Study On The Luminescence Properties Of Anthracenyl Bis-?-diketone Rare Earth Complexes

Luminescent lanthanide complexes based on ?-diketones have been widely used in fields such as sensors,fluorescence immunoassay,telecommunication and optoelectronic devices due to their high luminescence quantum yields(QYs).In lanthanide complexes,the large radii of Ln3+ions generally lead to the coordination of solvents and/or water,which was the major factor to reduce the QYs due to the quenching effects from the high energy oscillator.The realization of high QYs required the reduction of the non-radiation rate constant of the complexes and the group that can provide good sensitization of the luminescence of lanthanide ions.Therefore,two series of bis-?-diketone lanthanide complexes were designed and synthesized to achieve high QYs luminescent materials.1.The bis-?-diketone ligand 1,8-bis(4,4,4-trifluoro-1,3-dioxobutyl)anthracene(BTDA)with anthracene as the spacer group was designed and synthesized.Two ?diketone units were introduced into the 1,8-position of anthracene to realize the control of the structure of the bis-?-diketone ligand.The ligand reacted with lanthanide chloride salts at a 3:2 molar ratio to form a three-layer binuclear lanthanide complexes[Ln2(BTDA)3](Eu,La.Yb,Nd and Gd).The ultraviolet absorption of ligands in the visible region effectively sensitized the near-infrared luminescence of Ln3+ ions(Yb3+,Nd3+),resulted in the red shift of the excitation wavelength.The photophysical experiments showed that[Yb2(BTDA)3]exhibited a high luminescence quantum yield of 3.3%.2.We designed three bis-?-diketones based on an anthracene skeleton,which was made by extending polyfluoroalkyl chains on above ligand BTDA.Three ?-diketone ligands(L1,L2 and L3)were obtained through the anthracene core further reacting with tetracyanoethylene(TCNE)by Diels-Alder reaction,in which the triplet energies of the ligands were regulated.Complexes(HNEt3)[Ln(L)2](Eu,Yb and Gd)were synthesized by the self-assembly of ligands with Eu3+ions in a 2:1 stoichiometric ratio.X-ray crystal diffraction analyses confirmed that the structure of the complexes was mononuclear.In addition,the introduction of TCNE enhanced the triplet(T1)energy level of the ligand and sensitizesd the luminescence of Ln3+ ions effectively.The photophysical experiments showed that(HNEt3)[Eu(L1)2 exhibited a hight luminescence quantum yield of 66.9%.