Monometallic and bimetallic europium(III) and terbium(III) complexes: Synthesis and luminescent properties

Eight new lanthanide complexes of the form Ln(L)3bipy and [Ln(L)3]2bpm were synthesized (where L = 2,2,6,6-tetramethyl-3,5-heptanedione (tmh) and 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione (tdh), bipy = 2,2′-bipyridine, bpm = 2,2′-bipyrimidine and Ln = Tb(III) or Eu(III)). The luminescent spectra are typical of Tb(III) and Eu(III) complexes with intense transitions at 545 nm for Tb(III) and 612 nm for the Eu(III) complexes. Energy gaps between the tmh ∗ orbitals and the 0DJ manifold of Eu(III) are too large to give efficient energy transfer therefore emission spectra for Eu(tmh)3bipy and [Eu(tmh)3]2bpm were not detected. Lifetimes are greatest for the Tb(III) complexes containing tmh terminal ligands while the longest lifetimes for the Eu(III) complexes occur with the tdh terminal ligands.