Four novel metal–organic frameworks constructed from benzimidazole flexible tetracarboxylic acid ligand, 1-(3,5-dicarboxylbenzyl)-1H-benzimidazole-5,6-dicarboxylic acid (H₄L), have been prepared by a solvothermal method in the presence of N-donor ancillary ligands (1,10-phen = 1,10-phenanthroline monohydrate, 4,4′-bibp = 1,4-di[pyridine-4-yl]benzene), namely, [Co₂(L)(H₂O)₃]_n (1), {[Cd₂(L)(1,10-phen)(H₂O)]·2H₂O}_n (2), {[Co₄(L)₂(4,4′-bibp)₂(H₂O)₇]·4H₂O}_n (3), and {[Ni₄(L)₂(4,4′-bibp)₂(H₂O)₇]·4H₂O}_n (4). Complexes 1 and 2 show a 3D supramolecular structure and crystallize in monoclinic space group P2₁/c. Complexes 3 and 4 are isomorphous and crystallize in monoclinic space group P_n, and the respective metals exhibit a similar coordination environment. The H₄L ligand behaved in different coordinated modes in Complexes 1–4, namely, μ₆-η¹:η¹:η¹:η⁰:η¹:η¹:η¹:η¹:η¹ in 1, μ₆-η¹:η¹:η¹:η¹:η¹:η¹:η²:η¹:η¹ in 2, there are two coordination modes (μ₅-η⁰:η¹:η¹:η⁰:η¹:η¹:η¹:η⁰:η¹ and μ₅-η¹:η¹:η¹:η⁰:η¹:η¹:η¹:η⁰:η¹) in 3 and 4. Furthermore, photoluminescence and magnetic properties have been studied. The results indicate that Complexes 3 and 4 show strong antiferromagnetic and ferromagnetic coupling through M–O–C–O–M interactions, respectively. In particular, Complex 2 can sensitively and selectively detect Fe³⁺ in aqueous systems, and the limit of detection (LOD) values of Fe³⁺ is ∼0.19 mM.

中文翻译：

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基于苯并咪唑柔性四羧酸的金属有机骨架：选择性发光传感 Fe3+、磁性行为、DFT 计算和 Hirshfeld 表面分析

由苯并咪唑柔性四羧酸配体 1-(3,5-二羧基苄基)-1H-苯并咪唑-5,6-二羧酸 (H ₄ L)构建的四种新型金属-有机骨架已通过溶剂热法在存在下制备N-供体辅助配体（1,10-phen = 1,10-菲咯啉一水合物，4,4'-bibp = 1,4-二[吡啶-4-基]苯），即[Co ₂ (L) (H ₂ O) ₃ ] _n (1) , {[Cd ₂ (L)(1,10-phen)(H ₂ O)]·2H ₂ O} _n (2) , {[Co ₄ (L) ₂ (4,4'-bibp) ₂ (H ₂ O) ₇ ]·4H₂ O} _n (3)和{[Ni ₄ (L) ₂ (4,4'-bibp) ₂ (H ₂ O) ₇ ]·4H ₂ O} _n (4)。配合物1和2显示出 3D 超分子结构并在单斜空间群P 2 ₁ /c 中结晶。配合物3和4在单斜空间群P _n中同晶结晶，并且各自的金属表现出相似的配位环境。H ₄L配体在配合物1-4中表现出不同的配位模式，即μ ₆ -η ¹ :η ¹ :η ¹ :η ⁰ :η ¹ :η ¹ :η ¹ :η ¹ :η ¹ in 1 , μ ₆ - η ¹ :η ¹ :η ¹ :η ¹ :η ¹ :η ¹ :η ² :η ¹ :η ¹在2 中，有两种配位模式（μ ₅ -η ⁰ :η¹ :η ¹ :η ⁰ :η ¹ :η ¹ :η ¹ :η ⁰ :η ¹和 μ ₅ -η ¹ :η ¹ :η ¹ :η ⁰ :η ¹ :η ¹ :η ¹ :η ⁰ : η ¹ ) 在3和4 中。此外，还研究了光致发光和磁性。结果表明配合物3和4分别通过 M-O-C-O-M 相互作用表现出强烈的反铁磁和铁磁耦合。特别地，配合物2能灵敏地和选择性地检测的Fe ³⁺在含水体系中，和检测限（LOD）的Fe的值³⁺是~0.19毫米。