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首页> 外文期刊>Chemistry: A European journal >Diamondoid Structure in a Metal-Organic Framework of Fe-4 Single-Molecule Magnets
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Diamondoid Structure in a Metal-Organic Framework of Fe-4 Single-Molecule Magnets

机译：Fe-4单分子磁体的金属有机骨架中的类金刚石结构。

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摘要

A 3D metal-organic framework (MOF) having single-molecule magnet (SMM) linkers was prepared in crystalline form by using a tetrairon(III) complex functionalised with two divergent pyridyl groups, namely [Fe-4(pPy)(2)(dpm)(6)] (1; H(3)pPy=2-(hydroxymethyl)-2-(pyridin-4-yl)propane-1,3-diol, Hdpm=dipivaloylmethane). Reaction of 1 with silver(I) perchlorate afforded {[Fe-4(pPy)(2)(dpm)(6)](2)Ag}ClO4 (2), which crystallises in a cubic face-centred lattice and exhibits two interlocked diamondoid networks. In 2, the SMMs act as linear ditopic synthons, and silver(I) ions as tetrahedral nodes coordinated by four pyridyl nitrogen atoms. The magnetic properties of 1 (S=5 and D approximate to-0.4cm(-1) in the ground spin state) are largely preserved in 2, which shows slow magnetic relaxation with an anisotropy barrier of U-eff/k(B)=11.46(10)K in zero field and 14.25(8)K in an applied field of 1kOe. However, crystal symmetry triggers highly noncollinear magnetic anisotropy contributions oriented at 109.47 degrees from each other along the threefold axes of AgN4 tetrahedra, a unique scenario fully confirmed by a single-crystal cantilever torque magnetometry investigation. Magnetisation curves down to 0.03K demonstrated the occurrence of a wide hysteresis loop when the magnetic field was swept along one of the four Ag-N bonds. By symmetry, the crystalline compound can then be persistently magnetised parallel or antiparallel to the four main diagonals of the unit cell, although the crystals have no overall second-order anisotropy.
机译：通过使用经两个发散吡啶基官能化的四铁（III）配合物[Fe-4（pPy）（2）（ dpm）（6）]（1; H（3）pPy = 2-（羟甲基）-2-（吡啶-4-基）丙烷-1,3-二醇，Hdpm =双新戊酰甲烷）。 1与高氯酸银（I）反应得到{[Fe-4（pPy）（2）（dpm）（6）]（2）Ag} ClO4（2），该晶体结晶成立方的面心晶格，并显示出两个互锁的菱形网络。在图2中，SMM充当线性对位合成子，银（I）离子充当由四个吡啶基氮原子配位的四面体节点。 1的磁性能（在自旋状态下S = 5，D约为-0.4cm（-1））在2中得到了很大的保留，这表明磁弛豫缓慢，各向异性势垒为U-eff / k（B）在零场中为11.46（10）K，在1kOe的应用场中为14.25（8）K。然而，晶体的对称性触发了高度非共线的磁性各向异性，它们沿着AgN4四面体的三重轴彼此指向109.47度，这种独特的情况已通过单晶悬臂扭矩磁力计研究得到了充分证实。磁化曲线低至0.03K证明，当磁场沿四个Ag-N键之一扫向时，会出现宽的磁滞回线。通过对称性，尽管晶体不具有整体的二阶各向异性，但是随后可以将结晶化合物与晶胞的四个主要对角线平行或反平行地永久磁化。

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