Synthesis,Structures and Water-soluble Luminescence Properties of Europium(Ⅲ)and Terbium(Ⅲ)Complexes Containing 2,6-Bis(imidazol-2-yl)pyridine
Rare earth luminescent materials have the advantages of sharp fluorescence emission peaks,long fluorescence lifetime and high chromatographic purity,making them widely used in luminescence sensing,biological probes and anti-counterfeiting.Two novel water-soluble mononuclear lanthanide i-onic complexes,(EuL3)Cl3 and(TbL3)Cl3,are synthesized from the complexation of Eu3+and Tb3+with 2,6-bis(imidazol-2-yl)pyridine(PyBim,L).The solid-state complexes(EuL3)Cl3 and(TbL3)Cl3 are iso-structural and crystallize in orthorhombic Pcca group.(EuL3)Cl3 unit cell param-eters are a=1.9111(11)nm,b=1.1406(6)nm,c=1.9470(10)nm,β=90°.(TbL3)Cl3 unit cell parameters are a=1.9123(3)nm,b=1.1381(2)nm,c=1.9412(4)nm,β=90°.The cen-tral lanthanide ions are nine-coordinated by nitrogen atoms from three pybim ligands,approaching the local symmetry of tricapped trigonal prism(D3h).In addition,the UV absorption intensity and fluores-cence emission intensity of the two complexes were measured by UV and fluorescence spectroscopy,both of which increased with the concentration of the complexes,and showed a linear relationship.The ultraviolet absorption intensity of complexes(EuL3)Cl3 and(TbL3)Cl3 conforms to Lambert-beer law,indicating that they have good solubility.The two complexes have high fluorescence emission,and the quantum yields of(EuL3)Cl3 are 17.57%±0.01%and that of the(TbL3)Cl3 are 16.02%±0.01%,respectively,indicating that pyBim ligand can serve as an effective antenna to ab-sorb and transfer light energy,sensitizing the coordinated lanthanide ions.
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