Enhancing the Magnetic Anisotropy in Low-Symmetry Dy-Based Complexes by Tuning the Bond Length

Abstract

One mononuclear complex [Dy(Htpy)-(NO 3 ) 2 (acac)] (1) and a tpy − -extended 1D chain {[Dy(CH 3 OH)-(NO 3 ) 2 (tpy)]•CH 3 OH} n (2) (Htpy = 4′-(4-hydroxyphenyl)-2,2′:6′,2′′-terpyridine, Hacac = acetylacetone) were successfully designed to investigate the effect of bond length tuning around the Dy III cation on the magnetic dynamics of single-molecule magnets (SMMs). Interestingly, two magnetic entities possess the same local coordination sphere (N 3 O 6 -donor) as well as the configuration (Muffin, C s ) of dysprosium centers. Only a slight difference in structure results from purposefully substituting the acetylacetone ligand in 1 with hydroxyl oxygen from tpy − linkage and one methanol molecule in 2. However, the remarkable differences in dynamics behavior were clearly found between them. Compound 1 possesses a thermal-activated effective energy barrier (U eff /k B ) of 22.7 K under a 0 kOe direct current (dc) field and negligible hysteresis loop at 2.0 K, while complex 2 shows high-performance SMM behavior with the largest energy barrier of 354.36 K among the reported nine-coordinated Dy III -based systems and the magnetic hysteresis up to 4.0 K at a sweep rate of 200 Oe s −1 . These experimental results combined with the previous reported data reveal that the shortest bond and the bond length difference around the Dy III center synergistically determine the dynamics of SMMs. The uniaxial anisotropy increases with the decrease of the shortest bond and the increase of the bond length difference, which is confirmed by the theoretical calculations.

Dysprosium(III) Metal–Organic Framework Demonstrating Ratiometric Luminescent Detection of pH, Magnetism, and Proton Conduction

“… The bond length of Dy–O water (2.4206 Å) is slightly longer than the average bond length of Dy–O carboxylate (2.3713 Å). Shape analysis using the SHAPE 2.1 software reveals that the coordination geometry of Dy III center can be described as a slightly distorted low-symmetry Muffin ( C s symmetry) with an agreement MFF-9 factor of 1.043 (Table S4), which is common for 9-coordinated lanthanide species. , Two Dy III centers are connected through four carboxylate groups to form [Dy 2 (CO 2 ) 4 ] binuclear cores, and the separation between two Dy III ions is 4.099 Å (Figure c). Each binuclear node is coordinated by eight separate H 2 dobdc 2– ligands (Figure S1b).…”

A mononuclear nine-coordinated Dy(iii) complex exhibiting field-induced single-ion magnetism behaviour

“…The result of analyzed magnetostructural indicates that the shorter the shortest bond length and the greater the bond length difference, the better the performance of the SMMs can be obtained, suggesting the uneven bond length distribution acts the building of high-performance SIMs, as observed in the previous literature. 36 …”

Effect of Ligands on Quantum Tunneling of Magnetization for Dysprosium C4v Single-Molecule Magnets with Theoretical Insights

“…28,29 Nonetheless, achieving high local symmetry in Dy III -based SMMs is challenging owing to their random high coordination number and variable coordination mode, given that Dy III -based SMMs typically exhibit low symmetry systems. 30,31 Therefore, investigating stochastically synthesized low-symmetry systems not only expands the family of Dy IIIbased SMMs but also contributes to an in-depth understanding of magnetic structure correlations and sheds light on the dynamic magnetic behavior of low-symmetry Dy III -based SMMs.…”

“…In addition, the influences of auxiliary ligands, decorating terminal ligands, and ligands with steric hindrances are also investigated. , However, there is an urgent challenge to understand how ligands can affect the Dy III -based SMMs performance. On the other hand, it has been shown that Dy III -based SMMs with high symmetry, including D 4 d , D 5 h , and D 6 d , tend to exhibit high performance and suppress the quantum tunneling of the magnetization (QTM). , Nonetheless, achieving high local symmetry in Dy III -based SMMs is challenging owing to their random high coordination number and variable coordination mode, given that Dy III -based SMMs typically exhibit low symmetry systems. , Therefore, investigating stochastically synthesized low-symmetry systems not only expands the family of Dy III -based SMMs but also contributes to an in-depth understanding of magnetic structure correlations and sheds light on the dynamic magnetic behavior of low-symmetry Dy III -based SMMs.…”