Dynamic Magnetic and Optical Insight into a High Performance Pentagonal Bipyramidal Dy<sup>III</sup> Single‐Ion Magnet

Chen, Yan‐Cong; Liu, Jun‐Liang; Lan, Yanhua; Zhong, Zhou; Mansikkamäki, Akseli; Ungur, Liviu; Li, Quanwen; Jia, Jianhua; Chibotaru, Liviu F.; Han, Junbo; Wernsdorfer, Wolfgang; Chen, Xiaoming; Tong, Ming‐Liang

doi:10.1002/chem.201606029

Cited by 99 publications

(59 citation statements)

References 46 publications

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“…As a summary, comparison of the results described herein with those previously described for Cy 3 PO (Chen et al, 2016 , 2017 ) seems to indicate that the lower cone angle for triphenylphosphine compared with tricyclohexylphosphine prevents the isolation of pentagonal bipyramidal complexes of triphenylphosphine oxide with dysprosium or terbium. In the same way, hexafluoroacetylacetone allows coordination of two phosphine oxide ligands, leading to coordination number of 8 for the lanthanoid atom while the more sterically hindered 2,2,6,6-tetramethylheptane-3,5-dione only allows linking one phosphine ligand, leading to coordination number 7 (Yanagisawa et al, 2017 ).…”

Section: Resultssupporting

confidence: 80%

“…In spite of these advances, it should be noted that most of the SIMs with high U eff and/or T B are air-unstable, and this is a handicap that must be surpassed. It must be noted that a series of simple, easy to obtain, and air stable phosphine oxide complexes [Dy(R 3 PO) 2 (H 2 O) 5 ]X 3 (R = Cy 3 or CyPh 2 , X = Cl, Br or I) show blocking temperatures between 19 and 20 K (Chen et al, 2016 , 2017 ), the largest ones among SMMs if the 60 K reported for the unstable [(Cp ttt ) 2 Dy][B(C 6 F 5 ) 4 ] is excluded. Accordingly, it seems that the coordination chemistry of lanthanoids with phosphine oxides is really interesting from the magnetic point of view.…”

Section: Introductionmentioning

confidence: 99%

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Field-Induced Single Molecule Magnets of Phosphine- and Arsine-Oxides

et al. 2018

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The coordination chemistry of dysprosium and terbium toward phosphine and arsine oxides was further explored. Thus, the new nitrate [M(NO3)3(Ph3PO)3] (M = Tb, 1; Dy, 2), [Dy(NO3)3(EtOH)(Ph3XO)2] (X = P, 3; As, 4), chloride [DyCl2(Ph3AsO)4]Cl (5), triflate [Dy(OTf)2(MePh2PO)4]OTf (6; OTf = triflate) and hexafluoroacetylacetonate [M(hfa)3(Ph3PO)2] (hfa = hexafluoroacetylacetonate; M = Tb, 7; Dy, 8) complexes were isolated and fully characterized. The crystal structures of 1·CH3CN, 2·CH3CN, 4, 5·2.75EtOH·1.25H2O, 6, 7, and 8 show MO9 cores in 1, 2, and 4, with highly distorted geometry, between spherical capped square antiprism and muffin-like, hexacoordinated environments for the dysprosium ions in 5 and 6, with octahedral geometry, and octa-coordination for the lanthanoid metals in 7 and 8, with geometry closer to square antiprism. Comparison of the magnetic behavior of all the complexes allows analyzing which metal ion (Tb or Dy), phosphine or arsine oxide, or anionic ligand favor more the slow relaxation of the magnetization. Alternating current magnetic measurements show that only 2, 4, and 8 present slow relaxation of the magnetization in the presence of an external magnetic field, 8 being the complex with the highest Ueff (44.85 K) of those described herein.

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Section: Resultssupporting

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Field-Induced Single Molecule Magnets of Phosphine- and Arsine-Oxides

et al. 2018

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“…These values are very similar to those of 2 , especially if the ESDs are considered. Dilution studies on other PB Dy III SMMs, such as Dy(OPCy 3 ) 2 (H 2 O) 5 Cl 3 , [Dy(OP t Bu(NH i Pr 2 ) 2 ) 2 (H 2 O) 5 ]I 3 and [Dy(CyPh 2 PO) 2 (H 2 O) 5 ]Br 3 (Table S37 in the Supporting Information), also only resulted in minimal changes in energy barriers.…”

Section: Resultsmentioning

confidence: 99%

“…There are two families of high‐ U eff Dy III SMMs: the Cp family with sandwich structures and the pentagonal‐bipyramidal (PB) family . The PB family of Dy III SMMs show more diverse magnetic properties, with U eff ranging from 22 to 1261 cm −1 .…”

