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

Novel 3d/4f heterometallic three-dimensional (3D) networks, based on CoII/GdIII 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 CoII 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 CoII(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. © 2016 American Chemical Society.