Research On Properties And Self-Assembly Of Coordination Polymers Based On Polyether And Five-Member Heterocycle Bridged Ligands

In the past few decades, the self-assembly of coordination polymers or metal-organic frameworks（MOFs） has been of intense interest in the fields of coordination chemistry and crystal engineering, not only due to their intriguing varieties of architecture and topologies, but also because of their potential application in the fields of gas adsorption and separation, drug delivery, magnetic material, chemical sensors, ferroelectricity, non-linear optics. To obtain functional MOFs, we designed and synthesized the open-chain polyether-bridged and heterocyclic-bridged organic ligands. Based on these ligands, twenty-three coordination polymers were obtained. In addition, the structures and properties of coordination polymers were discussed in the thesis. The main results are summarized as following:（1） Five isostructural organic guest loaded Cd（II）-MOFs, namely Cd（L1）₂（OTs）₂·2（THF）（1）, Cd（L1）₂（OTs）₂·2（C₆H₅F）（2）, Cd（L1）₂（OTs）₂·C₆H₅Cl（3）, Cd（L1）₂（OTs）₂·2（C₆H₅Br）（4） and Cd（L1）₂（OTs）₂·1.5（C₆H₅I）?0.5（H₂O）（5）, were generated from 1,2-bis[(3-（pyridine-4-yl）phenoxy]ethane and Cd（OTs）₂（OTs-= p-toluenesulfonate anion） in solution. In compounds 1-5, Cd（L1）₂（OTs）₂ framework is possessed of 2-fold interpenetrated 2D layers structures with the square-like nonpolar channels. After removal of the guest molecules, the guest-free Cd（L1）₂（OTs）₂ framework can reversibly adsorb Ph F, Ph Cl, Ph Br and Ph I at room temperature in the liquid phase. To confirm the selectivity, the host framework Cd（L1）₂（OTs）₂ was immersed in a mixture of halobenzenes. It was found that the polarity of homohalobenzenes affect the adsorption and selectivity of the host framework.（2） Based on the hydrophobic environment of square-like channels, a series of aromatic guest loaded host-guest complexes aromaticsìCd（L1）₂（OTs）₂, namely [Cd（L1）₂（OTs）₂]·benzene·1.5Me OH（6）, [Cd（L1）₂（OTs）₂]·2（toluene）（7）, [Cd（L1）₂（OTs）₂]·（o-xylene）（8）, [Cd（L1）₂（OTs）₂]·（m-xylene）（9） and [Cd（L1）₂（OTs）₂]·2（p-xylene）（10） were synthesized. The Cd（L1）₂（OTs）₂ framework can reversibly adsorb benzene, toluene, o-xylene, m-xylene and p-xylene. It is also able to effectively separate benzene/toluene/xylene in the liquid phase. In addition, it can effictively richen toluene or p-xylene in the dilute solution by the host-guest hydrophobic interactions.（3） Under different temperature and solvents, six new coordination polymers, [Cd（L2）（BDC）]·（Et OH）·（DMF）（11）, [Zn（L2）（BDC）]·（Et OH）·（DMF）（12）,[Cd₃（L2）（BDC）₃（DMF）]·0.25（DMF）（13）, [Zn₃（L2）（BDC）₃]（DMF）（14）, [Cd_1.5（L2）₂（BDC）_1.5]·0.5（Me OH）·0.5（H₂O）（15） and [Zn（L）（BDC）]（16） were synthesized by the polyether-bridged organic ligand 1,2-bis[4-（pyridine-3-yl）phenoxy]ethane（L2） as well as H₂ BDC with Zn（NO₃）₂ or Cd（NO₃）₂. In compounds 11 and 12, metal cations are briding by carboxylic groups, forming M₂（CO₂）₂ cluster. The clusters are linked by the ligand L2 and co-ligand BDC, constructing a 6-connected 3D α-Po（pcu） network. In compound 13 and 14, three metal cations are briding by six carboxylic groups, forming M₃（CO₂）6 cluster. The clusters are linked by L2 and BDC ligands, forming an undulated 2D layer. In compound 15, the ligand L2 and co-ligand H2 BDC with Cd（NO₃）₂ construct a 3D network under the hydrothermal condition. Compared with compound 15, compound 16 displayes a undulated 2D layer. In compound 16, it displays an 2D layer structure, which is interacted by π···π interactions forming 3D supermolecular structures. On the further research, it is found that the comformations of L2 ligand and coordination modes of BDC ligands play an important effect on the diversity of coordination compounds.（4） Seven novel coordination compounds 17-23 were synthesized by 1,3,4-Oxadiazole-bridged bisimidazole（L3） and different Zn（II）、Cd（II）、Hg（II） and Cu（II） salts. During the discussion of structures of compounds 17-23, it is found that the N orientations of imidazole group play a decisive role in the formation of M₂L₂ molecule or M₂L₄ cage. Meanwhile, the dimension of coordination polymers can be increased by the addition of the co-ligand.In summary, twenty-three novel coordination compounds were synthesized by the open-chain polyether-bridged ligand or heterocycle-bridged ligands with transition metal ions. It is found that the conformation of L ligands and/or coordination modes of BDC ligand have an important impact on the diversity and properties of coordination compounds.