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An extremely rare non-Kramers holmium(III) single-ion magnet (SIM) is reported to be stabilized in the pentagonal-bipyramidal geometry by a phosphine oxide with a high energy barrier of 237(4) cm−1. The suppression of the quantum tunneling of magnetization (QTM) at zero field and the hyperfine structures originating from field-induced QTMs can be observed even from the field-dependent alternating-current magnetic susceptibility in addition to single-crystal hysteresis loops. These dramatic dynamics were attributed to the combination of the favorable crystal-field environment and the hyperfine interactions arising from 165Ho ( I=7/2) with a natural abundance of 100 %. [ABSTRACT FROM AUTHOR]

An extremely rare non-Kramers holmium(III) single-ion magnet (SIM) is reported to be stabilized in the pentagonal-bipyramidal geometry by a phosphine oxide with a high energy barrier of 237(4) cm−1. The suppression of the quantum tunneling of magnetization (QTM) at zero field and the hyperfine structures originating from field-induced QTMs can be observed even from the field-dependent alternating-current magnetic susceptibility in addition to single-crystal hysteresis loops. These dramatic dynamics were attributed to the combination of the favorable crystal-field environment and the hyperfine interactions arising from 165Ho ( I=7/2) with a natural abundance of 100 %. [ABSTRACT FROM AUTHOR]

The perturbation to the ligand field around the lanthanide ion may significantly contribute to the magnetic dynamics of single molecule magnets. This can be demonstrated by two typical Dy4 cluster-based single molecular magnets (SMMs), [Dy4X2(μ3-OH)2(μ-OH)2(2,2-bpt)4(H2O)4]X2·2H2O·4EtOH (X = Cl and Br for 1 and 2, respectively), which were constructed by using 3,5-bis(pyridin-2-yl)-1,2,4-triazole (2,2-bptH) as the polynuclear-chelating ligand. Alternating-current (ac) magnetic susceptibility measurements show that the energy barriers in complexes 1 and 2 were immensely enhanced by comparing with our previous work due to the optimization of the ligand field around DyIII ions. Remarkably, their high thermal active barriers at 190 K (1) and 197 K (2) under a zero applied external dc magnetic field are also among the highest within the reported tetranuclear lanthanide-based SMMs. [ABSTRACT FROM AUTHOR]

This review outlines recent advances in the design of 3d-, 4f-, and 3d–4f type magnetic molecules for use as excellent cryogenic magnetic coolants based on the magnetocaloric effect (MCE), and the structure-magnetocaloric correlations of reported molecular coolants. Further improvements in the MCE values of molecular magnetic materials are also proposed based on assembly strategies from molecular chemistry and crystal engineering. [ABSTRACT FROM AUTHOR]

Two 3d–4f nanomagnets, [DyIII2CuII7] (1) and [GdIII6CuII12] (2), are synthesized under a two-step in situ reaction of picolinaldehyde. Not only the final adduct (hemiacetal), but also the intermediate (gem-diol) are “visualized” by X-ray single crystal diffraction. The Dy complex behaves as a single-molecule magnet, while the Gd complex exhibits a significant magnetocaloric effect. Theoretical calculations are employed to obtain the orientation of the magnetic moments and the magnetic exchange. [ABSTRACT FROM AUTHOR]

Manipulating bistability at the molecular level, especially in single-molecule magnet (SMM) and spin-crossover (SCO) materials, has attracted enormous recent interest due to their multifaceted magnetic behaviour and potential applications in devices. Moreover, their fascinating properties can be further modulated via chemical modifications and external stimuli, bringing about vast possibilities and valuable lessons. In this Feature Article, we present a selection of our research into this topic, as well as some other related achievements that have been made in recent years. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Briefly state the design strategies for luminescent lanthanide single-molecule magnets (SMMs). • Systematically survey the recent advances of luminescent lanthanide SMMs. • Discuss the magneto-luminescent behavior for lanthanide SMMs. Abstract Incorporation of two characters into one molecular entity is an effective way to afford bifunctional molecule-based materials. Lanthanides serve as a group of preferable objectives for the construction of luminescent single-molecule magnets (SMMs) due to their excellent performances in areas of SMM and luminescence for molecular materials, showing a great potential of applications in high-density data storage, quantum computing, light-emitting diodes, biofluorescence labelling, etc. This review concentrates on the design strategies for the construction of luminescent SMMs referring to the organic chromophores and transition metal-containing chromophores as the antennas, as well as the recent examples of luminescent SMMs. To investigate the magneto-luminescent behavior (including the magneto-luminescent coupling), a few of classical complexes are discussed in the review to emphasize the importance of studying the correlation/coupling between relaxation mechanism and luminescence for lanthanide SMMs. [ABSTRACT FROM AUTHOR]

