Effect of Nonconstituent Additive Ions on the Controlled Crystallization of Lanthanide-Based Preyssler Polyoxometalates

[Image: see text] Preyssler-type polyoxometalates (POMs) encapsulating lanthanide ions have been shown to provide ideal examples of single-molecule magnets and spin-qubits. However, the advances in this area are limited by the quality and size of the crystals. In this work, the role of additives ions in the crystallization of these POMs from aqueous solutions has been investigated. More specifically, we have studied the influence of Al(3+), Y(3+), and In(3+) on the crystallization process of K(12)[MP(5)W(30)O(110)] (where M = Gd and Y). The results show that the concentration of these ions in the solution plays an important role in controlling the crystallization rate of the grown POM crystals leading to a significant increase in their size, while showing very little or no tendency to be incorporated into the structure. This has allowed us to obtain pure Gd or Y crystals, as well as diluted magnetic crystals formed by the diamagnetic Y(3+) POM doped with the magnetic Gd(3+) ion.