Smart Organic Probes and Their Applications: Sequential Fluorometric and Colorimetric Sensing of Cu2+ and CN- Ions: A Review (2018-2025).

The detection of Cu²⁺ and CN^- ions is of significant importance due to their crucial roles in biological and environmental systems. While CN^- is widely utilized in industrial applications, its high toxicity poses severe risks to human health and the environment, necessitating precise monitoring. Similarly, Cu²⁺, an essential trace element, becomes hazardous at excessive concentrations, leading to liver damage, cardiovascular diseases, and ecological toxicity. Dual-channel sensors that employ both colorimetric and fluorometric responses have gained attention for their ability to detect multiple analytes simultaneously with high specificity, cost-effectiveness, and operational simplicity. This review highlights recent advancements (2018-2025) in smart organic probes for sequential fluorometric and colorimetric sensing of Cu²⁺ and CN^- ions. Various sensing mechanisms, including deprotonation, coordination, and addition reactions, have been explored to achieve selective recognition. The challenges associated with interference from other metal ions, solubility issues, and real-world applicability are critically analyzed. The development of multi-target sensors is emphasized, showing their potential for real-time environmental monitoring, medical diagnostics, and industrial safety applications. Future perspectives focus on improving probe performance through structural modifications, enhancing water solubility, and integrating smart materials for portable sensing platforms.