A three-dimensional twofold interpenetrated cobalt(II) MOF containing a flexible carboxylate-based ligand: synthesis, structure and magnetic properties.

The design and synthesis of coordination polymers (CPs) have attracted much interest due to the intriguing diversity of their architectures and topologies. The functional solid catena-poly[μ-aqua-triaqua{μ-5-[4-carboxyphenoxy)methyl]benzene-1,3-dicarboxylato}{μ-5-[4-carboxyphenoxy)methyl]benzene-1,3-dicarboxylato}dicobalt(II)], [Co(CHO)(HO)] or [Co(HL)(μ-HO)(HO)], was synthesized successfully by self-assembly of Co ions with 5-[(4-carboxyphenoxy)methyl]isophthalic acid (HL). The title compound was obtained under hydrothermal conditions and exhibits a twofold interpenetrated three-dimensional skeleton with hms 3,5-conn topology according to the cluster representation for valence-bonded metal-organic frameworks (MOFs). It has been characterized by single-crystal X-ray diffraction, IR spectroscopy, powder X-ray diffraction (PXRD), thermogravimetric analysis and susceptibility measurements. The antiferromagnetic coupling between adjacent Co centres occurs via superexchange through the ligands.