Synthesis And Properties Of Coordination Frameworks Based On N/O Multidentate Ligands

The aim of this thesis is the synthesis of new metal-organic frameworks (MOFs) based on four N/O multidentate ligands. Twenty-four new MOFs have been synthesized under the solvothermal or hydrothermal conditions and structurally characterized by single crystal X-ray diffraction, IR, elemental analyses and powder X-ray diffraction. The structures and topologies of these complexes have been analyzed in detail. And, the fluorescent, photocatalytic activity, magnetic and gas adsorption properties of part of complexes have also been investigated. The main contents of this work are summarized as below:In chapter1, a brief introduction of the research background of coordination polymers and the current progresses of coordination polymers based on multidentate ligands have been reviewed. Based on the aforementioned review, the foundation of this thesis has been introduced. Moreover, the progresses of this thesis have been outlined.In chapter2, we selected some auxiliary ligands with different size, flexibility and shape, and ten MOFs have been synthesized and structurally characterized based on2,4,6-tris(4-pyridyl)pyridine ligand. Complex1represents the first example of interpenetrated coordination framework with unique (3,6)-connected lohl topology. Furthermore, the photocatalytic activity and magnetic properties of1have been investigated. The structural difference of complexes1,5,6,9and10indicates that organic carboxylate ligands play important roles in the formation of such coordination architectures.In chapter3, two metal-organic hybrids (complexes11and12) have been synthesized by the introduction of polymolybdate. Both of complexes display three-dimensional "pillar-layer" frameworks based on bimetal-oxide inorganic layer. Good photocatalytic activities were observed for both complexes in the photo-decomposition of methyl orange solution under UV light irradiation. On the other hand, complex13possesses4-fold helical channel and is a water-stable MOF, which can sense anions with different geometries. The exchanged-products can be conveniently recognized by visual chroma. Moreover, the desolvated complex13 shows selective uptake of CO2over N2at ambient temperature.In chapter4, seven MOFs have been synthesized based on N/O multidentate ligands. The structural transformation between complexes16and17was achieved successfully by the pillar organic ligand under the same reaction conditions. The effect of synthetic conditions on the resulting structures have been discussed in detail. Moreover, the magnetic properties of16and17have been investigated and both of them show antiferromagnetic behaviour.In chapter5, four metal cluster-based MOFs have been obtained. The synthesis strategy of complex21opens up a new avenue for synthesizing metal cluster-based coordination frameworks. Furthermore, the gas adsorption and luminescent properties of complexes23and24have been systematically studied.In chapter6, a conclusion on this work is given.