Issue 44, 2022

Pseudo-mono-axial ligand fields that support high energy barriers in triangular dodecahedral Dy(iii) single-ion magnets

Abstract

The synthesis of air-stable, high-performance single-molecule magnets (SMMs) is of great significance for their practical applications. Indeed, Ln complexes with high coordination numbers are satisfactorily air stable. However, such geometries easily produce spherical ligand fields that minimize magnetic anisotropy. Herein, we report the preparation of three air-stable eight-coordinate mononuclear Dy(III) complexes with triangular dodecahedral geometries, namely, [Dy(BPA-TPA)Cl](BPh4)2 (1) and [Dy(BPA-TPA)(X)](BPh4)2·nCH2Cl2 (X = CH3O and n = 1 for 2; L = PhO and n = 2 for 3), using a novel design concept in which the bulky heptadentate [2,6-bis[bis(2-pyridylmethyl)amino]methyl]-pyridine (BPA-TPA) ligand enwraps the Dy(III) ion through weak coordinate bonds leaving only a small vacancy for a negatively charged (Cl), methoxy (CH3O) or phenoxy (PhO) moiety to occupy. Magnetic measurements reveal that the single-molecule magnet (SMM) property of complex 1 is actually poor, as there is almost no energy barrier. However, complexes 2 and 3 exhibit fascinating SMM behavior with high energy barriers (Ueff = 686 K for 2; 469 K for 3) and magnetic hysteresis temperatures up to 8 K, which is attributed to the pseudolinear ligand field generated by one strong, highly electrostatic Dy–O bond. Ab initio calculations were used to show the apparent difference in the magnetic dynamics of the three complexes, confirming that the pseudo-mono-axial ligand field has an important effect on high-performance SMMs compared with the local symmetry. This study not only presents the highest energy barrier for a triangular dodecahedral SMM but also highlights the enormous potential of the pseudolinear Dy–L ligand field for constructing promising SMMs.

Graphical abstract: Pseudo-mono-axial ligand fields that support high energy barriers in triangular dodecahedral Dy(iii) single-ion magnets

Supplementary files

Article information

Article type
Edge Article
Submitted
07 Jun 2022
Accepted
30 Oct 2022
First published
31 Oct 2022
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2022,13, 13231-13240

Pseudo-mono-axial ligand fields that support high energy barriers in triangular dodecahedral Dy(III) single-ion magnets

B. Zhang, Z. Cheng, Y. Wu, L. Chen, R. Jing, X. Cai, C. Jiang, Y. Zhang, A. Yuan, H. Cui and Z. Li, Chem. Sci., 2022, 13, 13231 DOI: 10.1039/D2SC03182E

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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