Synthesis And Characterization Of Some Molybdate And Borate

In the field of modern inorganic chemistry, many chemists have been trying to prepare new compounds in'one-pot'approach, which may lead to some delightful and unexpected structures as well as excellent physical properties, but most of the results are not as satisfactory as we have imagined, or even run counter to our original ideas. On the other hand, chemists are engaged in constructing new structures with functional building blocks by strong covalent bonds, ionic bonds or hydrogen bonds between molecules, resulting in new functional materials. Molecular assembly is just like building a house. The selection of appropriate bricks and the performance of bricks will determine the performance of the house.We decided to construct new functional compounds based on molybdenum oxide polyhedrons because of its stability and functionality. In the design of the experiment, we used molybdenum oxide polyhedrons and functional elements to assemble aiming at obtaining simple and stable functional materials. Organic molecules are used to modify the polyoxometalate cluster based on molybdenum oxide polyhedrons, resulting in new structural units. There are two reasons for this choice. First, in the organic reaction, there is a specific connection between the molecules, and it is easy to control; second, there are many molybdenum oxide clusters, which are not only stable in solution, but also have greater volume and length, which are suitable for constructing a porous material. The history of polyoxometalate clusters is nearly 200 years, and there are many types of POMs which can be used for synthesizing new building blocks.The following is a brief description of the chapters. In the introduction, we introduced the background and the current development of molecular assembly in various fields.In the second chapter, we report on the synthesis of five compounds, one-dimensional chain structure of the compound Ag3[MnMo6O18{(OCH2)3CNH2}2 (DMSO)6]·2(DMSO)(1); two-dimensional layer structure of the compound Ag3[MnMo6O18{(OCH2)3CNH2}2 (DMSO)6H2O]·2(DMSO)(2); with flexible chain bpp one-dimensional chain structure of the compound Ag3(bpp)2[MnMo6O1g {(OCH2)3CNH2}2(DMSO)2]·2(H2O)·6(DMSO)(3) and two-dimensional structure of the compound Ag3(bpp)2[MnMo6O18{(OCH2)3CNH2}2(DMSO)2]·2(CH3OH)·2(DM SO)(4); and with rigid chain bpe one-dimensional chain structure of compounds Ag3(bpe)2[MnMo6O18{(OCH2)3CNH2}2(DMSO)4]·6(DMSO)(5). These five compounds are assembled from two trishydroxymethyl-aminomethane modifid Anderson molybdenum cluster (MnMo6O18{(OCH2)3CNH2}23-) building blocks. By comparing the structure and experiment preparation of compounds 1 and 2,3 and 4, we found that two-dimensional layer structure can be further assembled from one-dimensional chain structure, the experimental evaporation rate has a great impact on the structure, and that the connection of building blocks will be more orderly with the time.In the third chapter, we describe three compounds Fe(H2O)2(MoO4)2·H3O (FeMo), NaCo2(MoO4)2(H3O2) (CoMo) and Mn2(MoO4)3·2H3O (MnMo) obtained by mix-solvothermal synthesis approach, which are all constructed by MoO4 tetrahedrons and MO6 (M=Fe, Co, Mn) octahedrons linked by direct corner-sharing. The magnetic measurements confirm the existence of intermolecular antiferromagnetic interactions in the three compounds. Different synthetic conditions lead to diverse magnetic properties at low temperature in studying CoMo.In the fourth chapter, we choose boron oxide polyhedron as a structural basis, because it has similar structure (triangle and tetrahedral configuration) as phosphorus oxide polyhedron in zeolite. Special guest molecules are imported into the structures. Two organic boric acid salts (C5H6N)(C9H14N)(B5O6(OH)4]2(B-1) and Na3[N(CH3)2][B5O8(OH)] (B-2) are obtained by solvent thermal synthesis. In the synthesis of compound B-1, pyridine works as solvent as well as reactant. There exists a reaction of pyridine alkylation. In the synthesis of compound B-2, DMF was decomposed to dimethylamine anion (CH3)2N-.According to the crystalstructuretm of compound B-2, the structure belongs to monoclinic P21 non-centrosymmetric space group, so we conducted its test of second-harmonic generation. The result showed that compound B-2 has considerable second-order generation with KDP. It is further proved that the space group of compound B-2 is non-centrosymmetric, and it is ready for the further test in physical properties.