Photoluminescence Studies Of Heteroatom-modified Bis-?-diketone Rare Earth Complexes

Recently,rare earth luminescent complex materials have been used in various fields due to their outstanding optical properties.However,due to rare earth ions have variable coordination numbers and lack clear coordination geometry,it has become a challenge to construct lanthanide luminescent materials with clear coordination-oriented ligands and great luminescence quantum yields.Two bis-?-diketone ligands were designed and synthesized in there,and the corresponding complexes were obtained by self-assembly with lanthanide ions.The photoluminescence properties are investigated,and the specific content is as follows:(1)We designed and synthesized the bis-?-diketone ligand 4,4'-bis(4,4,4-trifluoro-1,3-butanedione)diphenyl ether(OBTA)with diphenyl ether as spacer.Six binuclear three-strand lanthanide helicates[Ln2(OBTA)3(H2O)4][Ln=Eu(1),Gd(4)],[Ln2(OBTA)3(Bpy)2][Ln=Eu(2),Gd(5)],[Ln2(OBTA)3(Phen)2][Ln=Eu(3),Gd(6)]were synthesized by controlling the molar ratio of ligand to lanthanide ions(L:Ln3+=3:2).X-ray single crystal diffraction analysis showed that complexes 1-3 adopted triple-stranded dinuclear helicate structures,in which the water,2,2'-bipyridine and phenanthroline participates in the coordination of complexes 1-3,respectively.The photophysical properties of complexes 1-3 showed that the lifetime of complexes 1-3 was 375 ?s,440 ?s and 474?s,respectively.The emission quantum yields of complexes 1-3 with the value of(?overall=33%,39%,47%),respectively.(2)We designed and synthesized the bis-?-diketone ligand 3,3'-bis(4,4,4-trifluoro-1,3-butanedione)phenyl bipyridine(BTPP)with diphenylbipyridine as spacer.Three mononuclear lanthanide complexes(HNEt3)[Ln(BTPP)2][Ln=La(7),Eu(8),Gd(9)]were synthesized by controlling the molar ratio of ligand to lanthanide ions(L:Ln3+=2:1).A series of spectral characterization and quantum chemical semi-empirical calculations confirmed that the mononuclear lanthanide complexes with excellent luminescence properties have been successfully synthesized.Based on ther high-efficiency sensitization ability of bis-?-diketone ligand BTPP,the photophysical investigate showed that the lifetime of the complex(HNEt3)[Eu(BTPP)2](8)was 963.39 ?s,the emission quantum yield of(HNEt3)[Eu(BTPP)2]reached 59%.