Syntheses,Structures And Properties Of Rare Earth Coordination Compounds Based On Poly Carboxylic Acid And Terpyridine Carboxylic Acid Ligands

The design and construction of coordination compounds with novel structures and excellent properties have been the research hot topic to scientists,mainly because of their potential application in the optical,sensor,magnetism,catalytic and gas storage fields.The thesis is aimed at synthesizing rare earth coordination compounds which have good thermostability,luminescence and magnetic properties.There are twenty-two rare earth coordination compounds with different dimensionalities are successfully designed and synthesized by the reactions of 4,4'-sulfonyldibenzoic acid and 4'-(2-carboxyphenyl)-2,2':6',2,"-terpyridine with rare earth salts under hydrothermal conditions.These coordination compounds are characterized by X-ray single crystal diffraction,elemental analyses,IR spectra and X-ray powder diffraction.Their thermostability,luminescence and magnetic properties have been studied.The thesis includes three chapters as follows:Chapter 1:The research actuality of rare earth coordination compounds in luminescence and molecular magnetism were systematically presented.Reviews on research development of the magnetic propertie of 3D Gd? and Dy?-containing which exist cubane-like cluster,polycarboxylic acid and terpyridine carboxylic acid ligands were also briefly summarized.Chapter 2:Seven new coordination compounds have been synthesized successfully under hydrothermal conditions by 4,4'-sulfonyldibenzoic acid,phen and rare earth salts.1-6 show 3D net structures and 7-Na exhibits a 1D chain.Meanwhile,act as a typically organic base,triethylamine was discovered to be more effective for both crystal growth and the pH control than inorganic NaOH.The luminescence properties of 1-Eu,6-Y and Tb-sfdb have been researched,and the results reveal that the H2sfdb is capable of sensitizing the luminescence of Eu? and Tb? effectively,1-Eu and Tb-sfdb present red and green light.6-Y presents the phen ligand-centered emission and exhibits blue light.Based on that,by carefully choosing the beginning rare earth salts and optimizing the doping molar ratio of RE?,a set of Eur?-doped Tb? and Eu?,Tb?-doped Y? were successfully synthesized,at the same time,white light emission was obtained by changing the excitation wavelength.The magnetic studies of 1-5 and Tb-sfdb indicate that 2-Gd displays magnetocaloric effect and the maximum value is-?Sm=11.37 J kg-1 K-1,and 3-Dy shows slow magnetization relaxation behavior and the ferromagnetic coupling existed in cubane-like cluster[Dy4(?3-OH)4(phen)2]8+.Chapter 3:The ligand 4'-(2-carboxyphenyl)-2,2':6',2"-terpyridine(HL)has been designed and synthesized.With the introduction of aliphatic/aromatic carboxylic acid as auxiliary ligands,fifteen new lanthanide coordination compounds have been synthesized successfully under the hydrothermal conditions by HL and lanthanide salts.8-11 show OD structures,12-15 exhibit 1D chains and 16-22 present 3D net works.Meanwhile,reaction temperature and auxiliary ligands can regulate and control the structure to some extent and influence the coordination mode of HL ligand.The luminescence properties of 8-11 have been researched,and the results indicate that the HL is capable of sensitizing the luminescence of Eu? and Tb?effectively,8-Eu and 10-Eu,11-Tb present red and green light.9-Sm presents the ligand-centered emission.The magnetic studies of 12-Dy,13-Dy and 19-Dy reveal that 12-Dy exhibits slow magnetization relaxation behavior and the ferromagnetic coupling existed in[Dy2(COO)2(?2-OH)]+.