Coordination-perturbed single-molecule magnet behaviour of mononuclear dysprosium complexes

Abstract

By changing the ratio of reactants, two mononuclear Dy complexes, [Dy(phen)(acac)(3)] (1) and [Dy(phen)(2)(NO(3))(2)(acac)]·H(2)O (2) have been synthesized and structurally characterized. In 1, a Dy atom bearing square-antiprism coordination geometry exhibits SMM behaviour, while compound 2 with a bicapped-square-antiprism geometry does not show such SMM properties. The different magnetic behaviours seen in 1 and 2 are probably due to a different coordination environment and ligand field around the Dy(III) ions. The results proved the important influence of the structural environment of a SMM on its magnetic behaviour.

Two-color thermosensors based on [Y $$_{1-x}$$ 1 - x Dy $$_x$$ x (acetylacetonate) $$_3$$ 3 (1,10-phenanthroline)] molecular crystals

“…We therefore average the parameters and tabulate their average value in Table I. These parameters are found to be consistent with previous XRD measurements of [Dy(acac) 3 (phen)] MCs [71].…”

“…This energy transfer is typically radiationless and can occur via several possible mechanisms: electron exchange [48,53], dipole-dipole interactions (both allowed [62][63][64][65] and unallowed transitions [48,66]), dipole-quadrapole interactions [48], and excitons [67,68] This energy transfer has been empirically found to be most efficient if the ligand's lowest triplet energy level is between 0.23 eV and 0.62 eV greater than the lanthanide's primary luminescent state, as energy back-transfer is more likely to occur for energy differences of < 0.23 eV [51,69]. One such material, satisfying this criterion is [Dy(acetylacetonate) 3 (1,10-phenanthroline)] ([Dy(acac) 3 (phen)]) [52,[70][71][72][73], which is the subject material of this study. To demonstrate the energy level spacing of the ligands and Dy ion we provide a simplified energy level diagram in Figure 1 where the energy levels are taken from the literature [45,47,52,74,75].…”

“…This means that during excitation the primary absorption is due to the acac ligand, which can then nonradiatively transition to the lowest triplet state T 1 (energy ≈ 3.134 eV) via intersystem crossing. [70,71], a phosphor for white OLEDs [72,73], and a NIR optical phosphor for use in telecommunications [52]. In these previous studies the authors prepared the material with a Dy concentration of 100 mol%, while in our study we dilute [Dy(acac) 3 3 (phen)] MCs we use X-ray diffraction (XRD) with a Cu-Kα radiation source (λ=1.5418Å) operated at 40 kV and 40 mA.…”

Magnetic Memory from Site Isolated Dy(III) on Silica Materials

“…The oxygen ligands arise from the surface and should therefore impose a very asymmetric environment. In fact, 1,10-phenanthroline, a bidendate ligand, coordinates to Dy as evidenced by a shift of the aromatic ring (C=C and C=N) in IR (Figure S17), 33 thus showing that Dy was not incorporated in the bulk of the material similarly to what was observed for Cr and Yb. 23,30 …”

A Basis for Lanthanide Single-Molecule Magnets

“…Further studies for redox, heteroleptic, and multidecker species of this class of complexes [53][54][55][56][57] were performed and thus created a high effective barrier record of SMM field, U eff = 652 cm −1 (938 K) [56], which surpasses by an order of magnitude that obtained for the original Mn 12 SMM. Remarkably, the interest in new kinds of mononuclear lanthanide SMMs [58] is continuing in recent years, and some of them show the very high effective barrier and blocking temperature, such as β-diketone [59][60][61][62], organometallic [35,37,44,63], 2013 [74] and some low-symmetry [20,64] lanthanide systems (Table 1.4). As such, the mononuclear SMMs are called single-ion magnets (SIMs) in some recent papers.…”