Evolution from a single relaxation process to two-step relaxation processes of Dy2 single-molecule magnets via the modulations of the terminal solvent ligands

A photochromic trinuclear dysprosium(iii) single-molecule magnet with two distinct relaxation processes

Multifunctional molecules responsive to light are highly desired as components for the construction of remotely controlled nanodevices. Here we present a DyIII single molecule magnet (SMM) comprising dithienylethene (dte) photochromic bridging ligands in the form of a pyridine (py) derivative: 1,2-bis((2-methyl-5-pyridyl)thie-3-yl)perfluorocyclo-pentene (dtepy). The title trinuclear compound {[DyIII(BHT)3]3(dtepy)2}·4C5H12 (1) was synthesized by combining the low-coordinate dysprosium complexes DyIII(BHT)3 (BHT = 2,6-di-tert-butyl-4-methylphenolate) with dtepy bridging ligands in the 'open' form using n-pentane as a completely inert solvent. The trinuclear molecule comprises two different DyIII centers due to its quasi-linear geometry: a central trigonal bipyramidal DyIII ion and two peripheral ones with an approximate trigonal pyramidal geometry. Thanks to that, 1 shows two types of SMM behavior which is slightly affected by the photoisomerization of the photochromic dtepy bridges. The impact of the photoisomerization on the magnetization dynamics was studied by means of alternating current (AC) magnetic susceptibility measurements for the 'open' and 'closed' forms of the molecules. The changes between the 'open' and 'closed' isomers were further investigated by IR and UV-vis spectroscopy, suggesting the co-existence of the ligand-related photochromism and single-molecule magnet behavior in 1. However, the powder X-ray diffraction studies indicate loss of structural order in the first photoisomerization step preventing in-depth studies.

Regulating Magnetic Relaxations of Cyano-Bridged {DyIII MoV } Systems by Tuning the N-Sites in β-Diketone Ligands

Cyano-bridged 4d-4f molecular nanomagnets have re-called increasing research interests in molecular magnetism since they offer more possibilities in achieving novel nanomagnets with versatile structures and magnetic interactions. In this work, four β-diketone ligands bearing different substitution N-sites were designed and synthesized, namely 1-(2-pyridyl)-3-(3-pyridyl)-1,3-propanedione (HL1 ), 1,3-Bis (3-pyridyl)-1,3-propanedione (HL2 ), 1-(4-pyridyl)-3-(3-pyridyl)-1,3-propanedione (HL3 ), and 1,3-Bis (4-pyridyl)-1,3-propanedione (HL4 ), to tune the magnetic relaxation behaviors of cyano-bridged {DyIII MoV } systems. By reacting with DyCl3  ⋅ 6H2 O and K4 Mo(CN)8  ⋅ 2H2 O, four cyano-bridged complexes, namely {[Dy[MoV (CN)8 ](HL1 )2 (H2 O)3 ]} ⋅ 6H2 O (1), {[Dy[MoV (CN)8 ](HL2 )(H2 O)3 (CH3 OH)]}2  ⋅ 2CH3 OH ⋅ 3H2 O (2), {[Dy[MoV (CN)8 ](HL3 )(H2 O)2 (CH3 OH)] ⋅ H2 O}n (3), and {[Dy[MoV (CN)8 ](HL4 )2 (H2 O)3 ]} ⋅ 2H2 O⋅CH3 OH (4) were obtained. Structural analyses revealed that 1 and 4 are binuclear complexes, 2 has a tetragonal structure, and 3 exhibits a stair-like polymer chain structure. The DyIII ions in all complexes have eight-coordinated configurations with the coordination spheres DyO7 N1 for 1 and 4, DyO6 N2 for 2, and DyO5 N3 for 3. Magnetic measurements indicate that 1 is a zero-field single-molecule magnet (SMM) and complexes 2-4 are field-induced SMMs, with complex 4 featuring a two-step relaxation process. The magnetic characterizations and ab initio calculations revealed that changing the N-sites in the β-diketone ligands can effectively alter the structures and magnetic properties of cyano-bridged 4d-4f nanomagnets by adjusting the coordination environments of the DyIII centers.

