Synthesis, Characterization And Properties Of Complex Rare Earth Coordination Polymer Nano-structures

In recent years, micro/nanostructures with complex structure have beenintensively studied, owing to their unique properties and broad application fields.The rare earth coordination polymers coordinated with aromatic carboxylic acidbelong to one kind of important coordination polymer, because of their application inoptical, electrical, magnetic, catalytic and other special areas. There are few studiesand discussion on the application about the complex micro/nano structures. So in thisthesis, we mainly fabricated the rare earth coordination polymers coordinated witharomatic carboxylic acid by solvothermal method and microwave assistant method.We investigated the influences of various factors on the morphology of products. Atthe same time, various measurement technics were used to characterize the products.The synthesis mechanism and properties were also investigated. This work mayprovide method and experimental instruction for the preparation of other coordinationpolymers which are with micro/nanostructure structures.The main contents of this paper are as follows,(1) Preparation of3D cerium-based coordination polymer microstructures andtheir conversion to ceriaA simple and practicable hydrothermal process was engaged for the synthesis ofuniform three-dimensional (3D) flowerlike cerium-based coordination polymer (CP)microstructures employing1,2,4,5-benzenetetracarboxylic acid (BTTA) as the organiclinker and N,N-dimethylformamide (DMF) as the solvent. Ceria with similarflowerlike microstructures was obtained after thermolysis of the cerium-based CPmicrostructures at600°C for4h. The experiments tell us that the morphology of theprecursor can be controlled by these factors, such as reaction temperature, reactiontime and the ratio of reactant dosage. Meanwhile, the BET surface area of suchflower-like structures is much larger than that of commercially available ceria. On thisbasis, we also prepared other RE-BTTA CP and RE2O3flowerlike microstructures byemploying the same method.(2) Coordination polymers with core-shell structure: microwave preparation andcharacterizationA fast and facile synthesis of the two-step microwave process has beendeveloped without template or any surfactant, core-shell coordination polymer withthe europium-based infinite coordination polymer (ICP) as the core and lanthanum-based ICP as the shell has been successfully fabricated. The optimum synthesis conditions of the product were obtained via controlling the reaction time. SEM andTEM images indicate that, the product are uniform spheres with the mean diameter is550nm. The solid phase fluorescence results show that the Eu@La coreshellnanoparticles exhibited better fluorescence property than the precursor.(3) Preparation and characterization of europium-based hollow spheres ofnanoscale with mixed ligandsThe hollow spheres with mixed ligands:diphenyl dimethyl acyl-L-tartaric acidand pyridine,2,5-dicarboxylic acid were fabricated via microwave radiation in theabsence of surfactants. SEM and TEM were also used to detect the morphology of theproducts. The experimental results show that diameters of the products were about200-400nm. At the same time, other characterization methods were also performedto explore the sample. This method offers significant references to the other rare earthcoordination polymers with different morphologies.