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Using a novel tricompartmental hydrazone ligand, a set of trinuclear Dy3 complexes has been isolated and structurally characterized. Complexes Dy3 ⋅ Cl, Dy3 ⋅ Br, and Dy3 ⋅ ClO4 feature a similar overall topology but different anions (Cl−, Br−, or ClO4−) in combination with exogenous OH− and solvent co‐ligands, which is found to translate into very different magnetic properties. Complex Dy3 ⋅ Cl shows a double relaxation process with fast quantum tunneling of the magnetization, probably related to the structural disorder of μ2‐OH− and μ2‐Cl− co‐ligands. Relaxation of the magnetization is slowed down for Dy3 ⋅ Br and Dy3 ⋅ ClO4, which do not show any structural disorder. In particular, fast quantum tunneling is suppressed in case of Dy3 ⋅ ClO4, resulting in an energy barrier of 341 K and magnetic hysteresis up to 3.5 K; this makes Dy3 ⋅ ClO4 one of the most robust air‐stable trinuclear SMMs. Magneto‐structural relationships of the three complexes are analyzed and rationalized with the help of CASSCF/RASSI‐SO calculations. [ABSTRACT FROM AUTHOR]

Photosensitive lanthanide‐based single‐molecule magnets (Ln−SMM) are very attractive for their potential applications in information storage, switching, and sensors. However, the light‐driven structural transformation in Ln−SMMs hardly changes the coordination number of the lanthanide ion. Herein, for the first time it is reported that X‐ray (λ=0.71073 Å) irradiation can break the coordination bond of Dy−OH2 in the three‐dimensional (3D) metal‐organic framework Dy2(amp2H2)3(H2O)6 ⋅ 4H2O (MDAF‐5), in which the {Dy2(OPO)2} dimers are cross‐linked by dianthracene‐phosphonate ligands. The structural transformation proceeds in a single‐crystal‐to‐single‐crystal (SC‐SC) fashion, forming the new phase Dy2(amp2H2)3(H2O)4 ⋅ 4H2O (MDAF‐5‐X). The phase transition is accompanied by a significant change in magnetic properties due to the alteration in coordination geometry of the DyIII ion from a distorted pentagonal bipyramid in MDAF‐5 to a distorted octahedron in MDAF‐5‐X. [ABSTRACT FROM AUTHOR]

Three CoII complexes, [Co2(H2L1)2](ClO4)4·4CH3OH (1), [Co2(H4L2)2](ClO4)4 (2) and [Co4(H4L2)4](ClO4)8 (3), were constructed by the self-assembly of the symmetrical dihydrazone ligands H2L1 and H4L2 with CoII ions under different synthetic conditions. The fish-bone-like complex 1 was obtained using the ligand H2L1 in methanol via the solvothermal method, while the self-assembly of H4L2 with CoII ions is solvent-dependent, producing the fish-bone-like complex 2 and [2 × 2] grid-like complex 3. Magnetic susceptibility measurements and theoretical calculations reveal that the large negative D values for the three complexes stem from their easy-axis magnetic anisotropy. Ac magnetic susceptibility measurements disclosed field-induced slow magnetic relaxation behaviors and the presence of Raman and/or direct processes of the three complexes at various applied dc fields. [ABSTRACT FROM AUTHOR]

Terminal fluoride ligands generate strong magnetic anisotropy in air-stable chiral dysprosium enantiomers supported by a bulky equatorial macrocycle, exhibiting a typical zero-field single-molecule magnet behaviour. [ABSTRACT FROM AUTHOR]