Capping Ligand Perturbed Slow Magnetic Relaxation in Dysprosium Single‐Ion Magnets

Abstract

Single-ion magnets 1 and 2 and their diamagnetic analogues 3 and 4 for magnetic-site dilution were obtained through substitution of the coordinated water molecules of [Ln(TTA)(3)(H(2)O)(2)] (Ln=Dy (1, 2), Y (3, 4); TTA=4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedionate) by 2,2'-bipyridine (1, 3) and 1,10-phenanthroline (2, 4) capping ligands. Their structures and magnetic properties were investigated with the goal of identifying features relevant to modulating relaxation dynamics of single-ion magnets. The metal ions in all complexes adopt an approximately square-antiprismatic (SAP) O(6)N(2) coordination environment. The SAP polyhedrons for both 1 and 2 show slight longitudinal compression, while the coordination sphere of 1 deviates more from an ideal SAP than that of 2, as indicated by the skew angles of the SAP environment. The similar values of U(eff) for the two magnetically diluted samples imply nearly the same distribution of low-lying states for their Dy(III) centers, which is consistent with the slight axial contraction observed for 1 and 2 and further corroborated by ligand-field analysis. The fast quantum tunneling rate τ(QTM) of 1, which is about ten times faster than that of 2, can presumably be associated with the larger rotation of the SAP surroundings. This distortion may result in a significant transverse anisotropy terms, and thus strongly affect the dynamic behavior of the system.

Molecular single-ion magnets based on lanthanides and actinides: Design considerations and new advances in the context of quantum technologies

“…Some capping ligands can also cause distortions of the D4d symmetry, which results in larger off-diagonal anisotropy, and implicitly enhanced QTM [113].…”

Single-molecule magnetism of tetrapyrrole lanthanide compounds with sandwich multiple-decker structures

“…This provides an initial empirical single-ionic SMM model where the lanthanide ion is located in an antiprism coordination geometry. This model also works well for the single-ionic lanthanide SMMs, which were designed and synthesized early in the development of these compounds, such as the lanthanide polyoxometalates and-diketone-based systems [29][30][31][32][33][34][35] [(Pc 2 )Ln(Pc 2 )] -.TBA + (9b, 10b) can be obtained using the conventional redox reaction [40,41]. A comparative study detected a fairly significant upward temperature shift in the slow relaxation for 9a and 10a compared with that for the corresponding anionic species 9b and 10b with effective barrier heights U eff of 550 and 55 cm -1 for the former two species, respectively.…”

Highly pH-dependent synthesis of two novel three-dimensional dysprosium complexes with interesting magnetic and luminescence properties

“…13), consistent with the expected τ 0 values for an SMM. [33][34][35][36] This method has recently been developed by Bartolomé et al and has been applied in many compounds. 18 As for 2, both the in-phase ( χ′) and out-of-phase ( χ″) signals are very weak, hardly showing frequency dependence (Fig.…”