Helicate-to-tetrahedron transformation of chiral lanthanide supramolecular complexes induced by ionic radii effect and linker length

Yim, King-Him; Yeung, Chi-Tung; Probert, Michael R.; Chan, Wesley Ting Kwok; MacKenzie, Lewis E.; Pal, Robert; Wong, Wing-Tak; Law, Ga-Lai

Abstract

Controlled formation of desired lanthanide supramolecular complexes is challenging because of the difficulties in predicting coordination geometry, as well as a labile coordination number. Herein, we explore the effect of ionic radii and linker length on supramolecular species formation. A helicate-to-tetrahedron transformation occurred between [Ln2L13] and [Ln4L16] (Ln = La, Sm, Eu, Gd, Tb and Lu). For six lanthanide ions, the unfavored tetrahedron [La4L16] can only be observed in a concentrated mixture with the helicate [La2L13] where no pure [La4L16] species was isolated via crystallization. For Sm, Eu, Gd, Tb, the [Ln4L16] supramolecular tetrahedron can be isolated via crystallization from diisopropyl ether. A similar result was also observed for Lu, but the tetrahedral structure was found to be relatively stable and transformed back to [Lu2L13] much slower upon dissolution. No tetrahedron formation was observed with L3 giving rise to only [Ln2L33] species, in which L3 contains a longer and more flexible linker compared with that of L1. Results show that the supramolecular transformation in these systems is governed by both the ionic radii as well as the ligand design. Special focus is on both [Eu2L13] and [Eu4L16] which form chiral entities and exhibit interesting circular polarized luminescence.

Citation

Yim, K., Yeung, C., Probert, M. R., Chan, W. T. K., MacKenzie, L. E., Pal, R., …Law, G. (2021). Helicate-to-tetrahedron transformation of chiral lanthanide supramolecular complexes induced by ionic radii effect and linker length. Communications Chemistry, 4, Article 116. https://doi.org/10.1038/s42004-021-00553-8

• Journal Article Type: Article
• Acceptance Date: Jul 20, 2021
• Online Publication Date: Aug 5, 2021
• Publication Date: 2021
• Deposit Date: Aug 11, 2021
• Publicly Available Date: Dec 17, 2021
• Journal: Communications Chemistry
• Publisher: Nature Research
• Peer Reviewed: Peer Reviewed
• Volume: 4
• Article Number: 116
• DOI: https://doi.org/10.1038/s42004-021-00553-8
• Public URL: https://durham-repository.worktribe.com/output/1237690