Section: Introductionmentioning

confidence: 99%

A Study of Magnetic Relaxation in Dysprosium(III) Single‐Molecule Magnets

Ding

Han

Zhai

et al. 2020

Chemistry A European J

119

118

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Although the development of single‐molecule magnets (SMMs) is rapid, there are only two families of high energy barrier (Ueff) dysprosium(III) SMMs known so far: the cyclopentadienyl (Cp) family with a sandwich structure and the pentagonal‐bipyramidal (PB) family with D5h symmetry. These high‐barrier SMMs, which usually possess Ueff>500 cm−1 allow the separate study of the four magnetic relaxation paths, namely, direct, quantum tunnelling, Raman and Orbach processes, in detail. Whereas the first family is chemically more challenging to modify the Cp rings, it is shown herein that the latter family, with the common formulae [DyX1X2(Leq)5]+, such as X1/X2=−OCMe3, −OSiMe3, −OPh, Cl− or Br−; Leq=THF/pyridine/4‐methylpyridine, can be readily fine‐tuned with a range of axial and equatorial ligands by simple substitution reactions. This allows unambiguous confirmation that the Ueff mainly depends on the identity of X1 and X2, rather than on Leq. More importantly, the fitted parameters are barrier dependent. If X1 is an O donor and X2 is a halide, 500

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“…In principle, in the absence of QTM and TA-QTM (thermal activated as quantum tunneling of the magnetization), which shortcut the relaxation barrier to an effective value ( U eff ), T B increases with the height of the energy barrier. As the height of U primarily depends on the magnetic anisotropy, researchers have focused their attention on complexes containing lanthanide ions (and actinide) (Chen et al, 2016 , 2017 ; Ding et al, 2016 ; Gregson et al, 2016 ; Gupta et al, 2016a ; Liu et al, 2016 ; Goodwin et al, 2017 ; Guo et al, 2017 ), which exhibit large intrinsic magnetic anisotropy and large magnetic moments in the ground state. The use of lanthanide ions and, particularly the Dy III ion (a Kramers ion for which QTM should be forbidden in the absence of magnetic field) has led to metal complexes with higher energy barriers and improved SMM properties.…”

Section: Introductionmentioning

confidence: 99%

A Chiral Bipyrimidine-Bridged Dy2 SMM: A Comparative Experimental and Theoretical Study of the Correlation Between the Distortion of the DyO6N2 Coordination Sphere and the Anisotropy Barrier

et al. 2018

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Chiral bipyrimidine-bridged dinuclear LnIII complexes of general formula [(μ-bipym){((+)-tfacam)3Ln}2] and [(μ-bipym){((-)-tfacam)3Ln}2], have been prepared from the assembly of Ln(AcO)3·nH2O (LnIII = Dy, Gd), (+)/(−)-3-(trifluoroacetyl)camphor enantiopure ligands ((+)/(-)-Htfacam) and bipyrimidine (bipym). The structure and chirality of these complexes have been supported by single-crystal X-Ray diffraction and circular dichroism. The study of the magnetic properties of the GdIII complexes revealed a very weak antiferromagnetic interaction between the GdIII ions through the bipyrimidine bridging ligand. Ab initio CASSCF calculations indicated that the ground Kramers doublet (KD) of both DyIII centers is almost purely axial with the anisotropy axis located close to the two tfacam−ligands at opposite sides of each DyIIIatom, which create an axial crystal field. In keeping with this, ac dynamic measurements indicated slow relaxation of the magnetization at zero field with Ueff = 55.1 K, a pre-exponential factor of τo = 2.17·10−6 s and τQTM = 8 μs. When an optimal dc field of 0.1 T is applied, QTM is quenched and Ueff increases to 75.9 K with τo = 6.16 × 10−7 s. The DyN2O8 coordination spheres and SMM properties of [(μ-bipym){((+)-tfacam)3Ln}2] and their achiral [(Dy(β-diketonate)3)2(μ-bpym)]analogous have been compared and a magneto-structural correlation has been established, which has been supported by theoretical calculations. In contrast to the GdIII compounds, the magnetic exchange interaction between the DyIII ions has been calculated to be very weak and, generally, ferromagnetic in nature. Relaxation mechanisms for [(μ-bipym){((+)-tfacam)3Ln}2] and previously reported analogous have been proposed from ab initio calculations. As the magnetic exchange interaction found to be very weak, the observed magnetization blockade in these systems are primarily dictated by the single ion anisotropy of DyIII ions.

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Dynamic Magnetic and Optical Insight into a High Performance Pentagonal Bipyramidal Dy^III Single‐Ion Magnet

Cited by 99 publications

References 46 publications

Field-Induced Single Molecule Magnets of Phosphine- and Arsine-Oxides

Field-Induced Single Molecule Magnets of Phosphine- and Arsine-Oxides

A Study of Magnetic Relaxation in Dysprosium(III) Single‐Molecule Magnets

A Chiral Bipyrimidine-Bridged Dy2 SMM: A Comparative Experimental and Theoretical Study of the Correlation Between the Distortion of the DyO6N2 Coordination Sphere and the Anisotropy Barrier

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Dynamic Magnetic and Optical Insight into a High Performance Pentagonal Bipyramidal DyIII Single‐Ion Magnet

Cited by 99 publications

References 46 publications

Field-Induced Single Molecule Magnets of Phosphine- and Arsine-Oxides

Field-Induced Single Molecule Magnets of Phosphine- and Arsine-Oxides

A Study of Magnetic Relaxation in Dysprosium(III) Single‐Molecule Magnets

A Chiral Bipyrimidine-Bridged Dy2 SMM: A Comparative Experimental and Theoretical Study of the Correlation Between the Distortion of the DyO6N2 Coordination Sphere and the Anisotropy Barrier

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Dynamic Magnetic and Optical Insight into a High Performance Pentagonal Bipyramidal Dy^III Single‐Ion Magnet