Construction of NIR luminescent polynuclear lanthanide-based nanoclusters with sensing properties towards metal ions

Abstract

Two types of 4- and 9-metal lanthanide-based nanoclusters [Ln₂Zn₂(L¹)₂(OAc)₆] (Ln = Yb (1) and Er (2)) and [Yb₉L²(L³)₂(OAc)₁₅(OH)₈(H₂O)₂(DMF)] (3) were constructed using two Schiff base ligands that have long backbones with two and three phenyl groups. The molecular sizes of 1–2 and 3 are about 7 × 10 × 23 Å and 11 × 17 × 22 Å, respectively. These clusters exhibit typical NIR luminescence of lanthanide ions. Interestingly, 3 exhibits luminescent sensing of metal ions and exhibits high sensitivities towards Cd²⁺ and Co²⁺ ions at the ppm level.