Syntheses, Structures And Characterizations Of Inorganic Open-Framework Materials

Open-framework inorganic materials have extensive applications in adsorption, separation, catalysis, and host-guest assembly due to their uniform microporosity and tunable framework compositions. Zeolites, as one of the most important families in open-framework materials, have been pained great attention by the chemists. Their structures are based on corner-sharing TO4(T = Si, Al, P, B, Ge, Be, Zn, Co, etc.)tetrahedra forming three-dimensional four-connected open frameworks. Up to now, 179 zeolite framework types have been approved by the Structure Commission of International Zeolite Association (IZA), mainly including silicates (germanates), phosphates (arsenates), and both silicates and phosphates. In additionally, there are also some zeotype frameworks based on TOn (n = 3, 4, 5, 6) polyhedra, displaying rich structural diversities, such as, low-dimensional frameworks, frameworks with ultra-large channels or chiral channels, etc. The framework T atoms have covered most of the transition metal elements and main block elements in the element period table. Especially, those mateirals containing transition metal might offer potential applications in the area of photoluminescence, magnetism, sensors, etc. for their additional chemical and physical properties. This thesis refers to the study of inorganic open-framework materials in several systems, including main block silicates, main block phosphates, and transition metal silicates. A number of compounds with novel framework structures have been successfully prepared under hydrothermal or solvothermal conditions, and their syntheses, structures, and characteriztions have also been investigated in detail.1. To find a new zeolite, introduction of substituted elements into the frameworks is one of the effective methods. Here beryllium is selected as the alternative element. A new berylloslicate zeolite, K6[Be3Si7O20]·4.6H2O (denoted as JLBS-1) has been successfully prepared in a gel system of KOH?BeSO4·4H2O?SiO2?H2O. The structure of JLBS-1 is constructed from the 4.82 nets and spiro-5 units to form a 3Dimensional framework with 3Dimesional 8-ring channel system. Upon investigation of the construction regulations of this type of structures, a number of hypothetical energy feasible structures containing 4.82 nets and spiro-5 units have been predicted by computer simulation.2. Three new open-framework beryllophosphates, [C5H14N2]2[Be3(HPO4)5]·H2O (denoted as BePO-CJ29), [C6H18N2]0.5[Be2(PO4)(HPO4)OH]·0.5H2O (denoted as BePO-CJ30) and [Be12P8O32]·8H2O (denoted as BePO-CJ31), have been successfully prepared under hydrothermal/solvothermal conditions by using organic amine as the templates. Among them, BePO-CJ29 and BePO-CJ30 are the first two low-dimensional beryllium phosphates with unique architectures.1) BePO-CJ29 was synthesized by using (R, S)-2-methylpiperazine as the organic template and butan-2-ol as the solvent. The strict alternation of BePO4 and HPO4 tetrahedra results in a 1D infinite double chain containing12-ring apertures. Every double chain is constructed by the connection of two centrosymmetric single chains. There exist extensive H-bonding interactions between the inorganic chain and the organic amines, which appears to be a dominant factor in stabilizing the whole structure.2) BePO-CJ30 was synthesized under hydrothermal conditions by using (R, S)-2-methylpiperazine as the organic template. Its structure is constructed by the alternation of BeO4/HBeO4 and PO4/ HPO4 tetrahedra with diprotonated 1, 6-hexadiamine cations and water molecules residing in the interlayer. The complex layer is comprised of two coupled 4.8-net sheets.3) BePO-CJ31 was also prepared under hydrothermal conditions. Although ethanolamine is used as one of the raw materials, no ethanolamine was found in the framework structure. BeO4 and PO4 tetrahedra are connected to each other by sharing oxygen atoms to form a novel 2D layer. The layers are further linked together via BeO2(H2O)2 tetrahedra resulting a 3D open framework containing 8-ring channels.3. Manganese silicate might find extensive applications in magnetism, spectroscopy, and catalysis fields. However, to the best of our knowledge, few successes have been achieved on the syntheses of manganese silicates with stoichiometric amounts of Mn. In this thesis, two manganese silicates, Na2Mn3Si3O10 (denoted as JLMS-1) and KNa15Mn4Si12O36 (denoted as JLMS-2) have been successfully prepared under hydrothermal conditions.1) JLMS-1 is the first synthetic manganese silicate synthesized under supercritical water conditions. Its structure consists of layers of edge-sharing MnO5 and MnO6, which are linked together via isolated linear Si3O10 trimers to form a 3D open-framework with 6-rings apertures. Magnetic studies reveal that JLMS-1 displays a spin canting antiferromagnetic behavior below 40 K.2) JLMS-2 is a new manganese silicate synthesized under mild hydrothermal conditions. It consists of 12-rings of corner-sharing SiO4 tetrahedra linked together via corner sharing by single MnO6 octahedra to form a 3D open-framework. Magnetic measurement reveals that there is weak antiferromagnetic ineractions among the MnO6 octahedra.In summary, this thesis is mainly focused on the syntheses of inorganic open-framework structures. A number of compounds with various structure architectures have been successfully prepared, including four-connected three dimensional zeolitic framework structures, low-dimensional structures, and mixed octahedral/tetrahedral open frameworks of transition metal silicates, etc. It gives a broad investigation on the molecular engineering of inorganic open-framework materials from serial aspects of theoretical chemistry, synthetic chemistry, structural chemistry, and characterization.