Wei-Quan Lin

Switching the anisotropy barrier of a single-ion magnet by symmetry change from quasi-D5h to quasi-Oh

A reversible single-crystal-to-single-crystal transformation is used to dramatically change the relaxation behavior of a single-ion magnet. The coordination geometry of the DyIII site of a [Zn–Dy–Zn] complex changes from pentagonal–bipyramid (quasi-D5h) to octahedron (quasi-Oh), inducing an energy barrier change from 305 cm−1 (439 K) to a negligible value, respectively. Ab initio calculations reveal that the ideal D5h–DyIII is of perfect axiality with a substantial energy barrier in accordance with the experimental result.

CuIIGdIII Cryogenic Magnetic Refrigerants and Cu8Dy9 Single‐Molecule Magnet Generated by In Situ Reactions of Picolinaldehyde and Acetylpyridine: Experimental and Theoretical Study

A series of heterometallic [Ln(III)(x)Cu(II)(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(x)Cu(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 Dy(III) centers have been determined by using the CASSCF+RASSI method.

Multifunctional DyIII4 Cluster Exhibiting White‐Emitting, Ferroelectric and Single‐Molecule Magnet Behavior

Significant attention has been paid to the investigation of single-molecule magnets (SMMs) since the first Mn12 cluster with such properties was reported in 1993. During the past two decades, SMMs have experienced three generations of development, from the initially studied 3d metal clusters to mixed 3d–4f clusters, and now to 4f-based species. The drastically increased interest in 4f-based SMMs is because of their significant magnetic anisotropy originating from large unquenched orbital angular momenta. On the other hand, lanthanide-based complexes are also the subject of intense investigation as luminescent materials as a result of their large Stokes shifts and the very narrow emission bands observed. Recently, some pioneering studies have combined both properties to improve the performance and enlarge the application scope. A few Dy and Yb complexes have recently been shown to be luminescent SMMs. To further miniaturize molecule-based devices, multifunctional SMMs combining versatile physical properties, such as ferroelectricity, dielectricity, and chirality may be useful. The large inherent anisotropy of the Dy ion has made it an ideal candidate for the manufacture of a series of SMMs. Additionally, Dy can function as a yellow-light emitter. The combination of a yellow-emitting Dy unit and a blueemitting organic chromophore will result in dual-color Y/B emission from a single molecule that can be used to generate white-light emission. At the same time, the blue-lightemitting ligand (Figure S1 in the Supporting Information), 3,5-bis(pyridin-2-yl)-1,2,4-trizole (Hbpt), exhibits potential chirality because of the presence of torsion angles between aromatic rings, which may lead to a chiral structure from the Dy–Hbpt reaction system. Following the above-designed strategy, solvothermal reactions of DyACHTUNGTRENNUNG(NO3)3, Hbpt, and NEt3 have been carried out in different solvents. Luckily, colorless block-shaped crystals of chiral complex 1 (D-1 and L-1 are the two enantiomers), [Dy4ACHTUNGTRENNUNG(m-bpt)4ACHTUNGTRENNUNG(m3-OH)2ACHTUNGTRENNUNG(m-OMe)2ACHTUNGTRENNUNG(NO3)4]·3 MeOH, were obtained from a solution in methanol at 120 8C, which are very different from those obtained from solutions in ethanol. The phase purity of bulk 1 was confirmed by comparison of its powder diffraction pattern with that calculated from the single crystal study (Figure S2 in the Supporting Information). Single-crystal X-ray structure analysis reveals that complex 1 crystallizes in the monoclinic space group P21. The molecular structures are depicted in Figure 1 and show that all Dy ions possess distorted square-antiprismatic geometries with N4O4 coordination environments (Figure S3 in the

Symmetry-Related [LnIII6MnIII12] Clusters toward Single-Molecule Magnets and Cryogenic Magnetic Refrigerants

A family of high-nuclearity [Ln(III)(6)Mn(III)(12)] (Ln = Gd, Tb) nanomagnets has been synthesized, of which two are in D(2) molecular symmetry and the other two are in C(1) symmetry. X-ray crystallography shows that each of them contains a similar {Mn(III)(8)O(13)} unit, four marginal Mn(III) ions, and two linear {Ln(III)(3)} units with parallel or perpendicular orientation for high- and low-symmetry cores, respectively. For [Gd(III)(6)Mn(III)(12)], the distinct spins of the {Mn(III)(8)O(13)} unit lead to different spin ground states (S(T) = 23 for the high-symmetry one and S(T) = 16 for the low-symmetry one), and significant magnetocaloric effects are observed in a wide temperature range [full width at half-maximum (FWHM) of -ΔS(m) > 18 K] that can maximizes the refrigerant capacity, which may be attributed to the ferromagnetic interactions. By replacement of isotropic Gd(III) with anisotropic Tb(III), they behave as single-molecule magnets, with the high-symmetry one possessing a larger effective barrier (36.6 K) than the low-symmetry one (19.6 K).

A novel nanosized {Co16} metallamacrocycle incorporating four linear {Co4} subunits bridged by polytriazolate ligands.

The solvothermal reactions of Co(II) salts and three rigid polytriazolate ligands lead to a linear Co(4) cluster, [Co(4)(3,5-bptp)(2)(OMe)(2)(NO(3))(2)(MeOH)(2)]·1.5H(2)O·MeCN (1), and a square-shaped {Co(16)} metallamacrocycle, [Co(16)(1,3-bptb)(4)(3,5-bptpt)(4)(OMe)(12)(H(2)O)(2)]·25H(2)O (2), which comprises four linear {Co(4)} subunits similar to those of 1 bridged by the longer 3,5-bptpt(3-) ligands into a nanoscale molecular square.

Lanthanide oxide clusters: from tetrahedral [Dy4(μ4-O)](10+) to supertetrahedral [Ln20(μ4-O)11]38+ (Ln = Tb, Dy, Ho, Er).

Supertetrahedral clusters: A family of lanthanide oxide supertetrahedral T3{Ln20} clusters (Ln = Tb, Dy, Ho, Er; see figure) were obtained from the solvothermal reaction of lanthanide(III) salts with polytriazolate ligands that could be methylated and oxidized in situ.

Unprecedented ferromagnetic dipolar interaction in a dinuclear holmium(III) complex: a combined experimental and theoretical study

A ferromagnetic intramolecular dipolar interaction is observed and verified by both experimental studies and ab initio calculations on a dinuclear holmium(III) complex [Ho2(H2cht)2Cl4(H2O)(MeCN)]·MeCN.