Influence of the Structure of 3-Arylacetylacetonate Ligands on the Luminescence Properties of Eu3+ and Tb3+ Complexes

It was shown that in the series of complexes Tp 2 LnL (Ln = Eu, Tb; Tp – = tris(pyrazolyl)borate anion; L – = 3-arylacetylacetonate) the energy of the triplet state of L – decreases with elongation of the conjugation chain of the aromatic substituent, resulting in change of the nature of emission from metal-centered to ligand-centered. It was found, that the introduction of two antenna ligands of different nature leads to increase of the luminescence quantum yield (to 74%) in the case of the Tb 3+ compounds, probably, due to optimization of energy transfer. In the Eu 3+ compounds it leads to emission quenching, likely, as a result of increased efficiency of energy transfer and non-radiative deactivation of the excited states.