Synthesis and Structure of a Novel Supramolecular Compound [Co(2,2′-bipy) (H2O)4] [trans-1, 4-chdc] and Separation of Isomer of 1, 4-Cyclohexanedicarboxylic Acid1

A supramolecular compound, [Co(2,2′-bipy) (H2O)4] [trans-1, 4-chdc] (compound 1) (2,2′-bipy = 2,2′-bipyridine, 1,4-chdcH2 = 1, 4-cyclohexanedicarboxylic acid), was synthesized and characterized by single-crystal X-ray diffraction analysis, IR spectrometry, TG analysis, and elemental analyses. Single-crystal X-ray diffraction analysis revealed that [Co(2,2′-bipy) (H2O)4]2+ units and adjacent 1, 4-chdc2− formed a single layer by hydrogen bonding and electrostatic interactions along the ac-plane, and two symmetry-related single layers interacted with each other by hydrogen bonding, resulting in a double layer, which further formed a 3-D structure by π-π stacking. The most attractive structural feature of compound 1 is that 1, 4-choc2− possesses only trans-conformation although there are both cis- and trans-conformations in the raw material.