One 12-metal Cd(II)-Yb(III) nanoring, [Cd8Yb4L8(OAc)(8)]center dot 4OH (1), with a size of 1.2 x 2.8 x 2.8 nm was obtained from a designed flexible salen-type ligand that has eight coordination sites (O and N atoms). The near-IR emission of Yb(III) at 983 nm was detected upon the excitation of ligand-central absorption at 386 nm. This Cd(II)-Yb(III) nanoring exhibits high sensitivity to nitrofuran antibiotics (NFAs) even in the presence of other antibiotics. The quenching constants and limits of detection of NFAs are 2.5 x 10(4)-4.5 x 10(4) M-1 and 1.5-2.8 mu M, respectively.