Synthesis, crystal structure, and characterization of two three-fold interpenetrating Co(II) coordination polymers based on 1,4-benzenedicarboxylic acid and length modulated bisimidazole ligands

<div><p>Two Co(II) coordination polymers, {[Co(bdc)(bib)(H₂O)]·H₂O}_n (<b>1</b>) and {[Co(bdc)(bibp)]}_n (<b>2</b>), where H₂bdc = 1,4-benzenedicarboxylic acid, bib = 1,4-bis(1-imidazolyl)benzene, and bibp = 4,4′-bis(imidazolyl)biphenyl, have been synthesized by solvothermal methods and characterized by IR spectra, element analyses, thermal analysis, powder X-ray diffraction, and single crystal X-ray diffraction. Complex <b>1</b> exhibits a 3-D pillared-layer framework, the ligands of bib and bdc link Co ions to generate a 2-D layer structure, which is further pillared by the bib, giving the final 3-D pillared-layer networks. The void in <b>1</b> induces the three-fold interpenetrating structure. Complex <b>2</b> features three-fold interpenetrating 3-D architecture, bdc and bibp both adopt a bidentate bridging coordination to link Co ions to afford right- and left-handed helical chains; these helices fuse together and form the 3-D framework.</p></div