Single-molecule magnets (SMMs) containing only one metal center may represent the lower size limit for molecule-based magnetic information storage materials. Their current drawback is that all SMMs require liquid-helium cooling to show magnetic memory effects. We now report a chemical strategy to access the dysprosium metallocene cation [(CpiPr5)Dy(Cp*)]+ (CpiPr5, penta-iso-propylcyclopentadienyl; Cp*, pentamethylcyclopentadienyl), which displays magnetic hysteresis above liquid-nitrogen temperatures. An effective energy barrier to reversal of the magnetization of Ueff = 1541 wave number is also measured. The magnetic blocking temperature of TB = 80 kelvin for this cation overcomes an essential barrier toward the development of nanomagnet devices that function at practical temperatures. [ABSTRACT FROM AUTHOR]

Abstraction of a chloride ligand from the dysprosium metallocene [(Cpttt)2DyCl] ( 1Dy Cpttt=1,2,4-tri( tert-butyl)cyclopentadienide) by the triethylsilylium cation produces the first base-free rare-earth metallocenium cation [(Cpttt)2Dy]+ ( 2Dy) as a salt of the non-coordinating [B(C6F5)4]− anion. Magnetic measurements reveal that [ 2Dy][B(C6F5)4] is an SMM with a record anisotropy barrier up to 1277 cm−1 (1837 K) in zero field and a record magnetic blocking temperature of 60 K, including hysteresis with coercivity. The exceptional magnetic axiality of 2Dy is further highlighted by computational studies, which reveal this system to be the first lanthanide SMM in which all low-lying Kramers doublets correspond to a well-defined MJ value, with no significant mixing even in the higher doublets. [ABSTRACT FROM AUTHOR]

[Display omitted] • The coordination chemistry of a hexadentate mixed ligand, H 2 bbpen, is introduced. • The lanthanide single-molecule magnets based on H 2 bbpen and derivatives are reviewed and the magneto-structural correlations are analysed. • The optical and chiral-optical properties of lanthanide complexes based on H 2 bbpen and derivatives are discussed. Lanthanide complexes are among the most active frontiers of functional coordination chemistry, especially due to their fascinating magnetic and optical properties. Among them, a hexadentate mixed ligand, H 2 bbpen, gave birth to some of the best lanthanide single-molecule magnets and photoluminescence complexes. Here we review the coordination chemistry, the single-molecule magnetism and the optical properties of H 2 bbpen-based lanthanide complexes, trying to find some magneto-structural and optical-structural correlations that can promote further developments in such a family and related systems. [ABSTRACT FROM AUTHOR]

We have reported two unprecedented single-ion magnets (SIMs) with the homoatomic LnN10 coordination geometry, where the central Ln (Ln = DyIII or ErIII) ion is interlocked by two pentadentate ligands (N5) affording a low symmetry polyhedron. Studies of dynamic magnetic behaviours show an effective energy of 79(4) K for [Dy(N5)2]3+ and 59(4) K for [Er(N5)2]3+, respectively. [ABSTRACT FROM AUTHOR]

