Characterization And Characterization Of Complex Materials With Carboxylic Acid Ligands With C2 Chiral Axis

In recent years, studies have shown that coordination polymers, especially for Metal-Organic Framworks (MOFs), as a kind of new functional crystalline hybrid materials, have commanded increasing attention in virtue of their potential application in many aspects. Chiral complexes, especially chiral porous MOFs, have received much attention because of their potential application in asymmetric catalysis, nonlinear optics, molecular recognition and chiral resolution and so on. Through racemic chiral organic ligands’spontaneous resolution to obtain the two pure chiral complexes which are enantiomers, is the earliest discovered chiral resolution approach. Even if this approach is simple and economy, up to now, there was only 5-10% of raceme can eventually spontaneous resolution, much less can the racemic ligand successfully spontaneous resolution, and it is not very clear explanation to the internal mechanism of the splitting method, so it is still in the initial to that the accumulation of research foundation, or deeper level related research theory and practical application, and all of these needed to be deeply and widely research.In the paper, we choose two C2 axial chirality ligands, 2,2’-bipyridine-3,3’-dicarboxylate-1,1’-dioxide (H2bdd) and 2,4,8,10-tetraoxaspiro[5.5] undecane-3,9-dicarboxylic acid (H2tud), to further carry on this study. Sixteen coordination polymers had been obtained by employing these ligands and transition metal, and studied on the characterization and properties in detail, the main research results are listed as follows:(1)Nine complexes 1-9 are obtained by means of using H1tud ligand, various transition metals (ZnⅡ/MnⅡ/CuⅡ/PbⅡ) and different soft ligands, 1,2-bis(4-pyridyl)ethane and 1,3-bis(4-pyridyl)propane, or rigid ligand,2,5-bis(4-pyridyl)-1,3,4-thiadiazole and 2,6-bis(1H-1,2,4-triazol-1-yl)pyridine, and are made systematic characterization and properties.(2) Seven complexes 10-16 are self-assembly acquired via H2bdd ligand, pyridinone derivatives (1,2-bis(4-pyridyl)ethane, 1,3-bis(4-pyridyl)propane,2,2’-bipyridine and 1,10-fenanthrolin) and transition metal (CuⅡ/CdⅡ), and have been characterized and made properties.(3)The self-split products of 14 and 15, and achiral 16 are received by the self-assembly process of soft ligand bpp, CuⅡ and H2bdd. Research exhibits that in this reaction system, the racemic ligand H2bdd first spontaneous resolution constructs chiral MOFs 14 and 15 in the crystallization process, and then occurs single crystal to single crystal transformation from 14 to 15, getting the final achiral 16.16 can also be obtained by solvent thermal. Calculations further evidence that the rationality of transformation between spontaneous resolution MOFs and achiral complexes. In addition, structure analysis show that the chirality of the axial chiral ligand in 14 and 15 transfer in the structure, and it is rare to the existence of chiral helical channel in the 3D structure. The adsorption performance study shows that it shows a selective gas adsorption for CO2.(4) Complex 9 is constructed by soft bpa ligand, CuⅡ and H2bdd. There exists two kinds of coordination geometry of cental Cu(II):six-coordinated octahedral geometry and five-coordinated tetragonal pyramid. And with the presence of 2D pore structure, porosity is 28.8%. The 9 exhibits step and selective gas adsorption for CO2, and adsorption curve shows a "door effect".(5) When introducing soft N-donor ligand (bpp) into CuⅡ/H2tud reaction system, the MOF 8 was prepared.8 is a 2D wave-like structure, and there is 1D water tape which consist of central symmetry water cluster (H2O)8, which as "glue" links adjacent 2D layers to form 3D supramolecular structure. Experiments show that 8 expresses good SOD activity.(6) In addition, studies show that the existence of weak antiferromagnetic coupling interaction between the Cu(II) ions which connected by carboxyl in 6. And for 7, there exists weak ferromagnetic property. The gas adsorption show that 12 and 13 have selective adsorption for CO2. Furthermore,1,5 and 12 perform good fluorescence property.