Photophysical Properties of Eu3+ β-Diketonates with Extended π-Conjugation in the Aromatic Moiety
Vladislav M. Korshunov, Alisia V. Tsorieva, Victoria E. Gontcharenko, Sergey R. Zanizdra, Mikhail T. Metlin, Trofim Polikovskiy, Ilya V. Taydakov
Abstract
The influence of the degree of π-conjugation in biaroylmethane ligands upon Eu3+ luminescence efficiency in corresponding neutral tris-complexes was investigated in depth. The data obtained by both steady-state and time-resolved luminescence measurements gave an inside into electronic energy transfer mechanisms in the abovementioned complexes. It was shown that extension of the π-system in the naphthalene moiety in comparison to the phenyl one lead to a substantial decrease of both the S1 and T1 energy of the corresponding symmetrical β-diketones, which, in turn, led to a decrease of the total quantum yield of respective Eu3+ complexes. The obtained results are of interest for the rational design of highly luminescent complexes with NIR-emitting lanthanides, as the resonant levels energies are low and can hardly be sensitized by common ligands.