Syntheses, Structures And Properties Of Some Coordination Polymers Based On Ligand 1, 3, 5-benzenetricarboxylic Acid And Transition Metal Ions

Porous coordination polymers have attracted considerable attention due to their potential applications in many areas, such as gas storage and catalysis. Many works reveal that the syntheses of porous coordination polymer are subject to many factors, such as the geometry of the ligands, solvents, template agents, counter ions, additional agents and so on. In this thesis, we investigated the reactions of the rigid ligand 1,3,5-benzenetricarboxylic acid (H3BTC) and transition metal ions Ni²⁺, Zn²⁺ and Fe³⁺. With different synthetic conditions controlled, we separated five conpounds and charactered theri structures. Magnetic properties and host-guest properties of partial conpounds have also studied and discussed.Compound [Ni₄(μ³-OH)₂(H₂O)₁₀(BTC)₂]·H₂O (1) is obtained under hydrothermal condition. It consists of double chains built up of tetrameric nickel units and BTC ligands. Hydrogen bond andÏ€-Ï€stacking interactions among these chains result in the three-dimensional structure of the compound. magnetic study reveals there are ferromagnetic interactions among the Ni²⁺ ions of each Ni4 units in the compound.Compound Zn(BTC)·NH₂(CH₃)₂·DMF (2) is obtained from the DMF solvothermal reaction of zinc acetate dihydrate with 1,3,5-benzenetricarboxylic acid. It is a three-dimensional porous metal-organic framework constructed from triangular and distorted octahedral building blocks, the framework of which can be described as a decorated rutile net. Desorption and adsorption experiments reveal that the framework is robust throughout the process of the release and re-adsorption of the DMF molecules, accompanying with severe distortion of the framework.[Fe₂(H₂O)₂(BTC)_4/3]·Cl·4.5(DMF) (3) an [Fe₄Cl(BTC)_8/3]·2Cl·H₂O·2.5(DEF) (4) are obtained by similar synthetic conditions except the solvents. The framework of 3 is a (3,4)-connected net constructed from mixed valent paddlewheel Fe2(II,III) unit and BTC linkers, while the framework of 4 is a (3,8)-connected net built from mixed valent square-planar Fe4(III,III,III,II) units and BTC linkers. Ion exchange experiment reveal that Cl- ions in the channels of 3 can be exchanged by SCN- ions with the framework retained throughout the process. Compound [Fe(II)Cl(HBTC)]·HTEDA (5) was by-product of the reaction for 4. It consists of two-dimensional metal-organic layers and protonated TEDA molecules between the adjacent layers.