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Investigate of the Syntheses, Structures and Performances of Novel Metal-Polycarboxylate Coordination Polymers

Author: TianGe
Tutor: ZuoShiLun
School: Jilin University
Course: Inorganic Chemistry
Keywords: Polycarboxylate Adipic acid Structure and properties Polymer structure Dicarboxylic acid Rare earth metals Topology Layered compounds Coordination Bipyridine
CLC: O631.3
Type: PhD thesis
Year: 2006
Downloads: 787
Quote: 4
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The research of metal-polycarboxylate coordination polymer remains an extremely active field of materials chemistry in recent years. The construction of metal-organic coordination polymer is of great interest due to their intriguing network topologies and their potential applications as catalysts, adsorption, nonlinear optical activity, electrics and magnetism. Crystal engineering based on organic linkers and metal centers (building blocks) with specific coordination geometries is an important approach in the preparation of coordination materials with desired functions. Numerous coordination polymers have been successfully designed and synthesized by using of either covalent bonds or weaker intermolecular interactions. In particular, these coordination polymers can be designed to create various sizes and shapes to possess potential applications in many fields. The aim of this thesis is to utilize the principles of crystal engineer to design and synthesize the metal-organic coordination polymers constructed from metal ions and multi-carboxylate ligands in order to find the new synthetic pathways of clustered metal-organic coordination polymer and explore their structural characters and their physical properties.The chiral compounds can be synthesized by using chiral reactants, solvents and/or auxiliary agents, by spontaneous resolution, or by the influence of chiral physical environment such as polarized light. Recently, chiral templates such as chiral metal complexes are used to form chiral metal phosphates. The transformation was achieved by chirality derection and chirality transfer. The phenomenon of spontaneous resolution is unusual in coordination chemistry, and the products are normally racemic mixture of left-handed and right-handed helical chains, although the each crystal is single enantiomer. We employed an achiral ligand pyridine-2, 5-dicarboxylic acid (H2PDC) and synthesized two 2-D layer coordination polymers Co(PDC)(H2O)2-(H2O) and Ni(PDC)(H2O)2-(H2O) containing two helical chains under the solvethermal condition. The synthesis did not involve any chiral reactant or solvent or other auxiliary agent. To our surprise, the resultant crystals were not racemic as evidenced by the observation of strong signals in vibrational circular dichroism (VCD) spectra and there exist the phenomenon of the enantionmeric excess. And the two compounds have the different magnetic properties although the structures are same.In the last few years, large amounts of coordination polymers based on metal ions and rigid spacer ligands such as di-carboxylates and tri-carboxylates have been successfully synthesized. Interestingly, compared to a lot of attempt aimed at the development of compounds containing rigid ligands, the use of flexible ligands offers a greater degree of structural diversity that are more difficult to predict and conformational flexibility to enhance the possibility of forming supramolecular isomers. However the control of the conformation of flexible ligands such as 1, 4-cyclohexanedicarboxylic acid (chdcH2) in the synthetic reaction remains a great challenge. 1, 4-cyclohexanedicarboxylic acid (chdcH2) possesses three preponderant conformations of two carboxylate groups, a,a-trans-, e,e-trans-, and e,a-m-chdcH2.In previous examples, the molar ratios of cis and trans conformations of have been controlled by changing the pH value in hydrothermal reactions. By changing the reaction temperature and pH value, cis and trans conformations of chdcH2 have also been successfully separated in hydrothermal reactions. But, there is no research on complete separation of cis and trans conformations of chdct^ in the different solvent system. In this thesis, we have been obtained seven novel polymeric frameworks. In the presence of different solvent, the cis and trans conformations of 1,4-cyclohexanedicarboxylic acid were successfully separated toward La-organic coordination networks. Four novel cis conformations of 1,4-chdc coordination polymers were synthesized by 1,4-chdc and metal ions Ce3+, Gd3+, Tb +and Cd2+ in the different solvent. A novel compound built up from 1,4-chdc and metal ions Zn2+ was synthesized in the different solvent which there exists cis conformation and trans conformation.The self-assembly of the frameworks is influenced by many factors, such as coordination nature of the metal ions, the structure of the ligands, the solvent system, the template, the pH value of the solution and reaction temperature. In the synthesis of metal-organic framework coordination polymer, the organic bases were found to play three dramatic roles in the formation of extended structures: (1) as a agent to deprotonate O-donor ligands;(2) as a structure directing agent;(3) as a ligand to coordinate to the metal ion. In order to understand the influence of organic bases on the structures of the coordination polymer, our investigation focus on the synthesis system of phen, hmt, 4,4’-bpy with 1,4-chdc and w-BDC. In this thesis, by using phen, hmt, 4,4’-bpy as organic bases, we have successfully prepared four new ID and 2D coordination polymers of 1,4-chdc and three new ID and 2D coordination polymers of m-BDC.In addition, we obtained five novel coordination polymers under hydrothermaland solvent diffused method by choosing pyridine-2,5-dicarboxylic acid(H2PDC) and pyridine-1,3,5 -tricarboxylic acid(HsPTC) with transition and rare metal ionso A 1D chain polymer was synthesized by H2PDC and Co2+ under mild condition. Three novel coordination polymers, which have OD, 2D layer and 3D framework, were synthesized by H2PDC and Zn2+, Ni2+, La3+. We also employed H3PTC with transition metal ion Zn2+ and synthesized a 2D layer coordination polymer.

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CLC: > Mathematical sciences and chemical > Chemistry > Polymer chemistry ( polymer ) > Polymer physics and physical chemistry of polymers > The chemical nature of polymers
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