Color-tunable and white-light emission of one-dimensional l-di-2-thenoyltartaric acid mixed-lanthanide coordination polymers

Abstract

A series of L-di-2-thenoyltartaric acid lanthanide coordination polymers, namely, {[La₂L₃(CH₃OH)₆(H₂O)]·CH₃OH·H₂O}_n (1), {[Ln₂L₃(CH₃OH)_x(H₂O)_6−x]·aCH₃OH·bH₂O}_n, [Ln = Eu (2), x = 2, a = 0.5, b = 0.25; Ln = Gd (3), x = 3, a = 1, b = 0; Ln = Tb (4), x = 2, a = 1, b = 0], {[(Eu_0.037Tb_0.963)₂L₃(CH₃OH)₂(H₂O)₄]·CH₃OH·2.75H₂O}_n (5), {[(Eu_0.051Tb_0.406La_0.543)₂L₃(CH₃OH)₂(H₂O)₄]·0.5CH₃OH·2H₂O}_n (6), and {[(Eu_0.068Tb_0.363Gd_0.569)₂L₃(CH₃OH)₃(H₂O)₃]·CH₃OH·H₂O}_n (7), have been synthesized using facile reactions of H₂L (H₂L = L-di-2-thenoyltartaric acid) with LnCl₃·6H₂O under ambient temperature. X-ray crystallographic analysis reveals that complexes 1–4 are isostructural, featuring one-dimensional (1D) ladder-like chain structures, in which the Ln³⁺ ions are bridged by the carboxylate groups of the ligands. The luminescent spectra in the solid state at room temperature reveal that complexes 2 and 4 exhibit the characteristic red and green luminescence of Eu³⁺ and Tb³⁺ ions, respectively, whereas complexes 1 and 3 display the blue emission of the ligand with a broad band centered at 422 nm. Notably, the mixed-lanthanide coordination polymers 5–7 exhibit color-tunable luminescence from yellow and white to blue upon variation of the excitation wavelength. It realizes color-tunable and white-light emission in 1D carboxylic acid mixed-lanthanide coordination polymers.