Two Luminescent High-Nuclearity Lanthanide Clusters Ln48 (Ln = Eu and Tb) with a Nanopillar Structure

Two nanosize lanthanide clusters Na-3[EU48O6(OH)(84)(tCa)(34)(gly)(12)(H2O)(22)]center dot 2Htca center dot 6Cl center dot 6H(2)O center dot NO3(Eu-48) and Na[Tb48O6(OH)(84)(fca)(26)(dmp)(14)(H2O)(24)]center dot 4Hfca center dot NO3 center dot 8Cl (Tb-48) have been isolated in the presence of the monodentate carboxylic acid and tridentate chelate ligands under solvothermal condition. Single-crystal X-ray diffraction analyses indicate that Eu-48 and Tb-48 feature a nanopillar structure constructed by [Ln(3)(mu(3)-OH)(4)] and [Ln(5)(mu(4)-O)(mu(3)-OH)(8)] building blocks. In the cavity of the nanopillar, two kinds of anion templates, i.e., NO3- and Cl-, exist, which connect with the nanopillar by hydrogen bond interactions. As the hitherto highest-nuclearity Eu and Tb clusters, the solid-state photoluminescence properties of Eu-48 (lambda(Ex) = 365 nm) and Tb-48 (lambda(Ex) = 370 nm) display dual emission from the characteristic emissions of Eu3+ and Tb3+ ions and weak ligand emissions. Nevertheless, the Eu3+-centered emission was shown under 395 nm excitation with no discernible ligand emission. Moreover, the luminescence properties of Eu-48 and Tb-48 display a response to temperature. With the temperature lowering, the emission peak intensities gradually increase, and good linker relations exist in the range of 118-298 K. This work provides a reference for choosing suitable ligands to synthesize the high-nuclearity luminescent lanthanide nanoclusters.