Syntheses, Characterizations And Properties Of Microporous Coordination Polymers Based On Rigid Ligands

Porous coordination polymers have attracted considerable attention due to their potential applications in many areas, such as gas storage and catalysis. Considering some synthetical factors on such materials, such as ligand, metal ion, solvent, temperature and so on, we investigated the reactions between the rigid multi-carboxylate ligands /mixed-ligand and transition metal ions to construct coordination polymers with novel architectures, to study the synthetic conditions and rules for these compounds, discuss how to give the target products and explore the relationships between structures and properties for these new compounds.Six compounds were separated on the basis of solvothermal technique and structurally characterized by elemental analyses, IR, XRPD, TG and single crystal X-ray diffractions. Host-guest properties, gas adsorption isotherm measurement or fluorescent activity of partial compounds have also studied and discussed.Compound [Ni(HBTC)(DMF)₂·(guest)] (1) is a 2D layer with porosity, in which the honeycomb grid layers are constructed by nickel-BTC groups and the polar positions on the nickel (II) centres are occupied by DMF molecules. The sheets stack along the c-axis to give the 3D structure.Compound [Ni(HBTC)(4,4'-bipy)·3DMF] (2) is built on the architecture of (1), that is employing a linear connector 4,4'-bipy to replace DMF solvent molecules on the polar positions of Ni (II) centers to construct a 3D porous network . Host-guest analysis revealed that (2) possesses permanent porosity and N₂, H₂ adsorption isotherm measurements gave good results on gas uptake.Compounds [Ni(HBTC)(pyz)·3DMF] (3) and [Ni₂(BTEC)(bipy)₃·3(DMF)] (4) were the products when pyz pillar replace bipy pillar and the BTEC ligand takes the place of BTC ligand based on the reaction system of (2) respectively and they are both 3D frameworks. The connectivity of (3) not (4) is similar to that of (2), but the space-filling modes of the three compounds can be viewed as a pillar-layer motifs. Host-guest analyses revealed that (2) and (3) still have permanent porosity which were further confirmed by N₂ sorption isotherm measurements.Compounds [Cd₂(BTEC)(H₂O)]·0.6DMF (5) and Cu₂(BTEC)(DMF)₂ (6) were obtained through solvothermal reactions of H₄BTEC ligand and transition metal ions Cd(II) or Cu(II). The framework in (5) possesses a 3D architecture with ordered 1D rhombus channels and shows some fluorescent activity. While compound (6) displays a 2D layer structure which consists of dinuclear Cu2 units with paddle wheels, the polar positions of Cu (II) centers are occupied by DMF solvent molecules. Different from that of (1), the DMF molecules are not perpendicular to the layers, the fact of which may restricts the trend on employing a linear connector to replace DMF solvent molecules to construct a 3D network.