The Syntheses Of Functional Coordination Polymers And The Influence Of Magnetic Field On Structure

Great efforts have been expended on crystal engineering of molecular based materials,especially coordination polymers,because of their fascinating structural diversity and potential applications in catalysis,luminescense,magnetism and porosity.Self-assembly method is the main synthetic strategy of molecule-based magnetic materials.The self-assembly reaction mainly depends on inner driving forces,which is difficult to control.However,as kind of exterior driving forces, magnetic field has been proved that it can be used as driving force in self-assembly reactions.Some products can be orientated and assembled to form ordered structure induced by external magnetic field.Also,the magnetic field can change the final products in some chemical reactions.Based on the above facts,it is believed that the supramolecular self-assembly involved paramagnetic metal ions reaction toward molecule-based magnet can be influenced by external magnetic field.It is also presumed that applied magnetic field can control the final products or enhance the magnetism of magnetic products.In addition,molecule-based materials with diversity of structural features can be modified and redesigned in molecular structure, which will be helpful to obtain multifunctional molecular materials.The main parts of the dissertation are summarized below:1.The magnetic field effect on the crystallization of molecule-based magnet is observed.It is clearly shown that the molecular magnet with an improved antiferrimagnetic coupling interaction and a smaller spin canting angle can be obtained under a 0.20 T applied magnetic field,which cause the change in ordering temperature,remnant moment and coercive field.The results indicate that magnetic field can influence the orientation of magnetic ions and accelerate the more ordered state of spins.2.The azido ion as a bridge has been an intriguing synthetic approach to molecular- based magnetic materials,due to their remarkable diversities in structural and magnetic behaviors.One polymeric Co~Ⅲ-azido coordination polymer with the tetradentate Schiff base salophen as co-ligand has been synthesized and characterized by single crystal X-ray diffraction.Two azide ligand acts with the end-on bridging coordination mode between Co(Ⅲ) and Na(Ⅰ) ions and one as a terminal ligand.The Compound has a supramolecular structure with hydrogen bond andπ-πinteraction.3.A 3D framework structure based on tetrazole and transition metals has been synthesized under hydrothermal conditions,which has the interpenetrating diamond-like supramolecular topology and is further characterized by FI-IR, elemental analysis and thermogravimetric analysis.