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The Saga of Ln SMMs continues in 2017

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The Saga of Ln SMMs continues in 2017


Publication:
Structural, Optical and Magnetic Investigations of Lanthanide complexes Involving Multichelating TTF-based Ligands
S. Speed, M. Feng, G. Fernandez-Garcia, F. Pointillart, B. Lefeuvre, F. Riobe, S. Golhen, B. Le Guennic, F. Totti, Y. Guyot, O. Cador, O. Maury, L. Ouahab
Inorg. Chem. Front. 2017, DOI: 10.1039/C6QI00546B


Abstract
The reaction between the 2-(TTF-fused-1H-benzimidazol-2-yl)pyridine alkylated either with the di-(pyrazol-1-yl)-4-pyridyl (L1) or dimethyl-2,2’-bipyridine (L2) moiety and 1 equiv. of Ln(hfac)32(H2O) (LnIII = DyIII and YbIII) leads to three dinuclear complexes of formula [Yb2(hfac)6(L1)]·2(CH2Cl2)·C6H14 (1) and [Ln2(hfac)6(L2)]CH2Cl2 (LnIII = YbIII (2) and DyIII (3)). The X-ray structures highlight square antiprism (D4d symmetry) and spherical tricapped trigonal prism (D3h) for the eight- and nine-coordinated lanthanide ions, respectively. Irradiation of the lowest-energy HOMO → LUMO ILCT absorption band induced a 2F5/2 → 2F7/2 Yb-centered emission for 1 and 2. Both YbIII ions displayed similar emissions in 2 while two distinct emissions were observed and attributed to the two YbIII ions in 1 depending on their coordination surroundings. Slow magnetic relaxation is detected by dynamic magnetic measurements for 3 with a measured relaxation time τ0 = 3.7(1.3) x 10-7 s and an energy barrier Δ= 39.6(2) cm-1. Taking into account the environment of both DyIII ions in 3, it was expected that both metallic centers displayed similar dynamic magnetic behavior. The latter was rationalized by ab initio CASSCF/SI-SO calculations.


Publication:
Uncommon lanthanide ions in purely 4f Single Molecule Magnets
F. Pointillart, O. Cador, B. Le Guennic, L. Ouahab
Coord. Chem. Rev. 2017, DOI: 10.1016/j.ccr.2016.12.017


Abstract
Since the 1990s and the discovery of the first Single Molecule Magnets (SMMs), chemists and physicists have been working in concert to elaborate such molecular systems and understand their peculiar properties. Especially the use of lanthanide ions in the design of SMMs exploded with the discovery of the first example of mononuclear TbIII-based complex which displayed a slow magnetic relaxation in 2003. This high-degree of interest comes from the diverse potential applications in quantum computing, high-density data storage devices and spintronics. Recently, the specific luminescence properties of the lanthanide ions were correlated to the magnetic ones. Even if the most common lanthanide ions used in the elaboration of SMMs are the DyIII, TbIII and ErIII ions, new SMMs involving others lanthanide ions (YbIII, CeIII, NdIII, HoIII and TmIII) started to emerge. This review presents the research endeavour in the area of these uncommon lanthanide-based SMMs and underlines the different approaches to better understand their physical properties.


Publication:
Slow Magnetic Relaxation in Chiral Helicene-Based Coordination Complex of Dysprosium
G. Fernandez-Garcia, J. Flores Gonzalez, J-K. Ou-Yang, N. Saleh, F. Pointillart, O. Cador, T. Guizouarn, F. Totti, L. Ouahab, J. Crassous, B. Le Guennic
Magnetochemistry 2017, 3, 2


Abstract
The complex [Dy(L)(tta)3] with L the chiral 3-(2-pyridyl)-4-aza[6]-helicene ligand (tta− = 2-thenoyltrifluoroaacetonate) has been synthesized in its racemic form and structurally and magnetically characterized. [Dy(L)(tta)3] behaves as a single molecule magnet in its crystalline phase with the opening of a hysteresis loop at 0.50 K. These magnetic properties were interpreted with ab initio calculations.