Coordination of lanthanides in the inverted cucurbituril supramolecular assemblies formed in the presence of tetrachloride zincate anion: Potential applications for isolation of lighter lanthanides

Coordination of supramolecular assemblies was investigated by reacting a series of lanthanide cations (Ln3+) with an inverted cucurbituril (iQ[6]) in the presence of tetrachloride zincate anion [ZnCl4]2−, as an structure directing agent in aqueous HCl (3.0 mol/L). Single crystal X-ray diffraction analysis revealed that the coordination of iQ[6] with Ln3+ gave rise to different interaction products and isomorphous groups with increasing atomic number. The interaction of iQ[6] with La3+ and Ce3+ immediately yielded precipitations and single crystal solids containing Pr3+ and Nd3+. No solids resulted from coordination of iQ[6] with Sm3+ and Eu3+, whereas single crystals solids were obtained from coordination of iQ[6] with heavy Ln3+, such as Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+ and Lu3+. Such coordination characteristics may offer a strategy for isolating a series of Ln3+ cations in patches.

Graphical abstractSupramolecular assemblies in aqueous HCl solutions was investigated by reacting lanthanide cations and inverted cucurbit[6]uril in the presence of tetrachloride zincate anion, potential applications for isolation of lighter lanthanides.Figure optionsDownload full-size imageDownload as PowerPoint slide