| dc.description.abstract | Microporous materials have widespread applications including ion-exchange, selective sorption or separation, and catalysis processes. New microporous compounds with novel structures and interesting properties are extremely desired for growing demands in technology.
This thesis descrives the synthesis, crystal structures and properties of organically incorporated transition metal germanates (series A), and uranium germanates (series B), which are classified on the basis of their structural characteristics and the methods of preparation. These compounds are synthesized by solvothermal, ionothermal, and high-temperature, high-pressure hydrothermal methods, and characterized by various spectroscopic techniques.
In series A, a zinc germanate, A1, was synthesized by solvothermal method. Its structure contains neutral infinite chains with empty 18-membered ring channels. This is the first example in literature where the fluorine atoms in the germanate cluster are characterized by 19F NMR spectroscopy. A niobium germanate, A2, was synthesized by using a deep-eutectic solvent as the medium for the synthesis. Its layer structure consists of NbGe6X19 clusters with 10 membered-ring windows. This is the first example of organically templated niobium germanate where the structure was characterized by single-crystal X-ray diffraction. This compound displays an intense SHG response.
In series B, the synthesis, crystal structures, and properties of three novel uranium germanates with various valence states of uranium are discussed. B1 is a mixed-valence uranium(IV,VI) germanate, Cs8UIV(UVIO2)3(Ge3O9)3•3H2O. B2 is a tetravalent uranium germanate containing four- and five-coordinate germanium, Cs4U([5]Ge2O2)([4]Ge3O9)2. B3 is a pentavalent uranium germanate containing four- and six-coordinate germanium, Cs3U[6]Ge([4]Ge3O9)2. These compounds have been structurally synthesized under high-temperature, high-pressure hydrothermal conditions and characterized by single-crystal X-ray diffraction. The valence states of uranium have been confirmed by X-ray photoelectron spectroscopy, electron paramagnetic resonance, UV-visible, and photoluminescence measurements.
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