Syntheses, Structures and Magnetic Properties of Cobalt(II) Coordination Polymers Based on Semi-Rigid Polycarboxylic Acid Ligand

Herein, two new Co(II) CPs, {[Co(H3L)(bpa)]center dot H2O}(n) (1) and {[Co-2(H3L)(2)(phen)(2)(H2O)(2)]center dot 3H(2)O}(n) (2) were hydrothermally obtained based on O-donor semi-rigid polycarboxylic acid ligand H5L (5,5'-((5-carboxy-1,3-phenylene)bis(oxy))diisophthalic acid) and N-donor coligands, such as bpa (1,2-bis(4-pyridyl)ethane), phen (1,10-phenanthroline hydrate). Both of them were studied by single crystal X-ray diffraction analysis, thermogravimetric analysis, infrared spectra, powder X-ray diffraction and variable-temperature magnetic susceptibilities. CP 1 features a one-dimensional chain, further stacked to a two-dimensional layer and three-dimensional structure through pi center dot center dot center dot pi stacking interactions and hydrogen bonds. CP 2 displays two-dimensional layers, which further extended into three-dimensional frameworks through C-H center dot center dot center dot pi interactions and hydrogen bonds. In addition, variable-temperature magnetic susceptibility data were investigated, indicating that the CPs 1 and 2 exhibited antiferromagnetic interactions.