Epitome of polyoxotungstate-coordinated lanthanide-based single-molecule magnets

Single-molecule magnets (SMMs) have garnered significant interest due to their possible use in high-density data storage devices and quantum computing. SMMs based on lanthanide-encapsulated polyoxotungstate (POT) have emerged due to their stability under ambient conditions and potential application in magnetic devices. The POTs can stabilize various anisotropic lanthanide ions (Ln(III)) with a range of strong to moderate ligand fields. The systematic combination of Ln(III) ions with POTs leads to significant perturbation in the electronic structure of the Ln(III) ion, which notably influences their magnetic properties. The magnetic properties of Ln(III)-POT clusters are highly dependent on the first coordination geometry and ligand field strength around the Ln(III) ions. Moreover, the bulky and diamagnetic POTs efficiently minimize the intermolecular magnetic interactions. As a result, the under-barrier magnetic relaxation is suppressed, and magnetic performance is enhanced. Over the years, a diverse array of Ln-POT SMMs have enriched the literature containing vacant POTs as building blocks (such as Keggin, Lindqvist, Wells-Dawson, and Preyssler types). In this review, we have discussed and summarized the effects of structural and bonding diversities of POTs on the SMM behaviour of Ln-POT clusters. This review aims to provide future direction and exploration of the challenging and compelling field of POT-based SMMs.