Lanthanide Single-molecule Magnets: Synthetic Strategy, Structures, Properties and Recent Advances

Single-molecule magnets (SMMs) show wide potential applications in the field of ultrahigh-density storage materials, quantum computing, spintronics, and so on. Lanthanide (Ln) SMMs, as an important category of SMMs, open up a promising prospect due to their large magnetic moments and huge magnetic anisotropy. However, the construction of high performance for Ln SMMs remains an enormous challenge. Although remarkable advances are focused on the topic of Ln SMMs, the research on Ln SMMs with different nuclear numbers is still deficient. Therefore, this review summarizes the design strategies for the construction of Ln SMMs, as well as the metal skeleton types. Furthermore, we collect reported Ln SMMs with mononuclearity, dinuclearity, and multinuclearity (three or more Ln spin centers) and the SMM properties including energy barrier (U_eff ) and pre-exponential factor (τ₀ ) are described. Finally, Ln SMMs with low-nuclearity SMMs, especially for single-ion magnets (SIMs), are highlighted to understand the correlations between structures and magnetic behavior of the detail SMM properties are described. We expect the review can shed light on the future developments of high-performance Ln SMMs.

Photocontrollable Magnetism and Photoluminescence in a Binuclear Dysprosium Anthracene Complex

By incorporating photoreactive anthracene moieties into binuclear Dy₂O₂ motifs, we obtain two new compounds with the formulas [Dy₂(SCN)₄(L)₂(dmpma)₄] (1) and [Dy₂(SCN)₄(L)₂(dmpma)₂(CH₃CN)₂] (2), where HL is 4-methyl-2,6-dimethoxyphenol and dmpma is dimethylphosphonomethylanthracene. Compound 1 contains face-to-face π-π interacted anthracene groups that meet the Schmidt rule for a [4 + 4] photocycloaddition reaction, while stacking of the anthracene groups in compound 2 does not meet the Schmidt rule. Compound 1 undergoes a reversible single-crystal-to-single-crystal structural transformation upon UV-light irradiation and thermal annealing, forming a one-dimensional coordination polymer of [Dy₂(SCN)₄(L)₂(dmpma)₂(dmpma₂)]_n (1UV). The process is concomitant with changes in the magnetic dynamics and photoluminescent properties. The spin-reversal energy barrier is significantly increased from 1 (55.9 K) to 1UV (116 K), and the emission color is changed from bright yellow for 1 to weak blue for 1UV. This is the first binuclear lanthanide complex that exhibits synergistic photocontrollable magnetic dynamics and photoluminescence. Ab initio calculations are conducted to understand the magnetostructural relationships of compounds 1, 1UV, and 2.

A mixed-valence [CoII4CoIII2] cluster with defect disk-shaped topology

The employment of the new Schiff base ligand 2-[(4-chloro-2-hydroxybenzylideneamino)methyl]phenol (H2L) bearing O2N donors for the preparation of a novel Co6 cluster is reported. The hexanuclear cobalt complex, namely, di-μ2-acetatotetrakis{μ2-2-[(4-chloro-2-oxidobenzylideneamino)methyl]phenolato}tetra-μ3-methanolato-tetracobalt(II)dicobalt(III), [CoII4CoIII2(C14H10ClNO2)4(CH3COO)2(CH3O)4], was obtained using Co(CH3COO)2·4H2O and H2L as starting materials in MeOH under solvothermal conditions. The six metal ions are linked together by the μ3-O atoms of four deprotonated MeOH molecules, two CH3COO- units and six phenolate O atoms of four L2- ligands to form a defect disk-shaped topology. DC magnetic susceptibility investigations revealed the existence of antiferromagnetic interactions in the Co6 cluster.

Three angular Zn2Dy complexes showing the effect of remote coordination at Zn and counter ions on slow magnetic relaxation at Dy centres

Three isostructural Zn2Dy complexes displaying the effect of remote coordination at Zn and counter ions on slow magnetic relaxation at Dy centres.

Macrocycle supported dinuclear lanthanide complexes with different β-diketonate co-ligands displaying zero field single-molecule magnetic behaviour

Three different sets of isomorphous dinuclear Gd/Dy complexes with an uncommon macrocyclic ligand and β-diketonate co-ligands were reported in which Dy2 analogues are zero field SMMs.