Synthesis And Properties Of Coordination Polymers Based On Flexible Nitrogenous Carboxylic Acid Ligands

In this thesis,a flexible nitrogenous carboxylic acid ligand,5-（4-pyridyl）methoxyisophthalic acid（H₂L）,containing both pyridine and carboxylic acid and five nitrogenous heterocyclic ligands were chosen to combine five metals（Cd,Pb,Zn,Ni,and Co）to afford eight different structures of coordination polymers using a solvothermal method.The structures and properties of the coordination polymers were investigated by Single crystal X-ray diffraction,X-ray powder diffraction,FT-IR,UV-Vis,thermogravimetric analysis,fluorescence identification,and electrochemistry.1.The main ligand（H₂L）was employed with the nitrogen-containing heterocyclic ligand 1,4-bis[（1H-imidazol-1-yl）methyl]benzene（Bimb）and the metal salt Cd（NO₃）₂·4H₂O under the solvothermal condition to form the coordination polymer[Cd（L）（Bimb）_0.5]_n（1）.The H₂L and the metal salt Pb（NO₃）₂ given the coordination polymer[Pb₁（L）Pb₂（L）]_n·H₂O（2）.The compound 1 shows a three-dimensional network structure,while the 2 only shows a one-dimensional chain-like structure.The fluorescence recognition test results of 1 and 2 are different,the 1 demonstrates better selective recognition of tryptophan（Trp）,while the 2 showed better selective recognition of 2,4,6-trinitrophenol（TNP）.A preliminary study of the fluorescence detection mechanism was carried out by investigating the effects of solvent,optimum water content,sensitivity,response time,and interference immunity during fluorescence recognition.In addition,the detection of actual samples using a spiked recovery method was also conducted.2.The main ligand（H₂L）,the nitrogen-containing heterocyclic ligands（1,4-bis[（1H-imidazol-1-yl）methyl]benzene（Bimb）and 4,4’-di（1H-imidazol-1-yl）-1,1’-biphenyl（dibi））and the Zn（NO₃）₂·6H₂O were used to obtain coordination polymer[Zn₂（L）₂（Bimb）]_n（3）and[Zn1（L）Zn₂（L）（dibi）（H₂O）]_n（4）.The compound 3 depicted a three-dimensional network structure while the compound 4 exhibited a two-dimensional structure.The subsequent experimental study proved that the 3 can selectively recognize Al³⁺and Mn O₄^-and the 4 is a good selective recognition sensor for oxyfluoroxacin（OFX）.After a careful study of the effects of solvent,optimum water content,stability,response time,and anti-interference on fluorescence recognition,a preliminary investigation of the fluorescence recognition mechanism was carried out.3.The H₂L,the nitrogen-containing heterocyclic ligands（1,4-di（1H-imidazol-1-yl）benzene（mida）,di（4-pyridyl）ethylene（diet）,1,3-di（pyridin-4-yl）propane（dpp））and the metal salts（Ni（NO₃）₂·6H₂O,Co（NO₃）₂·6H₂O）were applied to gain coordination polymer[Ni（L）（mida）_0.5H₂O]_n（5）,[Co（L）（mida）_0.5H₂O]_n（6）,[Co₁（L）Co₂（L）（diet）（H₂O）]_n（7）and[Co（L）（dpp）（H₂O）]_n（8）.All of the coordination polymers 5-8 have shown two-dimensional structure.The electrochemistry study of coordination polymers 5 and 6 has shown that the peak currents were significantly enhanced when the bare electrodes were modified by coordination polymers 5（Ni-MOF）and 6（Co-MOF）,the scan rates have a good linear relationship with the peak current values,and the charge transfer resistance was reduced for both Ni-MOF/GCE and Co-MOF/GCE.These results indicate that coordination polymers 5 and 6 are good candidates for electrode materials.