The field-induced blockage of magnetization behavior was first observed in an Yb(III)-based molecule with a trigonally distorted octahedral coordination environment. Ab initio calculations and micro-SQUID measurements were performed to demonstrate the exhibition of easy-plane anisotropy, suggesting the investigated complex is the first pure lanthanide field-induced single-ion magnet (field-induced SIM) of this type. Furthermore, we found the relaxation time obeys a power law instead of an exponential law, indicating that the relaxation process should be involved a direct process rather than an Orbach process.

Two unprecedented 3d-4f hexagonal metallo-rings {Ln(24)Cu(36)} (Ln = Dy and Gd) with a diagonal dimension of about 4.6 nm were facilely synthesized by self-assembly of Cu(II), Ln(III) nitrates and benzoate in the presence of triethylamine. Magnetic studies show slow relaxation behaviour for the dysprosium analogue and a large magnetocaloric effect (MCE) for the gadolinium analogue.

Two ferromagnetic μ-oxo(acetate)-bridged gadolinium complexes [Gd(2)(OAc)(2)(Ph(2)acac)(4)(MeOH)(2)] (1) and [Gd(4)(OAc)(4)(acac)(8)(H(2)O)(4)] (2) and two polymeric Gd(III) chains [Gd(OAc)(3)(MeOH)](n) (3) and [Gd(OAc)(3)(H(2)O)(0.5)](n) (4) (Ph(2)acacH = dibenzoylmethane; acacH = acetylacetone) are reported. The magnetic studies reveal that the tiny difference in the Gd-O-Gd angles (Gd···Gd distances) in these complexes cause different magnetic coupling. There exist ferromagnetic interactions in 1-3 due to the presence of the larger Gd-O-Gd angles (Gd···Gd distances), and antiferromagnetic interaction in 4 when the Gd-O-Gd angle is smaller. Four gadolinium acetate derivatives display large magnetocaloric effect (MCE). The higher magnetic density or the lower M(W)/N(Gd) ratio they have, the larger MCE they display. Complex 4 has the highest magnetic density and exhibits the largest MCE (47.7 J K(-1) kg(-1)). In addition, complex 3 has wider temperature and/or field scope of application in refrigeration due to the dominant ferromagnetic coupling. Moreover, the statistical thermodynamics on entropy was successfully applied to simulate the MCE values. The results are quite in agreement with those obtained from experimental data.

The comprehensive study reported herein provides compelling evidence that anion templates are the main driving force in the formation of two novel nanoscale lanthanide hydroxide clusters, {Gd38(ClO4)6} (1) and {Gd48Cl2(NO3)} (2), characterized by single-crystal X-ray crystallography, infrared spectroscopy, and magnetic measurements. {Gd38(ClO4)6}, encapsulating six ClO4(-) ions, features a cage core composed of twelve vertex-sharing {Gd4} tetrahedrons and one Gd⋅⋅⋅Gd pillar. When Cl(-) and NO3(-) were incorporated in the reaction instead of ClO4(-), {Gd48Cl2(NO3)} is obtained with a barrel shape constituted by twelve vertex-sharing {Gd4} tetrahedrons and six {Gd5} pyramids. What is more, the cage-like {Gd38} can be dynamically converted into the barrel-shaped {Gd48} upon Cl(-) and NO3(-) stimulus. To our knowledge, it is the first time that the linear M-O-M' fashion and the unique μ8-ClO4(-) mode have been crystallized in pure lanthanide complex, and complex 2 represents the largest gadolinium cluster. Both of the complexes display large magnetocaloric effect in units of J kg(-1) K(-1) and mJ cm(-3) K(-1) on account of the weak antiferromagnetic exchange, the high N(Gd)/M(W) ratio (magnetic density), and the relatively compact crystal lattice (mass density).

A toroidal magnetic moment in the absence of a conventional total magnetic moment was first observed in a novel tetranuclear dysprosium cluster with nonmagnetic ground state. The toroidal state is quite robust with respect to variations of the exchange parameters. W ith consideration of the potential applications in new storage and information-processing technologies, the researches on single-molecule magnets (SMMs) are recognized as an important area for molecular magnetism.1 Thanks to the large intrinsic magnetic anisotropy of lanthanide (Ln) ions, remarkable efforts have been focused on the pure 4f SMMs and single-ion magnets (SIMs) in recent years.2−7 For the SMMs incorporating multiple Ln ions, though weak magnetic interactions, the very large anisotropy favors the orientation of magnetization along an easy axis. The anisotropic barrier of an SMM is derived from a combination of both the single ionic anisotropy and exchange interaction in these complexes, 3b,6b while the zero-field splitting on Ln sites is much larger than the exchange splitting. Dy III is one of the most attractive heavy rareearth ions showing the following unique features: first, Dy III ions will always maintain a high-magnitude ±m J quantum number and a doubly degenerate ground state (ground Kramers' doublet) because of its odd electron count; second, a relatively large separation between the bistable ground state and the first excited state relaxes the spin much slower. Since the first case was revealed in the famous {Dy 3 } triangle, detection of the other lanthanide molecular species with toroidal magnetic moments has become an interesting topic of lanthanide-based SMM chemistry.2,3 The noncollinearity of the single-ion easy axes of magnetization of the Dy III ions leads to a nonmagnetic ground state, giving rise to the toroidal magnetic moments on the Dy III sites and also the slow relaxation behavior.6 Herein we report a novel {Dy 4 } SMM, [Dy 4 (μ 3 -OH) 2 (μ-OH) 2 (2,2-bpt) 4 (NO 3 ) 4 (EtOH) 2 ] [1; 2,2-bptH = 3,5-bis(pyridin-2-yl)-1,2,4-triazole], which is the first case of the {Dy 4 } family with a toroidal magnetic moment in the ground state.Colorless brick crystals of 1 were obtained from solvothermal reactions of Dy(NO 3 ) 3 ·5H 2 O with 2,2-bptH in the presence of triethylamine. Notably, the bpt − ligand with two bidentate chelating sites is, for the first time, used to produce Ln