Synthesis Of Metal-Carboxyl Extended Coordination Frameworks

Crystal engineering is an important part of molecular engineering and is involved with the behavior of molecules or chemical groups within the crystal lattice, the control of crystal design and properties, and the prediction of crystal structure. Recently, the new research fields in the crystal engineering contain inorganic-organic hybrid material, microporous material, molecular magnet and coordination polymers, et al. The research in these areas not only enrich the study of physical laws underlying the assembling processes and experiment of the synthesis chemistry, but also extend the application prospect in the area of electronic, optics, magnetism, catalysis and biology simulation. According to the principle of crystal engineering, it is possible to design and synthesis crystalline material by selecting certain geometric metal ions and special organic ligands. Meanwhile, by selecting functional metal ions and organic ligands with functional groups, crystalline materials with optics, electric, magnetism, resolution of racemates and catalysis can be synthesized. The carboxylate ligand has been widely used in the research of synthesizing new materials for its vast diversity and unusual features in the structure and various coordination modes.The aim of our work is to design and synthesize a series of metal-carboxyl coordination extended frameworks by selecting suitable ligands and metal ions. This thesis is completed by four chapters. In the first chapter, the concept and development of crystal engineering is briefly reviewed, with major emphases on the metal-carboxyl coordination extended frameworks, including the histories, new developments and potential applications. Also the goals and achievements of this thesis are summarized.Among the hybrid compounds there are metal oxalates which exhibit vast diversity and unusual features in structure. A variety of metal oxalates with 1D, 2D and 3D structures have been reported during the past years. The incorporation of the oxalate group in metal-oxo open-frameworks is also of interest because additional structure features may appear after the oxalate incorporation. In Chapter 2, two new indium(III) compounds with extended structures are introduced: [In2(SeO3)2(C2O4)(H2O)2]·2H2O (1) and [NH3(CH2)2NH3][In(C2O4)2]2·5H2O (2). In compound 1, indium-selenite chains are bridged by oxalate units to form two-dimensional (2D) In2(SeO3)2C2O4 layers, separated by non-coordinating water molecules. In compound 2, the indium atoms are connected through the oxalate units to generate a 3D open framework containing cross-linked 12-membered and 8-membered channels.Azobenzene derivative is a good candidate ligand for its excellent property in many areas such as nonlinear optics, photochromism, photoinduced birefringence, optical switching and image storage. However, reports on azobenzene, especially metal-azobenzene carboxylates are rarely been prepared.In Chapter 3, a series of 5 trans-ADBbenzene-4,4-dicarboxylic acid (ADB) assembly compounds are introduced: [Zn(ADB)] (3), [Zn(ADB)(phen)] (4), [Co(ADB)(phen)] (5), [In2(ADB)3(phen)2] (6), [Cd(ADB)(phen)]·H2O (7). The strategy is to design low-dimensional structures by appling the"ligand regulation"method and using the bridging ligands and terminal ligands. Compound 3-7 are 1D polymers with differentπ-πstacking interactions, H-bond interactions and different characterized supramolecular frameworks. Compound 3-5 and 7 exhibits zig-zag chains, whereas compound 6 consists of ladder-like chains with left and right-hand helixes combined by ADB ligands. The synthesis and structures are described and the role of factors in packing of molecules are probed.In Chapter 4, a compound exhibiting fantastic five equivalent interwoven three-dimensional nets is introduced: [Co2(ADB)2(H2O)(phen)2] 8. Two ADB carboxylates and one bridging water molecule bridge the adjacent Co(II) atoms, forming a paddle-wheel Co2(CO2)4(phen)2O motif as secondary building units (SBU). The SBU is further bridged by ADB ligands forming an abnormal 5-fold interpenetration of diamondoid networks. Left- and right-handed helixes, sharing the ADB ligands, have been found in the open frameworks. Characteristic weak overall antiferromagnetic interactions between the metal centers have been observed.