Systematic analysis of colorimetric and fluorescent sensors for the detection of tin ions

Due to its ductility and malleability, tin plays an important role in the automotive, electronic, and packaging industries and is also an essential trace mineral for humans to avoid poor growth, hearing loss, and cancer. Diversity colorimetric and fluorescent detections for tin ions have reported widely, but there is not systematical integration and analysis for these studies. We are to categorize all the probes based on coordinating functional groups/ligands such as imines, amides, amines, hydroxyls, and heterocycles (with N and S) involved for tin coordination and the signaling units. The performance of probes based on sensing phenomena such as color changes in the case of calorimetric, tin-induced "turn-on" or "turn-off" fluorescence, binding mechanism, and limit of detection are critically analyzed with respect to the structural motif. Nitrogen (imines, amines, and heterocyclic compounds), oxygen (carbonyl of amides, acids, and esters), and sulfur (heterocyclic compounds) in the probes are responsible for tin-coordination. Dual fluorophores or fluorophore combined with Schiff's bases exhibit more rapid response and higher detection limits than single fluorophores or chromophores. Problems and challenges in the field as well as possible future research directions are also presented with schematic illustrations.