Synthesis, Structures And Properties Of Coordination Complexes Based On N-heterocycle And Carboxylate Mixed-ligands System

The rational design and syntheses of coordination complexes continue to attract enormous interest because of the endless possibilities and inexhaustible synthesis options for tailoring their structures and properties. In this thesis, using different nitrogenous ligands and carboxylate ligands to react with metal ions,27new complexes have been obtained. They have been characterized by single-crystal X-ray analysis, elemental analysis, IR spectroscopy. Besides, powder X-ray diffraction, photolulninescence properties, magnetic properties, thermal analysis, and N2adsorption were also measured. Including:1. Using bpdb ligands and linear carboxylate ligands (1,4-benzene-dicarboxylic acid, and1,4-naphthalenedicarboxylic acid) to react with different transition metal ions under hydrothermal conditions, seven novel coordination polymers are obtained. Generally, the diverse structures are mainly attributed to the different inorganic building blocks and metal centers. The thermal stabilities of the complexes have been investigated. Photoluminescence measurements of2and6indicate that the emissions can potentially be assigned to the π*→π transitions of bpdb ligands. The magnetic measurement of5reveals that the characteristic of a system with dominant antiferromagnetic interactions between Co(II) ions. N2adsorption measurements of5and6were performed to estimate the porosity of activated samples.2. Using bpdb ligands to combine with monocarboxylic acid (p-nitrobenzoic acid, acetic acid), four interesting one-dimensional polymers which possessing1D Zigzag chain,1D ladder-like double chain, and1D linear chain structures have been synthesized. Besides, when the monocarboxylic acid ligands were replaced with angular dicarboxylate, four two-dimensional double-layered polymers have been obtained. By comparison, we find that the choice of metal centers significantly affects the networks of CPs. In addition, photoluminescence properties of8,9,10,12, and13; thermal properties of12and13; and N2adsorption of13were also measured.3. Using pyridyl-substituted nitronyl nitroxide as N-containing ligands (NITpPy and NITmPy), pnba as carboxylate ligand, to combine with rare earth ions, five new one-dimensional lanthanide-carboxylate complexes have been obtained that can be seen as doped with paramagnetic spin carriers (radicals) into the main lanthanoid carboxylate chain structure. Careful inspection of the structures reveals that guest molecules have a significant function in determining the structure. To the best of our knowledge, doped radicals as guest molecules in the lanthanide chain complexes haven’t been reported before. Besides, the magnetic studies show that very weak antiferromagnetic couplings exist between GdⅢ-GdⅢ, and magneto-structural correlations of the complexes have been discussed in detail.4. Using NITpPy radicals and methyl-benzoate ligands to combine with metal ions, five zero-dimensional transition metal complexes are obtained. Weak antiferromagnetic interactions between NITpPy radicals and metal ions of the complexes have been observed. Spin polarization mechanism and orbital symmetry are used to explain the magnetic coupling in these complexes. Besides, when NITpPy radicals were replaced with NITmPy ligands, two paddle-wheel dimeric copper complexes have been obtained. We successfully exploited the steric constraints of the methyl groups and induced the paddle-wheel to run.Their magnetic susceptibility were studied and discussed in detail.