Syntheses And Properties Of Crystal Metal-organic Frameworks

The research on metal–organic frameworks is attracted much attention in recent years not only for their intriguing topologies and structural diversity, but also for their great potential applications, such as in catalysis, adsorption, non-linear optics, fluorescence, electrical conductivity and. Pyridine carboxylic acid ligands is good candidate as organic building block to form intriguing varieties of architectures and topologies. Herein a series of porous MOFs materials were synthesized by self-assembly of transition metal ions and three kinds of pyridine carboxylic acid ligands. Furthermore, their thermal stability, sensing of metal ions, magnetism and luminescent properties were discussed.In chapter 1, the topic research background, the features and applications of metal organic framework material are introduced, and then we sketched out the significance and research routes of this project.In chapter 2, Regulating the temperature、pH、reactant ratio、solvents and auxiliary ligands,we synthesized eight novel MOFs by the volatilization or hydrothermal method, then we reasearched their crystal structures and properties. The eight MOFs are {[Zn4(mpydc)3(OH)2(DMF)2]·2DMF}n(1), [Zn(m-pydc)(2-Met)(DMF)]n(2), {[Co(mpydc)(DMAC)]·DMAC}n(3), [Co(m-pydc)(H2O)2]n(4), [Cu(m-pydc)(NH2-Py)(DMF)]n(5), [Cd(o-pydc)(DMF)2]n(6), [Mn(o-pydc)(DMF)]n(7), {[Cu(nic)2(DMF)]·DMF}n(8). Single crystal X-ray analyses revealed that 1 has peculiar three-dimensional ftz topology network, and the channels in 1 contain free lewis basic sites. Compounds 2 and 6 are all two dimensional hcb topology network with metal ions and ligands as three connected nodes. Compound 4 is also twodimensional hcb network topology, but the adjacent layers are connected by the intermolecular π–π interactions and the hydrogen bonds to form a three dimensional supramolecular network. Compounds 3 and 5 are all three-dimensional srs topology network with metal ions and ligands as three connected nodes. Compound 7 displays a 4-connected three-dimensional sra topology network which consists of one-dimension Mn(COO)2 chains and rhombic channels. Compound 8 displays a chiral three-dimensional qtz topology network with chiral channel contructed by helical chain. The guest DMF solvent molecules are wrapped in the one-dimensional chiral channel of 8.In Chapter 3, the thermal stability of compound 1-8 are demonstrated that the compound 2,4,7,8 have higher thermal stability properties with the decomposition temperature at 230℃, 350℃, 350℃ and 240℃ respectively. Metal ion sensitive properties of compound 1 was studied, the result shows that 1 has good fluorescence sensitivity properties to Cuii implying great potential as medical diagnostic reagents and ion sensor. Magnetic test and analysis of compound 7 suggested that it is antiferromagnetic magnetism. Fluorescent measure of 2 and 6 shows that compound 2 has strong emission peak under 530 nm(excited at 470 nm), compound 6 has strong emission peak under 400 nm(excited at 310 nm).In chapter 4, systemic summary and outlook for the whole work are carried out. We discovered compound 1 has good fluorescence sensitivity properties to Cuii. Further efforts will be focused on the construction of porous luminescent MOFs with tuned micropores to enhance their recognition selectivity and a variety of immobilized Lewis basic sites to induce preferential binding with respect to different metal ions, leading to highly selective luminescent MOF probes, which might be exploited for the sensing of metal ions in the near future.