From mononuclear to two-dimensional cobalt(ii) complexes based on a mixed benzimidazole-dicarboxylate strategy: syntheses, structures, and magnetic properties
From mononuclear to two-dimensional cobalt(ii) complexes based on a mixed benzimidazole-dicarboxylate strategy: syntheses, structures, and magnetic properties
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基于混合苯并咪唑-二羧酸酯策略的从单核到二维钴(ii)配合物：合成、结构和磁性
DOI：
10.1039/c8ce01931b
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发表时间：
2019-01-28
期刊：
影响因子：
3.1
通讯作者：
Huang, Xing-Cai
中科院分区：
文献类型：
--
作者：
Kong, Jiao-Jiao;Shao, Dong;Huang, Xing-Cai
以苯并咪唑衍生物和三种不同的二羧酸为基础，水热合成了三种新的钴（II）配合物，即[Co(1,3- bdc)(2)(MBIm)(2)](1), [Co(SCA)(2)(MBIm)(2)](n)(2)和{[Co(1,4- bdc)(3)(MBIm)(2)]中心点2DMF}(n) (3), （1,3- bdc =苯-1,3-二羧酸，SCA =琥珀酸，1,4- bdc =苯-1,4-二羧酸，MBIm = 5,6-二甲基苯并咪唑）。单晶x射线衍射结果表明，1是具有扭曲四面体几何结构的单核中性配合物，2是具有T-d对称排列的Co2+中心的一维（1D）链配位聚合物，3是由线性三聚体Co-3单元构成的具有混合T-d- o- h-T-d几何结构的几何挫败的二维（2D）框架。磁学研究表明，1和2中的Co2+离子具有易轴磁各向异性，并且在极低温度下，1和2的有效能垒分别为U-eff = 51.8 K和11.3 K，观察到场致慢磁弛豫行为。值得注意的是，综合体2是具有四坐标金属中心的1D SIM的第一个例子。对于3，即使在1.8 K下也没有建立远程磁有序，这主要归因于自旋受挫。这些研究表明，混合苯并咪唑-二羧酸盐策略是设计和构建具有不同磁性能和结构多样性的功能分子磁性材料的有效策略。
Based on a benzimidazole derivative and three different dicarboxylates, three new cobalt(II) complexes, namely [Co(1,3-BDC)(2)(MBIm)(2)] (1), [Co(SCA)(2)(MBIm)(2)](n) (2), and {[Co(1,4-BDC)(3)(MBIm)(2)]center dot 2DMF}(n) (3), (1,3-BDC = benzene-1,3-dicarboxylic acid, SCA = succinic acid, 1,4-BDC = benzene-1,4-dicarboxylic acid, MBIm = 5,6-dimethylbenzimidazole), have been hydrothermally synthesized and characterized structurally and magnetically. Single crystal X-ray diffraction revealed that 1 is a mononuclear neutral complex possessing a distorted tetrahedral geometry, 2 is a one-dimensional (1D) chain coordination polymer with the Co2+ centers arranged in T-d symmetry, and 3 is a geometrically frustrated two-dimensional (2D) framework constructed from linear trimeric Co-3 units with a mixed T-d-O-h-T-d geometry. Magnetic investigation revealed the easy-axis magnetic anisotropy of the Co2+ ions in 1 and 2, and field-induced slow magnetic relaxation behaviors were observed at very low temperatures with an effective energy barrier of U-eff = 51.8 K and 11.3 K for 1 and 2, respectively. Notably, complex 2 is the first example of a 1D SIM featuring fourcoordinate metal centers. For 3, no long-range magnetic ordering was established even at 1.8 K, which is mainly attributed to spin frustration. These studies illustrate that a mixed benzimidazole-dicarboxylate strategy is an effective strategy for the design and construction of functional molecular magnetic materials with distinct magnetic properties and structural diversity.