Luminescent metal-organic frameworks as optical sensors for selective sensing towards Fe³⁺ and Cu²⁺

The detection of metal ions in pollutants remains a serious requirement from both environmental and biological standpoints, which are of paramount significance. Recently, researchers have shown significant interest in porous luminescent metal-organic frameworks (LMOFs) due to their remarkable characteristics, such as high specific surface area, exceptional stability, and tunable structures. Consequently, LMOFs have emerged as promising luminescent sensors for detecting diverse species of harmful pollutants because these sensors offer rapid, straightforward, selective, and highly sensitive measurements of target analytes. In this review, we give a thorough overview of LMOF-based sensors for the remarkable and selective sensing towards Fe3+ and Cu2+, as the most important representations in metal ion sensing systems, and further classify these works as "turn-off/turn on" strategy. Four main luminescence sensing mechanisms, namely extensive energy absorption competition, weak interactions between the framework and metal ions, cation exchange, and collapse mechanism of the frameworks, are discussed, aiming to show the relationship between the structures and sensing activities.