Construction of a High-Nuclearity Elliptical Yb(III) Nanoring: NIR Luminescent Response to Metal Ions and Nitro Explosives.

One 14-metal Yb(III) nanoring [Yb14(HL)2L20(DMF)8(H2O)8] (1) with a size of about 1.1 × 2.5 × 2.7 nm was synthesized from a tridentate ligand. Under the excitation of ligand absorption bands, 1 exhibits the NIR luminescence of Yb(III) and displays high luminescence sensitivity and selectivity to Co(II), Cu(II), and 2,4,6-trinitrophenol (PA) at the parts per million level. The KSV values of 1 to Co(II), Cu(II), and PA are 6.0 × 104 M-1, 3.8 × 104 M-1, and 6.9 × 104 M-1, respectively. 1 exhibits high luminescent sensitivity to PA even in the presence of other explosives.