Luminescence behaviour in acetonitrile and in the solid state of a series of lanthanide complexes with a single helical ligand

摘要: Luminescence mechanisms of EuIII, TbIII, GdIII and NdIII complexes with a hexadentate ligand (abbreviated to EuL, TbL, GdL, NdL, respectively), which have two bipyridine moieties bridged by an ethylenediamine unit, been examined. Our molecular design is that each complex forms single helical polar structure based on the chelate ring retain solubility in solutions. EuL NdL show comparably bright emission from ff transitions both acetonitrile solution solid state. To understand mechanism detail, energy level triplet (T) state L has estimated phosphorescence measurements because shows no emission. The donor T acceptor EuIII or can overlap, indicating excited photon localized used for efficient emission, while not ππ* For luminescence quantum yield significantly dependent temperature state: over 90% at 77 K, observed room temperature, TbL This observation suggests emissive f-level TbIII are thermal equilibrium. described lanthanide stable their even solutions characteristic behaviour relaxation process ion. Furthermore HoIII (HoL) prepared its analyzed. HoL twisted arrangement moiety surrounding due small ionic radius HoIII.