Study On Coordination Polymers Based On Rigid Aromatic Carboxylic Acid Ligands And Their Properties

Currently, the design and synthesis of coordination polymers (CPs) have attracted ever-increasing interest not only due to their intriguing structural topologies but also their promising applications as functional materials in diverse areas, including gas storage, separation, ion exchange, sensors, magnetic properties, catalytic materials and so on. As for self-assemblies of CPs, the reasonable selection of multidentate organic ligands is critical. Among multitudinous organic ligands, multicarboxylic ligands have been proved to be good candidates. Moreover, multifunctional ligands combined carboxylate groups with nitrogen donor groups have been largely used to construct functional coordination polymers (FCPs). Meanwhile, changing the length and substituent groups of ligands, temperatures, pH values, solvents systems, introducing different metals and mixed ligands are important methods to construct CPs. In this work, twelve CPs were assembled. Three 3D microporous frameworks [H2N(Me)2]2[Zn4(L)2(H2O)1.5]·5DMF·H2O (1), [H2N(Me)2]2[Zn4(L)2(H2O)1.5]·4DMA·6H2O (2), [Mn2L(DMF)(H2O)] (3) have been synthesized based on 2,4-di(3’5’-dicarboxylphenyl)-benozoic acid (H5L) ligand. Three new CPs [Cd(5-ana)2]·(H2O)2 (4), [Cd(5-ana)(HCOO)] (5) and [Cu(5-ana)2] (6) have been synthesized based on 5-Aminonicotinic acid (5-anaH) ligand. Another six 1D lanthanide-based CPs chains{[LnL3(H2O)2]·H2O}n (Ln = Pr (7), Nd (8), Eu (9), Gd (10),{[DyL3(H2O)2]}n (11) and{[GdL2(phen)(OH)]}n (12) have been synthesized by employing 2-Fluoroisonicotinic acid (FINA) ligand. The structures of complexes have been determined by X-ray single crystal diffraction.1 and 2 are isostructures with two kinds of dinuclear [Zn2(COO)5(H2O)] SBUs and show new (5,5,5)-connected topologies; 3 with a kind of dinuclear [Mn2(COO)5(DMF)(H2O)] SBUs and shows (5,5)-connected topology; 4 is a 2D (4,4)-connected layered structure contains 1D open channels; 5 shows a (3,5)-connected 3D framework; 6 displays a 3D (3,6)-connected homochiral framework; There is a small 1D solvent channel in 7-10, in which water molecules are located. All these compounds have been characterized by powder X-ray diffraction (PXRD), elemental analyses (EA), infrared spectra (IR) and thermogravimetric analyses (TGA). Moreover the adsorption properties of 1 has showed that 1 exhibits high adsorption selectivity and storage capacity for CO2 over CH4 and N2 at ambient conditions. The luminescent properties of some CPs have also been investigated, and 9 shows red luminescence and exhibits the characteristic transition of the Eu3+ ion. The magnetic properties of 8-12 reveal that the weak antiferromagnetic coupling between the metal centers.