Colorimetric and Fluorometric Recognition of Al³⁺ using Thiazole-Based Schiff base: A Mini-Review

The recognition of Al³⁺ ion is significant due to their widespread presence in the environment and their potential toxic effects on human health. Therefore, the identification of these metal ions in various samples is of great importance. This review focuses on the key developments, design strategies, and progress of thiazole-based Schiff base chemosensors for the colorimetric and fluorometric detection of Al³⁺ ion. Thiazole Schiff bases displayed strong coordination affinity toward Al³⁺ through nitrogen, oxygen, and sulphur donor atoms, resulting in observable color variation and fluorescence enhancement. In this review, various thiazole-based Schiff bases are discussed to demonstrate their high selectivity, sensitivity, low detection limits (µM to pM), and rapid response times. The observed optical changes was demonstrated by different mechanisms, including chelation-enhanced fluorescence (CHEF), inhibition of photoinduced electron transfer (PET), intramolecular charge transfer (ICT), and excited-state proton transfer (ESPT), all of which play crucial roles in sensing behavior. Furthermore, several probes exhibit reversible binding and are applicable in environmental water and biological systems. Overall, thiazole-based Schiff base derivatives represent a promising class of colorimetric and fluorescent chemosensors for the detection of minute amounts of Al³⁺ ion, with wide applications in environmental monitoring, biomedical diagnostics, and intracellular imaging.