Coordination Chemistry of Al3+-Selective Colorimetric and Fluorescent Chemosensors: Advances, Challenges, and Future Directions

Abstract

The coordination chemistry of aluminum plays a pivotal role in shaping the design, performance, and applicability of Al³⁺-selective colorimetric and fluorescent chemosensors. Owing to the high charge density, strong oxophilicity, and kinetic inertness of Al³⁺, the development of selective molecular probes remains both scientifically challenging and technologically significant. This review provides a comprehensive and mechanism-driven analysis of recent advances in Al³⁺ detection, focusing on how ligand architecture, donor-atom arrangement, and coordination geometries govern sensing behaviors. Emphasis is placed on polycyclic aromatic frameworks, heterocyclic scaffolds, and Schiff-base-derived receptors whose coordination modes enable turn-on fluorescence, ratiometric responses, and visible color changes. By correlating coordination features with optical outputs, the review highlights insights into binding stoichiometry, chelation-enhanced fluorescence effects, and metal-induced structural rigidification. Current limitations—such as interference from competing metal ions, aqueous stability issues, and challenges in real-sample quantification—are critically examined. Finally, the review outlines emerging research directions, including multifunctional probes, bioimaging-compatible designs, solid-state sensors, and computationally guided ligand engineering, collectively offering a strategic roadmap for the next generation of Al³⁺-selective chemosensors.