Here we reported the deuteration of the metal‐binding equatorial water molecules in a reported HoIII single‐molecule magnet (SMM) with pentagonal‐bipyramidal geometry, from [Ho(CyPh2PO)2(H2O)5]3+ to [Ho(CyPh2PO)2(D2O)5]3+. The hyperfine structures originating from the nuclear spin of 165HoIII can be clearly observed. Moreover, the resulting magnetization dynamics revealed the switch of the relative relaxation rates for the two isotope‐isomorphic complexes—respectively faster/slower at low/high temperature. The noticeable isotope effect arises from not only the paramagnetic metal center but also the diamagnetic ligands, which can be explained by the ab initio calculated tunnel splitting and the involvement of the super‐hyperfine interaction related to the difference in the nuclear spin number of protium (1H, I=1/2) and deuterium (2H, I=1). [ABSTRACT FROM AUTHOR]

Here we reported the deuteration of the metal‐binding equatorial water molecules in a reported HoIII single‐molecule magnet (SMM) with pentagonal‐bipyramidal geometry, from [Ho(CyPh2PO)2(H2O)5]3+ to [Ho(CyPh2PO)2(D2O)5]3+. The hyperfine structures originating from the nuclear spin of 165HoIII can be clearly observed. Moreover, the resulting magnetization dynamics revealed the switch of the relative relaxation rates for the two isotope‐isomorphic complexes—respectively faster/slower at low/high temperature. The noticeable isotope effect arises from not only the paramagnetic metal center but also the diamagnetic ligands, which can be explained by the ab initio calculated tunnel splitting and the involvement of the super‐hyperfine interaction related to the difference in the nuclear spin number of protium (1H, I=1/2) and deuterium (2H, I=1). [ABSTRACT FROM AUTHOR]

A series of heterometallic [LnIII xCuII y] complexes, [Gd2Cu2] n ( 1), [Gd4Cu8] ( 2), [Ln9Cu8] (Ln=Gd, 3⋅Gd; Ln=Dy, 3⋅Dy), were successfully synthesized by a one-pot route at room temperature with three kinds of in situ carbonyl-related reactions: Cannizzaro reaction, aldol reaction, and oxidation. This strategy led to dysprosium analogues that behaved as single-molecule magnets (SMMs) and gadolinium analogues that showed significant magnetocaloric effect (MCE). In this study a numerical DFT approach is proposed by using pseudopotentials to calculate the exchange coupling constants in three polynuclear [Gd xCu y] complexes; with these values exact diagonalization or quantum Monte Carlo simulations have been performed to calculate the variation of the magnetic entropy involved in the MCE. For the [Dy9Cu8] complexes, local magnetic properties of the DyIII centers have been determined by using the CASSCF+RASSI method. [ABSTRACT FROM AUTHOR]

Combining Ising‐type magnetic anisotropy with collinear magnetic interactions in single‐molecule magnets (SMMs) is a significant synthetic challenge. Herein we report a Dy[15‐MCCu‐5] (1‐Dy) SMM, where a DyIII ion is held in a central pseudo‐D5h pocket of a rigid and planar Cu5 metallacrown (MC). Linking two Dy[15‐MCCu‐5] units with a single hydroxide bridge yields the double‐decker {Dy[15‐MCCu‐5]}2 (2‐Dy) SMM where the anisotropy axes of the two DyIII ions are nearly collinear, resulting in magnetic relaxation times for 2‐Dy that are approximately 200 000 times slower at 2 K than for 1‐Dy in zero external field. Whereas 1‐Dy and the YIII‐diluted Dy@2‐Y analogue do not show remanence in magnetic hysteresis experiments, the hysteresis data for 2‐Dy remain open up to 6 K without a sudden drop at zero field. In conjunction with theoretical calculations, these results demonstrate that the axial ferromagnetic Dy–Dy coupling suppresses fast quantum tunneling of magnetization (QTM). The relaxation profiles of both complexes curiously exhibit three distinct exponential regimes, and hold the largest effective energy barriers for any reported d–f SMMs up to 625 cm−1. [ABSTRACT FROM AUTHOR]

