| Metal-Organic Frameworks are drawing more and more attention from the chemists all around the world by its great porosity and controllable size. It has a reticular structure formed by metal ions as nodes and by organic compounds as ligand. It shows great potential and advantage in areas like fluorescence, magnetics, catalysis, gas adsorption and hydrogen storage, etc.In this paper,2,2’-bipyridine-3,3’-dicarboxylic acid (H2bpdc) has been chosen as the organic ligand, transitional metal cobalt and rare earth metal Neodymium, Samarium, Europium, Gadolinium, Terbium have been chosen as the central metal ions. A new series of metal-organic frameworks have been synthesized under hydrothermo conditions which formulas are {[Ln2Co(bpdc)3(OH)2(H2O)2]·(H2O)2}n,Ln=Nd, Sm, Eu, Gd, Tb. This paper systematically researched the synthesis, structures and relative properties of these coordinates. The main tasks and achievements are as follow:1. Reaction temperature, reactant mole ratio, system pH value, type and amount of the solvent, reaction time and cooling rates are under fully consideration by single variable method to analyze the impact of the reaction, through which the reaction process is optimized.2. Through Infrared Spectroscopy analysis, the coordination of metal ion and ligand is verified, and the coordination mode of the ligand is forecasted.3. The crystal structures are confirmed by Single Crystal X-ray Diffraction analysis. It shows that the crystals belong to monoclinic crystal system, P21/n space group. The ion Co(Ⅱ) has a coordination number of 6 and the ion Ln(Ⅲ) has a coordination number of 9, in which the Ln(Ⅲ) coordinates with the O atom from bpdc and H2O and the irregular polyhedrons are formed.4. The structures and purity of the samples are verified by XRD analysis.5. Thermogravimetric analysis showed that these MOFs share the similar thermo-stability, which can be exist under 300℃. Meanwhile, the TG curves show the decomposition process of water and organic ligand.6. Solid fluorescence spectrum analysis shows the fluorescence of the MOFs.{[Eu2Co(bpdc)3(OH)2(H2O)2]·(H2O)2}n can deliver red light under an exciting light with a wavelength of 390 nm and can deliver green light under an exiting light with a wavelength of 385 nm. Water has played an important role in the coordinates’ fluorescence. Meanwhile, the coordinate of {[Tb2Co(bpdc)3(OH)2(H2O)2]·(H2O)2}n can particularly response to the anion of F-.7. Diffuse reflection spectrum are tested by the Ultraviolet visible spectrophotometer. The optical band gap Eg are gained by F-E curves, so that the conductivity of the MOFs are judged: {[Ln2Co(bpdc)3(OH)2(H2O)2](H2O)2}n, in which Ln=Nd, Sm, Eu, Gd are insulated materials and {[Tb2Co(bpdc)3(OH)2(H2O)2]·(H2O)2}n is a kind of semi-conductor.This paper mainly focuses on the synthesis, structures and relative properties of a new series of 3d-4f metal-organic frameworks. The impact factors under hydrothermal condition, the structures, thermo-stability, fluorescence and conductivity are analyzed. It’s really an honor if it will make a difference in relative researches. |
PDF Full Text Request