Structures And Properties Of Complexes Based On Azolate Derivatives And Benzoic Acid Derivatives

The rare earth complexes based on azolate-derived ligands and benzoic acid-derived ligands have a variety of structures and special magnetic and optical properties.These kinds of complexes have a potential application prospect in molecular switching materials,new data storage materials,fluorescent materials and display materials.The study of structure and properties of these kind of complexes has become a hot spot in the field of magnetic and fluorescent research.In this thesis,three kinds of main ligands,including 2,6-dihydroxybenzoic acid(H3DHB),azotriazol-2,6-dihydroxy benzoic acid(H4ATB)and azotetrazol-2,6-dihydroxy benzoic acid(H4AFB)were used to syntheses the target complexes.H4ATB and H4AFB are synthesized from polyazoles and 2,6-dihydroxybenzoic acid.The magnetic and fluorescent properties of these complexes were also discussed and analyzed.The specific contents are as following:1.Three mononuclear rare earth complexes of[Ln(H2DHB)3(H2O)4]·2H2O(Ln=Dy(1),Tb(2),Eu(3))and three binuclear rare earth complexes of[Ln2(H2DHB)2(H2O)4(OAc)4](Ln=Dy(4),Tb(5),Eu(6))were constructed based on 2,6-dihydroxybenzoic acid(H3DHB).Fluorescence tests at room temperature show that the corresponding characteristic fluorescent peaks of Dy(?)?Tb(?)?Eu(?)ions can be observed in complexes 1-6.Complexes 1-6 can emit white light,green light,red light,white light,green light,red light under UV excitation,respectively.The results of ac magnetic susceptibility test show that complex 1 exhibits temperature and frequency dependence under 1000 Oe applied field,indicating that it has field-induced SMM behavior.The energy barrier value obtained by fitting is 119(9)cm-1.When complex 4 was tested under 1000 Oe field,only frequency dependence of the out-of-phase part signal above 2 K was shown,but no peak was appeared.In addition,the magnetic relaxation processes of complexes 1 and 4 were explained by ab initio calculations.2.Three Dy(?)complexes of[Dy(H3ATB)3]·3H2O(7),[Dy2(H2ATB)2(H2DHB)2(H2O)4]·2CH3CN·5H2O(8,CH3CN=acetonitrile),[Dy2(H2ATB)2(DCB)(DMF)2(H2O)2]·4DMF(9,DMF=N,N-dimethylformamide)were constructed based on 3-azotriazolyl-2,6-dihydroxybenzoic acid(H4ATB)as the main ligand and 2,6-dihydroxybenzoic acid(H3DHB)and terephthalic acid(H2DCB)as the auxiliary ligand.Single crystals were cultured and their structures were tested and analyzed.The results show that complex 7 is a mononuclear structure consisting of three H3ATB ligands and Dy(?)ion.Complex 8 is a binuclear structure of two H2ATB2-ligands and two H2DHB-ligands.Complex 9 is a one-dimensional chain structure obtained by replacing H2DHB-ligand with DCB2-based on the structure of complex 8.Complex 7 was used as a precursor to synthesize complexes 8 and 9,and 8 was further used to synthesize 9.The interesting structural feature lies in the flexible coordination patterns of phenoxo groups from 3-azotriazolyl-2,6-dihydroxybenzoic acid(H4ATB).The results of ac magnetic susceptibility test show that complex 7 exhibits SMM behavior under 600 Oe applied field,and the energy barrier value is 14(2)cm-1.Complexes 8 and 9 exhibit SMM behavior in the field of 0 Oe,and the energy barrier values obtained by fitting are 26(2)and 11(1)cm-1,respectively.In addition,the magnetic relaxation processes of complexes 7-9 were explained by ab initio calculations.3.Two Dy(?)complexes of[Dy4(HAFB)4(H2O)10]·2DMF·8H2O(10,DMF=N,N-dimethylformamide)and[Dy(HAFB)(H2O)2](11)were synthesized based on 4-azotriazolyl-2,6-dihydroxybenzoic acid(H4AFB).Single crystals were cultured and their structure were tested and analyzed.The results showed that complex 10 was a tetranuclear structure consisting of four HAFB3-ligands and ten water molecules.The structure of complex 11 is similar to 10.The carboxyl group of HAFB3-acts as a bridge to form a one-dimensional structure.The results of ac magnetic susceptibility test show that complexes 10 and 11 show the temperature-dependent out-of-phase ?M" peak signal in the 0 Oe field.The maximum temperature of the peak of complex 10 is located at 11 K,but no peak was appeared above 2 K of complex 11.