Study of lanthanide liquid-crystalline complexes by Photoacoustic and luminescence spectroscopy

Lanthanide complexes Ln(bta)3L2 (Ln3+: Eu3+, Tb3+ and Ho3+; bta: benzoyltrifluoroacetonate; L: N-octadecyl-2-hydroxy-4-tetradecyloxybenzal- dimine) are synthesized. Their photoacoustic (PA) spectra are reported and interpreted. In the region of ligand absorption, PA intensity increases for Eu(bta)3L2, Tb(bta)3L2 and Ho(bta)3L2, respectively. It is found that the PA intensity of the ligand bears a relation to the intramolecular energy transfer process. By comparison with luminescence spectra, the energy transfer process and phase transition of lanthanide complexes are studied from two aspects: radiative and nonradiative processes