Triazole-based lanthanide(III) adducts: Photo- and thermochromic luminescence
А. Н. Гусев, Mikhail A. Kiskin, Irina А. Lutsenko, Rоman D. Svetogorov, Sergey L. Veber, Olga Minakova, Vladislav M. Korshunov, Ilya V. Taydakov, Wolfgang Linert
Abstract
New series of Ln (III) adducts with triazole-based ligands has been synthesized and characterized as potential fluorescent emitters. The general formulas are Ln (C2H6O2) (H2O)2(NO3)3∙2bpt∙2H2O where Ln – Sm (1), Eu (2), Gd (3), Tb (4) and Dy (5); bpt - 3,5-bis(pyridine-4-yl)-1,2,4-triazole. The crystal structures of 2 and 4 were determined by single-crystal X-ray analysis. Luminescence studies have been carried out for the complexes in the solid-state phase. All luminescence spectra showed characteristic emission bands of lanthanide ions and broad band of ligand-centred emission that indicates about incomplete suppression of the ligand-centred fluorescence is observed. As a result, it leads to an inefficient ligand-to-metal energy transfer. Complexes of Tb(III) and Eu(III) ions demonstrate thermosensing properties based on dual emission as result of energy transfer between 3,5-bis(pyridine-4-yl)-1,2,4-triazole molecules and Ln (III) ions.