| Lanthanide metals have been widely used in metallurgy,catalysis,electronic industry,agriculture,medicine and other fields.As an important part of lanthanide metal researches,the study of lanthanide complexes has become an interdisciplinary subject and plays an important role in telecommunications,photocatalysis,life sciences,organic light-emitting diodes(OLED)and other fields.Lanthanide ions have the characteristics of large radius and high coordination number,the organic ligands containing N?O atoms can coordinate with them in various coordination modes to form stable lanthanide metal complexes.Aromatic carboxylic acidligands have strong coordination ability,large conjugation planarity and high absorption coefficient,which can form stable compounds with exce llent luminescent and magnetic properties through the coordination of oxygen in carboxyl with lanthanide metals.Therefore,we selected and synthesized a series of selenoacetic acid ligands to further explore whether there is a great breakthrough in fluorescence and magnetism by introducing selenium element on the basis of carboxylic acids.The main work of this paper as follows:1.Using 4-fluorophenylselenoacetic acid as the main ligand,1,10-phenanthroline as the auxiliary ligand,six lanthanide coordinatio n complexes[Ln2L6(phen)2](phen=1,10-phenanthroline,L=4-fluorophenylselenoacetate,Ln=Eu(1),Tb(2),Dy(3),Gd(4),Ho(5),Er(6))have been synthesized by reacting lanthanide(?)ions.The Single-crystal X-ray diffraction reveal that complexes 1-6 are isostructural and every Ln(?)adopts a nine-coordinated capped square antiprism geometry.The dinuclear molecules are further through the C-H···O hydrogen bonding interactions to form 1D chain-like and 2D supramolecular structure.Thermogravimetric analysis and powder X-ray diffraction tests show that complexes 1-6 have high purity and good thermal stability.At 298K,the photoluminescence properties and fluorescence lifetimes of complexes 1 and 2 were studied,temperature-dependent photoluminescence studies show the emission intensities and lifetimes for both complexes decrease upon increasing temperature,which indicates complexes 1 and 2 have the potential for sensing temperature.In addition,the magnetic studies reveal that complex 3 exhibits weak antiferromagnetic interactions.2.Using 2-thienylselenoacetic acid as the main ligand,1,10-phenanthroline as the auxiliary ligand,six lanthanide coordination complexes[Ln2L6(phen)2](phen=1,10-phenanthroline,L=2-thienylselenoacetate,Ln=Eu(7),Tb(8),Dy(9),Ho(10),Er(11),Sm(12),)have been synthesized by reacting lanthanide(?)ions.The Single-crystal X-ray diffraction reveal that complexes 7-12 are isostructural and every Ln(?)adopts a nine-coordinated muffin geometry.The dinuclear molecules are further through the C-H···O hydrogen bonding interactions to form 1D chain-like and 2D supramolecular structure.At 298K,the photoluminescence properties and fluorescence lifetimes of complexes 7-9 were studied the static magnetic properties reveal that complex 9 exhibits weak antiferromagnetic interaction and magnetic anisotropy,the dynamic magnetic properties reveal that complex 9 is a single molecular magnet with single magnetic relaxation behavior.3.Using 3,4,5-trifluorophenylselenoacetic acid as the main ligand,2,2'-bipyridine and1,10-phenanthroline as the auxiliary ligands,eight lanthanide coordination complexes[Ln2(L)6(bipy)2](bipy=2,2'-bipyridine,L=3,4,5-trifluorophenylselenoacetate,Ln=Eu(13),Gd(15),Tb(17),Er(19))?[Ln2(L)6(phen)2](L=3,4,5-trifluorophenylselenoacetate,phen=1,10-phenanthroline,Ln=Eu(14),Gd(16),Tb(18),Er(20))have been synthesized by reacting lanthanide(?)ions.The Single-crystal X-ray diffraction reveal that complexes13-20 are isostructural and every Ln(?)adopts a nine-coordinated tricapped trigonal prism geometry.The dinuclear molecules are further through the C-H···O hydrogen bonding interactions to form 1D chain-like and 2D supramolecular structure.The photoluminescence spectra of complexes 17 and 18 show that the energy transfer from the ligand excited state to the f excited state of Tb(?)is effective,and the characteristic emission peaks at the same position also confirm that the emission characteristic peaks of lanthanide complexes are mainly affected by the lanthanide ions.Magnetic studies of complexes 17-20 show that there are weak antiferromagnetic effect and obvious magnetic anisotropy between adjacent Ln? ions. |
PDF Full Text Request