Novel 3d/4f Metal Organic Networks Containing CoII Chiral Chains

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• 作者：Carlos Cruz ; Evgenia Spodine ; Andrés Vega ; Diego Venegas-Yazigi ; Verónica Paredes-García
• 刊名：Crystal Growth & Design
• 出版年：2016
• 出版时间：April 6, 2016
• 年：2016
• 卷：16
• 期：4
• 页码：2173-2182
• 全文大小：640K
• ISSN：1528-7505

文摘

Novel 3d/4f heterometallic three-dimensional (3D) networks, based on Co^II/Gd^III cations and imidazole-4,5-dicarboxylic acid (H₃IDC) and oxalate which are acting as main and auxiliary ligand, respectively, were hydro-/solvothermally synthesized using different synthetic strategies. While [Gd(H₂O)(C₂O₄)Co(IDC)(H₂O)_1.26(CH₃CH₂OH)_0.74]·1.75H₂O (1) was obtained in a one-pot synthesis, [Gd(H₂O)Co(HIDC)(C₂O₄)_1.5]·2.65H₂O (2) was obtained using a Co^II complex precursor. Both compounds crystallize in a monoclinic system within the centrosymmetric space group C2/c. These structures are characterized by presenting an intricate covalent 3D network. A notable aspect is the fact that in these centrosymmetric structures Co^II(IDC/HIDC) moieties are disposed along the networks forming alternate chiral chains, Λ and Δ. From a magnetic point of view, both (1) and (2) have antiferromagnetic interactions, but in (1) a magnetic order appears below 8 K, probably as product of uncompensated antiferromagnetic interactions produced by centers with different spin values. This ferrimagnetic behavior was verified by the hysteresis curve at 1.8 K, and by well-defined maxima, both in the in-phase and out-of-phase ac susceptibilities curves. Remarkably, this work reports efficient synthetic methods through which it is possible to generate 3d/4f networks, these being scarce in the literature.