Ionothermal Syntheses, Structures And Characterization Of Metal Phosphates By Using N-Alkyl Pyridinium-and 1,3-Dialkyl Imidazolium-based Ionic Liquid As Solvents And Templates

In recent years, microporous materials have been intensively studied. Among these microporous materials, metal phosphates and phosphites are quite attractive due to their rich structural chemistry and potential applications in catalysis, separation, adsorption, and ion-exchanging. These materials have been synthesized under hydrothermal or solvothermal conditions, by using organic amine, alkali metallic cations, metalic complexes as structure-directing agents. In 2004, Morris and coworkers reported a new type of solvothermal synthesis in which an ionic liquid or eutectic mixture was used as both the solvent and structure-directing agent in the preparation of zeotype aluminum phosphates. This new synthetic method has been termed ionothermal synthesis and the reactional media is completely ionic circumstance. To date, more and more attention has been paid to the ionothermal method due to the excellent solvating properties, vanishingly small vapor pressure, high thermal stability, and recyclability of ionic liquids as"green"solvent. Furthermore, the application of an ionic liquid as solvent and template can effectively remove the competition between template-framework and solvent-framework interactions that occurs inevitably in traditional preparation. The different chemistry of ionothermal solvent system produces conditions under which novel structures may be accessible.In this dissertation, we focus our study on the synthesis of metal phosphate and phosphite by ionothermal reactions. Eleven new compounds have been ionothermally prepared by using N-alkyl pyridinium- and 1, 3-dialkyl imidazolium-based ionic liquids as solvents and templates. These compounds have been characterized by single crystal X-ray diffractions, PXRD, elemental analyses, ICP analyses, IR spectra and TG analyses. These results will be introduced from the following four issues:1. A novel 3D chiral open-framework zinc phosphate, NIS-1 (Northeast Normal Univesity Ionothermal Synthesis-1), with low framework density and fascinating helical channels, has been ionothermally synthesized by using N-methyl pyridinium iodide as solvent and template. Meanwhile, three 2D layered zinc phosphates, NIS-2, NIS-3, NIS-4, have been ionothermally prepared in N-methyl pyridinium iodide, N-ethyl pyridinium bromide, N-propyl pyridinium bromide, respectively.2. A new layered zinc phosphate, NIS-5, was synthesized by using 1, 3-dimethyl imidazolium iodide as solvent and template. Meanwhile, a novel 3D non-centrosymmetric open-framework zinc phosphate, NIS-6, which exhibits remarkably low framework density and interesting helical channels, has been ionothermally synthesized by using 1-ethyl-3-methyl imidazolium bromide as solvent and template. Furthermore, a 1D aluminum phosphate, NIS-7,and its isostructural gallium phosphate,NIS-8,have been both prepared in 1-ethyl 3-methyl imidazolium bromide. 3. A vanadium-phosphorus oxide cluster,NIS-9 and a novel 3D chiral open-framework gallium phosphate,NIS-10,have been ionothermally synthesized in the presence of metal oxide,phosphoric acid, imidazole and 1-ethyl-3-methyl imidazolium bromide. For NIS-9, each V atom is chelated by one imidazole molecule, the negative charge of framework is balanced by three ionic liquid cations; while for NIS-10, only Ga(3) atom is chelated by one imidazole molecule, the negative charge of framework is balanced by one protonated imidazole and half of an ionic liquid cation.4. A novel 3D open-framework zinc phosphite, NIS-11, possessing low framework density and helices, has been ionothermally synthesized and characterized by using 1-ethyl-3-methyl imidazolium bromide as solvent and template.