Self-assembly of luminescent 42-metal lanthanide nanowheels with sensing properties towards metal ions and nitro explosives

Abstract

Two 42-metal lanthanide wheel-like nanoclusters 1 and 2 were successfully constructed from a tridentate vanillin ligand. The external and internal diameters of the wheels in the clusters are about 3.6 nm and 1.5 nm, respectively. The vanillin ligand exhibits a μ₂(η¹:η²:η¹) coordination mode in the structures of the clusters. In the solid state, 1 and 2 have open 3D channel structures. Upon excitation in the ligand absorption bands, 1 and 2 exhibit typical NIR luminescence of Yb³⁺ and visible emission of Sm³⁺, respectively. Interestingly, 1 shows lanthanide luminescent sensing towards metal ions and nitro explosives, especially to Cu²⁺, Cd²⁺ and 2-NP at the ppm level.