Intramolecular Energy Transfer in Mesogenic Europium (III) Adduct

摘要

The absorption and emission spectra of a liquid-crystalline melt prepared on the basis of a synthesized mesogenic europium (III) adduct are studied in the temperature range from 77 to 348 K. The main channels and rate constants of intramolecular energy transfer from ligands to Eu (III) ions are determined from the absorption and luminescence spectra and luminescence kinetics of the sample under study. It is shown that the liquid-crystalline melt of the europium (III) adduct has a high photostability and an intense luminescence in the temperature range from 77 to 300 K, which allows one to consider it as a promising material for optoelectronic devices. Above room temperature, the relaxation time of the ~(5)D_(0) level of Eu (III) ions sharply shortens. An analysis of the kinetics of the luminescence corresponding to the ~(5)D_(0) -> ~(7)F_(2) transition shows that the relaxation of the ~(5)D_(0) level in the temperature range from 300 to 348 K occurs through a charge-transfer state.