Combining Ising‐type magnetic anisotropy with collinear magnetic interactions in single‐molecule magnets (SMMs) is a significant synthetic challenge. Herein we report a Dy[15‐MCCu‐5] (1‐Dy) SMM, where a DyIII ion is held in a central pseudo‐D5h pocket of a rigid and planar Cu5 metallacrown (MC). Linking two Dy[15‐MCCu‐5] units with a single hydroxide bridge yields the double‐decker {Dy[15‐MCCu‐5]}2 (2‐Dy) SMM where the anisotropy axes of the two DyIII ions are nearly collinear, resulting in magnetic relaxation times for 2‐Dy that are approximately 200 000 times slower at 2 K than for 1‐Dy in zero external field. Whereas 1‐Dy and the YIII‐diluted Dy@2‐Y analogue do not show remanence in magnetic hysteresis experiments, the hysteresis data for 2‐Dy remain open up to 6 K without a sudden drop at zero field. In conjunction with theoretical calculations, these results demonstrate that the axial ferromagnetic Dy–Dy coupling suppresses fast quantum tunneling of magnetization (QTM). The relaxation profiles of both complexes curiously exhibit three distinct exponential regimes, and hold the largest effective energy barriers for any reported d–f SMMs up to 625 cm−1. [ABSTRACT FROM AUTHOR]

Hyperfine interaction, isotope effect, magnetization dynamics, single-molecule magnets, super-hyperfine interaction Inside Cover: Magnetization Dynamics on Isotope-Isomorphic Holmium Single-Molecule Magnets (Angew. Keywords: hyperfine interaction; isotope effect; magnetization dynamics; single-molecule magnets; super-hyperfine interaction EN hyperfine interaction isotope effect magnetization dynamics single-molecule magnets super-hyperfine interaction 26870 26870 1 12/15/21 20211220 NES 211220 B Nuclear-spin driven relaxation b collaborating with the ligands in lanthanide single molecule magnets (SMMs) remains ambiguous. [Extracted from the article]

Keywords: hyperfine interaction; isotope effect; magnetization dynamics; single-molecule magnets; super-hyperfine interaction EN hyperfine interaction isotope effect magnetization dynamics single-molecule magnets super-hyperfine interaction 27074 27074 1 12/15/21 20211220 NES 211220 B Das Zusammenwirken b von kernspingetriebener Relaxation und den Liganden in Lanthanoid-Einzelmolekülmagneten (SMMs) ist nicht vollständig geklärt. Hyperfine interaction, isotope effect, magnetization dynamics, single-molecule magnets, super-hyperfine interaction Innentitelbild: Magnetization Dynamics on Isotope-Isomorphic Holmium Single-Molecule Magnets (Angew. [Extracted from the article]

Multifunctional material: A remarkable case of a single‐molecule magnet that demonstrates white‐light emission and ferroelectricity was observed in a butterfly‐shaped chiral DyIII4 cluster, [Dy4(μ‐bpt)4(μ3‐OH)2(μ‐OMe)2(NO3)4]⋅3 MeOH (bpt=3,5‐bis(pyridin‐2‐yl)‐1,2,4‐trizolate, see figure). [ABSTRACT FROM AUTHOR]

Single-molecule magnets (SMMs) are regarded as a class of promising materials for spintronic and ultrahigh-density storage devices. Tuning the magnetic dynamics of single-molecule magnets is a crucial challenge for chemists. Lanthanide ions are not only highly magnetically anisotropic but also highly sensitive to the changes in the coordination environments. We developed a feasible approach to understand parts of the magneto-structure correlations and propose to regulate the relaxation behaviors via rational design. A series of Co(II)-Dy(III)-Co(II) complexes were obtained using in situ synthesis; in this system of complexes, the relaxation dynamics can be greatly improved, accompanied with desolvation, via single-crystal to single-crystal transformation. The effective energy barrier can be increased from 293 cm−1 (422 K) to 416 cm−1 (600 K), and the tunneling relaxation time can be grown from 8.5 × 10−4 s to 7.4 × 10−2 s. These remarkable improvements are due to the change in the coordination environments of Dy(III) and Co(II). Ab initio calculations were performed to better understand the magnetic dynamics. [ABSTRACT FROM AUTHOR]