Europium Coordination Compound with Highly Improved Luminescent Quantum Yield

The luminescent properties of two Eu3＋ compounds based on quinoline-2-car- boxylic acid （Hqc）, [Na2Eu2（qc）6（CH3COO）2（H2O）4].2DMF （1） and [Eu2（qc）6（H2O）6].3H2O （2）, as well as their syntheses and structures are reported. Both compounds are formed by slow evaporation at room temperature and exhibit zero dimensional dinuclear structures. It is worth mentioning that a 4.5-fold enhancement in luminescent quantum yield is achieved by reducing the nonradiative deactivation, through which the quantum yield increases remarkably to 67.62% for 1 compared with 12.18% for 2.

Structure regulation for ultra-high luminescence quantum yield lanthanide complex and simultaneous detection of cancer marker and ferrous ion

The exploitation of a highly selective and sensitive probe to detect both cancer marker and metal ion is of great importance.In this work,the "one stone two bird" agent of 1,10-phenanthroline(phen) is designed to disrupt the polymeric lanthanide MOFs(LnMOFs,[Ln(CHO_(2))_(3)]n,Ln=Tb,la;Eu,1 b,CHO_(2)=formic acid) {[Ln(CHO_(2))_(4)·(C_(2) H_(8) N)]n,Ln=Y,2 a;Gd,2 b;Dy,2 c,C_(2)H_(8) N=dimethylamine}) into a soluble mononuclear species [Ln(phen)_(2)(NO_(3))_(3),Ln=Tb,3 a;Eu,3 b] as well as to provide an antenna for efficient photons absorption,resulting in an ultra-high luminescence quantum yield(QY,90%) europium complex.The luminescence QY is among the highest record of monomeric(zero-dimensional) lanthanide complexes.Furthermore,mononuclear Tb3+complex(3 a) functions as a multiplex sensor towards both Fe^(2+)and cancer marker of 5-hydroxyindole-3-acetic acid(5-HIAA).Importantly,the limit of detection(LOD)for sensing 5-HIAA is an ultra-sensitive value of 1 × 10 s mol/L,which is even lower than that necessary for the early diagnosis of carcinoid tumors.More interestingly,sensing results in simulated urine reveals that 3 a has potential application for early diagnosis in the clinic.

Mechanisms and absolute quantum yield of upconversion luminescence of fluoride phosphors

Mechanisms of upconversion luminescence（UCL） of SrF2：Er phosphors corresponding to the 4G11∕2→4I15∕2,2H9∕2→4I15∕2,4F5∕2→4I15∕2,4F7∕2→4I15∕2,2H11∕2→4I15∕2,4S3∕2→4I15∕2,4F9∕2→4I15∕2, and 4I9∕2→4I15∕2 transitions upon excitation of the 4I11∕2 level of Er3＋ions were investigated. Energy transfer upconversion processes are responsible for the populating of the 2H9∕2,2H11∕2,4S3∕2, and 4F9∕2 levels. Cooperative process is the dominant mechanism of luminescence from 4S3∕2 and 4F9∕2 levels for SrF2：Er with high concentrations of Er3＋ions. The UCL from 4G11∕2 and 4F5∕2 is explained by excited-state absorption. Cross-relaxation processes take part in the population of 4F9∕2 and 4I9∕2 levels. For quantifying material performance, the Er3＋-concentration dependence of UCL and the absolute quantum yields of SrF2：Er were studied. The most intensive visible luminescence was obtained for SrF2：Er（14.2%） with 0.28% maximum quantum yield.

Synthesis of Highly Luminescent LnMOFs through Structural Regulation

Two series of three dimensional(3D)lanthanide metal-organic frameworks(LnMOFs)of[Ln(tftpa)1.5(phen)(H_(2)O)]_(n)(Ln=Sm 1a,Eu 1b,Tb 1c,Dy 1d,H2tftpa=tetrafluoroterephthalic acid,phen=1,10-phenanthrolin)and[Ln(tftpa)1.5(bpy)(H_(2)O)]_(n)(Ln=Sm 2a,Eu 2b,Tb 2c,Dy 2d,bpy=2,2'-bipyridine)are obtained by structural regulation.Results reveal that the 3D LnMOFs show high water-and thermal-stability.Interestingly,through selecting the perfluorinated ligand,and using bpy as an auxiliary ligand to hold back the solvents near to the lanthanide ions,2b,and 2c show high luminescence quantum yield(QY)of 74.50%and 60.03%,respectively.In order to further improve the luminescence QY,the auxiliary ligand of phen with larger conjugation and more rigid structure is synthesized to replace bpy,and fortunately,higher luminescence QY of 80.73%(1b)and 75.17%(1c)are realized.