A systematic study of the influence of non-covalent interactions, pH, and temperature on the synthesis and structures of metal-organic frameworks.

摘要

This dissertation describes the syntheses and characterizations of new metal-organic hybrid framework compounds, and the investigation of various factors that can influence the formation of frameworks. A series of coordination polymers based on topologically identical chains have been synthesized and their structural relationships have been investigated. Primarily, the influence of non-covalent interactions, such as hydrogen bonding, pi-pi, and CH-pi interactions, on the coordination modes of the BDC ligands, geometry of the chains (zigzag vs. crankshaft configuration), and chain packing among these compounds have been studied. The pH and temperature effects on the composition and dimensionality of the Ni-BDC-2,2'-bipyridine system has been systematically studied since the structural chemistry of polycarboxylate aromatic ligands, coordination modes and protonation states of these ligands, are markedly sensitive to synthesis conditions. Five new compounds have been synthesized from the same reaction mixture but different pH and temperature.; As part of the strategy used to construct frameworks, the uranyl cation as a molecular building block has been combined with rigid bridging ligand to form extended structures analogous to known simple hydrogen bonded organic networks. The in-situ hydrolysis reaction of cyanide to carboxylate, one of advantages of hydrothermal technique, was applied in this work. The influence of substituent of the dicarboxylate ligands and non-covalent interaction on the interpenetration of the framework was investigated.; Low temperature solution routes to precursors of gadolinia doped ceria, Ce0.9Gd0.1O2-x (GDC) using simplest organic connectors such as formate and carbonate were investigated. The conditions for high yield, high purity, and small particle size were investigated. The calcination of precursors and densification of Ce0.9Gd0.1 O2-x (GDC) powders sintered at different temperatures were investigated. The ionic conductivity of GDC was measured and compared with literature data.