Synthesis And Properties Of Transition Metal Coordination Polymers Based On V-type Biimidazole Ligands

Design and synthesis of coordination polymer materials with novel structures and excellent properties have been a hot spot in the research of chemistry and materials science.Rational design and synthesis of coordination polymers with unique structures and specific performances,and intensive study on structure–property relationships are the important research contents of coordination polymer materials.In this thesis,by using 1,3-bis(1-imidazolyl)benzene as the primary ligand,eighteen novel transition metal coordination polymers have been prepared under solvothermal conditions and structurally characterized by single crystal X-ray diffraction,IR,elemental analyses and powder X-ray diffraction.The coordination frameworks of these complexes were investigated in detail,and the relationships of ancillary ligands and synthetic conditions toward the frameworks were summarized.In addition,the thermostability,magnetic and fluorescent properties of some complexes have also been investigated.The main contents of this thesis are summarized as follows:In chapter 1,a brief summary of the research background and the progress of coordination polymers based on bis-imidzole ligands are concisely provided.The research significance and main results of this thesis are also presented.In chapter 2,by using two different Y-shaped polycarboxylates as ancillary ligands and distinct transition metal ions,five metal-organic framewroks have been successfully synthesized and structurally characterized.Structural analysis shows that complexes 1-3 present two-dimensional(3,8)-connected layer structures,and complexes 4 and 5 exhibit three-dimensional “pillar-layer” structures with(3,8)-connected tfz-d net.In addition,the ancillary ligands with the same shape exert little influence on the connected modes of topological structures while the flexibility and coordination site affect the dimensionality of the frameworks.Furthermore,the magnetic properties of some complexes have been investigated in detail and complexes 4 and 5 show spin-canting antiferromagnetic ordering behavior.In chapter 3,by using three different aromatic dicarboxylates as ancillary ligands and distinct transition metal ions,ten transition metal coordination polymers have been synthesized and structurally characterized.All of them present two-dimensional layer structures,except that complex 9 exhibits three-dimensional 4-fold topological structure.The size and flexibility of aromatic dicarboxylate exert little influence on the final frameworks.Furthermore,the magnetic and fluorescent properties of some complexes have been studied in detail.In chapter 4,with the ancillary ligand of 4,4'-oxydibenzoic acid,three Zn(II)complexes have been synthesized by varying synthetic conditions(temperature and solvents),and structurally characterized.Complex 16 exhibits three-dimensional 2-fold topological structure,while complexes 17 and 18 present two-dimensional layer structures.The investigation suggests that the temperature has an impact on the conformation of ligands and further affect the coordination framework of target complexes,while the dimensionality and porosity are affected by the use of different solvents.Moreover,the luminescent properties of 17 and 18 have been investigated and the results reveal high sensing sensitivity towards nitroaromatics.In chapter 5,the conclusion of main contents and improvements is drawn.