Syntheses, Structures And Characterizations Of Novel Open-framework Metal Phosphates/Phosphites

The increasing demand of chiral materials for enantioselective catalysis and separation,and the importance of chirality in biological processes have stimulated extensive research inthe synthesis of chiral open-framework materials. The control of chirality in the synthesis ofopen-framework materials is particularly difficult due to the unclear formation mechanism ofthe inorganic framework assembled around the organic templates. Recently, natural chiralamino acids as the attractive building blocks or templates have been used for the synthesis ofchiral open-framework structures. Up to now, two compounds with chiral inorganicopen-framework phosphates/phosphites structures have been synthesized by using chiralamino acid molecules as the templates or ligands.Extra-large pore open-framework structures are of great importance for their widespreadapplications in catalysis, adsorption and separation of bulkier molecules. In recent years,several synthetic routes for the synthesis of extra-large pore frameworks have been developed.Among them, a feasible synthetic approach is the replacement of PO₄3^-by HPO₃2-which maydeduce the linkages of P-O-M in the framework and generate more-open interruptedframework structures. By using this approach, several metal phosphites with extra-large poreshave been successfully synthesized.In this thesis, extensive study has been done for the synthesis of new phophates andphosphites by using different amino acids or organic amines as the templates or ligands. Weaim to synthesize chiral open-frameworks by using chiral amino acid and develop newextra-large pore and large pore open-frameworks through the replacement of PO₄3^-by HPO₃2-units. Main results include:1. Chiral biological L-tryptophan molecules has been successfully introduced into thehydrothermal reaction system to synthesize chiral zinc phosphite,[Zn(HPO₃)(C₁₁N₂O₂H₁₂)](denoted as ZnHPO-CJ56). ZnHPO-CJ56possesses infinite edge-sharing ladder-like4-ringchains built up from the alternation linkage of ZnO₄tetrahedra and HPO₃pseudo-pyramids.The strong VCD signals indicate that the initially added chiral L-tryptophan molecules arenot racemic even through the hydrothermal reaction, and the as-synthesized compound has optical activity. ZnHPO-CJ56can emit strong light due to the existence of L-tryptophanmolecules.2. Ionothermal system has been employed to synthesize a novel hybrid zincophosphatemonomer containing amino acid,[Zn(HPO₄)(H₂PO₄)][C₆H₁₀N₃O₂](denoted as ZnPO-CJ58).The inorganic framework of ZnPO-CJ58consists of4-rings formed by ZnO₃OHisandPO2(OH)₂tetrahedra. The HPO₄moieties and histidine molecules hang on the Zn centers.Such framework is stabilized by extensive multipoint hydrogen bonds involving thephosphate units and histidine molecules forming a pseudo-3D supramolecular structure. Itexhibits photoluminescence due to the existence of L-histidine molecules. Interestingly,ZnPO-CJ58can transform into a layered structure (C₆H₁₀N₃O₂)Zn₂(HPO₄)(PO₄)·H₂O(ZnPO-CJ36) through further reacting with water or zinc acetate dihydrate in water at80°Cfor1hour.3. A new open-framework indium phosphate-phosphite [In9(H₂O)₆HPO₃)13(H₂PO₃)₂(PO₄)(HPO₄)][(C₆N₂H₁₈)₃](denoted as InHPO-CJ1) has been hydrothermally synthesized by using2-methyl-1,5-pentanediamine as the structure-directing agent. Such framework is featured bya two-dimensional (2D)4,6-net composed of pseudo-pyramidal units and InO6octahedraconnected through bridging oxygen atoms. The inorganic layers are linked through In2P3O9pillars to generate a three-dimensional intersecting channel system defined by extra-large16-ring along [100],[010] and [110] directions.31P MAS NMR has been studied to confirmthe four different coordinations of P atoms in the as-synthesized compound.4. A new open-framework cobalt nickel phosphate(C₆H₁₆N₂)₃·[Co₁₃Ni₈(H₂O)₆OH)12(PO₄)₆HPO₄)₆](denoted as CoNiPO-CJ4) has beenhydrothermally synthesized by using2-methyl-1,5-pentanediamine as the structure-directingagent. It presents a one-dimensional extra-large24-ring channels running along the [001]direction. The dimension of the pore opening is15.10×12.882.5. Two zincophophites possessed similar structures,(C_5H7N₂)₂·[Zn₃(HPO₃)4](denoted asZnHPO-CJ70) and (C₆H₁₈N₂)·[Zn₃(HPO₃)₄](denoted as ZnHPO-CJ71) have beensynthesized under hydrothermal and solvothermal conditions by using4-aminopyridine and2-methyl-1,5-pentanediamine as the structure-directing agents, respectively. The connectionof the ZnO₄tetrahedra and HPO₃pseudopyramids to form a layer containing4-and8-rings.Such layers are connected via Zn-O-P linkages to constitute the open-framework structures ofZnHPO-CJ70and ZnHPO-CJ71with8-,8-and12-ring channels along[100],[010] and [001]directions.6. A novel layered zinc phosphate-phosphite (C₆H₁₇N₃)[Zn₃(PO₄)₂(HPO₃)]·H₂O (denoted asZnHPO-CJ72) has been hydrothermally synthesized by using1-(2-Aminoethyl) piperazine as the structure-directing agent. Single-crystal X-ray diffraction analysis reveals that thecompound possesses2D layered structure containing4-and8-rings constructed by ZnO₄tetrahedra and PO₄3^-/HPO₃^2-anions, Diprotonated1-(2-Aminoethyl) piperazine cations residein the interlayer regions. The compound exhibits strong fluorescence emissions in the solidstate at room temperature.