By utilizing two similar tetrapyridine ligands, tetrakis(4-pyridyloxymethylene)methane (L1) and tetrakis(3-pyridyloxymethylene)methane (L2), four distinct metal–organic frameworks (MOFs), with formulas [Co(NCS)₂(L1)]·CH₃OH (HUST-13, HUST = Huazhong University of Science and Technology), [Co(NCS)₂(L1)] (HUST-14), [Co(NCS)₂(L2)]·2(CH₃OH) (HUST-15), and [Co(NCS)₂(L2)] (HUST-16), have been successfully constructed by adjusting the reaction solvents. After structural characterization, four Co-MOFs exhibit versatile topological structures and a single cobalt node with octahedron configuration. The synergistic effect between the steric configuration of ligands and the structural director of solvent molecules must be responsible for the generation of the distinct topological structures. Magnetic studies reveal the presentation of different slow magnetic relaxation phenomena in these Co-MOFs, which should be ascribed to the different orientations of the magnetic anisotropic axis of cobalt ions in the corresponding frameworks. The related results adequately illustrate the feasibility of the construction strategy for single ion magnet (SIM) MOFs and inspire other research strategies for the development of molecular magnets.

中文翻译：

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调节钴金属-有机框架的结构以微调慢磁弛豫行为

通过利用两个相似的四吡啶配体，四（4-吡啶基氧基亚甲基）甲烷（L1）和四（3-吡啶基氧基亚甲基）甲烷（L2），四种不同的金属有机骨架（MOF），具有化学式 [Co(NCS) ₂ (L1) ]·CH ₃ OH (HUST-13, HUST = 华中科技大学), [Co(NCS) ₂ (L1)] (HUST-14), [Co(NCS) ₂ (L2)]·2(CH ₃ OH) (HUST-15) 和 [Co(NCS) ₂(L2)] (HUST-16)，已通过调整反应溶剂成功构建。在结构表征之后，四个 Co-MOF 表现出通用的拓扑结构和具有八面体配置的单个钴节点。配体的空间构型与溶剂分子的结构导向器之间的协同效应必须负责产生不同的拓扑结构。磁性研究揭示了这些 Co-MOF 中存在不同的慢磁弛豫现象，这应该归因于相应框架中钴离子的磁各向异性轴的不同取向。