Synthesis, Structures And Properties Of Metal-Organic Frameworks Constructed Via Mixed-Ligands

Metal-Organic Frameworks (MOFs) have been one of the fastest growing aspects in cross fields of energy, materials and life science, because of their intriguing topology structures and potential applications as functional materials in gas adsorption and separation, catalytic activities, optoelectronic materials, magnetism, and so on. According to the theories of crystal engineering, thirty-eight novel MOFs constructed by the mixed-ligands on the basis of polycarboxylate and pyridine connectors have been synthesized and determined by X-ray single crystal diffraction analysis. These complexes have been characterized by elemental analysis, fluorescence, variable temperature magnetic susceptibility measurements, EPR spectra and cyclic voltammogram. The main contributions in this work are below:1. Thirteen transition metal complexes and two 3d-4f heterobimetallic complexes have been obtained using rigid dicarboxylate species with different orientations of the functional groups as the ligands. A systemic study of the isomeric effect on the generation of dimensional frameworks has been done, and the EPR spectra and magnetic susceptibilities of selected complexes have been measured.2. Using the benzenetricarboxylic acid and derivatives as the linkers, thirteen complexes have been synthesized, and their fluorescence and magnetic properties have been studied. Notably, the ideal topologies of complexes 20 and 21 have not been encountered in MOF chemistry, which has been deposited in the RSCR and named as zlm net.3. Benzenetetracarboxylic acid was chosen as the ligands, six complexes have been gained. The results revealed that the temperature and the metal-ligand ratio play important roles in the design and synthesis of crystal materials. The 3D network of complex 33 can be interpreted topologically as a novel (4,4,10)-connected 2-nodal nets, which has not been appeared in MOF chemistry and has been deposited in the RSCR named as zim net.4. Using 5-(biscarboxymethylamino)isophthalic acid and 5-(4-carboxyphenylazo)- isophthalic acid as the connectors, three transition metal complexes and two rare earth complexes have been obtained. The magnetic susceptibilities of complex 35 were determined.