Today, water quality monitoring is crucial due to the health and environmental consequences of water pollution. Recently, various attempts have been made to construct rapid, sensitive, and selective heavy metal ion sensors. Fluorescent sensors are popular owing to their high specificity, sensitivity, and reversibility. Rhodamine derivative-based biosensors are acknowledged as a promising chemical for the synthesis of chemosensors due to their remarkable measurable properties, including responsible absorption rate, electromagnetic emission coefficient, significant fluorescent quantum yield, stability against photoenergy, and extensive wavelength range. The detection of metal ions in various concentrations by rhodamine probes followed multiple mechanisms, one common pathway is opening the spirolactam ring within the rhodamine scaffold which leads to colorimetric and fluorometric signals. Rhodamine itself is less emissive and less colorful when the spirolactam ring is present within the framework and would become strongly emissive with versatile coloring range (red, orange or purple etc.) once the ring is opened. Numerous efforts have been undertaken to employ rhodamine-based chemosensors (RBC) for the detection of diverse metal ions in analytical studies (both in-vivo and in-vitro way). This article therefore discusses the major method and potential strategy for RBC and this review is expected to bring new clues and bright ideas to researchers for further advances in rhodamine-based chemosensors in the future.