Slow magnetic relaxation in Dy₂ and Dy₄ complexes of a versatile, trifunctional polydentate N,O-ligand

Abstract

A binuclear DyIII complex exhibits slow relaxation of magnetization under an applied dc field, while its tetranuclear counterpart exhibits “true” zero-field SMM behaviour.

A Family of Lanthanide Hydroxo Carboxylates with 1D Polymeric Topology and Ln4 Butterfly Core Exhibits Switchable Supramolecular Arrangement

“…The previous data highlight the pivotal role of the ligand field in the appearance of magnetic anisotropy for lanthanide ions. Although Shiff bases, beta-diketonates, pirazolates, and carboxylates (pivalates) were reported to be appropriate choices for the construction of Ln 4 clusters with slow magnetic relaxation, ,,,− no significant attention has been paid to date to the intermolecular arrangement of tetranuclear clusters, supposing magnetic behavior to be more strongly affected by the local coordination environment. The reported Ln 4 compounds give the unique opportunity to reveal the effect of clusters connection and modification of the magnetic properties.…”

“…Thus, despite the almost identical local structure of Dy 4 and Dy 4 ′ compounds, the dehydration procedure affects the magnetic behavior. This effect can be ascribed to structural changes and relative shortening of the inter-cluster distances and rearrangement of Dy ions’ magnetic anisotropy axes …”

A Sodium Sodate as Precursor for Lanthanide Bis(4-R-benzoxazol-2-yl)methanide Single-Molecule Magnets

“…Such findings, however, are transferrable to multinuclear systems. For example, the highly anisotropic building unit Cp 2 R Dy + (R = alkyl group) of these systems has been used to form halide-, oxo-, or radical-bridged multinuclear systems with superior magnetic properties. , …”

Asymmetric Dinuclear Lanthanide(III) Complexes from the Use of a Ligand Derived from 2-Acetylpyridine and Picolinoylhydrazide: Synthetic, Structural and Magnetic Studies

“…The appearance and the slowing down of the relaxation when applying a small dc field is expected when the magnetization relaxation is dominated by quantum tunneling (quantum tunneling of magnetization, QTM) [3,77] and/or Raman processes [78]. In the QTM case, the application of a dc field minimizes the probability of the magnetization to tunnel, as already observed in many Ln(III) SMMs [18,19,23,34,57,69,79]. The temperature and frequency dependencies of the ac susceptibility were thus studied under an optimum dc field (i.e., a dc field for which the relaxation process of the magnetization exhibits a good compromise between its characteristic time and the intensity of the relaxation mode) of 600 Oe for 3•2.5MeOH and 1000 Oe for 4•3MeOH•0.5H 2 O (Figures 8 and 9).…”

“…The first generation of SMMs was based on transition-metal complexes [ 3 , 4 ]. Trivalent lanthanides, Ln(III)s, came into the scientific scene of the SMM area in 2003 with the mononuclear, double-decker complexes [Ln III (pc) 2 ]¯ (Ln = Tb, Dy; pc 2− = the phthalocyanine dianion) [ 5 ], and they are currently protagonists [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ] in the interdisciplinary field of molecular magnetism. The latest scientific breakthrough was the synthesis of [(η 5 − cp*)Dy(η 5 − cp iPr5 )][B(C 6 F 5 ) 4 ], where cp* is the pentamethylcyclopentadienyl(−1) group and cp iPr5 is the penta-iso-propylcyclopentadienyl(−1) ligand [ 35 ].…”