Ion Thermal Synthesis And Structure And Properties Of Zn(II)/Co(II)-terephthalic Acid Metal-organic Framework Materials

Metal-organic frameworks ?MOFs? have gained considerable attention in recent years, due to their novel controllable structure and the applications in adsorption, catalysis, drug delivery, and so forth. Ionothermal synthesis is an environmentally-friendly method, in which ionic liquids ?ILs? act as reaction media, structural templates or charge-compensating groups.Herein,1,4-benzenedicarboxylate acid ?H₂BDC? with simple configuration as ligand reacted with Zn?NO₃?2·6H₂O or Co?NO₃?2·6H₂O at different reaction conditions by using three kinds of 1-methy1-3-alkylimidazolium halide [RMI]X ?R= alkyl, R= E: ethyl, P:propyl, B:butyl, A:amyl; MI= imidazolium; X= Cl^-, Br^-, I^-? ILs as reaction media. Eleven Zn-BDC and twelve Co-BDC compounds were obtained, which were investigated by testing the single crystal structure, PXRD, IR, TG, fluorescence, dye adsorption and magnetism. The influence of ionic liquids on the structures and properties of the complexes was explored. The main work is as follows:1. Eleven Zn-BDC compounds were ionothermally synthesized with three kinds of [RMI]X, which can be divided into two types:2D [RMI]2[Zn₃?BDC?₃X₂] ?Type A, Compounds Znl-Zn2, Zn4-Zn6, Zn8-Zn11? and 3D [Zn?BDC??H₂O?] ?Type B, Compound Zn-3?. Type A is the primary structure model, showing a ?3,6? topological network. Type B obtained from [BMI]Cl, [AMI]Cl and [AMI]Br as media, is simplified as a 4,4-connected{4²·8⁴} topological network. These compounds were characterized by PXRD, TG, and fluorescence, whose analyses demonstrate the combination effect of the RMI+ templating effect and X- controlling the structure types:1) Type A changes into Type B through the boundary from [PMI]Cl, via [BMI]Br, to [AMI]I as the reaction media; 2) The decomposition temperatures of the compounds in Type A decrease with the alkyl chains increasing in RMI+cations.3) compared to the emissions of the ligand, the compounds with the larger RMI+, or X= I- exhibit red shifts in their emissions. In addition, the dye adsorption measurements indicate the Zn-BDC compounds can adsorb dyes with different configurations, suggesting the potential applications in the removal of pollutant or macromolecular capture.2. Ionothermal synthesis of H₂BDC and Co?NO₃?2 with there kinds of [RMI]X as slovents produced twelve Co-BDC compounds, which can be divided into two main types of frameworks:2D layered [RMI]₂[Co₃?BDC?₃X₂] ?Type C, compounds Col-Co4, Co5-Co7, Co9-Co12? and a 3D architecture [AMI]2[Co3?BDC?4] ?Type D, compound Co8?. Type C have the same ?3,6? skeleton as Type A and Type D grows into a 3D architecture based on BDC2- ligands linking similar 2D grids as those in Type C. The combing effect of [RMI]+ cations and X-anions on the structure construction passes to the TG behaviors in Tpye C. The decomposition temperatures of the [RMI]₂[Co₃?BDC?₃X₂] frameworks decrease with the alkyl chains in [RMI]+increasing, and the halide ionic affect the fluorescence. Similarly, by investigating the magnetism of compounds containing Br-, the 2D exhibit ferromagnetism with similar magnetic parameters, while the 3D compound reveals antiferromagnetism.