Syntheses, Crystal Structures, and Properties of New Coordination Polymers Incorporating 3,3-Dimethylcyclopropane-1,2-dicarboxylate and 4,4′-Bipyridine Ligands

Three coordination polymers, [Zn(dcd)(bipy)(0.5)](n) (1-Zn), [Co(dcd)(bipy)(0.5)](n) (2-Co), and [Cu(bipy)(2)(H2O)(1.5)center dot(Hdcd)(2)center dot(H2O)(3.5)](4n) (3-Cu) (dcd = 3,3-dimethylcyclopropane-1,2-dicarboxylate dianion, bipy = 4,4 '-bipyridine) were prepared by hydrothermal reactions. They were characterized by elemental analyses, FT-IR spectra, single-crystal X-ray diffraction, X-ray powder diffraction, photoluminescent and magnetic techniques. Single-crystal X-ray diffraction studies reveal that 1-Zn and 2-Co are isostructural and characteristic for 1D metal-organic chains constructed by dcd bridging. Both of them contain mononuclear metal ions simultaneously bridged with short carboxylate bridges and long bipy spacers, resulting in a 2D grid framework. 3-Cu is a neutral sandwiched ionic solid consisting of the positively charged trinuclear copper-based coordination polymer and discrete Hdcd anions. 3-Cu features two kinds of independent layers, which are further packed into a 3D supramolecular structure by strong hydrogen bonding interactions. Furthermore, 1-Zn displays fluorescent emission assigned to the intra-ligand fluorescence emission. Both 2-Co and 3-Cu exhibit antiferromagnetic coupling interactions. The carboxylate bridges existed in mu(3)-dcd ligands can effectively mediate the antiferromagnetic interaction between Co-II ions in 2-Co, whereas strong hydrogen bonds are effective magnetic exchange pathways in 3-Cu.