Design principles for metal–organic receptors targeting optical recognition of Pd(ii) in environmental matrices

Abstract

A precise detection of palladium (Pd) ions is a critical challenge with significant socio-economic implications across various industrial and chemical sectors. Due to its widespread use and poor biodegradability, Pd²⁺ accumulates in environmental ecosystems, posing severe risks to both the environment and living organisms. Consequently, there is a strong demand for selective, sensitive, and user-friendly detection methods. Among emerging strategies, optical detection techniques (both luminescence and colorimetric) using metal-based receptors have gained considerable attention. These sensors offer distinct advantages over traditional organic probes, including large Stokes shifts, long emission lifetimes, exceptional photostability, enhanced water solubility, recyclability, and remarkable chemical versatility. These attributes make them highly suitable for diverse applications in sensing and bioanalytical fields. This review provides a comprehensive overview of recent advancements in luminescent and colorimetric metal-based probes, including metal complexes and metal–organic frameworks (MOFs), for the selective detection of Pd²⁺. It discusses key design strategies, critical performance factors, and future prospects, offering valuable insights for researchers working on the next-generation sensing platform.