Different interpenetrated coordination polymers based on flexible dicarboxylate ligands: topological diversity and magnetism

Abstract

Through tuning the nature of the secondary ligands, the ligand-to-metal molar ratio and the metal ions, four coordination polymers, namely {[Ni₂(bcp)₂(4,4′-bipy)₂(H₂O)₄]·3.5H₂O}_n (1), {[Co₂(bcp)₂(bpt)₂]·2.29H₂O·bpt}_n (2), [Co₂(bcp)₂(bib)]_n (3) and {[Co(bcp)(2,2′-bipy)(H₂O)]·H₂O}_n (4), have been synthesized and characterized. The structural feature of 1 shows a 3D three-fold parallel interpenetrating framework with CdSO₄ topology. 2 exhibits a 2D→3D interpenetrating motif with pseudorotaxane. Compound 3 shows two identical 2D layers with 2²·4⁸·6⁵ topology that are interpenetrated in a parallel fashion, resulting in a twofold interpenetrating motif containing polyrotaxane and polycatenane character. However, a 1D zipper-like double-stranded chain is observed in polymer 4. This work evidently indicates that the effect of the secondary ligands and geometric preferences of the metal centers are critical in the construction of the resulting networks. In addition, the magnetic properties of compounds 2 and 3 were also discussed.