Photoluminescence of Lanthanide–Titanium–Oxo Clusters <b>Eu<sub>9</sub>Ti<sub>2</sub></b> and <b>Tb<sub>9</sub>Ti<sub>2</sub></b> Based on a β-Diketone Ligand
Weidong Liu, Guanjun Li, Han Xu, Ming‐Hao Du, La‐Sheng Long, Lan‐Sun Zheng, Xiang‐Jian Kong
Abstract
A series of acetylacetone-protected lanthanide–titanium–oxo clusters (LTOCs), formulated as [La6Ti(μ3-OH)8(acac)12(CH3O)2(CH3OH)6] (La6Ti; Hacac = acetylacetone) and [Ln9Ti2(μ4-O)(μ3-OH)14(acac)17(CH3O)2(CH3OH)3] [Ln = Eu (Eu9Ti2) and Tb (Tb9Ti2)], were synthesized through the reactions of LnCl3·6H2O (Ln = La, Eu, and Tb), Hacac, Ti(OiPr)4, and triethylamine in methanol. Crystal structural analysis shows that La6Ti exhibits an hourglass-like structure consisting of two La3Ti cubane subunits by sharing one Ti4+ ion, while Eu9Ti2 can be viewed as a combination of four Eu3Ti cubane subunits by sharing three corners and one side. The photoluminescence (PL) measurements show that Tb9Ti2 exhibits excellent PL properties with a high quantum yield (QY) of 34.8%, while Eu9Ti2 only has a QY of 1.4% because of the different photosensitizations of ligands to Eu3+ and Tb3+ ions in the photophysical process.