Synthesis, Crystal Structures And Properties Of Nickel Metal Coordination Polymers Constructed By Mixed-ligands

In recent years, research of the design and synthesis of coordination polymers has become a hotspot in structural chemistry and materials chemistry, not only their novel and fascinating topologies, but also tremendous potential applications such as gas adsorption, storage and separation, molecule magnets.The controllable synthesis of coordination polymers is still a great challenge because there are many factors that play important roles in their self-assembling such as the chemical structures of the ligands, the anions, reaction temperature, pH value. Among these factors, it is well-known that structures of the ligands play crucial roles in the design and construction of desirable coordination polymer. Therefore, the design and selection of ligands is crucial. Generally speaking, carboxylic acid compounds with variety of coordination modes are selectively used as building units. In recent years, some N-donor bridging ligands with-CH2-alkyl spacers have been widely used by coordination polymer researchers. Because the flexible nature of spacers allows the ligands to bend and rotate when coordinating to metal centers so as to conform to the coordination geometries of metal ions. Furthermore, coordination polymers made from long bridging ligands can possible give rise to the formation of large voids, which have some value in terms of gas adsorption. In this work, some carboxylate acids with O atoms and flexible1,1’-(1,4-butanediyl)bis(imidazole) with N atoms as mixed ligands are selectively used as building units reacting with metal ions Ni2+, lastly three novel complexes have been obtained by hydrothermal reaction through metal-ligand coordination. We obtained Crystal structures by X-ray single crystal diffraction. And their structures have been charactered by elemental analysis, powder X-ray diffraction, IR spectrum, and thermogravimetric analysis. Our main work as follows:1. A novel complex [Ni(L1)(bbim-4)]n (L1=p-Phenylenediacetic acid anions, bbim-4=1,1’-(1,4-butanediyl)bis(imidazole) was synthesized by hydrothermal reaction under160℃. In complex, the L2link the Ni (Ⅱ) ions to form a infinite 1D zigzag chain, which are further linked by L2in two bidentate chelating coordination fashion to give the2D layer structure. Lastly, the parallel2D networks stack along the along the c-axis to form a3D supramolecular structure via van der Waals interactions. Study of the variable-temperature magnetic susceptibility indicate there are antiferromagnetic between the NiⅡ ions.2. A novel complex [Ni(L2)(bbim-4)]n (L2=o-phthalate acid anion, bbim-4=1,1’-(1,4-butanediyl)bis(imidazole) was synthesized by hydrothermal reaction under160℃.Compound [Ni(bbim-4)(L1)]n is a three-dimensional porous coordination polymer with triangular channels. Gas adsorption and desorption toward N2, CO2, H2study suggest that the complex have adsorption properties. This nature of the χMT vs T curve is a signature of the global ferromagnetic behavior of the coordination polymer.3. A novel complex [Ni(L3)(bbim-4)(H2O)2]n (L3=fum anion, bbim-4=1,1’-(1,4-butanediyl)bis(imidazole) was synthesized by hydrothermal reaction under140℃. In the compound, the1,1’-(1,4-butanediyl)bis(imidazole) link the NiⅡ ions to form a infinite1D zigzag chain, which are further linked by fum anions to give the2D layer structure, then2D layers interpenetrated in an inclined mode to generate a unique3D polycatenation network. The hydrogen bonds exist between the water molecules and fum anions, which further stabilize the3D supramolecular structure.