Crystal structure and luminescence spectra of Eu(DBM)3 4,4’-BIPY complex

The title complex,C55H41O6N2Eu,Mr=979.91,crystallizes in the monoclinic space group C2/cwith a=2.0413（4）,b=2.5556（5）,c=0.8926（3）nm,β=104.64（2）°,μ=14.44cm-1,T=295K and the finalR=0.043.The structure was solved by the heavy-atom method and refined by the full-matrix least-squarestechnique for 64 non-hydrogen atoms anisotropicaUy for 2180 reflections with I≥3σ（I）.The title complexforms one-dimensional chains through C-C bonds between pyridine rings of 4,4’-bipyridine.The centralEu（Ⅲ）ion is coordinated to six oxygen atoms and two nitrogen atoms and its polyhedron is a distorted squareantiprism.The high resolution laser excited excitation and luminescence spectra show that the complex pos-sesses two Eu（Ⅲ）sites with the energy difference 39 cm-1of 5D0 levels in excited state.The radiationless energytransfer to a great extent between the two Eu（Ⅲ）sites and the dominant luminescence of Eu（Ⅲ）site withlower energy as the complex was excited have been supported by the selectively excited luminescence spectra,time-resolved luminescence spectra and selectively excited luminescence decay curves.