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An unprecedented two-step spin-crossover behavior with the sequence of γHS=1↔ γHS=3/4↔ γHS=1/4 was observed in two-dimensional Hofmann type coordination polymer [Fe(isoq)2{Ag(CN)2}2] (isoq=isoquinoline), which resulted from three crystallographically inequivalent FeII sites with distinct transition temperatures. [ABSTRACT FROM AUTHOR]

The pentagonal bipyramidal single-ion magnets (SIMs) are among the most attractive prototypes of high-performance single-molecule magnets (SMMs). Here, a fluorescence-active phosphine oxide ligand CyPh2PO (=cyclohexyl(diphenyl)phosphine oxide) was introduced into [Dy(CyPh2PO)2(H2O)5]Br3⋅2 (CyPh2PO)⋅EtOH⋅3 H2O, and combined dynamic magnetic measurement, optical characterization, ab initio calculation, and magneto-optical correlation of this high-performance pseudo- D5 h DyIII SIM with large Ueff (508(2) K) and high magnetic hysteresis temperature (19 K) were performed. This work provides a deeper insight into the rational design of promising molecular magnets. [ABSTRACT FROM AUTHOR]

A series of heterometallic 3d-Gd3+ complexes based on a lanthanide metalloligand, [M(H2O)6][Gd(oda)3] ⋅3 H2O [M=Cr3+ ( 1-Cr)] (H2oda=2,2′-oxydiacetic acid), [M(H2O)6][MGd(oda)3]2 ⋅3 H2O [M=Mn2+ ( 2-Mn), Fe2+ ( 2-Fe) and Co2+ ( 2-Co)], and [M3Gd2(oda)6(H2O)6] ⋅12 H2O [M=Ni2+ ( 3-Ni), Cu2+ ( 3-Cu), and Zn2+ ( 3-Zn)], are reported. Magnetic and heat-capacity studies revealed a significant impact on the magnetocaloric effect depending on the anisotropy of the 3d transition metal ions, as confirmed by comparison of the observed maximum values of −Δ Sm between complexes 2-Co and 1-Cr. In these two complexes, the 3d metal ions have the same spin ( S=3/2 for Co2+ and Cr3+ ions), and the theoretical calculation suggested a larger −Δ Sm value for 2-Co (47.8 J K−1 kg−1) than 1-Cr (37.5 J K−1 kg−1); however, the significant anisotropy of Co2+ ions in 2-Co, which can result in smaller effective spins, gives a smaller value of −Δ Sm for 2-Co (32.2 J K−1 kg−1) than for 1-Cr (35.4 J K−1 kg−1) at Δ H=9 T. [ABSTRACT FROM AUTHOR]

Based on the analogous kagomé [Co3(imda)2] layers (imda=imidazole-4,5-dicarboxylate), a family of pillar-layered frameworks with the formula of [Co3(imda)2(L)3] ⋅(L) n ⋅ xH2O ( 1: L=pyrazine, n=0, x=8; 2: L=4,4′-bipyridine, n=1, x=8; 3: L=1,4-di(pyridin-4-yl)benzene, n=1, x=13; 4: L=4,4′-di(pyridin-4-yl)-1,1′-biphenyl, n=1, x=14) have been successfully synthesized by a hydrothermal/solvothermal method. Single-crystal structural analysis shows a significant increase in the interlayer distances synchronized with the extension of the pillar ligands, namely, 7.092(3) ( 1), 10.921(6) ( 2), 14.780(5) ( 3), and 19.165(4) Å ( 4). Despite the wrinkled kagomé layers in complexes 2- 4, comprehensive magnetic characterizations revealed weakening of interlayer magnetic interactions and an increase in the degree of frustration as the pillar ligand becomes longer from 1 to 4; this leads to characteristic magnetic ground states. For compound 4, which has the longest interlayer distance, the interlayer interaction is so weak that the magnetic properties observed within the range of temperature measured would correspond to the frustrated layer. [ABSTRACT FROM AUTHOR]

A Hoffman-like coordination polymer with appreciable porosity and uncoordinated pyridyl groups, namely, [Fe(2,5-bpp){Au(CN)2}2] ⋅ x Solv (2,5-bpp=2,5-bis(pyrid-4-yl)pyridine; Solv=solvent), was synthesised and characterised. A series of fascinating spin-crossover behaviours with abrupt, stepwise and hysteretic features were obtained by exchange with a range of protic solvents (ethanol, n-propanol, isopropyl alcohol, sec-butanol and isobutanol). Guest-host hydrogen-bonding interactions involving the H-accepting site of the framework are primarily responsible for the pronounced cooperativity of these spin-crossover behaviours. Meanwhile, the tunable critical temperatures over a range of about 130 K are presumably attributable to a certain degree of competition between internal pressure and local electronic influences of solvents. [ABSTRACT FROM AUTHOR]

The transformation of MnII glycolates (glc) between the three-dimensional coordination polymer [Mn(glc)2] n ( 1) and discrete mononuclear phase [Mn(glc)2(H2O)2] ( 2) can be reversibly switched by water molecules, which dramatically change the magnetocaloric effect (MCE) of MnII glycolates from the maximum of 6.9 J kg−1 K−1 in 1 to 60.3 J kg−1 K−1 in 2. This case example reveals that the effect of magnetic coupling on MCE plays a dominant role over that of other factors such as magnetic density for 3d-type magnetic refrigerants. [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]

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 NGd/ MW ratio (magnetic density), and the relatively compact crystal lattice (mass density). [ABSTRACT FROM AUTHOR]

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]

The pentagonal bipyramidal single‐ion magnets (SIMs) are among the most attractive prototypes of high performance single‐molecule magnets (SMMs). A fluorescence‐active phosphine oxide ligand is introduced, and by combining dynamic magnetic measurements, optical characterization, and ab initio calculations, the magneto‐optical correlation of a high‐performance pseudo‐D5h DyIII SIM with large Ueff = 508(2) K and high magnetic hysteresis temperature of 19 K, [Dy(CyPh2PO)2(H2O)5]Br3⋅2 (CyPh2PO)⋅EtOH⋅3 H2O (CyPh2PO=cyclohexyl(diphenyl)phosphine oxide) was studied. This work provides a deeper insight into the rational design of promising molecular magnets. More information can be found in the Full Paper by M.‐L. Tong, J.‐L. Liu, et al. on page 5708 ff. [ABSTRACT FROM AUTHOR]