The Synthesis, Characterizatipn And Properties Of Several Homochiral Coordoination Polymers

Because of their important potential applications in the stereoselective separation of molecules, asymmetric catalysis, ferroelectric materials, non-linear optical (NLO) materials and so forth, more and more synthetic chemists and researchers committed to the research on a new class of compounds (so-called homochiral coordination polymers). In this paper, we employ optically pure chiral organic ligands as building units, to assemble with transition metals, thirteen novel compounds were obtained based on construction strategy of chiral coordination polymers. The detailed structural features were analyzed. Furthermore, characterization and the fluorescence, magnetism of these compounds have been preliminary investigated.Employing a homochiral ligand,2-(1-Hydroxy-ethyl)-3H-benzoimidazole (Hebim) which is similar to benzoimidazole in conformation, to assemble with transition metals, we synthesized successfully four chiral coordination polymers (w1-1to w1-4). Compound w1-1and w1-2are enantiomers. The isolated building unit connects four adjacent ones through hydrogen bonding interactions, giving rise to an interesting layer-like structure. Compound w1-3and w1-4are enantiomers. Compare to w1-1, the benzoimidazole of Hebim ligand in w1-3adopt μ2-bridging coordination mode, leading to a121helix. The results demonstrate that the absolute configuration of organic molecules (R or S) can control the direction of helix (P-helix or M-helix). Based on the mixed ligands strategy, we choose L-Hebim, D-Hebim ligands and oxalic acid to assemble with zinc(II), compound w1-5was obtained successfully. Owing to the coexistence of an equal amount of Hebim with the opposite handedness in the structure of w1-5, compound w1-5is a achiral compound. The fluorescent property of this compound was preliminary investigated.In order to expand the structural diversity of the homochiral coordination polymers, the coordination modes of ligand should be more diverse. We choose another homochiral ligand,2-(1-Hydroxy-ethyl)-3H-benzoimidazole-5-carboxylic acid (Hebimc), to assemble with transition metal Cd(II), four homochiral coordination polymers (w1-6to w1-9) were synthesized successfully. Compound w1-6and w1-7are enantiomers. By adding e-urea as co-solvent to the synthetic procedure, we obtained another pairs of enantiomers, compound w1-8and wl-9. All of them are built from fascinating butterfly-like chains via hydrogen bonding interactions, generated a three-dimensional supramolecular framework with irregular channels. The fluorescent property of this compound was preliminary investigated in the solid-state at room temperature. The results demonstrate that the addition of e-urea have important influence on the resulting structure. Take a comparison between compound w1-6and w1-8, the one butterfly-like chain in w1-6change to the two parallel chains in wl-8, and the direction of channel, shape and size of channel are obvious different.Alanine and lactic acid are two important small molecule acid in our daily life. A deliberate assembly of optically pure alanine and transition metal Ni (Ⅱ) leads a pair of novel enantiopure4-connected compound w1-10and w1-11.These two coordination polymers integrate the zeotype topology (sod) and homochiral nature. Magnetic data analysis shows the presence of ferromagnetic interaction between Ni2+ions in the three-dimensional homochiral framework materials. In addition, based on the consideration of successful construction strategy in Zeolitic Imidazolate Frameworks (ZIFs), we employ the mixed linkers strategy (imidazole and optically pure lactic acid) to assemble with Ni(Ⅱ), two supramolecular compounds w1-12and w1-13were obtained under solvothermal condition. These two compounds are built from fascinating chains through hydrogen bonding interaction, giving rise to a layer-like structure with a sql topology.In addition, the elemental analysis (EA), X-ray powder diffraction (PXRD), thermogravimetric analysis (TGA) and solid-state circular dichroism (CD) measurements on these compounds were performed. Based on the analysis of results in this paper, we have come to some preliminary conclusions.