| In recent years,the design and synthesis of lanthanide complexes have received extensive attention,not only because of their structural diversity,but also because of their potential applications in adsorption,catalysis,magnetism,and photochemistry.We synthesized two selenite ligands,2-thiophene seleninic acid and 3,4,5-trifluorobenzeneseleninic acid,and selected two carboxylic acid ligands,benzothiophene-2-carboxylic acid and 3-chloro-2,4,5-trifluorobenzoic acid ligand,reacted with N-auxiliary ligand to obtain 27 kinds of binuclear lanthanide metal complexes.The synthesized complexes were characterized by X-ray single crystal diffraction,infrared spectroscopy and XRD powder diffraction,and the magnetic and fluorescent properties of some of the complexes were explored.The main work of this paper is summarized as follows:1.Synthesis of 2-thiophene seleninic acid ligand,six dinuclear monomolecular complexes were synthesized by reacting N-auxiliary ligand（phen）and lanthanide metal salts with stirring at room temperature,[Eu2（L）4（phen）2（NO3）2]（1）和[Ln2L6（phen）2]（Ln=Eu（2）,Tb（3）,Dy（4）,Er（5）,Ho（6））.The single-crystal structures show that complexes1-6 are binuclear monomolecular structures,each asymmetric unit containing a unique Ln IIIion.The adjacent lanthanide metal ions are bridged together by deprotonated2-thiophene seleninic ligands,forming one-dimensional chain,two-dimensional layered and three-dimensional supramolecular structures through intermolecular hydrogen bonding.Through XRD and TG analysis,the results show that the complexes 1-6 have better purity and higher thermal stability.The solid-state fluorescence properties of complexes 1-4 were tested,and the corresponding emission spectra and fluorescence lifetimes were obtained.The data of complexes 1 and 2 prove that the emission characteristic peaks of the lanthanide metal complexes are not affected by the complex structure,but mainly by the central ion.The magnetic study of complex 4 shows the weak ferromagnetic interaction and slow magnetic relaxation behavior of Dy IIIion.The corresponding energy barriers and pre-exponential factors are obtained by fitting the Debye equation.2.Synthesis of 3,4,5-trifluorobenzeneseleninic acid ligand,four dinuclear monomolecular complexes were synthesized by reacting phen and lanthanide metal salts with stirring at room temperature,[Eu（L）3（phen）]（Ln=Eu（7）,Tb（8）,Sm（9））和[Nd（L）3（H2O）2]（10）.Single crystal analysis shows that complexes 7-10 are isostructural,belonging to the Triclinic crystal system,and the space group is P-1.The deprotonated3,4,5-trifluorobenzeneseleninic acid ligand adopts only oneμ-1k（O）;2k（O’）bridging mode for coordination,and the adjacent molecules of complex 7 pass through C-H???O hydrogen bonds form two-dimensional layered supramolecular structure,while complex 10 forms three-dimensional supramolecular structure through hydrogen bonding.The solid-state fluorescence test of complexes 7 and 8 was carried out at room temperature,indicating the characteristic emission of EuIII(5D0→7F0-4)and TbIII(5D4→7F6-3),and the corresponding CIE coordinates（0.6595,0.3400）,（0.3527,0.5786）,and fluorescence lifetimes of 1.24 ms,0.91 ms.The magnetic properties of complex 8 show that there is antiferromagnetic interaction of LnIIIions.3.Based on benzothiophene-2-carboxylic acid ligands,eight dinuclear lanthanide metal complexes were synthesized by reacting with phen and lanthanide metal salts at room temperature,[Ln2（L）6（phen）2]（Ln=Eu（11）,Tb（12）,Dy（13）,Gd（14）,Ho（15）,Er（16）,Nd（17）,Sm（18））.Single crystal analysis indicated that complexes 11-18 were isostructural and crystallized in the C2/c space group.In complexes 11-16,adjacent molecules are connected by C-H???S hydrogen bonds to form an infinite two-dimensional layered supramolecular structure.In complexes 17-18,adjacent molecules are connected by C-H???O hydrogen bonds to form a one-dimensional chain structure,and on this basis,two-dimensional supramolecular structure is formed via C-H???S hydrogen bonds.The solid-state photoluminescence properties of complexes 11-12 were tested at room temperature,showing characteristic fluorescence emission of Eu IIIand Tb IIIions in the visible region.The magnetic properties of complexes 13,15 and 16 were tested in the temperature range of 1.8-300 K,and the antiferromagnetic behavior of complex 13,15 and16 was indicated.4.Based on3-chloro-2,4,5-trifluorobenzoic acid ligand,four dinuclear monomolecular complexes were synthesized by reacting N-auxiliary ligands（phen,2,2’-bipyridine）and lanthanide metal salts with stirring at room temperature,[Tb2（L）6（bipy）2（H2O）2]（19）,[Ln2（L）6（bipy）2（CH3O）2]（Ln=Dy（20）,Ho（21））,[Ln2（L）6（phen）2（H2O）2]（Ln=Eu（22）,Gd（23）,Tb（24）,Dy（25）,Ho（26）,Sm（27））.In complexes 19-21,adjacent molecules are connected into one-dimensional chain structure through C-H???O and O-H???O hydrogen bonds,and then further through O-H???O hydrogen bonds to form a supramolecular structure.Complexes 22-23 are eight-coordination biaugmented trigonal prism,and adjacent molecules form one-dimensional chain structure through O-H???O hydrogen bonds,and then form two-dimensional layered structure through C-H???F hydrogen bonds.Complexes 24-26 are eight-coordination square antiprism,which form 2D layered structure through C-H???F,C-H???F hydrogen bonding,and then 3D superstructure through CH???O hydrogen bonding.Complex 27 exhibits nine-coordination tricapped trigonal prism,and the adjacent molecules are connected by O-H???O hydrogen bonds to form one-dimensional chain structure.The magnetic and photoluminescence properties of some of the obtained complexes were tested to explore whether different ligands have effects on the photoluminescence and magnetic properties. |
PDF Full Text Request